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Author Topic: deviations of 0.3 mm, in small parts: MACH3  (Read 6969 times)

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Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #10 on: January 07, 2010, 04:38:51 PM »
"Under all circumstances, most tooth-belts have remarkable backlash" - That's just not true.  There are MANY toothed belt systems that have essentially zero backlash, otherwise you would not see them used in CNC drives.  XL belts are VERY common in CNC equipment, as are the newer, and even better, GT2 belts.

Regards,
Ray L.
Regards,
Ray L.
Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #11 on: January 07, 2010, 04:55:40 PM »
Well...not under ALL circumstances. But in this instance, where a length of belt is used with a pinion pulley, Konrad is right. Using a toothed belt and 2 pulleys as a reduction drive is dandy to run a ballscrew, but don't expect much from a *belt n' pinion* for a metal cutting machine. Wood router....maybe. Pick and place, torch/plasma, plotter.....fine.
My 2,
RC
Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #12 on: January 07, 2010, 05:27:11 PM »
 ::)

maybe "under all circumstances" was a little keen   ;D

In fact, I don't know any manufacturer that sells his toothbelts as "zero backlash"...
They all advertise how much the reduced the remaining problems in application.

But on the other hand, depending what is surrounding the toothbelt drive, the backlash and resilience of the belt driven stage becomes just irrelevant.
For example, using a belt as a reduction stage between drive motor and screw, is very common and does not affect the machine's precision in critical means.
Another example is using a belt-drive as "torque distribution" in machines that use two or more screws in parallel.


I like Overloaded's words "Wood router....maybe. Pick and place, torch/plasma, plotter.....fine."
Everything depends on the force applied by/to the system and the desired precision.

Konrad

PS:
* now putting the pair of gold scales back into the locker...*
« Last Edit: January 07, 2010, 05:29:09 PM by Konrad K »

Offline RICH

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Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #13 on: January 07, 2010, 06:03:48 PM »
It's an accuracy issue that you need to come to terms with. Your "system" is what it is. Usualy you would set the steps per unit based on the longest travel, say 150mm then the 28 mm error would be very small. But the accuracy may be  different along  the travel, in some range of travel, etc. So you have a choice, without getting into offsets / changing the piece dim's, or tool used, etc. of living with it, modifying / improving the machine or using experience to end up with what you want.

I took a quick look at the site and didn't see any closeup's of the machine, so i can't make any specific comments that may be easy and cost effective to improve on the machine. 

Just make sure the steps per unit are a good comprimise.
RICH

Offline BUG

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Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #14 on: January 07, 2010, 06:24:08 PM »
You may have found the problem. This weekend more tests carried out, for sure and I explain that I get back.

Thanks

Excuse my English

Offline BUG

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Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #15 on: January 20, 2010, 04:17:03 PM »
I'm doing more tests to get the result.

But if I can say that the machine is capable of making 5 pieces of complex milling and are all identical. But not so far drawn accurately.
Re: deviations of 0.3 mm, in small parts: MACH3
« Reply #16 on: March 02, 2017, 08:52:42 AM »
Hi, have you had any luck yet BUG?
I am experiencing the same issue