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Author Topic: Taper Turn Wizard - JT2 Morse taper not right  (Read 3337 times)

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Taper Turn Wizard - JT2 Morse taper not right
« on: March 16, 2016, 04:30:09 AM »
Hi,

I have just turned a JT2 taper with mach3's taper turning wizard, unfortunately the angle is not correct and I don't know why.

If you look at the finishing cut , this is incorrect to.
My machine is set to work in mm.
Any ideas what I am doing wrong ?

 X end +12.39 , Angle +2.335 , X Start 14.2 , Z End -22.23 , Z START +0.0 , Clearance 1.0

roughing feed rate +100 , Roughing depth +0.1 , Finish Feed rate +50 , Finish Depth +.05

The final finish cut Gcode also looks wrong

F50
G1 X12.3084
G1X14.2029 Z-22.23
G0 X16.2
M5

The spec for the JT2 taper is :- small end 12.39 mm, big end 14.2 mm,  Angle  2.335

Offline Hal

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #1 on: March 18, 2016, 02:34:20 PM »
Try an angle of 1.4312 degrees.
.6/12=.05
inverse tan of .05=2.8624 degrees of cone
2.8624/2=1.4312 degrees per side for a Jarno Taper #2

Offline Hood

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #2 on: March 19, 2016, 03:09:38 PM »
I think the wizard is screwed, seems to be the clearance value that affects the final path.

I never use the wizards so have never noticed it but Mach Turn is very basic in its built in functionality, very little in the way of canned cycles and the wizards are not really the best. A while back I spent a few days re-doing a few of the wizards so I could have different tools for rough and finish and different finish amounts for X and Z but before I could take them to the workshop to try them out my hard drive got corrupted and I lost them :D
So I decided CAM was just the easiest way and haven't messed with them again.

Hood

Offline RICH

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #3 on: March 19, 2016, 09:07:30 PM »
I believe what Hal posted is correct as the angle is 1/2 of the total taper angle. Also don't recall but you may want to input out to 5 decimal places
since it dosen't take much for the taper not to be correct. Been a while and not sure if it additional decimal places will be used ( the threading wizard does use them ).

The screen could be improved some by extending the yellow line some and showing it as the alternate interior angle to what is currently shown.

Have used it to cut #1, 2, And #7 tapers and the Wizard  worked fine.

Once you get the taper right. try threading it, and if you want a true test of your lathe try it with a two start taper thread  on it. ;)

RICH
« Last Edit: March 19, 2016, 09:11:40 PM by RICH »

Offline Hood

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #4 on: March 20, 2016, 04:09:00 AM »
Meant to say, I think it is a Jacobs Taper the OP is after rather than Jarno, if so his numbers are close.
Hood

Offline Hood

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #5 on: March 20, 2016, 04:21:37 AM »
Just looked again at the wizard and if you have zero for finish feed and path, in other words tell the wizard you are doing a  rough cut only, then I think it works.
Hood
Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #6 on: March 20, 2016, 04:46:48 AM »
Thanks for all your help.

The taper is for a Jacobs chuck.

Summing up , i am a bit confused from the  reply's

Do i only need to change the clearance to zero , or also change the angle to ?

Cheers

Mark
Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #7 on: March 20, 2016, 04:51:01 AM »
Sorry I meant to say :-

set the clearance to zero and
half the tapper angle for the jacobs chuck.

Offline Hood

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #8 on: March 20, 2016, 04:52:32 AM »
No, the clearance needs to be larger than the roughing depth, it can be just fractionally bigger but it is not affecting things unless you do a finish pass.

So if you just enter the values you had above but instead of Finish Feed and Pass values you just enter Zero for them, in effect tell the wizard you are just doing rough cuts, you will then end up more or less what you want, the last pass code I get by doing that is
G1X14.2029 Z-22.23


Hood

Offline Hood

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Re: Taper Turn Wizard - JT2 Morse taper not right
« Reply #9 on: March 20, 2016, 04:53:51 AM »
Regarding taper angle , if you are set to Dia mode then the value you use will be the angle you have above, if Rad mode then I am not sure as I have never used Rad mode.
Hood