Experimenting with options for vacuum clamping - Taibao, Taiwan

[liaoh75]

Hi Gerald and all Mechmate builders, I have been lurking around here for a long time watching and learning over the last several months and have finally decided to jump in and begin my build. I am an American Citizen (of Asian descent) working in Taiwan long term. I think I have it easier than a fair number of fellow builders as this country is quite the manufacturing haven. I have access to all kinds of things here. I hope to build the CNC router I've always wanted. I have to say that I wouldn't even attempt this if it wasn't for the helpful people on this forum who contribute selflessly. I'll be building on the conservative side using mostly recommended components. After building some confidence, I'll tap into the vast resources here in terms of electronic components and the ability to Laser cut and machine steel. I hope to have fun, learn a lot, and hopefully contribute in some way to this great Mechmate community.

[Greg J]

Welcome David,

Just be for warned, this is addictive. :)

Oh, to be in Taiwan. I agree. It is a manufacturing haven. I wish to visit Taiwan and South Korea. South Korea's ship building industry is something I must witness.

[Gerald D]

Welcome David,

It is going to be useful to have an agent over there! :)

[hennie]

Welcome David,

Start dreaming your MechMate number!:)

[domino11]

Welcome David!
Hope you enjoy your adventure here. :)

[liaoh75]

Thank you all for the warm welcome. I'm in the process of acquiring steel components consisting of 7" (180mm X75mm @21kg/meter) channel and cross support chanels. I asked them about the 60 degree cuts but they don't have the right equipment to cut at an angle at the lowest price place in town. This would mean I would have to either cut the angles myself or take the 10 meter chanel to another place for cutting. Can anybody attest to the feasablity of trimming the angles (final length on my table size is 3070mm) myself with a good cutting disk on a handheld angle grinder? Any advice or words of wisdom would be appreciated as I've never worked with such a large hunk of steel before.

[Kobus_Joubert]

Hi David, I left my ends at 90 degrees. Firstly I was lazy/afraid to try and cut them myself, secondly IF...I plan to put some sort of indexer on the machine, I then already have a flat surface to fit the indexer onto. Just my 'logic' lazy thought. Good luck.

[Gerald D]

David, I don't know how you plan to to make your rails M1 10 1*0, but consider that lengths of channel makes a good work surface for clamping the rails onto.

The angles (both main beams and cross supports) are optional, purely for aesthetics.

Can anybody attest to the feasablity of trimming the angles (final length on my table size is 3070mm) myself with a good cutting disk on a handheld angle grinder? Any advice or words of wisdom would be appreciated as I've never worked with such a large hunk of steel before.

Totally feasible if you have the patience and are allowed to make whining noise for a while :) Will ask somebody in my workshop to cut a beam like that today and to record the time and disk wear.

[Gerald D]

Trimmed a cross-support channel 76x38x6.7 that was already cut to length, with this disk (http://wueko.wuerth.com/cgi-bin/wu_proddetailpdfframe.pl?873567084358511050174;SHO WDETAIL;;0664131150;0000;;;;;;;;;;;;;;;;;;;;;;;;;; ;12144601645108). Took 43 seconds and 1.5mm off the diameter of the disk. (if that link does not work, it is a Würth, part# 0664131150)

[liaoh75]

Wow, that was quick. I thought there would be at least a 24hr wait before someone would stumble upon my post earlier.

Gerald:
Because of the fact that these guys are the cheapest in town (by a pretty big margin), they have a large quantity of "standard" sizes but not a large variety of dimensions. They also force you to buy the full length of stock which is unfortunately 10 meters. (We are talking about the main chanels here.) My plan was to get two 3.07 meter pieces and that would leave me with one piece which would be almost 4 meters to clamp and cut my rails with. I will buy all my chanels from these guys. I'll have to buy my rails and other parts from somewhere else as they only sell chanel and flat bar but no angles or square or round tube. After re-reading my earlier post, I discovered that it wasn't very clear. Sorry about that. I was contemplating cutting the angles on the main chanels with the angle grinder. The cross supports are small enough (I think) where I can use my 14" chop saw which I purchased for this project .

Kobus:
Can you draw me a simple diagram of the placement of such an indexer? Have you put one on your machine yet and if so could you send me the link to the post with some pictures so I can better understand what this indexer thing is all about as I am very curious. I've read in many places about builders who plan to put one on their machines but haven't seen a picture of one yet.

[Kobus_Joubert]

David, try talking to Uncle Art ...http://turningaround.org/4_axis_mill.htm .
Or search on this forum for ART...you should find some answers.
Still in the future for me.

[Gerald D]

Pictures of Indexers (http://www.mechmate.com/Forum/messages/2/60.html)

Also wanted to cut a scrap of main beam with a small angle grinder as a test, but we don't have any here now. It should take about 5 minutes and one disk. Completely feasible. Part of the trick would be to cut only the web at 60 degrees, and cut the bottom flange at 90 degrees (The other flange remains 90 degrees as per your supplier's cut). Cutting the bottom flange at 90 degrees makes it easier to fit part 1010324

[liaoh75]

Gerald, thank you for the link to "Pictures of Indexers". That was way cool. I think I'll put that on the back burner until I'm ready for that. My immediate challenge will be the kitchen table project and working with steel. I'll have a go with the cutting of the main chanel with the angle grinder. I'm heading into the laser cutting shop tomorrow morning to submit the DXF files for cutting. I have a friend comming back from a trip home (U.S) with the following goodies:

(4) PK296A2A SG7.2 Oriental Motors Steppers (man, are those steppers EXPENSIVE),
(4) Gecko G302V drivers (with a set of extra fuses as recommended on this forum),
"Mechmate Kit" from Superior Bearing including 14 vee wheels and 6 eccentrics,
35VDC 500 VA Power supply from Antek

In mid July, I will have two whole weeks to do nothing but work on this beast. I can't wait. In the mean time, I'll begin the "kitchen table" project and continue to get necessary parts.

