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Messages - BJenkins

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1
General Mach Discussion / Re: Backlash Settings
« on: July 28, 2009, 05:38:24 PM »
Thanks!

I will check out the videos. I hadn't thought of searching YouTube for Backlash even though I do use YT as a search resource. I'm sure this will help.

I'm in the middle of perfecting a first CNC project and I plan on attempting to smooth out my machine more to reduce the backlash. I thought that .0095 might be a bit high and now I know it is. In general, my parts are coming out good except for a circle cut or two and they are almost good enough. After I do another tune up, I plan on posting my results here.

Using backlash has definitely helped and now I want to reduce it more.

BillJ



2
General Mach Discussion / Re: Backlash Settings
« on: July 25, 2009, 05:00:38 PM »
Very good points.
Thank You!
BillJ

3
General Mach Discussion / Re: Backlash Settings
« on: July 25, 2009, 05:39:11 AM »
OK, Thanks again. I cut some small parts tonight and a good number of them are circle cuts. I will inspect them closely tomorrow. Does backlash help or hurt when cutting circles. As I cut these circles, I wondered if I should have turned the backlash off.

BillJ

4
General Mach Discussion / Re: Backlash Settings
« on: July 24, 2009, 06:22:45 PM »
Thanks for the help. I've got a much better understanding now. I probably still have my wheels just a little tight and I could tighten the belts a little as well.

I want to try the 50-50-50 rule and I found the Shuttle wheel setting under General Config and I'll change that to a value between .005 and .05 and set the Backlash speed to 50% to start with. I use steppers and I'm not sure what you mean when you say SS.

Now I know that .0095 is still a bit high, I will try to smooth out the mechanics a bit more but I'll first start with the settings and I'll eventually do another adjustment. Although my setting is a little high, the Backlash adjustment does seem to take care of my issues but I realize now that I really need to use a accurate measurement device and method to get it spot on.

One other point made was about using a prep step to eliminate the backlash before you start the job. Now that sounds like a good practice but I'm going to have to think about how to do that. I'll probably figure out a method to draw an extra tool path move that will do a mini movement above the work in the direction that I'm about to cut. Is that what you do?

I appreciate the information.
BillJ

5
General Mach Discussion / Backlash Settings
« on: July 24, 2009, 06:59:54 AM »
I'm new and I'm trying to fine tune my small wood working CNC router. I found that I had a first pass issue that caused the first pass to cut into the part by as much as .025 and then the remaining cuts would be spot on. I added Backlash to Y of .024 and this cleared the first pass issue.

I adjusted my machine so that the Y axis moves much more smoothly now. I had the V-Wheels too tight. I was able to reduce the backlash setting to .0095. I found that adding the same .0095 value to the X axis cleared up a very slight first pass issue on the X axis as well.

Is a Backlash setting of .0095 for X and Y a reasonable number for a CNC router designed for wood or should I continue to try to smooth out my machine movement? Everything looks right now including circles but it is hard to tell via the old eye ball method.

My Backlash speed is set to 100%. This seems to work but I wonder if this setting should be lower. ??? I did have an issue once during test cuts and jogging where the machine would trip. I turned Backlash off and the problem went away. I turned Backlash back on and the tripping came back, finally I changed the setting to .1 and the problem did not come back and then I changed back to .0095 and I have not experienced any more tripping issues. My machine is set to run at 60 IPM Max at the moment.

Thanks,
BillJ

6
General Mach Discussion / Re: Stopping and resuming
« on: July 24, 2009, 06:00:57 AM »
I found that my Safe Z Setting was set to Machine Coordinates. I experimented and changed it to Work Coordinates and Z now moves to +.2 above the work as I want. I guess since I don't use a Home Switch set up (at least not yet) that I don't use Machine Coordinates. I'm a NewBee.
 
I experimented with the Run From Here command again and it did work although at this point, I will keep my hand on the emergency shutoff when I try this due to lack of confidence. It's a little scary. Ha!

Now I have a question regarding Backlash settings that I will post in a new thread.

Thanks!
BillJ

7
General Mach Discussion / Re: Stopping and resuming
« on: July 17, 2009, 04:56:49 PM »
I will do some experimenting but I don't think I lost steps.

I will also confirm that machine coordinates are set as I said. I'm on the home computer so I will need to confirm that the setting is set to machine coordinates but I am pretty sure that this is the case.

I will report back after I have a chance to check this.

Thanks,
Bill

8
General Mach Discussion / Re: Stopping and resuming
« on: July 17, 2009, 04:44:40 PM »
Hi Hood,

Thanks for helping again. I have my safe Z set to machine coordinates.

Bill

9
General Mach Discussion / Re: Stopping and resuming
« on: July 17, 2009, 02:40:47 PM »
Yes this does help (Thanks!) but I need to go over a couple of points just to make sure.

First, I do pick a line in the code that is out of the part. The problem is, after going through the Run From Here steps, and select Cycle start to re start the job, my Z goes all the way up to the positive Z limit and crashes and then requires a reset. I have my safe Z set to .2 and the line in the code I pick is also .2 out of the part. I can only guess that there is a setting that I have missed or that I am not following the procedure correctly.

You mentioned that Run From Here starts at the line before the line that has actually been selected. Does this mean then, if I want to start on line 19, that I really need to set line 20?

Thanks for the help.
Bill J.

10
General Mach Discussion / Re: Stopping and resuming
« on: July 16, 2009, 05:44:33 PM »
I also have issues with the Run From Here option. I would like to try the Set Next Line option but I don't understand how you "single step" through the first part of the program to insure that the spindle turns on and etc.

If someone finds time, I would appreciate learning the step by step method.

I find that when I attempt a Run From Here command, that my Z always moves to the Max Z positive limit and causes a reset.
I have my safe Z setting selected to .2

Thanks!
Bill J.

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