Making Skins #74 - Brisbane Australia

[domino11]

Congrats Ross! Nicely done!!

[rcboats1]

Very nice, congrats. That spindle is so quiet you can hear the V wheels rolling. (I really like that since I have the same spindle for my build ).

[riesvantwisk]

Congrats from me aswell!

[jhiggins7]

Ross,

Congratulations on completing your MechMate and earning Serial #74.

I really like your video showing the quick, smooth movements of your MechMate.

Here is the Updated Builder's Log.

Please let me know (PM or Reply to this Thread) the dimensions of your MechMate for the Builder's Log. Also, please review your Log entry and let me know any changes you want to make.

[Surfcnc]

Thanks Mike for my number.
NUMBER 74, I like the sound of it when you say it out loud, haha

And ... Thank you to Sean, Stefan, Heath and Kelly.

Today was spent preparing for my next adventure, practising CAD to toolpaths.
Also did some more homework on my partly implemented RS485 VFD plugin for Mach3.

I worked away so studiously even the dog had decided I was boring her by the end of the day.
Might be time for a wave when the next swell arrives midweek.
Now if I can just get the MM to shape my next board for me!

Regards
Ross

[jhiggins7]

Thanks for the PM, Ross.

The Updated Log is here.

[Red_boards]

Well done Ross. This has been an impressive build to follow (everything done to a "T").
Regards
Red

[Surfcnc]

Hi All

Fixed the Huanyang VFD to use MattyZees pluggin.
As we all had pretty much established, EMI was the issue.
Today I quickly further experimented with placement of the clip on torriod magnets and my hunch to follow how data cables are sometimes treated for EMI fixed the issue.
Note I have attached a torriod to both ends of the RS485 communication cable.

IMG_1115.jpeg

The spindle control on Mach3 responded perfectly up to 22,00 RPM after tweaking a max spindle speed default in Mach3 that was set to 8,000 RPM.

Note at this stage only the PC with the Mach3 controller and the VFD spindle combo are running.
A further significant note is that earthing is not yet in place on my machine.
It is feasible that anything may happen as additional systems are put in place but it was great to see the spindle and pluggin work together so faultlessly.

That would be a very big thanks to MattyZee.

Regards
Ross

[AuS MaDDoG]

Well Done!!

Awesome news Ross!! sounds like there is hope for Skippy and I then
I might need to see if I can get some of those clip on torroids you are using.

Once again good work!! and a Merry Christmas to you and your family Ross.

Cheers
Tony.

[Red_boards]

Gee Ross,
You really did hit your straps in the home straight.
Regards
Red

[Surfcnc]

Very close to the design measurements, I am pleased that I have to use a vernier to find any variation from design.
IMG_1119.jpeg

Set the machine running with a V bit (totally the wrong thing to use but all I had) and produced this acrylic panel.
IMG_1120.jpeg

VFD update

Mixed results with the machine itself included into the test environment.
The spindle rarely stops after a run at high RPM but at lower RPM like 8,00 RPM it regularly stops after running the G code.
I have not given up just yet but could not resist running the machine and seeing what it can do.

Regards
Ross

[Surfcnc]

Acrylic machining videos.

Wide View
http://www.youtube.com/watch?v=NakBfccU2dc

Close View
http://www.youtube.com/watch?v=l7jMVdovc8s

Regards
Ross

[isladelobos]

Nice new machine !!!! and good video quality

[Surfcnc]

Today some learner grade HSS 3mm end mills arrived in the post, so it was time to try to cut completely though some acrylic sheet into a spoil board.

IMG_1122.jpeg

It did not come off the machine in this state, the burs were removed and then the sheet was flame polished.
Totally impressed with Mechmate No 74 - What a creative tool.

The learning continues - broke one end mill by not raising the Z before jogging the x axis.
Also had a really good run with my VFD by starting it at 8 -10,000 RPM and then adjusting the RPM on the Mach3 screen.
The spindle stopped by itself after doing this rather lengthy cutout at 20,000RPM.

Regards
Ross

[AuS MaDDoG]

Ross,

Very nice!! and welcome to the broken bit club your Z axis will return to home once you fit your sensors, we done ours the other day and now it all works a treat.
Your acrylic piece looks great. Did you have any problems holding the material down whilst cutting and how did you deal with the small pieces being cut out?
Paul and I have a few other things we are going to try tomorrow with regards to the operation of our VFD's and will also be putting some further toroid ferrites onto the Gecko cables and any where else we might encounter any noise from, so we will see how that all go's and keep you posted. Sounds like you are having pretty good success and more importantly some fun in the process, its great to see the big blue MM in action.

