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Author Topic: Arcs in Turn wizards  (Read 8622 times)

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Offline TonyP

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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

Offline Hood

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Re: Arcs in Turn wizards
« Reply #1 on: November 21, 2007, 06:01:11 PM »
Had the same problem, I can't remember exactly what it was but I think it was related to me having the option on the ports and pins, turn options page for reversed arcs checked. I have a rear toolpost so it could be that you need it checked. Have a look in any case and either check or uncheck it and see what happens.
Hood

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #2 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

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #3 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

Offline Hood

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Re: Arcs in Turn wizards
« Reply #4 on: November 25, 2007, 04:57:32 PM »
Tony
 I am waiting on more tooling for my lathe so I have not done too much testing yet. I have only used the rear turret so far, hopefully  next week I should be getting into using the front post so will let you know what I find out.
 Have you made any progress/conclusions?

Hood

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #5 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



Offline TonyP

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Re: Arcs in Turn wizards
« Reply #6 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

Offline Hood

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Re: Arcs in Turn wizards
« Reply #7 on: November 26, 2007, 01:57:15 PM »
I remember reading recently on the Yahoo group that  Art said that front and rear toolposts weren't working correctly but I talked with Brian a bit later and he seemed to think they were. We didnt have time to discuss things and havent spoken about it since so I am not sure what the situation is although your testings seem to suggest its not working.
 

Hood

Offline DAlgie

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Re: Arcs in Turn wizards
« Reply #8 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.

Offline TonyP

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Re: Arcs in Turn wizards
« Reply #9 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