Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jimpinder on June 13, 2008, 01:53:20 PM
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Having taken the plunge, and set up my homing switches, I decided to become more professional , and fill in the offset table to bring various tools etc, into line with my chuck ( I am on the lathe at the moment, but the query applies to Mill as well)
I am missing something !! :-\
I fill in the fixtures table. I click select, I click save. The trouble is the entries are not constant. Sometimes they are there, other times the table has reverted to 0.0.0
At the moment g59p7 seems to be fairly constant - it is staying on the table, even after I shut down and start up again, but I did what I though was the same for g59p8 today - and after a couple of calls it had zeroed itself.
Can anyone tell me how to "freeze" the offset table - like the tool table (with which I have no trouble) :'(
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Afraid I dont have an answer for you Jim but I am curious when you would use a fixture offset on a lathe, just cant see the need for it, probably overlooking the reason though.
Hood
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I have made a drilling fixture on my cross-slide which will hold drills up to 12 or 13 mm. This is normally at a position near where the rear toolpost would be.
If I am machining a part, 16 of them as I did today, that involves centre drilling, I fit the appropriate drill in the fixture.
My g59p7 offset has the co-ordinates to bring the drill 0.0 position to the centre line of the lathe, with the drill point a fraction short of the chuck.
My G Code calls the offset, then moves the drill to x0 (centre line) z whatever to start the drilling. Once finished it can then cancel the offset, or call up the original one and carry on.
What it does mean is that I can get on with doing something else, instead of having to breakoff to do it manually.
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Isn't that what it would do if you had the tool set up in the tool offsets?
Hood
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The only thing I can fill in the tool table is diameter, length and wear.
This drill is to replace the tailstock drill, so the fixture has to move across to the cetreline of the lathe, and then move back out of the way when finished.
I can't find my camera, or I would send you a quick snap.
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Jim you set the X and Z offsets in the Turn tooltable. You set one tool up as a master (in reality its actually tool 0) and then every other tool is offset from that. I have ten tools in my turret and toolpost and if I call any of them and tell them to go to X0 Z0 they will all go to that position.
Hood
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Further to that, the tool table is actually offset numbers, I have lots of tools ready to go into my turret or toolpost. I have them marked with the slot number (1 to 10) and the offset number so my normal tool in slot 2 is marked 0202, I have another tool which is set up for that slot in offset 12 so I have marked on the tool that it is 0212, then another that is offset 23 so it is marked 0223. If I place any of these tools in slot 2 and call T02** where ** is the offset it will go to X0Z0 if I request it to do so.
I have quite a lot of 40 taper holders spare from my milling machine, they are collet holders and also morse taper holders. I have made up a holder with an internal 40 taper for my front toolpost and can put any tool into it, whether its a morse drill, a small drill or boring bar held in the collet holder. If I have all of these different tools set in my tooltable then its just a matter of calling the correct offset and everything is where it should be.
Hood
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Good evening,
I use a jig with 8 locations to repeat 8 parts with 1 prog, the work offset table co-ordinates match the pitch of the actual jig.....simple.
The code just calls each fixture......still simple.
However, I have often asked myself if the table values could be locked. ( a tick box adjacent to each of the offsets).
Because. when I need to set zero of jig position 1 but inadvertantly have another fixture location (work offset) selected, when you zero each of the axis, this resets the values in the work offset table.
If I notice my error, I correct this by just entering the correct position again in the offset table, but its cought me out more than a few times and a few broken tools.
Its driver error but quite easy get wrong.
So maybe the reason for the offsets changing is when you zero but have the wrong offset selected ?????
Mach is superb.
Derek
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Hood - Yes I understand what you mean with the Tool Table - perhaps I should have done that instead of the offsets. I think I was just in the mood to play with the offsets. I shall try the tool table. I have that set up for my quick change front tool post, with the various tool numbers in. If this drilling fixture is in effect, a back tool post, does it just mean bigger offsets ???
Derek - Yes - that is exactly what I mean. I have also spotted the fact that if I zero the DRO.s with the offset selected, it zero's the offset. I don't always spot it. I haven't broken any tools yet, but I've had to hit the stop button a few times.
