Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: mikeyz3385 on December 22, 2010, 04:29:03 PM
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Hello,
Recently i've been messing around making threads since i just hooked up a pulse card. I wanted to move on and try my luck at a tapered thread but am having some trouble. When in the simple threading wizard, what does the taper value represent? Is it measuring an angle, depth, length? Here is my dilema. I found a piece of scrap that had a taper on it and i wanted to follow that taper with a 16tpi thread. I did some math and came up with a number i thought was right for the taper but obviously it wasn't cause it dug into the part. Plan b. I went ahead and rewrote a program for that exact taper so i was able to see what it looked like on mach 3. Then i wrote the threading part and kept messing around with the taper number till it looked like it matched the taper on the turn. My problem is what is the math formula to find that taper number instead of me guessing.
The part measurements i have are ... The taper starts from .310 and goes all the way up to .750 . The taper is 1.850 long and the wizard taper number i came up with that looked close was 21.50. Am i right? Try not to laugh as i am still only learning haha
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No need to feel silly , it's a good question never asked to my knowledge.
G76 cycle provides for a taper in one of it's parameters, but, if you post the code as G32 from the wizard , the generated code shows the beginning and end X moves so you can find which units are correct when using the wizard.
I don't know if the units are a ratio of diameters ...taper per foot...degrees ( decimal ).......whatever ........so need to check.
The manuals don't define input value and not sure it follows what is in Smid's description.
A quick look at the turn options dosen't provide a default for a taper ( i mention this because it could be a disaster for obvious reasons ) so need to confirm.
That said, I will take a look, post here, and add the info to the Threading on the Lathe write up.
RICH
BTW: M1076.MIS is the macro for threading.
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Thank you for looking into this, its been bugging me all day. What exactly do you mean by posting it as g32 from the wizard?
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If you go to Operator menu then edit button scripts when in the wizard you will see the Post Code button flash, click on it and you will see a line that says Test = False, change the False to True and your code will post as the expanded G32 rather than the G76.
Hood
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I am having no success on playing with the wizard to cut a tappered thread........it will cut a taper though! ???
There were some postings that said it would not do a tappered thread some time ago.
DAH.......nothing is ever simple and not in the hacking mood. :D
How's your recollection on this, Hood?
RICH
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Only done a few tapered threads and its not been recently so cant even remember if it was the wizard I used or not. Will have a mess with it tomorrow if I get time and post results.
Hood
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If you go to Operator menu then edit button scripts when in the wizard you will see the Post Code button flash, click on it and you will see a line that says Test = False, change the False to True and your code will post as the expanded G32 rather than the G76.
Hood
There is a different looking macro under that button on mine.
Are we to change the t - f in the 1076 macro in the M3 folder instead of the one under the button ?
Or do I have the wrong macro there ?
Thanks
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No you are correct and I am getting old and forgetful ;) My excuse other than that is I have had too many hours staring at a post processor trying to figure out what the hell I am doing ;D
Hood
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Thanks Russ, Graham, and Hood for some info on this,
The Simple Threading Wizard will do tappered threads. There are are a few things that the user needs to be aware of when using it.
I'll post a little write up on it in the future.
what does the taper value represent?
Degrees ( in degrees and in decimal form / ie; 45.218 ).........the generated code will represent an angle = to 1/2 your inputed angle....I need to see what happens if using diameter or radius mode)
So for now be carefull....
piece of scrap that had a taper on it and i wanted to follow that taper
You will need to precisely locate the cutter point X & Z location based on the wizards generated code.
I would strongly suggest you try scribbing the cutting along the taper ( and very accurately measure the tapper you are going to follow), better yet, do a scribing test for a straight thread.
If test is good for a straight thread, move on, if not, don't waste your time trying to do a tappered or multi start thread as your lathes system is not capable.
BTW, if you really want to have fun playing around and testing out your lathe, cut a tapered thread using alternate flank cutting and a single sharp pointed tool. If that works do the same
for a four start tapered thread. If that works you win the prize! ;)
RICH
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Merry Christmas to all. Rich how do i go about getting the degrees of that taper? Do you know a formula i can use. Trying the taper number of 21.5 was still actually off alittle. I also switched the wizard to post at g32 but it seems to be more of a pain to go through the lines and check all the positions rather than just hitting a button and saying a prayer. I need to buy a bar of plastic :)
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How to change the m1076 Machro can be found in the Threading on the Lathe write up , Section 7.2 / page 47.
How to set the Mach Lathe for different cut type and infeed- " " " , section 7.1 / page 44. ( not documented anywhere else i may add)
How to measure a taper: Use an indicator accurately located on the lathe center line, move along Z and note the change in X required to maintain same indicator reading,
ANGLE= Arc Tangent of X axis move divided by Z axis move ........you can use the DRO values....just one way.
How to cut a tapered thread? Haven't had a chance to write something up.............!
The problem is the wizards for both cutting just a taper and taper threading post code pathing that starts away from the end of the piece and cross the X & Z axis.
You must have that since the axis must accelerate to the feedrate requested. So you need to to be able to know how to set all up or combine the codes from the wizards. Now somewhere, i have a modified wizard from a friend which will cut a taper from where you define the small diameter and where it finishs without doing that ( if i can find it and test it as that would simplify things some), but, you still need to adjust the threading inputs accordingly. Now i will add that it depends on how one defines a tapered thread; add threads along the taper, cut a NPT ( and there as are different definitions / accuracy / formulas for an NPT thread...may as well add the Britt part to it! ).
One also needs to ask what the tapered thread will be used for.
So in time and until then if your playing around be carefull, and yes a prayer can help...... ;D
RICH
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The taper angle in your case will be:
tan-1(((0.750-0.310))/2)/1.850)
BTW, cut a taper thread only once, couple years ago, and it worked fine with the simple treading wizard.
Dan
EDIT: Ha.. ha. You're quick Rich. You posted the answer while I was typing ;)
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Happy New Year,
Have a read of the attached........
Maybe Brian or Art can shed some light on the wizards wand. ;)
RICH
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Can you rotate your spindle? cut the taper then the thread....
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TramAlot,
Normal practice would be to cut the taper first and then do the threading to the taper.
Two different programs with different pathing.
Not sure what you mean. ???
It is possible to do some "unconvention" machining.
RICH
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my machines are Sherlines, the lathe spindle rotates.
I am unconventional