Messages

291

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 10, 2016, 09:30:44 AM »

Russ,
I didn't realize your drives were AC powered, I was thinking the trandmsformer was for a DC power supply which would have needed filter caps.
The shielding I was speaking of is cable shields. If your machine has cable carriers to the moving parts and they contain signal wires along with motor cables and neither are shielded that could be a problem.

292

General Mach Discussion / Re: Control inputs - active low/high?

« on: July 09, 2016, 08:06:50 PM »

Good electrical practice is good practice CNC or not. I build waste treatment plants, always have to think "if it fails what would be best?". So high level float switches are always wired normally closed

293

General Mach Discussion / Re: Where are tool length offsets referenced from?

« on: July 09, 2016, 08:03:40 PM »

Good for you!

294

General Mach Discussion / Re: Am I loosing Steps, and what should I do

« on: July 09, 2016, 08:02:26 PM »

Surprisingly nice looking construction. Ferrules on the wires is very good. Drives should have been mounted with heat sinks vertical but my Leadshine drives don't produce much heat. I see a toroidal power supply transformer which is good, but where are the filter caps located? Hard to see how the grounding is done. You should not be concerned about earth grounding. That's a safety issue if not connected but not a control issue. The way the grounding is done inside though is very important. All grounds from every device, circuit boards, drives, motors, etc. must all come back to one ground bus by individual conductors. If any ground wire is connected to multiple devices that is bad. It is hard to tell if any wiring is shielded cable. Cable shields if they exist should only connect at one end, typically at the panel ground bus. However if they are already connected to the case of a device like a motor that is grounded to the frame then they should be insulated from ground at the panel end. If cables for devices like limit switches, signal wires to drives and such are not shielded they should not be bundled with spindle or stepper motor wires but should be separated as far as possible. Last thing. The USB cable may have a shield connected at both ends. The PC has a ground wire to the power source, and the machine has a ground wire to the power source, making a rather non-obvious ground loop that often causes problems.

295

Mach4 General Discussion / Re: Procunier Tapping

« on: July 05, 2016, 12:48:15 PM »

When I looked at G-code and didn't see a canned cycle I thought you were programming by hand. If you are using a Cam program then the subroutine method is of no use.

296

General Mach Discussion / Re: Where are tool length offsets referenced from?

« on: July 05, 2016, 08:29:15 AM »

I played with tool offsets in Mach 3 over the weekend, it has been awhile.  It looks like experimenting from the diagnostics screen give you the best information about what is going on.  As I thought the tool offset actually occurs when the next Z move is commanded not when you call G43 H(tool offset#)  Also the manual is a little confusing, seeming to say that offsets can't be negative. But reading closely the H number can't be negative but the offset can.

297

General Mach Discussion / Re: Where are tool length offsets referenced from?

« on: July 04, 2016, 10:44:35 PM »

No I never did the part. It barely fit in the machine and the flanges were the easy part.  The interior had to be machined too, and down inside at a depth of over 6" was a 6" diameter internal thread and a tapered seat! If we did try to machine it the whole operation from roughing to thread milling would have to be done completely blind. I think they finally realized this was beyond us and sent it to someone with the right equipment.

They hired a new machinist that was very good, and we got a second machine. I continued doing all the programming, until they replaced me because  they said I was too slow. Funny part was I wrote 4 times more programs than we actually ran, because there simply wasn't enough machine hours to do all the work they were sending to us!

298

Mach4 General Discussion / Re: Procunier Tapping

« on: July 04, 2016, 02:05:03 PM »

Way too much work. Use a G85 bore cycle with the Procunier. G85 is modal, call it once then make the rapid moves to each hole location. Cancel after last hole with G80. When I programmed manually I would put all my hole location rapid moves in a subroutine. Load spot/chamfer drill, G81, call subroutine, G80, load tap drill, G83, call subroutine, G80, load tapping head, G85, call suroutine, G80, done. If the spot drill went all the right places so did the drill and tap!

Don't program manually much anymore, I use CamBam instead.

299

General Mach Discussion / Re: Where are tool length offsets referenced from?

« on: July 04, 2016, 01:37:31 PM »

Once tool length offsets have been entered, and a length offset has been applied for a tool, then ANY tool can be used to pick up Z zero.

What hasn't been mentioned is that after loading a tool you need to call G43 H(offset #) to apply the offset.  Can't remember when it actually gets applied, an immediate Z move or on the next Z move. To cancel the offset use G49. Be careful doing this! Canceling an offset with a long tool still in the spindle can be really bad!

Bit of a funny story about this process. I was hired as a machine designer at a machine shop. A few days later they fired the machinist running a Fadal 4020. They asked me if I could run it as I had a little CNC experience.  Sitting in the machine was a great big valve casting with a flange on top that needed to be milled, drilled, and backfaced too. There was a 1" wide slot already milled into face of the flange. I asked another machinist what the slot was for?  He said "He does that for every job. That's the Z zero finished surface where he sets off all the tools." Oh yeh he understood tool offsets, Not!

300

General Mach Discussion / Re: Where are tool length offsets referenced from?

« on: July 03, 2016, 01:27:55 PM »

By the way, unless you have really accurate homing switches, or pick up home from an encoder index mark, using the machine coordinates is pretty much useless except for soft limits.  I only implemented limt switches on all axis to prevent a hard crash against the end stops. Mine are simply wired in series and connected to a hard wired E-stop circuit.