Anybody tell us the answer - or do we just live with it.
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Jim, yes just bigger offsets, easy enough to do if you use the tool setting page in turn, just have a known length and dia in the chuck and then set up your new tool to it. Dont set Rear or Front in the tool table, if you have it set as default for Front then keep every tool as front as putting it as a rear tool will screw things up. The Turn tooltable hasnt worked properly for changing between Front and Rear but I have a kind of work around at the moment. I have a few weeks of messing around with it to do, different types of tools etc then once I think I have found all the pitfalls Brian is going to try and get this issue sorted once and for all.
Derek,
I am presuming you are talking Mill with your offsets?
Hood
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Hi hood,
Yes, it's the mill work ofsets.
My main 2 jigs (8 locations each) I have set up the offsets as 11 to 18 for jig 1 and 21 -28 for jig 2.
For genneral work I use G54, load the job in the vice, zero and away I go.
If by accident I zero an single job "thinking" I'm set to G54 but have another ofset selected, it overwrites the offset table with the current position.
So I try to check the work offsett table before running with the 8 way jigs and double check the toolpath.
It's down to my pilot error but I would like to be able to lock the ofset number for the particular jigs. (i.e 11-18 and 21-28)
I set up the first position of the jig with g54 selected and in the ofset table the first position is set to 0,0,0. (I'm not using home limits) all the other locations are reference from position 1. (offset 11 or 21).
I guess this is just a bit of idiot proofing ;D ;D and thats why it would help me :) :)
ATB
Derek.
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I woke up this morning with the answer.
When on "Machine Co-ordinates" the DRO shows that figure, which it gets directly from it's own internal DRO. When you are looking at program co-ordinates, it gets the "Machine Co-ordinates" and then looks to see what the active offset is, and then adds (or sudtracts) that.
The problem is we can change the program co-ordinates on the screen - but Mach must still satisfy the equation. It cannot change the "Machine Co-ordinates" so it does the only other thing, and changes the active offset.
The only way to get round this is to use an offset as a gash one, and select this first, before you change any DROs. On page 2 of Mach - Midi Alt2) there is a DRO for the Work Offset. Putting a 1 in there selects G54, which I suppose could become the gash offset.
There appeasr to be a fault in the MDI line, because I cannot get it to take G59. As soon as I type the 9, it clears. Therefore on the MDI you are limited to G54 to G58. It will take a number in the Work Offset though and select all the g59 offsets as well.
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There appeasr to be a fault in the MDI line, because I cannot get it to take G59. As soon as I type the 9, it clears.
What exactly are you meaning by that Jim? are you meaning the MDI line clears as soon as you type the 9 of G59?
Hood
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Yes - exactly that. I have just tried it again now. Started up Mach 3. I have the fixture table filled with offsets.
On the MDI page, I type in G55 - fine -up comes G55 right up to G59.
I type in G and 5 and as soon as I type the 9 the MDI line closes.
This is my office computer - using Mill. I haven't tried it on the workshop computer.
I know the G59P7 and P8 work in a GCode program, because I was using it yesterday, so I am at a bit of a loss.
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HI JIM, I just tried the G59pxx command on the MDI here and it works just fine. V3.041
For what it is worth, (;-) TP
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Yes meant to say it works fine for me as well, thoought maybe it was a limitation of a demo but removed my licence and it still worked so thats not the problem.
Hood
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Jim, I have seen similar things when I assigned hot keys to buttons other than the Default Mach. 9 on the numeric pad is Page Up if number lock isn't on, same as jog Z+.
Brett
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Just tried all combinations I can think of as well and all seem fine here.
Brett
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Yes - I was using the numeric keys above the letter set. This gives the effect I was talking about .
If I use the number pad, I can get the numbers 5 and 9 to register, if the number lock is one way (sorry I don't know which). If I toggle it the numbers don't register.
So I can get there if I need to.
Thanks Brett
;D
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No problem Jim. Thank you for helping out.
Brett