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Author Topic: Trouble cutting accurate parts  (Read 15855 times)

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Re: Trouble cutting accurate parts
« Reply #40 on: December 18, 2013, 10:32:36 AM »
Fantastic!   I'll go play with it right now!

Thanks a bunch.

Offline RICH

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Re: Trouble cutting accurate parts
« Reply #41 on: December 18, 2013, 10:50:37 AM »
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My question .............Is the mapping functional or actualy implemented?
Brett, thanks for the confirmation that it's functional ( just being lazy here).

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Rich, but I respectfully disagree.
No problem Capt and if axis comp works for you that's great since I never used it.
Let us know how it works for you, now and in the future.

Just a few comments:
Accuracy or true resolution only comes from the SYSTEMS  over all mechanical ability.
IE. In testing we found that timing belt tension can affect positional accuracy, verified by varifying the tension and monitoring
pulse count info at each interface of the electronics and physicaly measuring via a known stantard.
If like backlash comp, which i used, and helped me for some time.........but, when doing 3d machining it just didn't cut it.
When engraving or machining small stuff nothing beats true mechanical ability. Backlash can be problematic even when
compensated.

I am just saying that software solutions just mask the mechainical problem.

Enough of being anal about it, just spent a lot of time in the past trying to get my machines accurate.

Have a Merry Christmas,

RICH
Re: Trouble cutting accurate parts
« Reply #42 on: December 18, 2013, 11:34:39 AM »
I agree 100% with you Rich. I'm just trying to get the best possible setup without throwing more money at it (for now).

I'll try the mapping thing, then let you all know how it went.

Merry Christmas and/or Happy Holydays to you all.

Re: Trouble cutting accurate parts
« Reply #43 on: December 18, 2013, 02:15:40 PM »
Well, so far it has been a bit frustrating.

I started mapping the ballscrew and recording values as I went, which by the way were a lot better than I was expecting, but nothing showed up in the graph on the screen, just a red horizontal line. It might be because the extremes of travel were in the .5" range, while my errors were in the 0.001" range, but it looked flat lined and I couldn't find out how to adjust the graph vertical range.

Anyway, I went with that, sent the mill to 0 and enabled the X mapping correction. Unfortunately Mach3 X axis DRO read +1.#QNB, I'm not sure what it meant.

Sending X back to 9.000 resulted in an inch of travel, then the motor started seizing and rattling like it was having a heart attack, and the table stopped moving. I did this a few times then I mostly gave up on the mapping idea.

Obviously I'm doing it wrong, or mapping is not working right (it's probably the first option).

Offline Chaoticone

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Re: Trouble cutting accurate parts
« Reply #44 on: December 18, 2013, 03:12:32 PM »
I'm not too concerned with the line looking flat. It should look pretty flat unless your making huge compensations I would think. I don't know how to explain it any better than in my previous post. You move to a distance and the DROs show current position. Say 1.000 for example. Then you measure and if you actually moved 1.002 you would enter that as the actual distance (1.002) and set a point. Repeat this process for the length at what ever resolution you want........ every inch for example. Get all your points set and enable screw mapping for that axis. If your screw holds better than your backlash of .003 and I would think it does....... you will be wasting your time IMO. Rich is spot on in regards to mechanical ability. Screw mapping and/or backlash comp are at best a bandaid for a situation requiring surgery to correct. If they will hold you until you see the Dr. that's great but betting your life on it would be a mistake.

Brett

;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!