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Author Topic: My Fixtures are not "fixing"  (Read 6255 times)

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Offline jimpinder

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My Fixtures are not "fixing"
« on: June 13, 2008, 01:53:20 PM »
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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Offline Hood

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Re: My Fixtures are not "fixing"
« Reply #1 on: June 13, 2008, 02:03:58 PM »
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

Offline jimpinder

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Re: My Fixtures are not "fixing"
« Reply #2 on: June 13, 2008, 02:43:32 PM »
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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Offline Hood

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Re: My Fixtures are not "fixing"
« Reply #3 on: June 13, 2008, 02:47:18 PM »
Isn't that what it would do if you had the tool set up in the tool offsets?
Hood

Offline jimpinder

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Re: My Fixtures are not "fixing"
« Reply #4 on: June 13, 2008, 03:02:11 PM »
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.
Not me driving the engine - I'm better looking.

Offline Hood

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Re: My Fixtures are not "fixing"
« Reply #5 on: June 13, 2008, 03:06:02 PM »
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

Offline Hood

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Re: My Fixtures are not "fixing"
« Reply #6 on: June 13, 2008, 03:22:41 PM »
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
Re: My Fixtures are not "fixing"
« Reply #7 on: June 13, 2008, 05:38:45 PM »
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
You can "chop it off" but can't "chop it on"

Offline jimpinder

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Re: My Fixtures are not "fixing"
« Reply #8 on: June 14, 2008, 04:56:29 AM »
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.
Not me driving the engine - I'm better looking.

Offline Hood

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Re: My Fixtures are not "fixing"
« Reply #9 on: June 14, 2008, 05:30:44 AM »
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