boring a tapered hole with a ball em

[cherokeechief79]

i have a pitman arm from a jeep that has a taper in it for a tie rod.to upgrade to heavier steering you have to open the taper to a larger one for 1 ton chevy drag link ends.ive done this plenty of times before but i programmed it in smartcam a looooong time ago.this program would spiral once around and then feed down at an angle and then do another complete arc and so on till it got to the bottom.i used comp on it too.i would like to redo this in mc 9 but was wondering if i could get the toolpath to do a true helix without the "zipper"line going down to the bottom.i fooled around with it a bit last nite but didnt really get the results i wanted.the taper is 7.153 deg included angle and goes roughly from about .722 dia to 790 dia at the top.

 

the easy way would be to just buy a reamer but this has always worked well for me before and automotive taper reamers are expensive.

anyone ever do something like this?

[chip]

Yes. I've cut tapers like that all the time. Mastercam has perfect toolpaths for features like that!

[cherokeechief79]

do i create a helix 1st and then follow it?do i create a surface then drive off of that(thats how i did it in sc)do i use the bore mill cycle and add the taper angle?

any suggestions?

[3R!< W3NG3R]

I would do it with a surface and use a contour path for that. There are ways to get rid of the zipper effect too.

[gcode]

Create a surface that extends above and

below the required cut by more than the radius of

the ball endmill

Draw a circle defining the top diameter

Use the toolpath Surface Finish/Blend

Blend requires 2 chains...

use the circle and a point at the center of the circle

Select Spiral in the "Cutting Method" dropdown

Use "Depth Limits to control the start and

end of the cut

[edmBosto]

I prefer to drive it off of a surface with just enough bypass. I would rough with a surface finish contour toopath starting at the top and working my way down then finish with a surface finish flowline going up and down on the Z with an exceptable stepover similar to a radial toolpath the finish is better that way and there is no zipper line as you speak of.

 

The high speed radial in X2 will also do a step over that is similar to the flowline traveling on the Z axis

HTH

[Kelly Burns]

Easiest way just do a 2d contour at the top and then in depth cuts give it your angle you want to carry thru. I do this on long internal tapered hollow pins with thin walls that a taper reamer just grabs and spins the part. Put in a wear comp and your all set to dial it in.

[cherokeechief79]

thanks for the ideas.i was hoping the bore mill cycle would do it but i guess not.(maybe its circle mill i forget)i was hoping to just plug in the deg of 7.153 and let it go.i guess ill just do a spun surface and do it that way.

this angle is also 1.5 in per ft so ill just draw it and trim it down.

the taper is already there in the pitman arm i just have to open about .025 per side to make it bigger.

 

thanks

mark

[cherokeechief79]

thanks kelly!i like the idea of just plugging in the angle without having to draw anything up.can i get rid of the zipper line with this method?

[Kelly Burns]

Not sure, I usually usually use an inserted cutter with a .030 radius (square endmill) If you set your cut depth pretty close you can get a pretty good finish. Most of the tapered pins I cut are above the 5" length and I run a rough and a finish pass on them. They take forever though.

[Chipmakr]

+1 on the 2-D contour + depth cuts + taper.

 

If you are looking for EASY this is it. I would think useing lead in/lead out and only sweeping the angle like 5 degrees would have a chance of getting rid of any witness marks.

[HEAVY METAL]

maybe overlapping the leadin/leadout would get rid of zipper?

[edmBosto]

With the flowline up and down you WILL get rid of the zipperline. For what it is worth.

Cheers

[cherokeechief79]

ok so toyed with this on fri nite .creating a cone surface gave me very unsatisfactory code even though my post is set up for arcs with z movement instead of polylines.iw would have gotten it done ok but i could never get it dne in one continuous path like i wanted.same with 2 d contour with depth cuts and an angle.what i used was the thread mill option.this was very little input and gave me exactly what i wanted.there was a prompt for the angle and the depth.for pitch i just used .003 and it spiralled down just like i wanted.the output was g03 also like i wanted.i just said left hand thread from top to bottom.

ill try to put a file up on the ftp site!

 

thanks for all of the help!

[cherokeechief79]

forgot to add thaqt the leadin and out was also very easy with this method

[robk]

Linky

[cherokeechief79]

i put it on the ftp site under tierodtaper3.nuthin too fancy but it sure worked well for me!

[Henk]

HTH web page

[cherokeechief79]

finally got to cut it this morning,

came out great.finish looked like glass!