Cheers
Tony.

[Surfcnc]

Hi Tony

I modeled the worst case scenario, so I let the pieces find their own way out of the cuts and also let the machine cut the final piece out (around the outside) without any restraint as a test to see what might happen. Very surprised by the lack of drama but the possibility of it firing out a piece always exists.

My hold down for the acrylic sheet was pretty high tech too, two clamps and two gyprock screws.

Yep I have to put some more wires / sensors in myself.
Now you are an electronics EXPERT after wiring your table maybe you could drop by and finish it off in 10 mins for me - if only hey.

Regards
Ross

[Surfcnc]

I am really starting to get the feel for cutting with the Mechmate, but the need to expand my cutter set to make the process more efficient became quite obvious.

As a starting point I have ordered or already have.

1 - 1mm carbide 2 flute end mills
2 - 20 and 90 degree carbide V bits
3 - 3mm HSS HRC40 2 flute end mills
4 - 3mm HSS HRC40 2 flute ball mills
5 - 6mm carbide 2 flute HRC45 end mills
6 - 6mm carbide 2 flute HRC45 ball mills
7 - 12mm HRC45 4 flute end mill

The cutter set is deigned to cover V carving, detailed finishing work, timber cutouts and general roughing with the 6 or 12 mm cutters.
My preference is for 2 flute cutters from my hand routing experience as these gave a fast feed rate if required.
The 4 flute 12mm roughing bit was an exception to my general rule as it was at a good price, so my feed rate will decrease as a consequence of this purchasing decision.

Although the lure of machining alloy is very strong, initially I will stick to the softer materials before attempting to make something like belt reduction drives.
Obviously depending upon what you are doing the cutters change accordingly but any input on my basic cutter set, examples or advice forum members might like to contribute is most welcome.

The cutters are all China sourced and the all up cost of the set is no more than $100 AUD.
Initially (and maybe permanently) expensive cutters are off my list until my expertise or a specific job warrants the purchase.

Regards
Ross

[digger]

Originally Posted by Surfcnc

The 4 flute 12mm roughing bit was an exception to my general rule as it was at a good price, so my feed rate will decrease as a consequence of this purchasing decision.

Ross,

are you sure that you need to decrease feed rate when you use 4 flute cutter? I read somewhere that you need to decrease rpm two times, because you have two more flutes. Maybe I am wrong?

Milosh

[Surfcnc]

Hi Milosh

There appears to be lots of confusion and also some pretty strong opinions on the web this issue.
I tend to think of router cutters in terms of a saw blades - for example a 24 tooth rip blade is quick and rough while a 100 tooth melamine blade is smooth but slower.

Set up a piece of hardwood on a table saw and rip it with the two blades and you soon figure more teeth does not equal more removal of the stock and more feed speed.

Probably comes down to two factors..
1. the amount of power available per tooth per rev to do the work.
2. the relative openness of the lower toothed cutter to eject the waste.

Always willing to learn if there are any well considered explanations of why I might be wrong though.

Regards
Ross

[digger]

Originally Posted by Surfcnc

Hi Milosh

There appears to be lots of confusion and also some pretty strong opinions on the web this issue.
I tend to think of router cutters in terms of a saw blades - for example a 24 tooth rip blade is quick and rough while a 100 tooth melamine blade is smooth but slower.

Set up a piece of hardwood on a table saw and rip it with the two blades and you soon figure more teeth does not equal more removal of the stock and more feed speed.

Probably comes down to two factors..
1. the amount of power available per tooth per rev to do the work.
2. the relative openness of the lower toothed cutter to eject the waste.

Always willing to learn if there are any well considered explanations of why I might be wrong though.

Regards
Ross

Ross,

I am willing to learn as well.
It is true that saw blade with 24 tooth will cut faster than 100 tooth blade but why this logic is not applicable here - I have no idea.

Here is a link to a wiki http://en.wikipedia.org/wiki/Milling_cutter and it said that:

"Typically, the more teeth a cutter has, the more rapidly it can remove material. So, a 4-tooth cutter can remove material at twice the rate of a 2-tooth cutter."

I am not expert in this, but would like to learn.

[riesvantwisk]

I did notice that a small 4 flute endmill has more problems getting the material away, where a 2 flute endmill has less problems doing this, I can imagine that if your endmill gets full of wood ships because it cannot move them fast enough out of the way, cutting speed will be slower.

If in general I agree then a 4 flute can cut away twice as fast compared to a 2 flute, given that it can move teh chips away fast enough. However my logic tells me it needs twice as much power to do so.

