I don't know what's happening.

[Waylon80]

Hello everyone newbie here. So far I've cut quite a few parts with just minor problems that I managed to work out. But anyways I've been working on this sign and it keeps messing up I don't know why but it will randomly stray away from the path during cutting I've tired cutting it 3 times happens everytime pulled the torch off three on a sharper to draw it out to see if it was a problem in the g code and no it drew out just fine. One of the times I cut it I noticed it dragging my torch across the plate so I raised the volts on the dthc to raise the torch solved that problem but not it won't cut a straight line right without turning left or right causing it to throw the whole design off I'll attach the pictures from the first time I cut it and the last time I cut it of where it's messing up

[Waylon80]

Here's the pictures of it after the first cut

[Waylon80]

Over all cut never got finished because it torch dived when it got all out of whack and tried cuting over material that'd all ready been cut.

[Waylon80]

Ok I'll have to upload my pictures later using the laptop not enough cellular service to do it by phone right now.

[acourtjester]

One thing when you put the sharpie on did you slow the movements down?
I would look at the setscrews in the pulleys one may be slipping at higher speeds. When you as it won't cut a straight line do you mean only moving the X or Y axis or a diagonal line which would be moving both axis at the same time to make the line.

[Waylon80]

Here are the pictures of my problems notice it's like the whole gantry shifted to the left and started cutting everything off. Also notice that on some cuts it it started but when it came to the lead out it went crazy and the part never got cut out. And no I never changed speeds when I put the sharpie on though I did change it before I cut it the second time I figured the cut distance was to low since it was dragging the torch on the plate so I raised the volts and raised the speed as well.

[Waylon80]

The first picture is from when I cut it the first time

[Waylon80]

Here is the dxf file

[Waylon80]

I don't know if I'm losing steps or if I'm getting some kind of interference. But I do know it cut 2 different signs perfect after this one.

[Waylon80]

If you'll look at the last picture you'll see what I'm talking about when I say it not cutting straight. In that picture you can see the start point where it leads in then when it was suppose to finish the cut it goes crazy and moves to the right then arc lead out.

[acourtjester]

When working on a problem you need to break it apart is it software (G-code) or mechanical. Since you can use a sharpie and is follows the G-code with out problems. Then you understand it is mechanical ( the movement is not following the G-code) The torch dragging was G-code and you corrected it.
Now you need to closely look over your table drive to find what is slipping. Is one of the motors stalling you should hear that if it is, that would change positions also.

[Waylon80]

Oh yeah it's for sure a mechanical problem. Turned off all power to the motors to see if I could move it by hand....no way. Motor's gear was to tight against the rack. What brought me to checking all this was that the motors were actually losing step and I didn't know this because I don't have any homing switches let so basically for the time being just been setting a point to start cutting manually. Well last night I actually marked a spot in the table considered home and ran a dry run of it and it was horrible when I started doing the outside cut with all the letters it lost step bad so I ran it again and I noticed that my gear on my X axis (short axis) was slipping on the shaft. The gear is only held on by a slip collar that's suppose to tighten the gear all the way around the shaft of the motor. Well I guess with the motor itself being to tight to the gear rack it was causing it to pinch and slip. So I backed the motor off and out a little bit and I'll be dang if the whole gear and slip collar didn't just fall right off the shaft. Well I tired tightening it back on the shaft and can not get it to stay at all. I'll tell you what I need but I've got no idea on the specs or how to read the specs on what spur gear I've got but what I need is a gear itself that has a tapped hole with a set screw instead of this slip collar junk. Because I had the same problem trying to get all my gears on the motors when I first built the table and apparently there still not tightening down.

[acourtjester]

You may take the gear to a machine shop that has a gauge see attached to find the pitch of the gear.
I bought one of these many years ago (much cheaper then hobby guy)
http://www.use-enco.com/1/1/67226-14-04 ... gages.html
This is what I use on the table I build it is a 20 degrees pressure angle if your is a 20 degrees rack he has different shaft sizes for the gear.
http://www.ebay.com/itm/291378806106?_t ... EBIDX%3AIT

[Waylon80]

Mine has 15 teeth but that it the kind of gear I wish I could find. I got my gear rack and pinion with my gantry from procut Cnc. I got there LT gantry kit.

[Waylon80]

Ok I totally forgot that I emailed Rob over at procut asking about the gear racks when I was having trouble the first time the gear racks are 1/4" 24 pitch.

[acourtjester]

You will need more info about the rack to buy a replacement gear. There are 2 common gear types in the US 14.5 and 20 pressure angle gears this has to do with the shape of the gear tooth and they will not mix 14.5 is the older type. Other things like diameter determine the number of teeth and effect your ratio for steps per inch calibrations. Simple re-calibration will correct axis movement.

[_Ogre]

in this pic it looks like your material moved, try to clamp it down

[Waylon80]

Ok I emailed asking about the pressure angle it is 14.5. So now if I can just find the right gears for a 1/4" shaft.

[Waylon80]

in this pic it looks like your material moved, try to clamp it down

I wish that was the problem lol but it's a full 4'x8' sheet and after discovering the slipping gear on my axis I'd have to say it lost step badly.

[Waylon80]

Hey will someone make my day and tell me I just found the right gears lol I found these on Amazon I'll have to check the outside diameter on the ones I got but other than that are these the correct ones? Thanks for all the help

http://www.amazon.com/Boston-Gear-Press ... th=1&psc=1

[BTA Plasma]

Slip collar will not work well with any kind gantry weight. Your best bet is to use some Loctite on the gear shaft hole. Also if you check out your motor tuning values for X and if its a direct drive your probably somewhere in the neighborhood or 1020 steps per. If that is the case the gear in the link is correct.

[Brand X]

I had the same gears on my .250/ 24 gear rack.. Want some used ones? Still work fine.. I have a few laying around.. I put a little drill point divot on the shaft, just to give a bit better bite. Along with some Loctite. It never loosened and was used about ten years..