[liaoh75]

Hi Everyone, sorry about the long delay before getting back to posting something. I have included some pictures to show my progress. I know I have gone against the grain as far as the control box being mounted on the machine, but I think this is the best configuration for me. I will fit a large shopvac filter to the intake. I will be using 2 - 6 inch 220vac fans for ventilation. One fan will draw air into the control box and the other one on the other side will pull air out.

One strange thing - When I got my 20 tooth pinions, the guy I got them from didn't know much about what he was selling. Anyway, can someone identify this thing? It is 33 mm in diameter. I doesn't appear to be metric or U.S. inch stardard. Can anyone shed some light on this weird pinion?

If anyone see anything wrong with my build, please let me know. It's been a fun ride and I look forward to seeing this thing move. Comments and suggestions are greatly welcomed.

[Alan_c]

David - very nice, I like it, especially the intergrated control panel - keep us informed as to how well it works and if you experience any "problems". Very sturdy looking table.

[Greg J]

David,

Nice work!!!!

It's interesting to see the different configurations.

[Gerald D]

A nice surprise David - very good work!

Before we guess which gear that is, how wide and tall is the rack?

[Gerald D]

That could be a metric module 1.5 with the rack being 17 x 17mm?

[liaoh75]

Thanks Gerald, Alan, and Greg for the feedback and comments.

Gerald, the rack is measured at 16 X 16mm. The place I went to buy it specializes is making custom pullies (maybe custom belt drive?), pinions, gears, racks, and sprockets. They acutually have the equipment to cut a blank from round stock and make whatever gear you need on-site. However, I was surprised when the man told me that the pinion I wanted was a standard, but he didn't know anything else. Believe me, I was scratching my head on the way out with four pinions and eight 1-meter long pieces of rack.

[liaoh75]

Just to give you guys a good laugh, I want to share a funny story. It wasn't funny at the time, but now I chuckle as I think about it. If you look carfully at picture 4, you can see the top of a large fan just above the Y-car. The fan was abandoned in a building where I work. I took it home and fixed it up and noticed that it was driven by a 1/2 horse power motor. When I turned it on, the fan was so strong it pushed itself on the wheels I mounted with wheel locks engaged. Well, that isn't the funny story but just background information so you will understand what happened. Here goes. I had not mounted the stops on the gantry yet when I turned on the super fan and walked away to get a clean rag from another room and heard a thunderous bang. I ran back to see what happened to find the gantry on the floor, two cracked section of cable chain, and a BENT Y-rail. I almost had a heart attack. With the gantry riding on the X-rails so smoothly, the fan had blown the gantry right off the table. I had to re-drill, cut, and grind the y-rails. Obviously, I had not put in the stops on the gantry yet but I couldn't believe the wind from a fan could move the 100 lb + gantry and y-car. Luckily, there wan't any other damage and the motors had not been installed at that time. Gerald, my hat's off to you for designing such a tank. No twist in the gantry or anything else outside of a scratched-up paint job. Sorry, if you don't think the story was funny but I am certainly laughing AFTER re-making the y-rails. That is why the Y-rails are not painted in the pictures.

[Greg J]

David,

That is a good story. :) The best lessons and experiences come from the day to day work.

[Gerald D]

Hi David, that's a good story! :D

Your gear pitch is definitely metric module 1.5. In the spreadsheet (Gear Speed Steps Freq Calculator.xls) you downloaded, change Module Number to 1.5. It should work quite well.

[hennie]

I like that box mounted under the table, nice!

[Robert M]

Nice work David
Guess you must of sleep in the shop to make this happen so quickly :eek:
I can see why your laughing now that it is over, but my hart can only sympathize...:o
Thanks for sharing this
Robert ;)

[javeria]

WoW David, thats a nice build.

[liaoh75]

Thanks for all the compliments guys. I will post more pictures as my build continues. I had two and a half weeks of vacation time where most of the work took place. I think I'll have to slow down a bit now because I gota go back to work now and only have weekend time and occasional early mornings and late evenings. Boy, has it been fun. I think I got the CNC itch some of you guys have been talking about. Definitely addictive!!

Gerald, thank you for the info on my rack and pinion numbers. Have I got the wrong rack and pinions? Should I go back to get "Module 1" instead of using Module 1.5. Will there be any difference in the performance. Will my machine run rougher?

[Greg J]

only have weekend time and occasional early mornings and late evenings. Boy, has it been fun. I think I got the CNC itch some of you guys have been talking about. Definitely addictive!!

David,

It only gets better. :D:D:D

[Gerald D]

David, I think your machine will run pretty well with that module 1.5 rack/pinion. Anything less than 20 teeth starts getting a bit rough.

Most of us are using around 30 teeth, and we then have the option to go to a smaller pinion for a finer/smoother cut (you don't have that option with the 1.5 module).

You are lucky in that you have the OM motors with the 7.2 gearboxes. If you had direct drive motors, that module 1.5 would not have worked.

You do have the benefit of a bigger/thicker/stronger/deeper gear tooth than the rest of us. In fact, I think you have a slightly better technical solution.

[liaoh75]

Gerald, thanks for the input on my rack/pinion. I read up almost every day and I don't know how you run a business and answer everyone's questions so quickly.

