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Messages - NiOBoBeO

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1
I have done simply XML rebuild several times with no apparent improvement. Prior to reading the horror stories about background or Internet functions causing issues with mach3, I had a bunch of stuff on there. Reformat will rule all that out (I hope).

2
I'm in the process of reformatting and reinstalling now. I guess I will just keep a frequent backup of the XML file so that can be part of my troubleshooting process.

Thanks for the input.

3
The issue only arises when I have bc turned on. It seems like the general attitude is that I can just do without compensation... That is something that is yet to be determined.

The reason that this is an issue is due to the potential for acrylic re-weld. It's happened a couple of times on the slower sides.

4
Rich,

Thanks for the quick reply. I looked through the code and it doesn't seem to change (attached). I have tried installed two versions and have the same results:

R3.043.058
R3.043.022

Glad to hear I'm novel!


5
Hey everyone. I posted about this a few weeks ago, but the thread died and can't be accessed any more- so here it is again.

I have a 'JoesCNC Hybrid' that I have been trying to debug and I cannot get backlash comp to work properly. I suppose that's a bad way to describe it- from what I can tell, the software is taking up the correct amount of backlash, but the movement that follows is poor. This is an issue as the end mill really starts to warm up when the move is slow and rough.

I have read / watched Hoss' information on backlash compensation and the odd results, and as result, I had started out with my backlash comp velocity set to 100% and the shuttle accel to 0.005s. Obviously, this did not resolve the issue. I have played with several different combinations of shuttle accel and % velocity, here is I brief log:

1. Followed the advice of several threads by changing shuttle accel from 0.005 to 0.05, and then to 0.5. Each change made the affected movement more and more rough, 0.5 being the worst.

2. Given trend, placed shuttle accel at 0.0005s. The movement is still messed up (see videos), but this is the smoothest setting.

3. Any change to % velocity for backlash comp does exactly that, but after the backlash is taken up, it begins to move rough once more.

Here are links to videos that show the issue (CAM set to 80 ipm, but slows down to 20 ipm on negatives):

*http://www.youtube.com/watch?v=r5Q5VG9CGAE
*http://www.youtube.com/watch?v=HEaD1JbSfno

Given the number of different shuttle accel / % velocity combinations I have tried, I am really hoping there is some other setting that is causing the issue. I have attached my current .XML file for reference, but feel free to ask about anything.

Thanks,
Anthony

6
Gerry,

Thanks for the reply. I have seen the video before and my settings are the same (0.005s shuttle accel / 100% backlash velocity). The R&P setup is spring loaded- I'll attach a picture. As I mentioned before, I have achieved as little backlash as I can without major design alterations.

Why would CNC routers typically not employ backlash compensation??

I understand that there is no universal fix to this type of issue, but from what I can see, the shuttle accel and % velocity that the backlash travels at are the main influential factors. Are there other settings that compensation is a function of?

I cannot say for sure, but I feel like this issue used to be less pronounced; I would like to try the build that I initially started with and see what happens. I found the change log, but is there anywhere to download the previous Mach 3 builds?

Thanks,
Anthony

7
General Mach Discussion / New Machine Configuration & Backlash Comp Issues
« on: February 22, 2012, 08:49:05 PM »
Before I start, I would like to say that I have spent the last week or so reading forum after forum about the various woes associated with backlash compensation. It was only about halfway through my search that I realized the odd relationship between mach 3 builds and the G540 controller... I guess its been cleared up since 09'-10'??

For the last couple of weeks I have been struggling to put the finishing touches on my 'JoesCNC Hybrid" rack and pinion CNC router. The main issue is that when enabled, the backlash compensation causes very rough movement when the compensation is actually utilized. Here is a short video where the machine moves around a 10" x 10" square, ending with a diagonal move to the center:

http://www.youtube.com/watch?v=ClhI3ujGxks&context=C39d6143ADOEgsToPDskJ5XPMdYpc8zU6xOPTZdKYW

Thus far, I have tried the following:
1.Tore down and rebuilt each of the mechanical components twice in an effort to remove as much mechanical backlash as possible. In general, I am very pleased with the results: backlash of 0.0043" in the y-axis and 0.0070" in the x-axis (zero-backlash nut in the z-axis does a great job).
2. Re-read the mach 3 manual and performed a careful step-by-step re-installation of the software.
3. Verified BIOS settings for the parallel port.
4. Sent my controller back to Gecko to have them take a look at it. They couldn't find anything specifically wrong with the drivers, but they replaced the motherboard as a precaution.
5. Tuned the g540 trim.
6. Changed shuttle accel setting. I read several accounts of people changing this value from 0.005 (my current setting) to 0.05, and 0.5; the vibration that you hear in the video gets worse and worse as I go toward 0.5 setting.

Naturally, I can turn off backlash compensation and everything sounds / moves fine. I wanted to see if anyone else has run into this combination of symptoms before I request phone support, but if it gets to that point, I will post the results. My XML file is attached.

Thanks,
Anthony

8
Hi! My name is Anthony. I am a mechanical engineering grad student at the University of Central Florida. Over the past 6 months, we have (slowly) constructed a 'JoesCNC Hybrid' CNC router with a G540 / Mach 3 control-based system. Our typical application is simple test rig fabrication, usually from acrylic sheet material. As with many of you, I have been drawn to the Mach forum looking for assistance with our final machine configuration- and this is where the expertise seems to pool!

I look forward to learning with all of you.

Thanks,
Anthony

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