[Surfcnc]

Hi Milsoh

I like the way you checked your facts. Before I replied to you I actually read that wiki article, however my experience both with saw blades and router straight cutter bits is not consistent with the wiki article.

If we were to assume 2000 watts of power was available for four flutes, the maximum power available per flute per rev would be 500 watts. With 2 flutes the maximum power available per flute jumps to 1,000 watts or 100 percent more power. In the two flute cutter each flute has significantly more power to tear away more material, hence my rougher and faster comment. The four flute has half the power per flute but twice the strikes rate per rev, hence the smooth but but slower comment.

Reis - we are both looking at the same thing it appears.

Regards
Ross

[bradm]

Interesting topic. I think the data and formulas on these pages agree with wikipedia.

I think you want to avoid being in a situation where the available power is the limiting factor. If it is, you end up with a non-optimal chip load, which leads to tool heating. I've certainly seen this effect with wide blades on an underpowered table saw. You make the necessary compromises to allow the tool to work, but it's not desirable.

[Surfcnc]

Hi Brad

To quote the link for all to read

"Chipload is simply defined as the thickness of a chip which is formed during the machining of a material.
Chipload is critical because if the chip is the proper size, the chip will carry away the heat promoting long tool life.
If the chip is too small, the heat is transferred to the cutting tool causing prematurely dulling.
Too high of a chipload will cause an unsatisfactory edge finish, or part movement.
.
The formula to calculate your chipload is: Feedrate / (RPM x # of flutes)"

Note the formula does not include a variable for power, so to put it another way chipload is all about getting the right size chip or a good quality edge.
My experience with the table saw and router cutters has been where the input power has been the limiting factor to feed rate.
From memory the table saw is 3HP and the router is 2HP.
Within these power ranges the effect of increasing the number of flutes or teeth on absolute speed of forward movement is very obvious.

Before the interweb and such wonders, the rules of thumb were if the router bit chatters - too fast, if it burns - too slow.
I have seen black and burnt work pieces on this forum from new users thinking slow is good while not realising all that power creates heat.
My point here is that there is a counter intuitive element to the question of feeding the bit into the workpiece.
I still cringe walking though markets where "craftsman" show their burnt and furry router edges for all to see.
Tiger stripes - push too hard (furry), stop for too long (burn) then push too hard again.

As always I remain willing to review my thoughts as any further information becomes available.
One thing that is important is to ensure that we are all actually discussing the same thing.

Regards
Ross

[Surfcnc]

Hi Ries

Thanks for your input on static and the Z touch sensor on Tony's thread.

Reading my PMDX 122 manual it does not appear that the input pin is opto coupled.
Paul and Tony have multiple PMDX 125 Break Out Boards so they will have to do their own manual reading on that front.

All I have to do now is figure out how to make one work !!
While I'm at it, might an optocoupler(s) be useful in managing our VFD signal issues on the RS485 cable or am I just being overly optimistic.

Regards
Ross

[Surfcnc]

Look what I found !!

www-cel-com RS 485 Opto Coupler.pdf

Skippy reverse engineer this immediately
Any comments would be appreciated.

regards
Ross

[Surfcnc]

The link failed here is a direct link
www.cel.com/pdf/appnotes/an1047.pdf

Ross

[danilom]

Optocoupler is only used to get you separated from one side of signal so if some overvoltage comes that way it does not damage anything except optocoupler (its just a transistor with photosensitive base and a led)
it can not eliminate interferences. only filters or shielding can help.

[Surfcnc]

Hi Danilo

Seems I can not agree with anyone at the moment but I remain determined to let the facts lead the exchange of information.

The link I have posted directly above states in the first page, first and second columns ...

"Second is the isolation of the control equipment from high voltage devices or noise generators such as motors.
This is a growing problem in todays inexpensive motor controllers.
The communications interface is the only isolation barrier between the high voltage, high inductance motor windings and the programmable Logic Controller (PLC) that controlls it.
However the high common mode noise immunity provided by the data interface opto couplers effectively blocks inductive noise while also providing safety isolation"

Unlike the wiki article on cutters we have discussed before this is directly from the manufacturer of the device, if this s not true it would be deception rather than a mistake or incomplete understanding.

After some late night googling, I have located several devices that are drop in solutions for the RS 485 bus, all claiming to elimate inductive noise as well as providing the electrical isolation you mention.

Regards
Ross

[domino11]

Ross,
We have used opto-isolator type devices many times at work for just this type of noise suppression. Noise suppression and voltage isolation, as long as the device bandwidth meets your requirements a win win situation.