[liaoh75]

I've been so busy figuring out the CAM portion of this endeavor, I forgot to update my personal thread. I've been cutting away (mostly testing) using Vectric Vcarve trial and Cut3d trial versions. Gerald, would you please be so kind as to move my personal thread to Machines already cutting. I'll be posting some pics after I decide on which CAM application I will end up with. I'm cutting mostly rubbish at the moment but pretty amazing rubbish:D.

Right now, I'm very busy researching CAM stuff and Eastern Spindles. Man has it been a great ride. What a rush to think the average Joe Blow like me can build and run a CNC router. I used to think stuff like this was reserved for equipment from multi-million dollar companies. Thus far, I have to say the Mechmate has exceeded every expectation. It runs more smoothly than a commercial machine made in Taiwan I checked out on September 16, 2008. I am blown away. For those that are still hanging out wondering if it is really as good as people on this forum say it is, get started; you won't be sorry. The education you get from Gerald, the people on this forum, and the experience of doing it yourself is worth more than words can describe.

[Alan_c]

Hey hey hey! what's the secret, lets see some pics as proof :D I am interested to see the completed machine and how that electrical panel looks now that its working.

[Greg J]

Congrats David.

Pictures Please. :)

It is a beautiful design, don't you think. The college of MechMate. :cool:

[liaoh75]

I'll post some pics over the Weekend. It's still not 100% complete. It is just "usable" at this stage for testing. Push buttons and limit stuff are not hooked up yet. I am going to be mounting the computer and monitor in a console attached to the machine itself. This will come later. This software and spindle stuff has my full undivided attention at the moment.

If you guys really want to see some of the amazing rubbish I've been cutting, I don't mind posting the pics but it's nothing to write home about.

[javeria]

rubbish is what we like - clean machines are regular! :)

[liaoh75]

Ok, here are the pics I promised to post. Any comments or suggestions would be greatly appreciated. I am far from finished so everything is not very organized and the wires are not very tidy at this point but I'm cutting away. I did not post pics of the computer stuff as that will be changing so that will be coming. I've got a custom made box on the way that is being fabricated as I am posting this.

I've got an idea for routing the dust hose and that will be coming also. I think I'll be borrowing an idea from a car wash. I'll explain that later when I post pics after it is finished.

I've been experimenting with all of the vectric demos and you may recognize a few of the items. I am in experimenting stage where I'm trying to determine what can be cut and with what cutting tools. I will also be posting the cutting bits I've been using. I am still playing with Ucancam and Type3 but find both to have a steep learning curve. I don't know if it's just me not being very CAM savy or the applications are not setup for the average Joe. However, I have to say that I'm leaning toward the Vectric products for their ease of use despite the higher price tag.

Has anyone used Type3 and if so how do you like it? The information I have is that it is from France and is highly respected but from my initial testing, I have to say that it is not very well documented and difficult to use thus far. Maybe I'll change my mind later. I'm using a borrowed security dongle for evaluation.

[DMS]

Really nice CB david. Good going.
How long, what tool and feed rate for Alu plate ?

[javeria]

David, I thought you were going to use the chinese spindle, is it still in your plan?

[Gerald D]

That is a neat location for the laser pointer

[liaoh75]

Irfan, I AM going to use a Chinese Spindle. However, I had already bought a 3.25 HP Porter Cable production router motor, had it on hand, and couldn't wait so I designed a simple clamp and had it cut out of 12mm thick steel and mounted it to get some cutting action going. The time frame is about two to three weeks I hope. I got your address and will be going to check out the shipping rate to your location from here.

Sharma, the tool I used was a 6mm endmill for roughing and a 3mm ball nose for final but the 3mm ball nose was too short and I program it to run too fast so I gave up on it but will be repeating the same cut again using a 6mm ball nose for rough cut and 3mm extended ball nose for finishing pass going very very slowly. Part of the reason for giving up was the fact that I could not find a good way to clamp the piece down. No matter what I tried, the Big Blue Beast (as I have constantly see it refered to as) is so powerful that it just dug into the aluminium and moved the whole piece along with my crude clamping setup and messed up my 3mm ball nose in the process. Slow, Slow, Slow, as in 3-5 mm a second will be my next attempt. The rough was set at 10 mm a second with a 6mm endmill and that was even a little on the fast side. The aluminium is so soft and melts at such a low temperature, it gummed up the bit and I had to clean it off several times during the roughing pass. I hope I have answered your question.

[javeria]

Hi david thanks for your help! appreciate it. did you also check on what inverter (vfd) they are using?

certain grades of Alu are machinable at such high router RPM we have to select appropriate grade of Aluminium.

just my 2c.

[liaoh75]

Irfan, the inverter they are using is made by a company called "Sunfar". I will get model numbers and specs later. When I had my lengthy conversation with Mr. Tzao, he indicated that the spindle I will get will be the same as the one that was mounted to his commercial machine but the inverter may not be the exact same one. I'll inquire more about why before I part with my 30,000NT (~$1000 U.S. dollars).

[liaoh75]

Gerald, you really don't miss much. The Laser pointer is just experimental at this time. It is neither wired up or appropriate setting made in Mach3 yet. Still figuring that out. I have Mr. Tzao checking on the availability of bearing kits for the Chinese Spindle. Sorry it's taking so long as the day job is really getting in the way of all this fun.

BTW: The Module 1.5 rack is working out great without a hitch. Do you see anything wrong with the placement of any of my components?

[Gerald D]

David, no rush on finding out about the spindle bearings - we have 7 spindles lying around at the moment. But I think that other people should also be interested in the bearing aspects.

