Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: marktaft 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
-
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
-
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
-
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
-
Meant to say, I think it is a Jacobs Taper the OP is after rather than Jarno, if so his numbers are close.
Hood
-
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
-
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
-
Sorry I meant to say :-
set the clearance to zero and
half the tapper angle for the jacobs chuck.
-
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
-
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
-
Here is a screenshot of what I entered and the last pass highlighted.
Hood
-
I'll check out the Wizard based on diameter and radius modes with and without a finish cut and see what the backplot
of the code tells me.
Will post the results here.
Hopefully sometime today,
RICH
-
Ok just ran it again but this time I looked up the specs for the Jacobs, the length is 22.352mm (0.88in) where you had 22.23
So if I use the value of 22.352 then I can use the finish pass and any clearance and get a very close value to what it is meant to be, see screenshots, with different clearances.
Hood
-
Fooled around with the OD Taper Wizard a little.
Code generated was fine if in RADIUS lathe mode, but, I got some mixed results when checking it out if in Diameter mode.
So need to do some more checking. I'll post a link to a document that will be in Members Doc's explaining it all.
Be carefull when using the wizards as some do not work for both lathe modes. Don't remember which ones though.
RICH