Messages

191

General Mach Discussion / Re: spindle encoder?/

« on: August 04, 2007, 10:49:46 AM »

I used PDMX's spindle sensor, but see now that it's discontinued. You can just use a proximity sensor for this, possibly not use a metal disc with a cutout on the spindle, but a tab. But that might just be the NO/NC part reversed, I don't know. I had big problems with interference with mine for awhile, spindle would read in the millions of RPMs, Bob Campbell suggested I use a small capacitor across the signal lead and to ground. That fixed 90% of the problems, last one was I had the signal wire going into the power supply/ Gecko/ BOB box, and the wire was close to the torodial transformer. Tywrapped it up away from the trans and all was good.
                          DaveA.

192

General Mach Discussion / Re: Help with acceleration and speed settings

« on: August 02, 2007, 08:20:13 PM »

I have a large gantry router, not controlled by mach though. It is fast, and the gantry is heavy. Don't have numbers for you here however. it uses about 600 oz/in steppers, driving a tooth belt reduction at a guess, 10:1 reduction, then this drives a 20 tooth pinion onto the rack. big difference to yours, but it also uses 90 volts, the motors got hot enough that I watercooled them. I run it over 100 hour jobs at 700 inches per min with no problems. Sounds like your motors need some gearing possibly.
                             Dave.

193

General Mach Discussion / Re: can someone recommend a decent limit switch

« on: July 30, 2007, 06:49:23 PM »

I uesd a prox switch for the X axis on my lathe, and a roller micro for the Z axis. The Z axis doesen't have to be very accurate as you are always resetting the zero for the end of the stock. The X axis, on the other hand, must be dead accurate because this is the machine's accuracy, with the tools you have set. If the X axis is not accurate then the diameters will be different with each tool you use, which is a problem for a lathe. I used a tenth microstepping Gecko drive, a .200" ballscrew, and drive it 2:1 with a tooth belt, this gives tenths of a thouasandth in diameters of inches, which is a standard lathe accuracy limit.
                                                 Dave A.

194

General Mach Discussion / Re: Mach Lathe questions/problems

« on: June 17, 2007, 01:31:05 AM »

Agreed that tool 1 is the reference tool, usually is, and Mach3 lathe is set up to do it like that as well.

195

General Mach Discussion / Re: Mach Lathe questions/problems

« on: June 16, 2007, 08:15:13 PM »

I guess I don't send it home, or to any G offset value, I just avoid that, I'm used to  Fanuc as well with no G54- 58 work offsets like the mills do. My company's OT control used no work offset really. Mach lathe has too many options for lathe I guess, which tends to confuse people. I use the Mach silverblue screen, very very nice for lathe, never have used the original one. After you set a tool up, I pull the stock out of the chuck and use the MDI line, G0 X1 Z0 and make sure it goes where you think it should. I have never used a home position on a lathe, with some strange shaped parts you can get in trouble with a fixed home position so don't reccomend it.

196

General Mach Discussion / Re: Mach Lathe questions/problems

« on: June 16, 2007, 05:42:51 PM »

The lathe offsets are tricky for sure, but it's really simple once you have had experience with it. I don't use any G code homing or work offsets in the program. I start the machine up and send both axis to home, this sets the machine position to the last set tool position. Unlike a mill, there is really only one work offset change needed, the Z axis position, that will depend on how long your part needs to be to be able to part it off when it's finished, how much is sticking out of the chuck. Use persistant tool offsets and the control will start with the last used tool. I set home with the "Set home" X and Z buttons first. Just above that is the work offset display, put Z 0.00 in the Z offset and the diameter of the piece of stock you will set your tools to in the X offset display. Put in tool 1, and set that in the tool number box as well, and jog up to the face of the material, after facing it off, and touch off on it. Without moving the tool, go to the tool offsets page and hit "Touch Z", making sure that the control has tool 1 loaded. Make sure the tool tip radius is set then as well. Go back to the jog page and do the same for the X axis. If your chuck has any perceptible runout you will need to turn a small amount off the diameter with jog mode then measure the diameter and load the number in the work offset display, before setting the X axis. Go through and change tools on the display and do the same for another, assuming you DO have a quick change toolpost. If you don't, you will have a hard time trying to do much, you have to constantly reset tools for anything you do. This is probably as clear as mud right now, ask more and I will tell more if I can.
                   DaveA.

197

General Mach Discussion / Re: Lathe offsets

« on: June 15, 2007, 02:15:31 AM »

Not much of the lathe stuff ever seems to get worked on, that would be one of them. The lathe version of Mach3 switches between diameter and radius for quite a bit of stuff, you really have to watch it sometimes and try to learn it well.

198

General Mach Discussion / Re: setting up Mach3 lathe

« on: May 23, 2007, 07:30:34 PM »

If it's something simple like a tapered part, then you should try the turn wizards. You can also use a couple of them and cut and paste the code out to make a combined part. You can also get Mach3 to write code to a DXF, however it won't rough it out, only the finish profile will be coded, which isn't much good unfortunately. This is where you will need Bobcad to post code.

199

General Mach Discussion / Re: Stepper Torque

« on: May 23, 2007, 01:31:52 AM »

Generally it's the more voltage the better, I tune this by the motor temps while running under load, some say you can go to 150F, which I think is correct. 24 volts does sound a bit low as well.

200

Competitions / Re: ******Guess and win a G100 Grex******

« on: May 22, 2007, 12:47:43 PM »

Guessing in the low numbers, say 2,233,333
DaveA.