Messages

111

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 28, 2007, 03:59:57 AM »

Thanks Ian, I don't want to put you to a lot of trouble, but overall diameter etc. would be a useful starting point. It would be nice to just build something that already works without designing everything from scratch. I don't want to use compressed air so it'll be a worm & ratchet or something similar.
From my limited experiments I find the toolplate rather restrictive and time consuming to set up. I think I would get on better with a set of tools that I can use for general purposes & quick setups. I don't envisage vast production runs of anything.

Tony

112

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 27, 2007, 08:48:01 AM »

Ian,

while we are in contact, I believe you have an ATC for the TCL. Would it be possible to have a few basic dimensions of the rotary tooplate? Also is it's centre hieght on the spindle centre?  I'm in the process of trying to come up with a design for mine and it would save some time if I knew the limiting dimensions. I've never examined one closely, but from photos it look as though the tools are retained by a wedge action. Is this so?

Tony

113

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 27, 2007, 04:38:42 AM »

Yes I can see that would be a problem, but in this case I was effectively just locating tool tips, without any other distractions. The way I understand offsets is that they are the numbers to be added to the master tool location to place the new tool tip in the same location. Obviously you don't actually want to place the tips of a front & rear tool in the same position for any other condition but zero diameter, as they will normally cut from opposite sides of the stock.

By the way, I haven't had a definitive answer to my question as to the 'front' toolpost of a slant bed lathe. Which is it?

Tony

114

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 26, 2007, 09:09:31 AM »

Hood
Further to my previous post- I spent another frustrating hour or so playing offline with offsets etc.
 
The first observation is that the x offset dro on the main tools screen seems to read diameter while the offset in the table is halved, for radial movement I suppose. ( machine is in diameter mode).
If I set tool 1 as master and zero everything ( machine co-ords etc.), do a move to say X50, Z50 switch to tool 2, touch x & z & all makes sense. I get a table offset of x -25 z -50. I can switch backward & forwards between tools, do moves, return to tool1  g0 x0 z0 and still have all readings at zero.

The difficulty is then with tool3 which is say, a parting tool in a rear toolpost. So I declare tool 3 as a rear tool & set the distance between toolposts to -100mm, say. I move to x00 z00 in tool 1, change to tool 3 & touch x & z.I rather expected the axis coordinates to go to -100, but no I get -150! Bear in mind that nothing has actually moved here, I'm just changing tools backwards & forwards. Now for the fun bit - I change back to tool1. Do I get back to Zero? No it's -50. The table offsets have remained at zero for all but tool 2 in all this.There seems to be some interaction between tool2 & 3 so it's possible to get all sorts of combinations in the DRO. You can even catch it changing it's mind now & then.
I find all of this extremely confusing (probably you do too). The answer is that you really can't switch toolposts in the current version, but it would be really useful to be able to do so.


Tony

115

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 26, 2007, 05:02:56 AM »

Hood
I've found that if I check 'reversed arcs' and specify a front tool, the code generated by the wizard runs fine. Any other combination gives silly results. This makes me think that what looks like a rear tool on the TCL is really a front tool, and I have the convention wrong. There is a bit in the Mach turn manual about 'looking at a slant bed lathe while lying underneath' which sort of supports that theory.
Still on front & rear toolposts, I'm convinced that there is something wrong with the application of offsets in the toolsetting menu. I can't yet describe it properly, but its possible to corrupt offsets in one tool by setting another in the opposite toolpost.
My son and I playing for an hour the other day, trying to make sense of it, with 3 carefully labelled tools on a toolplate. We set a master tool & jogged back and forth trying to achieve 2 front tools & one back. Anything set as front works correctly when switching tools, but as soon as a rear tool is introduced everything goes wrong. The distance between front & rear toolposts also comes into play, just to confuse matters.
I know the manual does not recommend switching toolposts dynamicly, but I think it just doesn't work. It is some time since I heard of any work being done on the Turn program - certainly there's been nothing in the release notes.

Tony

116

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 22, 2007, 06:20:59 AM »

It suddenly ocurred to me that I don't know what the covention of 'front' & rear is on a slant bed lathe. On my TCL125 the x axis goes more +ve as the slide moves up. I mostly use a tool above the work, so an infeed is going negative. Do I call that a front or a rear toolpost? I've assumed it to be rear but only in relation to normal lathes. This may be my problem with the arcs.


Tony

117

General Mach Discussion / Re: Arcs in Turn wizards

« on: November 22, 2007, 05:00:18 AM »

Hood,

thanks for the reply. Its certainly to do with the reversed arcs & rear toolpost. If I check reversed arcs & specify a front tool all is well. I haven't found a combination yet that works for rear tools.

I found the cause of my problem with the wizards locking out on V2.60 was that I hadn't re-loaded the wizards when doing the upgrade. They work just the same as the old version now.

Tony

118

General Mach Discussion / Arcs in Turn wizards

« on: November 21, 2007, 04:34:50 PM »

I've been playing with the turn wizards and have come across a problem with the OD arcs. When I set up say, a hemisphere, on the end of a bar  using OD Arc, the code generated is a G03. This produces a toolpath which goes all the way round through the work. If I manually change all the G03's to G02's all is ok. The same applies to the OD Arc2. I haven't tried any of the other arc wizards yet.

This is on V 2.52, which is on my lathe PC. I have the latest version  V 2.6 on another PC, just to play with, but I find that if I go into the wizards they won't post code and I can't get out of the wizard program.

Is it just me?

Tony

119

General Mach Discussion / Re: Front & rear toolposts in Machturn

« on: November 06, 2007, 05:10:43 AM »

Ian,
thanks for the code - it all makes sense now. I've even run it and cut a part in PVC. I did have to alter it to suit my axes, however. My x gets more positive as the cross slide moves up - I think yours must be the other way round. I also altered line 100 to a G01 move. With my current motor setup the code takes 35 secs to run, which is not too bad I think.

Tony

120

General Mach Discussion / Re: Front & rear toolposts in Machturn

« on: November 04, 2007, 12:39:35 PM »

LM2917N-8

A national device - got one in my hand.

Tony