My Shopbot PRT Project

[donclifton]

I purchased parts to a Shopbot PRT from a fellow Shopbotter that didn't come with motors, gears, racks or frame. I built the gear head using 2 x 4 x 1/4 box tubing and delrin gears. It has a 4kw (5hp) china spindle with a Teco (Westinghouse) inverter. all the wires for the motors and controller are from Igus and are Shielded. The energy chain is also from Igus. I running Mach 3 as my control software with Gecko drives.
https://www.dropbox.com/sh/pdaks2b3ul9bl2s/odUfD9FxCe

Don

[jzarski1]

Hey Don,

That looks good. I am glad you put it all together. Do you have a link to that sheilded cable. I am having a few issues with loosing steps on my conversion. I am sure it is noise as I am using unshielded cable.

John

[donclifton]

Hi John, I have to lookup the wire I used.
Don

[donclifton]

John, I think putting a .02uF cap between your Limit switch terminal and ground will take care of the noise problem. The cable I used was Igus CF6-07-05 @ $2.14 per foot.
Don

[jzarski1]

Hey Don,

I am not getting a limit switch trigger. I am loosing steps in random places. I can run 10 sheets of just one but I get random step loss on the Y axis. On my machine that is the long axis. It's so random, that's what makes me believe noise is the issue. I even purchased a smooth stepper and have the same issue.

John

[donclifton]

I have never lost steps from noise but have from over driving my steppers. What have you got your rapids set @ and are you running a Smoothstepper or PP?
Don

[jzarski1]

I took the smooth stepper out. I could not get it to work. Keep getting driver interference problem. So I am back to the PP. rapids are set low, I think at 300 IPM with an Accel of 20.

John

[donclifton]

That's pretty fast for a PP. using my SS I can get around 1500ipm for show but I cut at about 150 to 175.
Don

[jzarski1]

I cut at 175 IPM. My rapids are set to 300. So you think the motors are the cause not noise????????? Would I be better off getting rid of the geared motors and going with belt reduction?

John

[donclifton]

If the motors are the ones that came off the machine you sold me they might be a little under powered. I think they are some were close to 260oz hold motors. I run 400 to 640 motors. No I don't thing your having noise problem with your motors just maybe over driving then on your rapids. try slowing your rapids down and see how they do. What are you using for a power supply, I would try running around 70 volts. The geckos can take 80 volts.
Don

[jzarski1]

Power supply is a 65. It was the one that the Shopbot controller was using. I will slow my rapids down and see what I get.

John

[carlcnc]

John
just some things I learned ;
If you have the issue with parallel port and smooth stepper
it probably isn't noise.
check that you aren't feeding the motors too many amps,
check that all 4 wire connections at the driver are cinched down well
a loose one can give you lost steps[intermittent torque] it can result in lost steps, which becomes more pronounced as the moor heats up, and will eventually kill a drive,
if there are any soldered connections in the motor cables, a cold/poor solder joint will act same as a loose connection.
in Mach, make your step pulse as "wide" as possible its the last setting in axis tuning I would set it at 5

good luck
Carl
ps; be sure the neg side of your power supply connects to "star" ground

[donclifton]

all good advice
Don