Plasma/router table build progress

[mcArch]

I've posted some of this project in another thread, but I think I may have maybe hijacked Lamicron's "Plasma table construction in progress" thread a little, Sorry lamicron, did not intend that, Pete Stenebaugh has been very helpful with this too. These last few photos did not make it into the last post in that thread.

Issues I'm thinking about are thc, how important is it?, extreme accuracy of parts is not critical, cutting like 14ga. to 3/8" material with plasma Miller 625.
The machine is also meant to mount a router to & use to cut wood, foam, & plastics.

Still working on the low cost end bearing mount for the threaded rods & the ball screw on the z-axis. I am thinking of adapting a tapered bearing set for the thrust bearing for the one end mount of the ball screw (Z-axis) & for the 3/4"10 acme threaded rod on the X & Y axes. Also, the synchronization of the Xaxis drive rods I have not nailed down, thinking of using a chain & sprockets. Would a bicycle chain & sprockets have too much play in it for this use? how about a chain from like a garage door opener? I suppose that if the tolerance is +/- .003" or so, or the added backlash between this chain/sprocket plus the threaded rod/nut is +/- .004 or .005" it would be ok. ??

[scrambled]

now that is a big piece of round stock to use for the x axis!!! I love it. Bigger is always better.


Keep up the good work



Steve

[mcArch]

Well, I figured I could not go wrong, & I has those columns sitting in my stock racks here for about 7 years, so, they'll work, nice & stiff, & keep it simple.
thanks.

[mcArch]

The X gantry is rolling on the 3 1/2" pipe rails today. The y rails at the top of the x gantry are deflecting about .030" (with feeler guages) under the preload of the tensioners, see pics. You can see a little light between there.



I will have to fabricate a tension rod truss piece for underneath these 2-1/2" pipe rails to take that out. Other than that, it is rolling very smoothly. I wanted to make the end connections adjustable so the checking & wracking due to moving the table around & welding could be calibrated & it's trussed to keep the weight down.

At first I located both adjustment bolts (both the compression pipe & the two 1/2 threaded rods) on the lower end where the rollers are, this allowed the roller bracket to twist under its own weight ever so slightly.

I realized I should have welded the compression pipe at the lower end to take out the moment stress & put the adjustment bolt at the top. It is much stiffer this way.







More next week

Cheers.

[mcArch]

We've got the machine running now, the x only chugs along at like 12ipm cutting with the 3/4" dia router bit, have not turned the plasma on yet, next couple days will tell that. We had to do some fine tuning with our low cost bike chain drive, the sprockets are really too thin for alignment, but we were able to make the vinly lined guides & use a spring loaded tensioner underneath that just lets the chain ride on a small section of 1" pipe. It seems to work ok for now. We got another 400ozin motor to slave the x with on the other rod, but we didn't get the mount bolts aligned well enough yet, then the keyboard or something must have hit the y motor drive & it got toast, so we unhooked the x-slave motor that we got & used that driver for the y & was able to get it back up & running at the slower speed at least. We still have to make an enclosure for the electronics, a better table surface for the monitor/keyboard, & a cover for the plasma while it's in router/dust mode. The threaded rods could use dust covers too.

We have a problem with the limit switches falsely tripping in Mach though, we could not get it to stay reset, so I just turned it off at the switch & it's working ok, just have to watch it like a hawk in case something goes wrong. I'd like to get that resolved, but have no idea what else to try, have tried all the stuff the mach manual & FAQ's suggest, nothing helps. We have all the switches set up where the circuit is closed until tripped, maybe that's backward? I cannot figure it out.

Working well overall, cannot complain for what we have into it . . . still lots to do, but I think it can produce at least.

I have a couple short videos (.mov's) about 1mb or so, but I cannot figure out how do knock the size down to post them here in the zone, I can email if anyone is interested.

[mcArch]

Much thanks once again too everyone on CNCzone, the info here in the zone is really great & has been a tremendous help in our building this table. Here are some of the first pieces done with the plasma setup, I'm still switching the plasma on by hand with a remote switch I mounted by the computer . . . still trying to figure out how to control it w/ Mach3.

Is anyone using Probotix drivers & controller? I am trying to figure out if I can use one of the pins to control the torch on/off on a plasma setup. I will have 3 axes with 2-motors on the x axis. Motor A will be slaved to the x. Anyone know if there's a way to use one of the home/limit switches(typically an input pin) for an output to control the plasma on/off? Also, how would I do it? with a relay, & how do I figure what specs I need the relay, amps/volts?

