There is a setting for backlash but for it to work properly on some machines you need to be in exact stop mode. Best thing is to eliminate the backlash, comp really isnt the best solution. Just my opinion
Hood

Oh, he got me, he got me. I've been bamboozled. It's a set up. The old look, over there trick.

Just so everyone will know, that is exactly what I was going to say,........ only better.

and slower

guys I have a Dayton Router

(READ>>>> home made by some Chinaman on 20Cents per day making his wages on the parts he didn't fit into my machine - Sorry for the tears [for further background check out the CNCZONE forum and search for Dayton routers ] )

Anyway onto my question... I am trying to cut this file out (see attached) but instead of a smooth constant motion i get some smooth tool paths and some jerky cresent type movement and a lot of start stop or as I like to say SLAM/START- BANG/STOP.  I and using 300" steppers on a rack and pinion drive the motors are set to (see attached file)  the feed is mm/min(G94) and not per REV (G95) I have tried reducing the feed rate fromm 4600mm/Min (which is ok for Xmas cut outs) to 2400mm/Min but I still get the jerky overshoot cutting in some areas. ... Oh the material is an extreamly hard Polycarbonate.  If this has any bearing on the whole situation

Hi Salty,
   First things first, the code you have here will give you the shutters I think. What cam package did you use to generate the code? It looks to me like a bunch of short point to point moves, no arcs. Do you have an arc fit vectors option in your cam package?

Brett

EDIT
I didn't see a G64 to put you in CV mode either.

HEY guys it's me again,

I fixed my backlash problem, and things are working out now, but something extremely weird just happened,

The x axis suddenly stopped moving, see how if you disconnect the parallel port the computer still thinks it's connected and keeps on trying to move the axis, well it doesn't move the x axis, but it moves the other two noramlally, I don't get it, someone HELPPPPPPP

never mind, restarted the comp and it fixed itself, I still don't get it though!!!!!

Hi Salty,

This may sound daft but drop the feed rate down to 200mm/min and see how that cuts, it should cut sweet.

Chances are it will cut it just as quick.

Graham.

Brett,
 
        Thanks for that I had to have a look to see what G64 (CV was) and I will try this to night, the program I'm using is MC9, you might have noticed that the file is a 3D shape and Mach3 originally didn't like changing from G17 (x-y cutting plane ) to a G18 (X-Z cutting plane) it kept claiming the start of arc is different to end of arc in previous line, even when I-J incremental mode was changed.  (if you want the DXF or MC9 file I will post)

    So I re-drew the shape and made it a spline instead of a chain. then re-analysed the tool path and this is the result.  (note: the mold that the sunnies sit on thru which I suck the vacuum was cut using the same point to point style of programming [cutter was 3/8" ball mill with 8% overlap at 4600mm/min ] the only difference between then and now is that I have changes spindles from a Ryobi 2Hp router to a VFD 1.4Kw high speed spindle - I wonder if the spindle frequency is interferring with the steppers??)

Graham

     I did notice that cutting at 4600mm/min took 1M43S to cut and at 2600mm/min only took 3Sec -- so to get this clear in my own head (this could take a while ) ....is you theory that the router won't try to accelerate to full speed at the same time as it's trying to slow down?? 

ONE OTHER POINT OF NOTE...       Last night I tried to get a video of the cutter in action, but for me to set up and start filming I reduced  the speed using the FEED RATE OVERRIDE and upon dropping the speed to 20% of 4600mm/min,  it did as advertised --cut slower.. but it  also kept the chunky action at the end on each line or direction change... (that sudden start stop).

I wonder if its worth trying to reduce the acceleration and/or max speed to ensure a softer start and more constant run speed...... but then wont Brett's G64 do the same thing, Find out the answer to these and other intriguing questions in next weeks exciting episode of the day in the life of a Dayton Owner VTIC

Hi Salty,
   I would like to see the DXF. I may be leading you astray with the G64. That will smooth a point to point program however, Graham is one of the G code Gurus. I'm certainly not. If this program ran to your satisfaction before I would think it should now.

the only difference between then and now is that I have changes spindles from a Ryobi 2Hp router to a VFD 1.4Kw high speed spindle - I wonder if the spindle frequency is interferring with the steppers??)

Hmmmmm, this is interesting. How are you driving your spindle or sending the varying voltage to the VFD? I had another member call me yesterday with some interesting problems with his VFD.

Brett