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Messages - dray

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1
General Mach Discussion / Re: z axis moving up
« on: June 29, 2012, 12:04:45 PM »

Hi Rich
We finally got it solved. That 20" dia. circle really shows up the errors The following settings have stopped the errors. Only the Z axis had power to the stepper during the testing. I am sending pictures of the pointer and scale used to determine the errors.

kernel 25000 hz
pulses/inch=25601 for Z axis
vel.= 20"/min., accel.= 2, step and dir.= 1 Us
set computer to "standard pc"
turned on the Sherline 1/2 pulse

I ran a 1" test up and back to zero 20 times with out any visible error.

We than cut a 5" diameter buffalo nickle very nicely in MDF.

Thanks to everyone for your help and suggestions, and especially you Rich, Mach 3 is an exellent program and at a very reasonable price.

dray

2
General Mach Discussion / Re: z axis moving up
« on: June 29, 2012, 11:36:10 AM »
Hi Rich
I am attaching 3 file. 2 of which are photos. thanks
dray

3
General Mach Discussion / Re: z axis moving up
« on: June 27, 2012, 06:07:20 PM »
Hi Rich
Finally got started improving the 20 inch circle segment and a more accurate .1 inch scale on the machine frame. will send a photo of setup. seems like it always over shoots in the up direction and when going back down falls short of the previous point. With a 1 inch travel seems to average .1 inch error. I put a scope on the LPT cable on pins 6 & 7 and there is only 3.5 volts available and are very jittery when running some gcode. I think I saw a way to use a 5 volt pull up on these pin just have to find it again.

dray

4
General Mach Discussion / Re: z axis moving up
« on: June 10, 2012, 02:25:16 PM »
Rich
Thanks and I will try to get some more data. But right now am on a 5 day camping trip so it will have to wait till I return.

dray

5
General Mach Discussion / Re: z axis moving up
« on: June 09, 2012, 11:20:49 AM »
Rich
Finally got some testing done hopefully in the right manner. I want to thank you for your patience. I am attaching a text file which explains the test as it was easier to write up in notepad.

dray

6
General Mach Discussion / Re: z axis moving up
« on: June 07, 2012, 07:53:09 PM »
Tweakie.cnc
Yes I've been trying anything that I could change but none of it effects the error that happens. Automation suggested a test using a pointer on the shaft of the stepper and a mark on the case. If I run a loop of say 50 cycles of back and forth for 1 revolution on any 1 axis at a time they all show an error in the up direction if that particular stepper was used on the z axis. This is run on only one axis at a time. Any suggestions? I have another bob with drivers on order just so I can eliminate that component. The error of .003"-.004" is very repeatable. It just seems to let the 000 position move ever so slightly with each rev.

dray

7
General Mach Discussion / Re: z axis moving up
« on: June 07, 2012, 05:51:54 PM »
Rich
After I have diabled x and y, moved z in the up direction, set the 00 and aligned the marks ,am I to cycle up and down or just return to 00?  If Icycle up and down I have an error of not being a 00 but the DRO shows 000.

dray

8
General Mach Discussion / Re: z axis moving up
« on: June 07, 2012, 07:41:37 AM »
Rich
I will try that later today. Not sure what that will prove as what I am doing is the same as the type movements the z axis does in 3d. The error I'm seeing has nothing to do with backlash or straight line movements. The test I run only involves the stepper and it's repeatabily back to 00.
dray

9
General Mach Discussion / Re: z axis moving up
« on: June 06, 2012, 07:28:58 PM »
Rich
I only test 1 axis at a time. I am sending the gcodes i am using. Hope this helps explain the tests
dray

10
General Mach Discussion / Re: z axis moving up
« on: June 06, 2012, 02:41:44 PM »
Hi Rich
I'm sorry for the confusion. The test I run is to rotate the stepper back and forth 1 revalution for 50 cycles and stops at 000. But all of the axis wind up having an error of .004" always in what would be the up direction if on the z axis. The DRO reads 000 but pointer is 4 pulses from start position. Vel and accel do not change the error. If I double the length of the test the error doubles. At first I thought it was only on the z axis, but now realize the same happens on all axis. The z error really shows up in 3d cuts because of the frequent direction changes. The x and y axis are driving the machine during the test. Any help will really be appreciated

dray

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