Messages

211

General Mach Discussion / Re: Out of round holes

« on: September 24, 2012, 09:19:42 AM »

What does a Harley drive belt look like?
Hood

It's about 1-1/2 wide and 3/8" thick....and very expensive when you have one custom made that is 20+ feet long.  It's the drive belt Harley Davidson used on their motorcycles.  Koike is using a flat roller drive with a stainless steel band on their smaller waterjet machines.  I would have thought that the drive rollers would slip, but they said they don't slip until they exceed 6 ft/lbs.  I suppose if you hit 6 lb/lbs of torque something has gone wrong anyway.

212

General Mach Discussion / Re: Out of round holes

« on: September 23, 2012, 07:48:42 PM »

Actually, roller chain is zero backlash as long as sprockets are tight to the shafts and chains are slightly tensioned.  Belts, unless use as a primary (motor to final drive), have too much flex.  You can have backlash just from belts stretching.  The commercial plasma machines that use belt drive use something that looks like a Harley drive belt.  With the holes he posted a photo of, the backlash should be easily detected by tugging on the axes with the machine turned on.

We just serviced a router with rack and pinion that had the same issue.  A set screw had come loose on the Y axis pinion.  You could feel the backlash by tugging on the Y axis.

Looks like a router.  Ball screw would be the best option.  Ball screws are hard to use on plasma machines because of the cutting speeds needed. 

213

General Mach Discussion / Re: RAPID TO STOP AT A WHOLE NUMBER (How To)

« on: September 22, 2012, 09:08:25 PM »

That function would have to involve the planner to be able to deaccel to a known point.

If you can change the jog speed on the fly, then you can write your own planner.  You have a current position (123.654) and a known point (124.000).  All you have to do is write a loop to decell and stop at the known point.

If I really wanted to pursue something like this, I'd write a simple for loop and see if you can decell the jog speed on the fly. (Hint for the OP)

214

General Mach Discussion / Re: RAPID TO STOP AT A WHOLE NUMBER (How To)

« on: September 22, 2012, 01:10:30 PM »

Don't know if it would work unless I tried it, but I'm thinking a custom jog button that when pressed triggers the OEM jog function, but then when released, looks at the current position compared the next highest or lowest whole number and ramps the jog speed down and stops at the target number.  You can change the jog speed, just don't know if you can do it programatically and on the fly.  You'd have to ramp from 100% down to 0 in a for loop.   What you'd be doing is decelerating to a target point. 

215

General Mach Discussion / Re: Plasma conversion

« on: September 21, 2012, 07:07:18 PM »

rrc1962
I am interested whether my thinking was correct or not in that copper would need higher currents. I just thought this going on my welding experience but thinking about it plasma likely doesnt really have to heat up the material like welding does so possibly there is no problems?
Hood

We only cut light gauge copper...like 20ga.  I just use the same setting as CR steel.  Copper does conduct heat better than steel though, so I could see how on heavier gauge copper a little more current may be needed.

216

General Mach Discussion / Re: Plasma conversion

« on: September 21, 2012, 09:42:45 AM »

Plasma will cut anything that conducts electricity.  Copper produced a lot more smoke and mess that steel though.  0.7mm is some thin material.  You'll need to have your feedrates up around 160+IPM.  Some mills can't move that fast.  Can you sub the job to someone who has a plasma table?  You could also build a small XY table pretty cheap.  For a few small parts now and then, I wouldn't even worry about a THC.

Keep in mind, most, if not all of the the Chinese plasma cutters use HF arc start, and that cause all sorts of havoc with your CNC electronics.

217

General Mach Discussion / Re: Cutting Ht.

« on: September 18, 2012, 09:49:02 PM »

Any chance you can get Jonathan to pay you a visit.  Some hands on training would do you a world of good.

218

General Mach Discussion / Re: Disable jog on only 1 axis.

« on: September 17, 2012, 09:33:25 PM »

If it is just required during setup could you not have some VB in the Start button that would look to see if the axis is inhibited and then if it is either ask the operator to enable or do it itself?
Hood

That could work.  Just automatically turn off inhibit on X and/or Y prior to running a program, then turn back on when the program ends.  Thanks for that tip.

219

General Mach Discussion / Re: Cutting Ht.

« on: September 17, 2012, 09:22:35 PM »

BobCAD is not the best program to use for plasma.  You should be setting your initial cut height after piercing, but after that the THC takes over.  Since BobCAD is not really designed for plasma, it doesn't have a lot of the capabilities specific to plasma.  You can get around that by building that functionality into macros, then just post the macros.  SheetCAM has most of that built right in and is WAY easier to use than BobCAD.

220

General Mach Discussion / Re: Get a pierce but no axis move

« on: September 17, 2012, 09:02:00 PM »

With the A40 I can tell you that if it's piercing and not moving, it is because it has no arc transfer signal.  That could be a problem with the THC, could be you are piercing too high or could be you have too much pierce delay.  You won't need any pierce delay on material less than 3/16".  The arc OK signal from the plasma passes through the THC, so I'd go down that path.  The issue raising up during a cut would also be a THC thing. 

.09 on the pierce height is too low.  We pierce all day long at .2" at 40 amps.  When the consumable get worn I may have to drop to .18.  When you pierce real low, you just blow slag back on the tip and waste it.  What are you cutting?  How fast?  How much current?

You need to hit up ProCut for some support.  They took your money.  They need to figure our why it's not working properly.  It may be an issue with the table or it may be something you're doing wrong.  Without knowing their product, it's difficult to make that call.