Messages

161

General Mach Discussion / Re: I really need some help!!!!!

« on: December 23, 2007, 04:46:30 PM »

I'm going with stalling motors. See if the gib are too tight, or if you have not enough voltage for the motors, or if the motors themselves are too small. Also, turn the aacceleration down a bit, that might help you out but still is not really the cure.
          DaveA.

162

General Mach Discussion / Re: Need a little spindle encoder timing help

« on: December 18, 2007, 01:32:46 AM »

Make sure your encoder signal wires are far away from your power transformer windings if possible, the AC in the transformer will induce wild RPM readings.
       DaveA.

163

General Mach Discussion / Re: Trouble cutting accurate parts

« on: December 15, 2007, 05:48:29 PM »

I have to add, you are asking a $400 Harbor Freight mini mill, with the original Chinese leadscrews, NOT ballscrews, to be accurate within .005". That machine doesen't even have tapered gibs, it has setscrews that you load the parallel gib with, very flexible setup as the table loads go through these tiny setscrews. Maybe you need to map the leadscrews with Mach's mapping feature. Or spend the money and buy ballscrews for it.
    DaveA.

164

General Mach Discussion / Re: Trouble cutting accurate parts

« on: December 14, 2007, 01:38:25 AM »

Two things come to mind here, an 1/8" end mill is a tiny tool to ask to not flex and walk around in 1/8" thick material, and secondly, Plexiglass has horrible moisture absorbtion rates and will expand with just a small humidity change, you didn't say how big your parts are, on a mini mill can't be very big but still the stuff is trouble to keep a size with. It can also cause semi melted chips to build up on a cut surface after the mill has passed, causing size increases. Try a larger mill bit, and make sure the swarf is sucked out or something while it's cutting.

165

General Mach Discussion / Re: why is mach suddenly doing this?

« on: December 02, 2007, 11:43:41 AM »

Did you hit the E stop before the machine was finished moving so you could look at the displays?
     DaveA.

166

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 26, 2007, 08:43:40 PM »

When you set a tool in turn, make sure you set it as the true diameter of a reference diameter, for example, if you have an exact 1.000" diameter ground pin in the chuck, set the tool as 1" in diameter and don't set that as zero. A lathe always uses X zero as the center of the part. I saw a post a few weeks ago where somebody was setting X zero on a reference part diameter and set that to zero. This way you would certainly have problems with X axis offsets between front and rear toolposts.
              DaveA.

167

General Mach Discussion / Re: Lathe Threading

« on: November 19, 2007, 06:09:25 PM »

I see what you mean, and it makes sense. The case is unusual though, most machines have some stiction as this is the large surface contact areas needed to ensure rigidity. Yours must be a small machine, I imagine. There would be one drawback to the spring/ gas strut idea though. It would work for an OD cut, but if you then wanted to use a boring bar and load the cross slide in the opposite direction, the spring would be fighting you and cause all kinds of sizing problems.
     DaveA.

168

General Mach Discussion / Re: Lathe Threading

« on: November 19, 2007, 04:31:10 PM »

More often than not on this forum, guys try to make mach's backlash compensation take care of way too many machine mechanical problems, which it can't totally solve. If you have a ton of X axis backlash because you are trying to use the original leadscrew instead of a decent ballscrew, you will never really be happy. The more X axis backlash you have, the slower you will have to run the spindle while threading, and a lot of other functions as well. Note too, that there is a setting for backlash compensation speed, which may help here a little. And, when threading (screwcutting) manually, I always cut a small relief groove the depth of the thread at the end point to save the tool and to give somewhere to be able to time the end of cut, so you are not really much worse off if your backlash problems are causing this anyway. As to the use of a damper on an axis, I have never seen this used, the servo/ stepper is your damper in conjunction with acceleration/ Decell speeds set properly.
        DaveA.

169

General Mach Discussion / Re: Calculating What kind of power i need for rack and pinion 4x8 table

« on: November 15, 2007, 09:59:43 PM »

I have essentially this machine you have. It will rapid at those speeds, but with motors about half the size you have. Note that voltage is your friend when you need power with steppers, mine runs at 90 volts. Mine has some reduction before the rack, I have never counted teeth on the belt drive but would estimate it to be 10:1 reduction. I think that you will get what you want with those huge motors if you have maybe 70 volts feed to them. Apples to apples engineering you know....
               DaveA.

170

Sieg Machines / Re: Does Mach3 work with the new Seig KC6 CNC lathe?

« on: November 10, 2007, 12:39:17 PM »

Well, on page two of the PDF link it shows a Mach screenshot for the PC controlled version, so my bet would be that it does work with it