Messages

191

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 20, 2013, 07:33:21 PM »

The little hydraulic intensifier at the heart of this drawbar is the coolest design I've seen for a Belleville drawbar solution:

http://www.sdmfabricating.com/LOD.html

That intensifier plus one small air cylinder is all you need.

Regards,
Ray L.

192

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: January 20, 2013, 06:26:06 PM »

If anyone's interested,Ive just made power draw bar for my tool changer,used a stack of belvilles,a 20mm spring collet ala tormach.
 To power it I used 2  50mm dia 20mm stroke air cylinders in parallel,with a bar joining the 2 piston rods, that in turn operates on a pivoted crank arm giving a 3-1 advantage,its got loads of power I can plough a 18mm dia ripper 10mm deep through ali at 250mm pm no problems no slip, good enough for me and most folks I guess ?

My first attempt was a large stepper with a 1.5mm pitch lead screw operating the 3-1 lever I had micro switches, and a logic circuit controlling it.All i can say is it cost me a fair amount of time and money and never really worked reliably, and even with all that mechanical advantage it never really had the grunt.I would advise from my own experience don't go down that route!
 

Tony

Sounds like a very reasonable solution.  By my calculation, you're getting on the order of 1500# drawbar tension (assuming some frictional loss) - not enough for really maximum retention on a TTS holder but enough for many/most machines.  A leadscrew I would not expect to work well - the frictional losses in the screw/nut will kill you. 

I've got a new PDB design I'm building now that will be REALLY cool, simple, cheap, and tiny - even smaller than the impact wrench PDBs.  It's already been proven functionally.  But, it's top-secret for the time-being, because I plan to sell them.

Simpson better get cracking on his ATC! I'm already working on my second one, for my new machine!

Regards,
Ray L.

193

General Mach Discussion / Re: W2000 & Mach?

« on: January 19, 2013, 12:25:51 PM »

I ran my machines for years on an ancient 540MHz/512KB machine.  Never had a single problem that could be tied to PC performance.  The only way to know if it'll work is to try it.

Regards,
Ray L.

194

General Mach Discussion / Re: Vise placement/reference?

« on: January 18, 2013, 01:50:00 PM »

If working with a vise, you will, most of the time, find it most convenient to do your CAD drawings such that the left rear corner of the blank is the drawing origin.  If you're doing a long piece, and it hangs over the end of the vise, get a "vise stop" which will give you a sold reference against which to align the stock, so your origin can still be at the top-left corner of the stock.  There are nice stops which mount to the vise, and to the table.  I made myself one like this:  http://www.edgetechnologyproducts.com/pro-stop.html  It's one of the most useful tools I've made.

Regards,
Ray L.

195

General Mach Discussion / Re: M code for e-stop

« on: January 17, 2013, 04:37:34 PM »

There is no M-code for E-stop, but you could create one in VB.  Not sure why you'd want to though....

Regards,
Ray L.

196

General Mach Discussion / Re: Five Axis

« on: January 16, 2013, 11:09:14 AM »

Where a machine homes is strictly a matter of personal preference, because it really doesn't matter to the operation of the machine.  There is no "right" position for home, except, arguably, for the Z axis home should always be full up.  Most machines have X/Y/Z homes at one extreme of travel.

Regards,
Ray L.

197

General Mach Discussion / Re: 3d 2 1/2d cam program

« on: January 10, 2013, 11:16:20 PM »

Look at SheetCAM - www.sheetcam.com

Regards,
Ray L.

198

General Mach Discussion / Re: Macro generated GCode hesitation

« on: January 10, 2013, 06:11:21 PM »

Why not simply use G2/G3?  What you're doing will be very slow, because you're generating lots of very short, straight lines, which is a terribly inefficient way to generate any circular move.

Regards,
Ray L.

199

General Mach Discussion / Re: 2 flute vs. cutter , plastic

« on: January 10, 2013, 03:51:51 PM »

You won't get a clear surface, no matter what tool you use.  After cutting, pass a flame over the cut edge to melt it, and it will flow into a glass-smooth, crystal clear surface.  But, too much, and it'll catch fire.

Regards,
Ray L.

200

General Mach Discussion / Re: Ebay 4 Axis USB CNC Controller?

« on: January 07, 2013, 02:30:07 PM »

I have not used the card, but by looking at the top-left corner of the board, it seems to be a DC-DC boost or step down add-on module, I don't think it's a good design, may cause interferences or skipping steps, you can check it out with seller, most likely they know nothing about the board.

Not sure what you base that on....  There is not a reason in the world a switching converter like that cannot be used on that board without any problems whatsoever.  Those things are now absolutely trivial to design, and work extremely well.  Getting missed steps as the result of using that kind of converter would be a sign of monumental incompetence on the part of the designer.

Regards,
Ray L.