No, I see nothing wrong with your component placements. You have even got a tiny 0,0 written on the right corner ;)

[DMS]

David, thanks for your input. This is the problem with Alu I was thinking of. May be Onsrud Alu bits help https://www.onsrud.com/xdoc/metal
https://www.onsrud.com/xdoc/AluminumRougher

[liaoh75]

Last weekend, my computer wouldn't boot up. I took it in and they said nothing was wrong so I brought it back and the same problem occured. It freezes in the middle of a cut and the screen gets all blocky and patchy colors. The motherboard was an ASUS with integrated graphics. I did some research and read somewhere that integrated M/Bs are not good for running Mach3. So, I bought a new motherboard, memory, and reloaded everything thinking everything was going to be just like before. Was I in for a shock:eek:!!

Everything appeared ok until I started jogging the X and y axis. What's happening is so strange that it's hard to describe. If I hold down the left or right arrow keys to jog the gantry from one end of the table to the other, it seizes up after a few seconds and makes a strange whining noise. Initially I thought it was the pinion getting stuck so I removed the springs and let the motors hang and tried it again. Again I get the same noise. It seams as if the pulse stream is getting interupted but the strange thing is, it's not just one motor. If I hold down the arrow keys, X1 and X2 seizes up at the same time under absolutely no load. Now get this, the problem doesn't show up when I'm cutting something. It only shows when doing jogs on X and Y axis. Z axis seems fine at the moment. If I set the jog speed to 20% of full speed, it doesn't happen:confused:. Is there something going on with the pulse stream?? Does anyone think trying a PCI based parallel port would help?

My motors are tuned according to instructions, I'm fairly sure everything is grounded.

Any assistance on this would be greatly appreciated. I remember reading about a similar situation many months ago on this forum but, I can't find it. Please Help!!

[J.R. Hatcher]

David my guess is it's in the motor tuning setup. It sounds like you are over driving the motors and missing a lot of steps thus the "strange whining noise". We need more info. What type of motors, are they geared, what's the setup in motor tuning, how fast are you jogging when it happens. etc. etc. etc.

[Gerald D]

Have you tried another PC?

[Roadkill_321]

Hi David, I think it was Doug's thread where he had a similar problem.

I also had this problem and it turned out that I was running the motors too fast.

Try this link http://www.mechmate.com/forums/showthread.php?p=8655&postcount=140

[Doug_Ford]

You've got a good memory John.

David,

Same thing happened to me. I tinkered with the settings in Mach3 and if I recall correctly, once I slowed down the acceleration rate, it started acting right. Or maybe it was when I slowed down the jog speed. That was so long ago, I can't remember for sure. But I'd bet a six pack that it's just one of the speed settings in Mach3. Good luck.

[Marc Shlaes]

David,

You are an artist. Your machine is simple, elegant and beautiful. I love your pc box. Where did you get that industrial trackball??? Very nice.

Good job,

Marc

[gmessler]

David,

Your setup looks great. I like the way you have your computer mounted.

Marc,

Here is a site I found for track balls.

http://www.ikey.com/ProductsList/?menu=2&prodListID=6&showAll=1&source=0I2403&jadid=36776108022&jk=mountable%20track%20ball&js=4&jmt=4&jkId=8a8ae4cc1c8c21c4011cbd446f6546ec&jsid=11206&jt=1&

Hope it helps.

Greg

[Gerald D]

That "swinging" computer mount is strong enough to carry the control box as well. Nice job!

[liaoh75]

Thanks to all who have made suggestions and compliments. I started out with the intention of making my build self contained.

Gerald, my intention is to try another PC tomorrow.

JR, Here is the detailed info on my machine:

Motor OM PK296A2A-SG7.2 geared motor
Motor Drives: Gecko G203V X4
B.O.B.: PMDX-122
Power Supply: Antek 35VDC 500VA

Mach Settings:

Metric Mode
Velocity: 17,000 units/min ~ 283mm/sec ~11.15 Inches/sec
Acceleration: 700

When I changed the computer, I didn’t change any settings. I just copied the configuration file over to the new computer. Just a note though, this problem did occur on the old computer as well, but once in a blue moon. The whining noises I mentioned earlier only occur when the motor seizes up.

Another observation: When I had the motors disengaged from the rack as I was doing slow jogging, I noticed that the sound of the motors is not smooth. It almost seems as if the pulse stream is getting interrupted somehow. Also when the motors seize up, they seize up at the same time. It doesn’t seize up one motor at a time.

I read somewhere a while back (not on this forum) that the parallel port that comes with the motherboard is inferior to PCI based add on boards. I remember reading about the fact that dedicated PCI parallel cards pulse smoother and takes some of the processing away from the CPU. Has anyone heard of this?

[Marc Shlaes]

JR has been using one that is integrated for about 7-8 months with no such problems. His motherboard is the Intel "Little Valley" mini ITX.

[Richards]

I'm betting that the problem is being caused by Mach 3 settings. The PMDX-122 break out board should "buffer" any substandard signals being generated by your computer's parallel port.

In your Mach 3 settings, reduce the top speed by 25% and see what happens. If that cures the problem, then play with some numbers between your current settings and the lower settings until you find a number that always works.

You may find that the acceleration needs to be reduced. The ideal acceleration for a stepper motor is not linear. If you plotted an acceleration curve, it would have a steep, almost straight portion, followed by a long curve that allowed the motor to get to its highest speed without missed steps; however, that kind of curve does not work in most CNC environments because you need to move various axes at various speeds. That means that linear acceleration is required. That also means that the acceleration "ramp" needs to be longer than optimum.

