Problems with erratic cutting on my PRT with 4G

[terryjones]

The picture you see here is my second attempt to cut this file without success. The first attempt, the lines were in slightly different locations than the second. The middle pocket file cut perfectly along with the rope, v-carving text and the cutout. I just can't seem to get the carving tools file to look good. I have checked my power with an electrician and the 3 phase converter is producing balanced power to the spindle and vacuum blower and at the proper voltage. The pinion gear set screw is tight. There was a slight bit of end play in the z axis which I reset the eccentric nut to where I could not turn the guide wheel with my fingers. I will be glad to send the file for anyone to try if they like to help me diagnose this frustrating problem.


3870

[pwbell]

Any chance of a loose or dirty Collette? My Z value changed several times as it looks like here. I found a very dirty Collette with packed saw dust preventing a proper tightening. Good luck!

[terryjones]

Thank you for your thought but the collet is new out of the box. All other cuts made with this collet and other 1/4" bits are perfect.

Terry

[ken_rychlik]

Terry, what is it designed in and how does the preview rendering look? How long of a file is it? If it's not to big I may run it for you. I have a prt 4G with router.

[ken_rychlik]

The closer I look at it it seems like cut is moving back and forth. left to right. Check your pinion gears and make sure the set screws in them are tight.
Kenneth

[terryjones]

Kenneth,
Thank you in advance for your quick response.
The design is in PW (#11157) Get Carving Quickly; Included with all new ShopBots, I believe its the 5-Business Sign, it is 61808 lines of code.

All pinion gear set screw are tight. I checked those last night.

Terry

[cnc_works]

Looks to me like you are missing steps on at least the z axis and the horizontal axis. The z is getting deeper and the horizontal is shifting to the left. It is unlikely to have anything to do with the collet because that would only affect the z movement. The fact that it occurs on two axis that we can see makes it less likely to be a binding issue causing the lost steps. The error appears cumulative to me. I would be checking grounding issues and RF generation (though issues that I thought were RF in the past have either gone away or diminished with proper grounding) also perhaps data transmission on the usb. At any rate, electrical of some sort. Is it only this file that you are having trouble with?

Donn

[ken_rychlik]

I have an old version of PW that I don't use. I went with vectric stuff. Fast and easy. Considering it is a demo file, I am thinking the file is fine. If you can't move the machine around when the motors are locked in, Donn may have the best solution.
It also wouldn't hurt to drop the springs on the x and y motor axis and see how smooth everything rolls without the motors engaged. Just unhook the spring tension and swing the motor down so the gear is not touching the rack. Mine rolls glass smooth that way. For the Z you can pull the motor mount bolts and slide it up and down by hand as well. Does it have the spring upgrade to help fight the gravity of the motor weight?

The file is not to big to run, but I think it is more of a machine issue rather than toolpath.

The offer still stands about running the file, but try donn's ideas and check over the machine for smoothness first.

Then email me the toolpath if you want me to run it for you.

Kenneth

[jamesgilliam]

Terry, I would have to agree with Donn also. I have a prt without the 4G board and it does look like you are loosing steps. What are your move speeds? Even with the board upgraded you could be cutting too fast with the multiple changes in speed a file like this calls for.

[terryjones]

I have run numerous other files, cutting about 30 different letters in 3 different fonts. I have made a sign for a company that I designed in Aspire without any hiccups at all. My machine is grounded as per the ShopBot manual, the gantry moves smoothly in all directions.

The middle pocket file cut perfectly along with the rope, v-carving text and the cutout had no flaws at all and none of those areas even needed sanding.

With all that said, I am thinking it is that carving tools file that is corrupt. ShopBot is sending me a new CD to try.
Donn so far this is the only file I am having trouble with.
Ken I have sent you the files and I will do what you suggest with dropping the springs.

Terry

[ken_rychlik]

I got the file. I sent you a response. The beginning of the file shows the move speeds as 5,5 I think thats the trouble.

You could probably get by with 5 inches a second on the x and y, but the Z can't handle that kind of diving speed.

[cnc_works]

Ken, I agree, 5,5 is definitely high. Even on the x and y if they were trying to keep up with that speed on a 3d file ramping and acceleration could well cause problems. That being said, if Terry is successful at cutting similar files with the same settings, all bets are off. Good luck!

Donn

[terryjones]

Kenneth,
You are exactly correct!! The file cut perfectly. The CD "Get Carving Quickly" after reviewing the entire CD is written with those high values on all projects. Sorry I didnt not get back on the forum to imform you to good news last night. I had shut everything down electrically due to tonadoes and lightning within 5 miles of the house and gather my family to seek cover in the center bathroom of the house for about an hour. Everything is fine here, it all moved north to Mena, AR.
Thank you everyone for your input and today I will call ShopBot to let them know the software is written too fast for at least the PRT.

Happy Easter,
Terry

[ken_rychlik]

Thats Great news. I have only been running mine a few months and can't believe how fast things are comming to me. It's pretty cool being about to help someone far away solve a problem.

Happy Easter

[erik_f]

You could check your usb speed also with the speed check in the control software.