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Problem setting up an xy table onto a Lathe
« on: September 14, 2007, 03:58:54 PM »
Hi All,

Some years ago In The Netherlands there was a company named Style that sold CNC-controlled  X-Y tables that could be retrofitted
onto a conventionally Lathe, and came with its own software.

The company stopped selling these units.
I still own one of these and would like to use it with Mach3turn. 


I have fitted one onto my Lathe and found my axis being not exactly parralel to the centreline of the rotary axis.

As an exact mechanically setup of the table is very difficult to do my Question is ;

Is there a way Mach3turn can compensate for this ?

Regards From The Netherlands
« Last Edit: September 14, 2007, 04:00:52 PM by dikkieduk »

Offline Hood

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Re: Problem setting up an xy table onto a Lathe
« Reply #1 on: September 14, 2007, 04:53:28 PM »
I think you can offset your axis in Mach mill so should be possible to do it in Turn as well. It is a wizard that does it for you in Mill.

Hood
Re: Problem setting up an xy table onto a Lathe
« Reply #2 on: September 15, 2007, 11:20:08 AM »
Thanks for your reply Hood, but i don't think the use of a wizard is the answer.

One option for me, is to adjust my axis in my cadcam , but i dont like the idea of  my gcodesprograms beeing "crooked",
and therefore i am looking for an (Onetime) compensation in the basic configurationsettings of mach3turn.

Offline jimpinder

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Re: Problem setting up an xy table onto a Lathe
« Reply #3 on: September 15, 2007, 03:24:24 PM »
Are you saying that the bed of your lathe is out of line with the spindle.

If not, I take it that the table is an independent piece of machinery that sits on the original lathe bed, but it is out of square and you cannot correct it. Does this provide vertical movement so you can use your spindle to mill pieces with ??

Either way, I think it would be very difficult for Mach Turn to provide an instant solution "on the move" so to speak. The offset to be provided would depend on the distance travelled, but then if you are applying this on an out of square axis, then another allowance would be needed. If you were turning on an out of square axis, then for every 1 inch of movement on the axis you would get the cosine of the angle movement in the tool.

The only thing I can think of in a simple way is to increase the number of pulses per inch on the stepper motor drivers to compensate for the shortfall. The only problem with this is, you could correct one axis this way, but the tool would also move marginally on the other axis and I cannot think of a way to rectifiy that.

The real alternative that I have just thought of is to write a VB script to put in the compensation automaticall to compensate and this would be relatively easy for say code g0 and g1, but how complicated they would be for g2 and g3 for example, I shudder to think.
Not me driving the engine - I'm better looking.

Offline Graham Waterworth

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Re: Problem setting up an xy table onto a Lathe
« Reply #4 on: September 15, 2007, 03:28:06 PM »
Can you post a picture of the set up and indicate where the error is, we may be able to think of a better solution with more detail.

Graham.
Without engineers the world stops
Re: Problem setting up an xy table onto a Lathe
« Reply #5 on: September 15, 2007, 07:30:21 PM »
Interesting,  I am in the middle of building a setup just like this. The lathe is an old one, about 1890, with a 10 ft bed and will turn about 40" diameter. We use it to true up railroad wheels- a pair of wheels together on its axle is hung between centers. The XY table need to only cover about 6" wide and 2 " in radius to do the standard railroad profile.

Ive got the table mounted on the lathe, and we cut the last pair of wheels manually. That made it clear CNC was the only way to go. I should have this running in 2-3 weeks, complete with a wizard to do the profile.

On the original question, if you set this up as an XY system instead of the common XZ for a lathe you can set the XY rotation. Once you measure the error all you need is a G68 R <angle> line at the start of every program.

However, I would take the time to get it mechanically aligned and not try to do this in software.

vmax549

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Re: Problem setting up an xy table onto a Lathe
« Reply #6 on: September 15, 2007, 08:34:44 PM »
How is it everyone seems to work on the same thing at the same time. I am currently grafting an Emco CNC bed onto a Southbend bed to do small cnc when I need it and can remove it for the Manual bigger stuff.

(;-) TP
Re: Problem setting up an xy table onto a Lathe
« Reply #7 on: September 15, 2007, 09:56:52 PM »
And I was so proud of myself for having such an original idea. I was sure No one else had tried that.

I saw the reverse once at Eastec. A guy mounted a lathe tool on its side on a block on the table of a Bridgeport, then put the workpiece in a collet in the spindle. He made some fairly interesting small turnings that way- limited by the spindle collet size.

Offline jimpinder

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Re: Problem setting up an xy table onto a Lathe
« Reply #8 on: September 16, 2007, 05:41:03 AM »
Ron - Thanks for that, I didn't think the answer could be catered for so simply (although I have my lathe in XZ) - but I shall bear it in mind for the future if I have problems.

I do agree that Dikkieduk would be better to get it mechanically in line, rather than correct it by software.

I also profile a lot of railway wheels - but in 7 1/4 inch gauge - so I am certainly not in the same league.

Is this by way of business or a hobby/preservation thing.

Jim Pinder
Not me driving the engine - I'm better looking.
Re: Problem setting up an xy table onto a Lathe
« Reply #9 on: September 16, 2007, 05:54:09 AM »
 Ron, i would like to set the table up as XZ for a lathe .

So i am looking for an overall offset (angle) compensation, in Mach3turn mode.
« Last Edit: September 16, 2007, 09:22:02 AM by Graham Waterworth »