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Author Topic: Lathe Tool Compensation Is there a better way??  (Read 12517 times)

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Offline tjhj

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Lathe Tool Compensation Is there a better way??
« on: January 15, 2010, 04:55:43 PM »
Hello All,
I have a 7x14 lathe and I feel I am dealing with tool changes the really hard way. So any advice or suggestions is really appreciated.

Ok I have a Quick Change Tool Post.
So attached is a picture to help explain if I am not using the correct terms.

If my tool post is always set at a Angular offset of 0 ( 90deg to the work piece) A standard offset can be made for each tool in the X and Z. This works in my mind.

Now if the tool post is anything other than 0. Lets say 30 deg. It happens alot for me to be able to work on larger pieces.
The X and Z offsets really become a triangle depending on the angular offset. Now I cant really find a good way to measure the angle of the tool post accurately in order to just do some math to find the new tool offset and get an accurate result.

Do you all just touch your tools every time you put a new tool on the post?
Does anyone use a Electronic Method of touching off the tool post?
There has to be a better way to set this up that I am missing.


Sorry the pic has all the chips I am mid project with many tool changes, hence why I am questioning a better way to do this.

Any suggestions are greatly appreciated.

TJ

Offline Hood

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Re: Lathe Tool Compensation Is there a better way??
« Reply #1 on: January 15, 2010, 05:12:47 PM »
Suppose the only way, other than touching off each time, would be to set up the tooltable with all your tools at all the different angles you use them at but obviously that would require you to be able to repeat the angular movement.
This is not a normal problem in industrial CNC lathes as they tend to have turrets with multiple tools and if a tool needs swapped for another the locating is accurate enough just to replace and then call the offset for that particular tool in combination with the slot it is in.
 I have often thought about doing something similar to the industrial tool probes on my lathe but just never got round to it as its not the easiest of things to do and certainly way harder than on a mill.
Hood
Re: Lathe Tool Compensation Is there a better way??
« Reply #2 on: January 15, 2010, 05:18:16 PM »
You would have to  be able to accurately and i mean accurately be able to locate the toolpost at an angle of say 30 degrees or whatever.

Then if you had tool one in the post at 0 degrees and you the turned the whole post that would then that tool would become a new number.

You would set all your tools from the master tool as is the case now.

So theoretically possible, but impractical IMHO

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline tjhj

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Re: Lathe Tool Compensation Is there a better way??
« Reply #3 on: January 15, 2010, 05:34:55 PM »
Ok thanks all,

Yep so there isn't really a good way.

If only I had a spare 50grand for a nice big lathe with a turret on it...  :-\

TJ

Offline Hood

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Re: Lathe Tool Compensation Is there a better way??
« Reply #4 on: January 15, 2010, 05:44:49 PM »
Dont need 50grand, mine only cost £300 :D fair enough I've probably spent another £1000 after that doing the retrofit LOL

You could probably design a setup similar to what you would use in mill to touch off to automatically enter your offsets but it would need carefull placement on a lathe and really needs to be retractable. Because it needs to be retractable it has to have an accurate means of positioning it, which in itself is not easy. Add to that the tools can be a long way off in two axis it would really require you to do the initial positioning of the touch off routine manually before you let the macro do its thing.

Hood

Offline tjhj

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Re: Lathe Tool Compensation Is there a better way??
« Reply #5 on: January 15, 2010, 05:52:34 PM »
LOL,
I payed more than that for my 7x14........

Im kinda stuck on how to isolate the tool from the work electrically. With out compromising the integrity of the lathe. Plastic has its ups and downs....

I was thinking about using some form of a paint or rubberized spray on, like that spray on electrical tape, it probably wont last forever, but should easily be touched up. On the tool holders them selves or the tool post.

Maybe a hard enamel type paint.

TJ
Re: Lathe Tool Compensation Is there a better way??
« Reply #6 on: January 15, 2010, 05:57:54 PM »
Similar to Reply #4
http://www.machsupport.com/forum/index.php/topic,11244.0.html

Or you could maybe make 1 special tool holder block with an offset to the rear for the larger parts.
RC

Offline Hood

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Re: Lathe Tool Compensation Is there a better way??
« Reply #7 on: January 15, 2010, 06:09:48 PM »
You dont need to insulate the tool, your probe has the insulation. I made up a thing for setting tools manually, its a piece of 75mm dia steel bored out to 50mm and in that a piece of delrin which iteslf is bored out and finally another piece of steel in that which protrudes out further. I have two small holes bored in the metal either side of the delrin and can fit a small circuit board with a battery and LED, when I bring the tool up to the frnt piece it will light the LED on contact and is extremely repeatable, I could I suppose write a macro to do the offsets automatically but at the moment I just press the buttons to enter things manually.
 What I do is I chuck this up, take a facing and dia cut with the master tool, fit the LED board and zero the Z of the master tool by touching off the end. I measure the dia with a mic and it should be whatever dia my master tool was already set to as I never change it. Next index the turret and manuall position the tool to touch off on Z and enter via buttons and DROs  into the tooltable, do the same for the X, then the next tool etc etc etc.
 Could be done in a similar fashion by just turning the dia and measuring with each tool but it would mean lots of wasted material if replacing lots of tools and also the Z would need feelers to get set correctly.
 The ideal situation for me would be to have this "probe" mounted on a slide so I could position it accurately and that way I would never need to do the initial turning and could then semi automate things, maybe one day...... ;D

Hood

Offline Graham Waterworth

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Re: Lathe Tool Compensation Is there a better way??
« Reply #8 on: January 15, 2010, 06:25:33 PM »
The other option is to make tool holders that hold the tools at 30 degrees and keep the tool post at zero.

Graham
Without engineers the world stops
Re: Lathe Tool Compensation Is there a better way??
« Reply #9 on: January 16, 2010, 07:04:13 AM »
http://www.mcmaster.com/#garolite-sheets/=5eckdn


This works for a strong, insulating packing material....Grade G-9