[partsman]

Made some more progress today. I got one of the e-stop buttons added, cooling fans installed, and the hard drive mounted. I also put a USB port on the keyboard tray for a usb memory stick. I'm going to put another USB drive on the rear for a remote pendant.

[BTA PLASMA]

That is incorrect. If you gain 0.01" in one direction you will lose it in the other. Backlash is not cumulative.

Yes your right. It was the wrong example.

[BTA PLASMA]

Its really the circles that will be affected more than a strait .010 over the geometry.

[partsman]

BTA PLASMA

Yes your right. It was the wrong example. A gear set takes up backlash when it decels so a bunch of straight line starts and stops will accumulate in the travel.

Also incorrect. There is no circumstance where backlash is cumulative (unless software is somehow incorrectly set to try to compensate for it). My gearbox with 0.001" of backlash will only ever produce an error up to 0.001" +/- on that axis no matter how many lines of code it is running. Circles, straight cuts, zig zags, or cutouts of monkeys riding on an elephant.

covered in great detail here-->

http://www.cnczone.com/forums/diy_cn...sh_please.html

[BTA PLASMA]

Partsman that was an applications guy here. What he failed to mention is that the setup of your steps per ratio can be off and will accumulate over distance if your backlash is too high. With a gantry being overly heavy and a motor beign undersized you can actually loose a few steps during acceleration with excessive backlash as well. Some things to think about when your calculating your steps per (which should be done with an indicator) Otherwise you are spot on. Carry on please.

-Matt@BTA

[partsman]

Thanks for the clarification Matt.


I made a little more progress today. I got the computer put into the housing and got windows installed. I need to tidy up the wiring on that.

I also got most of the wiring done on the button panel. I am waiting on my ground bus to get in so I can tidy up all of the ground wires.

Waiting on a couple shoulder bolts & then I can install my gearboxes and try out some movement. Getting close!!

[partsman]

My second attempt at the decals. it is far from perfect but I just decided that I was not going to spend any more time on it so I did the best I could with what time I had. After putting the decals on I buried them in several coats of clear lacquer.

[partsman]

It is alive!!! :banana:

No pictures today but I did get the Candcnc kit wired up and got some great movement. Everything seems to work very well. I could not visibly see or feel any backlash & the gearboxes were very quiet. The only problem is that I must have used set screws that were too small. I can not keep them tight no matter what I do. I tighten them until I'm afraid the alan wrench is going to break and then they are wobbling loose after about 15 seconds. I ordered some new 1/4" set screws that should be here Tuesday. Then I have to take all of them apart & re-drill & tap the gears.

[deuce217]

Will a 1/2x10TPI leadscrew offer accurate resolution on a table? I understand there is an issue with debris and other stuff acumulating on the threads of the shaft. But if they were to be protected from these elements would the ball screws or lead screws be ideal?

[partsman]

I'm certainly not a leadscrew expert but I think you should be able to gear it down just like a rack & pinion drive to get whatever resolution you need. I have a 5'x10' router with ballscrews that still has a belt reduction. I, personally, think screws are overkill for a plasma though

[deuce217]

Thanks for the quick reply. I will probably stick to a rack and pinion then. The more I read on the precision of the ball screws the more it makes me want them, I will save those for when I begin retro fitting my manual lathes to CNC. I think I will buy the 4x4 medium duty kit from Precision Plasma (using the Candcnc electronics) so I can study one of these up close. It will save me some money in the long run. I am loving this build you have going, I wish I had a large enough shop for a bug table like that. I look forward to seeing it all rapped up, especially when that scriber is in operation.

[partsman]

Here are a couple more pictures. The completed control panel and the mounted gearboxes. I will have a sheet metal cover that will go over the gearbox area to hide all of the wires & the open end of the aluminum tubing.

[partsman]

Just thought I'd throw an update out here.

Finally made my first cuts. Spent a full couple days chasing some very frustrating electrical gremlins. The cause seems to have been that my material that I was cutting was not grounded to the actual machine. It was up on temporary wood blocks while I was cutting out my slat holders. Never even gave it any thought but I think it was causing some voltage spikes & randomly kicked Mach into reset mode.

I will post some more progress pics here soon.

[partsman]

Just thought I'd throw an update out here.

Finally made my first cuts. Spent a full couple days chasing some very frustrating electrical gremlins. The cause seems to have been that my material that I was cutting was not grounded to the actual machine. It was up on temporary wood blocks while I was cutting out my slat holders. Never even gave it any thought but I think it was causing some voltage spikes & randomly kicked Mach into reset mode.

I will post some more progress pics here soon.