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Messages - motopreserve

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1
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 25, 2017, 09:30:03 PM »
That's some great looking work!  My clients lean a little less toward the grim reaper/skull & bones type of biker style, but I know good craftsmanship when I see it :)

Thanks for the info and links!

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General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 23, 2017, 09:06:27 AM »
RICH,

Once again, thanks for the great info.  Much of the concepts are familiar to me from research, and also my experiences with tweaking my 60 year old manual machines to work at their "best."  

I love the idea of checking torque.  Can you tell me the type of indicator you use?  I only have torque wrenches for the motorcycles, which I use often and may be able to rig something up that can at least measure the differences in torque required - but likely not accurate measurements of the actual torque (any adapters will throw off proper calibrated measurement).  But I think the torque differences would be the telling measurement while reassembling the axis to recognize the misalignment etc.

This is a brand new build, and the parts I had cut before this Z issue developed were plenty accurate enough for my needs.  None of the parts we make for motorcycles are mission critical (you are not going to crash due to failure/tolerances of anything we make).  But getting the machine to be as accurate as possible - and more importantly repeatable, is something I am more than willing to spend the energy on.  It's time well spent.  

You have made that job easier with your help and thorough explanations.

Attached is an example of a part cut on this machine.  The satisfaction of cutting it, and then mounting it perfectly to the bike is amazing! :)

Thanks again!

Scott


3
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 22, 2017, 07:55:35 PM »
Glad to hear you are well compensated - as well you should be! :). Actually, I helped out with a forum for a bit - a thankless job, so please know that I am indeed VERY thankful!

My only concern with this rigid coupler is of course any radial alignment issues that would not be compensated for. I know I shouldn't have it to begin with - but I did have some slight irregularities with the work done at the water-jetting place.

I may be able to tweak the motor alignment to ensure a perfect fit. Then I wouldn't really be too concerned. Especially since I realized that while pretty nifty, Oldham style couplers do not offer any axial support. I suppose that's only an issue when the motors are powered off.   I'll
Check what kind of play I have, as you suggested.

Any higher quality flex coupler (Bellows) is ridiculously priced. At that rate - cheaper to risk it and replace the damn motor if something wears :)

The motor shaft has a flat already - and I will try to file a small flat only the ballscrew end as well.

Now that I've got that sorted, time to get back to the list! :)

4
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 22, 2017, 05:32:42 PM »
Photo attached of the quickie coupler that I made on the lathe.


5
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 22, 2017, 03:23:44 PM »
Well RICH, I can't thank you enough!  I suppose the only thing left is to get your address so I can deliver you some whisky/wine/beer/chocolate/centerfinders.... Pick your pleasure or poison.  :)

Made a quick direct/rigid coupler, slapped it on there and the thing is repeating PERFECTLY!  Good grief I thought the stress would crush me!  Wondering if you have a suggestion for a more permanent solution for a coupler.  You said you were using custom ones with just Belleville washers as safety relief?  Do you have any photos?  I feel it's probably best to have some type of give for those "oh sh*t...." moments that may occur if Mach3 goes sideways.

I'm going to check the play even though it is working well now.  Just curious to see how she's holding up.  Forgot to do it when I pout the coupler on there - too excited to see if it fit right and helped at all. 

Really appreciate all your time and patience. 

Scott


6
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 22, 2017, 11:25:10 AM »
Will do.  I'll check the play when I disassemble for installing the new/test coupler.

Should be able to bang something out quick f I am just making a rigid coupler.  I have some aluminum round bar here in stock.

Thanks again!

7
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 22, 2017, 08:46:12 AM »
RICH,

The Oldham style couplers have a center piece of hard plastic, I assume to allow it to give (or break away) if some catastrophe happens, but not as squirrely as the style I have on there now.  They are made up of 3 parts total.  Like  the following:

http://www.ruland.com/ps_couplings_oldham.asp?gclid=Cj0KCQjw1a3KBRCYARIsABNRnxtK8nD8gPazSOpJwEocEMnJ-va7I0dhWuq2bf0DxIQDMpQayfq9X8gaAv-9EALw_wcB#about.

I could make something like this fairly easily.  Just need to raw materials - don't have it all in stock.

The thought of this all being caused by mechanical play is a little odd to me (although I also want to be sure that the mechanical side is correct!) - since the discrepancy always seems so uniform and cumulative.  Also, the strange issues I started having on the machine were also on the Z-Axis.  The thing went a little crazy and began hesitating.  I thought there was binding - but confirmed by hand-turning there was not.  Then when locating to WCS the Z-Axis would travel to the Machine zero point and make a weird noise, then sorta stall there, but think it was at WCS zero.  I reinstalled the software - and although it did not fix the issue we are discussing, it does seem to have stopped this weird behavior....for now :)

The support on the Z-Axis is provided by a BK20 fixed bearing block at the top.  It has the bearings seated inside the block, and the play is taken out by the 4-sided nut with setscrew that threads onto the end of the ballscrew.  I have attached a photo below of the type of bearing block I used.  

Thanks!

8
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 21, 2017, 10:13:50 PM »
PS: do you happen to know the calculation for determining the necessary kernel frequency?  I have search high and low and found conflicting reports.

Thanks!

9
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 21, 2017, 10:11:20 PM »
Thanks once again Rich. Very much appreciate all your help.

These couplers were not my first choice, and I have been planning on making some new ones on the lathe as soon as I waded through all the other things on the list. Seems like they just jumped to the top of the list!

My plan was for Oldham style. Do you have an example of the type you made?

I'm not sure if the bearing is preloaded an adequate amount. I do not have torque gauges to check. When I assembled the axis I made sure it did not have play - but that was without scientific measurements.

Sorry is this is redundant - but I was afraid I was confusing in my earlier posts. To be clear, the discrepancy I'm experiencing seems to be a constant distance traveled (up, then back down) - but each time it happens the travel up is a set amount less than it should be. So for example: spindle rises 100mm, comes back down and rests at 100.02. The next time it travels up and back, it rests at 100.04. Next 100.06 etc. although it's moving too fast for me to measure at the top of the axis, I'm visually seeing it after many runs of this same maneuver.

If you already had that down - please ignore it :)


10
General Mach Discussion / Re: Incorrect Z-Axis zero/home position
« on: June 21, 2017, 09:13:16 PM »
I ended up having some odd issues with the machine today. Not sure if they're related, but I decided to reinstall the Mach3 software. I was afraid that I may have messed something up by installing, opening and then deciding against a couple different screen sets. Unfortunately, the reinstall is still showing the same issues.

Not sure if I should have started from scratch and not used my old custom XML file???

I only have a couple shots on my phone right now. I can post some more details if you want to see a specific part of the Z-Axis.




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