There is the possibility that you have electronic noise, but if the problem is repeatable, then electrical noise can usually be ruled out. Noise tends to be random.

[DMS]

Nice setup David,that the parallel port that comes with the motherboard is inferior to PCI based add on boards.
Have to disagree with that, as most of MM are running on onboard parallel card. Besides all printers are running fine on that port.

I took photo of my TFT with stone age voltage and current detectors - Red- current detector, black - voltage detector.
shows presence of voltage and strong current fields.
Do you have screen between monitor and motherboard ? I can't deduce whether this is the reason of your problem.May be other members may through some light on it.

ps - oops, while I was typing and loading image, Richard posted. Anyway this can be taken as information.

[javeria]

Hi Sharma, that might bee the cause - but usually not - manjeet on one of his plasma cutter had a problem where the problem was a parallel port cable with really thin wires inside and that caused a lot of problem for him - it was solved when thicker wired cable was use for the PP.

Sharma, where did you get the voltage and current detectors i need to get one.
I have high power cables running near my house and would want to see how much we are in the problem.

RGDS
Irfan

[DMS]

where did you get the voltage and current detectors

In kabadi bazar:)

[javeria]

David did you solve your problem - if so can you share what had happened.

[liaoh75]

I finally solved the problem. It had something to do with the computer. I changed it out to another motherboard with INTEGRATED video and everything is back to the way it was before I changed out the first time. I wish I had a better technical answer for those that have been tracking this problem.

Interesting observations:

1) The problem still rears it's head once in a blue moon when jogging, but usually for the first few minutes of powering on. It almost seems as if powering on is producing some ultra strong pulse of EMI that has an effect on the control system. Then as I get going, the problem goes away. It's almost like a capacitor that charges and discharges and after the (EMI "charge") fades away, the problem goes away. I will be moving the PMDX and Geckos to the other control box on the left (see pics above) and all high voltage stuff will be in one box and the low voltage stuff will be in the other.

2) I've lowered my settings in mach to 15,000 pulses per min from 17,000 and that has helped and my acceleration setting is now at 550 vs 700.

Any other suggestions would be more than welcomed.

[DMS]

David,

What bit are you using for Alu ?
I 've tried various bits, feed rate, router speed, oil, but still not satisfactory cutting.

Thanks,

[J.R. Hatcher]

I have not tried these parameters. I watched a video and it was cutting perfect so I ask for this information. Here is what I was told. Hope this helps.

Cutter: 1 fulte, Belin 33060
Lubricant: None
RPM: 18,000
Feed Rate: 48 ipm
Cutting Depth: .020 per pass

[Gerald D]

Different types of alu cut completely differently. Some alu's are easdy to cut, others are nearly impossible. I don't have some names/specs over here at this PE airport. (Hennie, I'm watching you!) The lubrication/cooling of the bit is also critical.

[CNCQuest]

Hi David,

Nice MM built.

I have encountered the same kind of seizing and whining noise when doing a continuous jog in my cnc mill. It was solved by reducing the velocity and acceleration in the motor tuning page.

Quote: "I've lowered my settings in mach to 15,000 pulses per min from 17,000 and that has helped and my acceleration setting is now at 550 vs 700."

Is that 15,000 pulses per min the velocity or should that be 15,000 mm per min? What kernel speed are you using? Try lowering your velocity by half and gradually slide it back up until it whines again. Then, back off by about 10 to 25% lower.

Can you give more technical info on the Chinese spindle?

Thanks and 謝謝,
WT

[DMS]

Thanks J.R, and Gerald,

I have tried on 3mm Alu sheet with as low as 50 mm/min and 15000-20000 rpm.
With end mill, drill,vbit, ball now, etching bit, carbide 2 flute etc with gummy results.:(
J.R. I could not find Belin 33060 on google. Only this post of Gerald on shopbot - http://www.talkshopbot.com/forum/messages/29/11801.html?1140534866

Are you talking of these bits? http://www.plasticsmag.com/ta.asp?aid=4152
Belin 33060 search returned nil on this site.
If not then a link may help.

David,

As WT mentioned "Seizure problem", Initially I've tried higher acceleration, and had same problem, with bit research I set to 3000 mm/min for x,y, A and 500 for z, which is comfortable speed for gear 7.2 and 36 teeth pinion. Kernel speed 25000.
I used this sheet http://www.mechmate.com/forums/attachment.php?attachmentid=1148&d=1207239352 for calculations but when I used speed given in this sheet (20,000) I had noise and stall. For this geared steppers this seems to be very high. I checked pdf of motor spec where I found permissible speed 250 rpm for pk296-sg7.2.

What I actually did - I did axis calibration in Mach with help of "set steps per unit. I found 125 against excel sheet of 127.324, I used this formula for calculation -

Speed per mm per minute = drive micro steps X motor steps per rev. X motor max.RPM / steps per mm

= 10 x 200 x 250 / 125 (actual)
= 4000
I set for lower side i.e. 3000

Now in your case, you have 20 teeth pinion so your speed comes to nearly 2200.
May be this is helpful. I have done this 3 months ago and it is working fine till now.
So guys correct me if I am wrong any where. (I am bit forgetful these days :D and my wife has long list of complaints about undone works.)

Thanks,

[Gerald D]

The alu cutting posts have been copied to a new thread, where some previous posts on the topic are being collected:

http://www.mechmate.com/forums/showthread.php?t=1020

[liaoh75]

I've been very busy over the last few months. I run a language school in Taiwan and from October to December is a very busy time. Just a quick update on what's going on. I've taken apart the entire machine after satisfactory testing for a re-paint.

