Shifting of home position on X axis.

[PMK Digital Imaging]

Hi all,

I've recently had to reinstall the latest controller program a couple of times to get the controller software and firmware to update properly, but all seems good now.

BUT......I still get the random shift to the +X about 1/4" or so. It happens when I change bits and rezero Z. Needless to say this screws everything up when it cuts that way. What can cause a random shift of the X axis home by about 1/4"????

Do I need to rezero the XY home position every time I change bits?

It seems to be random. It doesn't do it every time.


Any ideas.......its only in the X axis.

Paul K.

[Brady Watson]

Don't know. But...from my experience I would tell you to install v3.6.46 and update the firmware. Then, if using the TC_Inch post processor, save out each toolpath by itself. Then just call up each toolpath after you have run your Zzero routine & you shouldn't have this issue.

Make sure your proximity switch targets are at least a 1/2" away from your 0,0 position.

-B

[PMK Digital Imaging]

Hi there,

Thanks for the quick reply. I'll give that a try.

I do save each tool path separately. It's only "now and then" do I get the +X axis shift from 0,0. Most of the time I don't have to re-zero the X,Y.

But, when I "trust the machine" it skips about 1/4" +X.

It's done it off and on since I've had the shopbot......about 4 years.

Most of the time........it's flawless!!!!!!!!!!! Sure hurts when your bit cuts through the finished parts......$100 of cherry down the tubes. OY!!!!!!!!!!!!!!

I'll try dropping back to that version of the controller software you stated.

Also.........I use Aspire......is the shopbot ARCS, Inch.......post processor the correct one?

Thanks again for your advice and help.

Paul

[Brady Watson]

You should be OK with that post via Aspire. Your machine should not need to be checked for 0,0 - it should be dead on ALL the time.

You didn't indicate if this was an Alpha or Standard, but I will assume it is a Standard for what I'll say next. Check your jog speeds and reduce them. Pull them down to say, 6,2 (XY,Z), since it is COMPLETELY possible to lose steps if they are too high. You can also lose steps while cutting, if you are too aggressive.

Also, run the //ShopBot3/Diagnostics/SpeedTest.exe (with SB3 closed) and see what you percentage is. If it is too low, the motors can choke and stutter at higher speeds (like when jogging home).

-B

[PMK Digital Imaging]

Yes, mine is the standard.
And yes, I tend to be a bit aggressive on the cutting speed.
I'll slow it down a bit. I get good clean cuts though and its not bogged down or sounding like its under a great load.

I might be pushing it a bit as you say.

Paul

[Brady Watson]

You may also want to adjust the Slow Corner Speed down to say 40, under the VR command. It will provide a little more speed modulation & 'cushion' when it changes direction, with negligible difference in elapsed time. Leave the other settings alone until you understand what they do. You can read the article here (http://www.shopbotblog.com/index.php/2008/03/a-ramping-the-vr-command-and-how-to-tune-your-tool-for-maximum-performance/).

-B

[PMK Digital Imaging]

I'll do that as well. I guess I've been asking my "buddy" to do a bit more than it was really intended to be capable of doing. Asking it to be a "production" machine rather than one geared for the "hobbyist." I'll slow things down a bit as you have suggested.

I wish I had more time to devote to the workings of my "buddy," but I have a full time job teaching at the university here and I'm building my retirement business, photo enlarging and printing. Doesn't leave much free time at all.

Thanks for your patience and words of advice. I'm sure things will be fine when I dial things back a bit as you suggest.

I'll let you know how it turns out with the modifications.

Best,
P