Dust foot and custom clamps done #3 - Conway, AR

[revved_up]

Congrats, and thanks for all the good close up pics also makes it alot easier to wrap my mind around this monster

[Doug_Ford]

Heath,

The only reason is cost. Enco advertises 1/4" carbide bits with 1/4" shanks for approximately $12. I didn't find any 1/2" shank 1/4" dia. bits but I didn't look too hard and I have to believe they must cost more. I'm expecting to snap a few in half so the cheaper the better.

[DMS]

Awesome Doug, Inspiring and Very welldone.

[Gerald D]

Doug, another thing about starting with small cheap bits, is that they make less sawdust. The high speed steel bits are a waste of money though - we saw them go blunt in seconds, over a distance of a meter [3 ft] in plywood, at which point they went black, made smoke and the y-car jumped off the rails.

[J.R. Hatcher]

Gerald you are thinking to small Doug's serial # should be
S/N 0000003

I kinda like the look and sound of S/N 0000005. Eat your heart out Doug see how nice it rolls off the tongue, go ahead enjoy your S/N 0000003 when I try to say it, it's a tongue twister, I didn't want the old 3 anyway

On the bit note, they make a double flute 1/4 solid carbide, not carbide tipped. They are brittle but take a small cut therefore easy on the machine.

[cobra427mnsi]

Just a quick thought on the solid carbide bits. If, at all possible, buy them from a machine shop or tool/die supplier rather that a woodwork supplier, they seem to be cheaper (not quality but price). That has been my experience, anyway.

Congrats Doug ! Now the learning begins !!

Paul

[Gerald D]

The serial no.s are no indication of the number of machines already built and running. Our machines don't have serial numbers - they have my blood on them!

Folk with personal threads here, and who have painted, logo'ed and cut; get the serial numbers. Their threads stay permanently on top (sticky threads).

[Greg J]

Doug,

Couldn't find on your thread or motor thread, what motor you went with.

Did you go with the PK296A2A-SG7.2 or the PK296A1A-SG7.2 ?

Interested in your motor performance. I know you just got the beast operating, so not really expecting motor performance results quite yet.

[Doug_Ford]

I went with the PK296A2A-SG7.2

I may have to work this weekend but if I don't, I'll try to at least post how fast she rapids at the different pulse rates.

[Roadkill_321]

You've got a beautiful machine there Doug. The level of craftsmanship around here is hard for me to compete with. How has the experimentation been going? Any more photo samples? Hope you're having a great time with your Mechmate.

John

[Doug_Ford]

Hey John,

Thanks but you can easily beat my level of craftsmanship. It's solid, dependable (I hope), and accurate but making it pretty was tough for me. Hopefully, my next one will be better.

It has been too cold down here for me to spend much time in the garage so I've concentrated on learning MagicTracer (a vectorization software), Mach3, and Sheetcam. Sheetcam is a great program and fairly intuitive but there is still quite a bit to experiment with. I found out yesterday that I have to work this weekend (which is going to be relatively warm) so I won't get to do much. Last night, I reset my step settings in Mach because it was telling me that I was traversing 136 inches in the X-axis and I knew that was incorrect. I checked the settings and sure enough, it was set at the default of 2000 so I used the spreadsheet Gerald gave us to fix it. I know I had set it correctly at some point but I may have forgotten to press the "save these settings" button before I left the screen. I also noticed that when I made the change, the IPM dropped from 1050 to 801. Dang it.

[domino11]

Originally Posted by Doug_Ford

Hey John,
Hopefully, my next one will be better.

Doug,
How many do you want to build?

[Doug_Ford]

Heath,

I want two wood cutting MMs and one plasma cutting MM. Of course, wanting and having are two different things.

[Greg J]

Doug,

Have you had any problems using the Vista OS?

If I leave Mach3 running, not doing anything, the computer crashes. A simple re-boot and everything fine, but it shouldn't happen in the first place.

I'm considering buying XP.

[Doug_Ford]

I haven't had any problems but I haven't logged that many hours in Mach on my machine. When you leave it idling, how long does it take before it crashes? I've probably left mine idling for at least 10 minutes.

[smreish]

Greg,
Please make sure that your settings do the following:
- all power saving features turned off
- all screen savers are off
- all sharing on computer is off
- you have look at and read the vista OS update information on the artsoft website. They do have a troubleshoot q&A
There is an optimizing file to help with bugs.
Good luck,
Sean
BTW....I love XP and Tiger Direct has xpPro for 139 this week.

[Greg J]

Doug,

It was left on for around 30 to 45 min. during the kitchen project.


Sean,

Thanks, I haven't check any of those setting. I'll also checkout Tiger Direct.

[domino11]

Has anyone been using windows 2000 for cnc work? I have heard a lot of people find it more robust than xp for this type of work. Uses less cpu and memory than xp as well. Just a thought.

[Gerald D]

We use win2000 - have no complaints

[Doug_Ford]

I finally got around to doing some rapid traverse tests today. My machine has Vampire Geckos, PK296A2A-SG7.2 motors wired half coil with 35 tooth pinions.

I started with the pulse rate set at 35,000. From a dead stop, she traveled six feet in an average of 5.825 seconds which is 12.36 inches per second. Then I increased the pulse rate to 45,000 and retuned the motors. Under the same conditions, she averaged 4.64 seconds which is 15.51 inches per second.

Something strange happened during the tests though. Sometimes, she would travel 66 inches and then lock up. If she didn't lock up on the first pass, then on the return pass, she would lock up in the first 6-12 inches. I gradually slowed the acceleration rate down and when I reached 25, she quit locking up. Now, I wish I had waited to special order the gantry tubes in a thinner wall size. I used 1/8 inch.