Gerald, I seldom spend much time on the main homepage but had a quick glance to find my build listed with a picture. I am honored you would place my build on your home page. I'll supply a better picture with appropriate Logo as soon as I finish the paint job. Thank you for providing the plans and thank you to all that helped on this fantastic journey. Thanks Team Mechmate!

[Gerald D]

Hi David. Good of you to call back in and let us know what's happening. Thanks.

[domino11]

David,
Did you ever get your labels? You are really close to a serial number. :)

[liaoh75]

Heath, Mechmate Logo has been on my Blue Beast for a good while. It has been very busy cutting away for quite some time now. We are finally moving to a Chinese Spindle after several bearing changes on the Porter Cable Router which held up surprisingly well. Some might find it interesting that the main reason for making the change is easier access to wider collet sizes available for an industry standard collet like the ER20. It is cheaper to buy a 3mm 0-flute solid carbide bit with a 3mm shank than a 3mm bit with a 6mm/.25 inch shank. We are going to keep the Porter Cable as a spare in case something happens to the Chinese Spindle.

I also have a two year old son and my better half that needs some of my time. I think I've been elgible for a serial number before the list broke double digits. However, I think I've just been so busy with the two growing businesses, I haven't made it a priority to get my serial number. After getting the spindle mounted, I will take pictures and post all the modifications with dust foot, replaced spider plate, and completed control console.

Thanks for the bump!

[Charlie]

Also make sure you set your steps per rotation. The 7.2s I believe are 1440 steps per rotation (0.25 step angle) not the 2000 that my Mach3 defaulted to. My motors ran so much better when this was set. If you have done this Great, but I didnt see it mentioned so I thought I better make sure.

[domino11]

David,
Good to hear everything is going well. Look forward to your new posts when you have the time. I have two little ones as well, so I know what you mean on the time issue. :)

[liaoh75]

Hi Charlie, thanks for the numbers, but believe my machine has already been set correctly but I'll double check!

[Gerald D]

Charlie, a typical stepper motor and gecko combination is 2000 steps per rev. Add a 7.2 gearbox to that motor and it becomes 14 400 steps per rev.

If one makes a mistake in this area during the Mach3 setup, it is immediately visible in the scale size of the parts you cut out........add a 7.2 gearbox and watch your parts get 7.2 times smaller! :)

[Charlie]

OMG what?
Well I need to figure this out then. Im looking into it right now but if you could post more info Ill take it. Maybe mine smoothed out because it was closer with ten steps at a time? See I had a rough spot in the rotation. It would come around then and make a little magnetic rumble. Ill try adding another zero. *embarrassed**
This is all still bench top work.
Charlie.

[Gerald D]

See Understanding & Selecting gear pinions - setting the steps per mm[inch] (http://www.mechmate.com/forums/showthread.php?t=239)

[Charlie]

I have been looking at this for hours. I now have it set at 3055.777488 steps per "unit". I had a full step/micro step lesson to learn. I will study the link Gerald thank you. Most likely I still have errors. The rough spot in my motor went away from something else because I reverted back some settings but the rough spot didnt return. Who knows?..I have been having a blast messing with them and making them sing.
Charlie.

Edit: Read the thread you linked and I was glad to know that I managed to get my 3055.777488 number before I read it. I thought you should know Gerald :)

[liaoh75]

It's been a good while since my last posting to my build log. I've been busy working on building a business around the machine and running my Language School. I've got a little more time now so I'm going to start working on catching you guys up that have been following my build.

I'm going to start putting together a vac hold down system with a target budget of $1500 total. Over the last several months I have been experimenting with a number of pumps. I've tried:

1) shop vacs (industrial - probably more robust than the revered Feins albet a bit more on the noisy side, but not too bad) They all seem to fall short in some way or another. Vac wasn't that great (6-8" Hg at best with no leaks) and air volume was marginal. Couldn't really hold parts very well. I setup a test bed for these experiments as I didn't want to commit to setting up vac plenum and sealing everything without deciding if it was finacially feasible to do this.

2) dust collectors 2hp and 12 hp These had tremendous air volume but gave about 2" Hg on the best test run. Cheap but completely out of the question.

3) Regerative Blowers. These actually would work if they were big enough. I tested a 7hp and 15hp unit and like the shop vacs, they didn't pull very much vac but was top dog when it came to air volume. The sales guy told me flat out not to use a regen blower for my application and suggested I look into roots blowers or oil filled vein pumps. He said that many have tried using regen blowers with marginal success.

4) roots blower. Here is where things started to get interesting. I found a vendor about a 1.5 hour drive from my location that sold referbished Japanese (hand-me-downs) I spoke to the owners for quite a while about the pros and cons of all the pumps he had on hand. I asked to test out his units with my experimental setup. He agreed and seemed quite confident that his 5 hp roots blower (2" port) would probably do the job. One week later, I showed up with my test board (4'x4' with routed out plenum and one hole in the middle (single zone). The bleeder was an import (Thailand) 1/4' run of the mill MDF board that was the same size as my experimental plenum. I had one metal ball valve with a vac gauge before the valve so I could see how much vac the pump delivered. I was quite surprised. After sorting out the plumbing, we fired up the 5hp roots blower. It was a noisy thing to be honest as the guy didn't put on the muffler for the test. The gauge jumped to about 17" Hg. I opened the valve to the plenum with bleeder only and the gauge fell to about 1" Hg. I started putting flat objects on the bleeder one at a time and slowly the gauge started to climb again. When the board was almost completely covered with pieces of board, the gauge leveled out at about 9". From reading on the shopbot forums, this seemed to be the magic number: 9". All the flat pieces adhered to the bleeder quite nicely and took a good amount of force to move them; Way more force than a 12mm (1/2") cutter would exert of a piece of board. I was blown away. Price: ~$800 U.S. dollars with a 1 year warranty

I then asked if I could try the next step up from the 5hp roots (2" in and out) to a 10hp version (3" in and out). Thats when I came to the realization that a $1500 competent vac hold down was possible. When he fired up the 10HP monster of a pump, the gauge instantly jumped to 23" Hg, I opened the valve with only the bleeder and still pulled 5" with nothing on the board. I put a 2' X 2' by 1/2" piece of acrylic on the board and couldn't budge it with two other people helping me. The rest of the bleeder was completely open. The vac gauge read 15" Hg. Price: ~$1000 US dollars with 1 year warranty. (This was the pump I ended up buying.)