On another note, I think I don't quite have enough torque on the x drive with just one motor. When you lose steps, does it sound like a toruqe limiter in a cordless drill? and the motor keeps trying to turn but the rod does not? My solution is to add another motor to the other drive rod & slave it to the x motor. You can see in the one photo if the circle where I lost X-steps, I have to listen to it & when I hear it start "grinding" I give the chain a little pull, I think it's just not enough torque on that axis. Really bites to have to try to re-align it & re-run the program.

Motors: 400oz/in steppers, bipolar parallel, 4 wire.

[millman52]

Originally Posted by mcArch Much thanks once again too everyone on CNCzone, the info here in the zone is really great & has been a tremendous help in our building this table. Here are some of the first pieces done with the plasma setup, I'm still switching the plasma on by hand with a remote switch I mounted by the computer . . . still trying to figure out how to control it w/ Mach3. Is anyone using Probotix drivers & controller? I am trying to figure out if I can use one of the pins to control the torch on/off on a plasma setup. I will have 3 axes with 2-motors on the x axis. Motor A will be slaved to the x. Anyone know if there's a way to use one of the home/limit switches(typically an input pin) for an output to control the plasma on/off? Also, how would I do it? with a relay, & how do I figure what specs I need the relay, amps/volts? On another note, I think I don't quite have enough torque on the x drive with just one motor. When you lose steps, does it sound like a toruqe limiter in a cordless drill? and the motor keeps trying to turn but the rod does not? My solution is to add another motor to the other drive rod & slave it to the x motor. You can see in the one photo if the circle where I lost X-steps, I have to listen to it & when I hear it start "grinding" I give the chain a little pull, I think it's just not enough torque on that axis. Really bites to have to try to re-align it & re-run the program. Motors: 400oz/in steppers, bipolar parallel, 4 wire.

I know nothing about Probotix drivers & controller & haven't heard of them.

Typically if you are going to slave a second motor to the same axis, In Mach there is a simple setup to slave the 2 motors together. you need a seperate driver to control the slaved motor & the chain from side to side isn't needed (& probably not desired as it only adds friction to overcome).

Yes if a motor is stalled from not being able to overcome weight/friction it will sound like it's wanting to come apart.

My on off controls are worked through a remote relay (table imput output) card. Mach turns on then off the relay to operate your torch with a MO3 & MO5 command respectively

[mcArch]

Millman, what is the relay driven from? Does the relay card run from the breakout board?

[millman52]

In my case I have a THC from www.candcnc.com the relay card is mounted at the table & hooked to the back of the THC using a 25 pin straight through parallel cable. The THC box sits beside my computer.

Since I know nothing at all about your system maybe a look at this relay card. Then look at the pdf wiring diagram for the card, might help get you started in the right direction. http://www.cnc4pc.com/Store/osc/prod...roducts_id=148

I'm not saying this is what you should buy merely that it is similar to most relay cards. Almost every manufacturer has some sort of solution for switching optioinal equipment on & off.

Can you post a link to the probotix drivers break out board etc. It would help if I knew what you have to work with.

[mcArch]

Here's the link to the breakout board I'm using:

http://www.probotix.com/breakout_boards/pbx-2/

Len is the guy who designed them & owns Probotix, he designed it to work with Mach3.

& here's the driver board that I'm using for all 4 motors:

http://www.probotix.com/stepper_motor_drivers/SideStep/

I'll take a look at the links you sent, thanks.

I got the X-axis working, you can see the "A" motor on the left side under the monitor, it's slaved to the X, I had found the slave setup in Mach3. I just took the chain off. "A" lost a few steps a couple times but I finally got it working pretty well, lots of adjustments on that left side (bearing preload & motor/shaft alignment). I have gotten 15ipm so far, haven't tried it faster yet, probably will step it up a little tomorrow.

Len also has a relay board there,
http://www.probotix.com/relay_boards...l_relay_board/

I'm just not sure where it would connect to the computer system, since I am using the A-axis motor where that rbx-1 relay board would normally connect, plus that Miller Spectrum 625 trigger signal is I think a 5v signal, not sure the amperage in the signal. Right now, I just have a remote wire run to a switch just like my limit switches (rated at 5A/125VAC) so I can switch the plasma on/off by hand.

Overall I can't complain, I do have nearly 48x96 cutting area & a full 16" in the z. My X is at 94.25" right now, but I can move the limit switches a little & get it to about 96.5".

[millman52]

Your best bet is to contact probotics tech help on this one. At a quick overview of the wiring schematics for the Probotics boards I can't really advise you what to do. I would think there would be a way to connect the relay board in addition to running 4 drivers.

[millman52]

Upon further research on installing a relay bord with your system. You'll have to install a second parallel port & additional break out card + the relay board. all together less than $100.00.