I traversed at least a dozen more times without a lockup. However, I refuse to believe that it was still accelerating after 66 inches and I'm wondering if she was binding up or something. I haven't had a chance to set the Y axis square to the X axis and when I turn her on she clunks so maybe I need to drop the motor and spin the pinion until she starts more smoothly. Maybe the clunk gets her out of square and creates a high torque condition. Maybe the rails are slightly wider at the 66 inch point on my machine and the additional torque required to drive the gantry assembly through that point is enough to stall the motors out. Anybody else have a theory?

[Gerald D]

You make no mention of the Velocity setting in the motor tuning. This is the place where you set the max speed. The computer frequency has to be adequate, but shouldn't be the limitation on the speed.

That start-up clunk is never totally eliminated, but it can be reduced by squaring and engaging the pinion to rack at a different pair of teeth.

[Doug_Ford]

Gerald,

I left the velocity setting on the highest possible which was 1030. I think that's inches per minute. I believe the computer is a 2.8 Ghz Pentium with 1 Gig of RAM. After I reset to the highest pulse rate, I ran the driver test like Art recommends and it appeared to be fairly stable. About as stable as his computer was in the tutorial. If the gantry had stopped at random locations, I would have suspected the pulse rate was too high but it kept stopping at the same two locations. Tomorrow, I think I'll raise the acceleration rate to 50 and try the test from the other end of the table. If it stops at the same location on the gantry, that would seem to indicate a binding/high torque condition at that point. However, if it traverses approximately 66 inches and locks, that would seem to indicate a problem with the computer keeping up. I'll let everyone know what I discover.

[Gerald D]

Apparently, the higher the set frequency of the pulse engine on the PC, the more chance for problems. The recommendation appears to be to set the PC frequency as low as possible. That means you have to calculate the frequency needed to move at your desired top speed. What is your calculated frequency for say 15 inches/sec? (By the way, the speeds you are mentioning already sound quite respectable )

On the acceleration and effect of mass, suggest you do a little test; clamp 20 pounds of iron on top of the gantry and see how much difference that makes. That will give an indication of what subtracting 20 pounds will do.

The pulse engine of Mach is not very smooth. It gets worse with bad PC's, or with multiple axes running at the same time. One day you will be able to plug a "Smoothstepper" between your PC and your BOB, but it is still under Beta test.

[Greg J]

Hey #3,

I've got a stupid question (I'd hate not to ask). On your shielded cable, did you order the total length and cut it into the segments you needed. There's nothing special about cutting shielded cable, is there?

I saw the $25 cut charge and was wondering if you had the vendor cut all your cables. That would be very expensive.

I'll figure my total lengths tonight and order cable tomorrow.

[sailfl]

Greg,

I talked to one vendor and they charge the $25 if they don't have the total size you are looking for and have to cut your needs from a larger spool. You buy total size and cut to your needs.

[domino11]

Greg,
We custom terminate shielded cable all the time at work. We just cut it with wire cutters and then strip back the outer insulation to expose the inner shield. If the shield is braid with no drain wire, we usually solder a drain wire to the braid. If there is an existing drain wire we just trim the braid even with the remaining insulation and connect to the drain wire. Use heat shrink sleeving to cover any soldered wire joints. Thats it. If you have any other questions just ask, I could show some pics.
Greg, why dont you try vendors like www.digikey.com or www.mouser.com. They carry a lot of cable and I dont believe they charge a cut fee. Just order the total you need and then cut to individual sizes.

One other note for people ordering cable, a lot of vendors will ship cable in various lengths unless you specify that you want a continuous length or a Minimum length. An example would be this, I order 500 feet of cable and don't specify continuous length. I might get 2 or 3 or more lengths that total 500 feet, if you specify min length then the pieces shouldn't be any smaller than the minimum length. This would be ok in the manufacturers eyes unless you specify continuous or minimum length. Just a note, because we buy a lot of cable where I work.

[Greg J]

Thanks Nils and Heath,

Nope, that answered the question perfectly.

[Doug_Ford]

Originally Posted by smreish

Doug,
How is that sheetcam coming along? I would be interested to know how well you like the nesting and layout features as well as ease of use.

I still have A GREAT deal of tweaking to do in Mach3 and squaring the machine next week....and longer

I love Sheetcam. Fairly intuitive. It is easy to layout several dissimilar pieces and move them around. I don't think it has an automatic nesting capability but it might and I just missed it.

I finally got the Y square to the X this morning so I plan to do a little cutting this afternoon. I didn't get the X absolutely square but it was close enough that I could live with it. Maybe later I'll go back and mess with it. I ended up .007" per 12 inches out of square.

Yesterday, I ordered the Clearvue Dust Collection system like Greg J. When I sat down and looked at how much I would save by building it myself, I decided it just wasn't worth it. I'm ready to cut and don't want to mess around with any other projects right now. The dust collection foot is going to take long enough. I'm still hoping to fabricate a foot using 6" duct work.

Congrats, Sean, on getting your machine cutting.

[Greg J]

Originally Posted by Doug_Ford

When I sat down and looked at how much I would save by building it myself, I decided it just wasn't worth it. I'm ready to cut and don't want to mess around with any other projects right now. The dust collection foot is going to take long enough. I'm still hoping to fabricate a foot using 6" duct work.

Doug,
That was one of my main reasons for buying the completed unit also.

When you say that you are fabricating a 6" duct work, is that all the way to the DC foot? I think you can come off the foot with 4" duct for a foot or two to clear the Y car, and transition to 6". Just curious, don't mean to tell you how to design your machine.

[Doug_Ford]

Greg J,

Yep. A sheetmetal 6" round to 10"X4" rectangular transition fits into the car. Figuring out the best way to attach it is the project currently on my plate.