We then moved to a final test with roots blowers which was a monster 18 hp blower with 4" ins and outs. The vac was about the same but the air volume was frighening. Gauge read 23" with valve closed and 19 with a fully open bleeder. Did the same test with the acrylic and it litterally sucked the acrylic out of my hand onto the bleeder board as it got close. I could litterally hear air being pulled though the 1/4" piece of MDF used as a bleeder. Just for grins and giggles, I put a 3" round puck on the board and even that was difficult to move. But, it also pulled a staggering 45+ amps - 3 phase 220 during the test. Also the price was out of my target budget range: $1800.

5) Becker 7.5 hp vein pump and also a variety of Alcatel pumps yeilded excellent results as well and was much more on the quiet side but they wanted an arm and a leg for them. I was quoted $2800 for the cheapest 7.5 hp (second hand) model and upwards of $5000 for one of similar performance to the 10HP 3" roots blower I ended up with.

That's long enough of an explanation for today as it's getting late so I'll leave you with a few pics.

One last thing: I got a great deal on a 10HP inverter through my Brother-in-law. $150 referbished "Rich" brand. I got this for soft start, RPM control, and power savings. More on this later. At this point the complete system is finished but I have not had time to take pictures. Here are the earlier pics of the blower itself:

[vishnu]

David,

That's a nice Vac pump and worth the price. Can you tell me the source of your purchase, i would love to have this setup. Waiting to see some videos of the pump working.

[Gerald D]

David, that is probably the best written research I have seen on vac holddown pumps!

(PS the correct spelling in this case is "vane" - seeing that you are a language school person :))

[javeria]

Ah very good writeup David, also put on a write up on the economics of running this along with mechmate -

[liaoh75]

Vishnu, the place I purchased the pump was a very traditional machinery dealer. They don't do any business outside of Taiwan. They mostly support the local factories (of which there are many) in the Kaohsiung area which is near the southern tip of Taiwan. I'm sure you could probably source one in your neck of the woods. Taiwan is really strange as a tiny shop the size of a two car garage had this thing in stock. Their warehouse is located about 20 minutes away if I remember correctly. Not the most attractive place but they carried reasonably priced roots blowers and other types of pumps. Another shop located about 150 meters away sold the exact same pump for almost twice the price with no warranty. The primary market for roots blowers is fish farming where they have to aerate the water to keep their fish alive and these pumps run 24-7 for months on end.

Gerald thanks for the correction on the "vane" spelling. I wrote it at about 1:30 in the morning.

Irfan, the economics is quite simple. On the power consumption side of things, it draws about 30 amps from the inverter at full throttle. On the supply side of the inverter, it's only pulling about 21 amps. However, I find that there is no need to run at full power as 10-12" is more than enough to keep my parts from moving for my application. Under most operating circumstances, it's taking in about 15 amps from the inverter and about 7-8 amps from the breaker. How the inverter achieves this is a complete mystery to me but somehow, I can verify that the inverter makes a huge difference in terms of power consumption. Another big advantage is the fact that I am able to control the speed of the motor so I only use what I need.

Also, the vac hold down is a real time saver. Before, I had to make a tool path for screws which I found to be more effective at holding things down than the traditional clamp (No disrespect, Gerald;)). Also, the cut quality increased as there is less vibration as the bit cut through the material. Although I feel that vac hold down is one of best hold down methods around, I still have to agree with Gerald's earlier posts about vac not being the end all solution. It's just one more tool at your disposal when you need to get a job out quickly and don't want to play the 101 screws game. I read about massive pumps being necessary that were 20+ HP drawing a shameful amount of power. After my research, trial, and error, I can honestly say to the Mechmate community that you really don't need that much power on a 4x8 CNC router if you choose the right pump. My roots blower is still noisy (but acceptable IMHO) placed in another room and gets pretty hot, but for the price/performance ratio it's hard to beat.

I basically save about 15-20 minutes per sheet of material (compared to screws) using the vac hold down. Some people might think that's not a whole lot, but multiply that by 15 sheets and you should get the picture. How much is your time worth????? I have to squeeze every minute out of my day to balance two businesses, a very understanding wife (pregnant with our second child), and a two year old that want's daddy to play with him. Worth every penny if you ask me.

I will post more pics of the completed setup in the next week or two. I'm working on a new dust foot right now.

[PEU]

pardon my ignorance (for real no pun intended) how does a blower creates vacuum? a venturi?

[bradm]

Pablo, Roots Blowers (http://en.wikipedia.org/wiki/Roots_type_supercharger) generally have two equal sized ports. Depending on which port you use, you have either a big blower or a big vacuum. You then need to deal with designing the rest of the system. If you use it as a blower, you need a filtered source of lots of air. If you use it as a vacuum, you probably want a muffler system for the exhaust.

[Alan_c]

Thanks for all the info Dave, would you mind showing some pics of the vacuum table and manifold?

[liaoh75]

Alan, I'm planning on doing just that. However, my shop is too messy right now. To be absolutely honest, I think messy is an understatement. I'm going to clean up a bit this week and take pictures after my dust foot is finished. I should be able to get pics posted by Sunday of next week.

[liaoh75]

Good reading to on vac hold down for those interested:

http://geoteched.com/VACUUM%20INTRODUCTION.htm
http://www.techno-isel.com/cnc_routers/technical_section/Vacuum_Hold_Down.htm

Prices like the one's mentioned on either of these links almost made me not even think about venturing into this method of hold down.

[Travish]

Does anyone have a source for these roots blower style vacuums here in the US?

[bradm]

Travis, I suggest you start with an E-Ebay search for "roots blower". That will give you a sense of the price ranges for new/rebuild/used/broken units. Then search for an industrial surplus / rebuilder in your area. These are large pieces of metal, and shipping will be significant. Note that if you don't have 30A of 3-Phase power to spare in your shop space, you probably don't want to be looking at these.

[domino11]

Or the money to run them... :)

[liaoh75]

The money to run them is not that significant if you pair it with an inverter and use only what you need. You will find that if you size your pump correctly with some spare overhead, often times, you'll run your pump at about 40-70% of max capacity and still maintain 11+ inches of Hg.

If anyone is interested, I'd be willing to negotiate a deal with my supplier to ship a quantity of the units here to the states. I'm sure the dealer will give me a good deal on say 10 - 15 units (fixed up, tested, and ready to go) riding piggy back on a container. Just an idea if you guys back home are interested. However, keep in mind that like Brad said, you'll need 3-phase 220 to run them. Also, I'll warn you in advanced, they are not exactly quiet either.

[Gerald D]

David, if you want to regulate the power consumption, you can just open a "leak" to reduce the holding pressure . . . . same effect as a VFD to reduce the speed, but less expensive.

[liaoh75]

Gerald, that's an interesting idea. I'll give that a try and report back as to the differences. At first I got the VFD for soft start as I got the VFD for about the same cost as a dedicated soft start circuit. I've got a release valve for removing my pieces without shutting down the blower so that will be easy to try. Thanks for the tip!

[liaoh75]

Gerald, you are correct. I bypassed the inverter and tested the "spring a leak" suggestion and indeed, the current consumed came down but not as much as using an inverter. With all valves closed, I am pulling about 22" Hg drawing about 29 amps without the inverter. To achieve the same 22" with the inverter, it's pulling about 21 amps.

Using the front four zones (half of my table size), I try to maintain about 12" Hg to make sure nothing will move. Springing a leak without the inverter the pump is pulling about 16amps without the inverter. To achieve the same hold down capacity with the inverter, I only draw about 10 amps. The "pro" to the spring a leak method is that the pump runs cooler with more air flow.

If I measure current after the inverter, I'm reading the same 16 amps but I'm only drawing 10 amps from the breaker???? Can anybody explain how this feat of magic occurs???

Here are some pics I promised.

[danilom]

Great setup David!

But where does that rust on the screws and plate comes from?

[KenC]

David,
I'm not expert but I'll have a go at the phenomena.
As we already knew, an inverter takes in AC power, rectify to DC then choop it up accordingly to make AC of desired frequency & voltage to facilitate speed variation while still maintain the torque characteristic. On the pre-text that there is a fixed relationship between the voltage & the frequency to maintain the torque characteristics, this is why inverters are more efficiency then without. From here, I presume the different current measured is due to the difference in the frequency of the input & output voltace.

[lumberjack_jeff]

Very nicely done.

[KenC]

I was in Taiwan over the weekend & couldn't resist to pay David & his MM a visit.
David flooded me with his warm hospitality & unselfishly sharing his knowledge.
Only had a few hours with him & I was so impressed & intrigued by his work & completely forgot about taking any picture....
I wished I had more time... but I promised I'll be back.... as soon as I can fish a good air passage bargain from AirAsia.
After seeing his rig, I am now totally convinced that a vacuum table speed reduction & vacuum table are not luxurious indulgent...
Now I have to figure out what else can I pawn to get hold of a root blower...

[liaoh75]

Ken, I am always happy to have you over. Next time, I promise I'll have the camera ready for the occasion. I've been so busy with work over the last several months that I hadn't had much time for or have been too busy to keep this magic of sharing knowledge going on this great forum. Right after you left, I completed that sign you saw leaning on the wall. After the 15mm of acrylic was cut, it turned out beautifully. I will take some pictures of my work and post it here. Stay tuned!

[southernduckie]

Hi David,

just caught up on your post the answer to the VFD reducing the current draw is that it fixes the Power Factor of the motor and draws mostly True power from the mains instead of Inductive power that is drawn by coils of wire aka inductors (like the windings of a motor)
A inductor(motor) will draw power during one part of the Alternating voltage waveform and then feed this back to the mains in another part of the waveform without it actually doing any useful work (ie: wasted current draw) Large industrial sites need to manage this load by installing capacitors at the switchboards or paying extra for there power.
Love your MM truly a well thought out layout.

[liaoh75]

Hi Andrew,

Thanks for the post. Inverters are still a mystery for me. Thank you for your compliment on my layout; however after a few years building a business (it wasn't easy in my neck of the woods) I find that there were things that could have been done better. We built this when we had minimal funding and was a part time hobby. Gerald's beast is still serving us well today. I'll do a full write-up of all that has transpired since my last post as soon as I can.

Cheers,
David