[Malish]

I have to do a part that has 16 slots that are 2.146" long x 0.095" wide x 0.240 deep. One end of the slot has a 0.03" radius fillet in the corners, the other end has a ramp @ 60 degrees. What would be the best way to program the slot to end up with the ramp as shown on the picture? I attached a STEP file of the 3d model if anyone wants to try it out.

Thanks,

Tim

[SBC Cycle]

Man, that's a tough one. Do the inside corners on the ramp have to be crisp?

[Malish]

I would prefer t hem to be crisp, but a little bit of a radius from a ball mill would be acceptable.

I have programed a part similar to this manually before, but the part was 24" diameter and we used the rotary table with it. I used a flat end mill and moved from X(value), Y0 to the next X(value),Y0 and did a z move with it. I did it using incremental steps as shown below

N20 G91
N30 G01 Z-0.1 F5.
N40 G01 X-0.0652 Z-0.113
N50 X-1.986
N60 Y0.0062
N70 X1.986
N80 X0.0652 Z0.113
N90 Y-0.0062
N100 X-0.1305 Z-0.226
N110 X-1.9207
N120 Y0.0062
N130 X1.9207
N140 X0.1305 Z0.226
N150 Y-0.0031
N160 G00 Z2.
N170 G90

This works great if your on the X-axis, but I was hoping to use Bobcad to program it and not have to get the rotary table out for a 6" diameter part.

[TonyW]

Honestly to me this looks like an EDM job. Just my 2 cents

[Force]

Honestly to me this looks like an EDM job. Just my 2 cents

Your 2cents is correct IMHO either solid electrode or better still 3D wire.

[Malish]

I forgot to mention it, but the part is in plastic, so no EDM or electordes will work.

I tried the splice radial and it works, but it skims over the rest of the block. Is it possible to get the slice radial to only do the slots?

[Force]

Material aside how do you plan to mill the sharp corner....

[Machineit]

I would contact your customer and find the purpose for the ramp and see if there is another way to do them. Probably makes little sense to make them that way and if they are really necessary just file them.

Otherwise, short of standing them up and making a special extended endmill, it is not practical.

Mike

[TonyW]

Ok. Here comes something old school I've done this before and it works. Being that it's plastic should go quick. You will need to setup a rotary table at the angle you need. Then get yourself a high speed steel lathe blank, grind it to the width of the slot. Grind a cutting angle on the end of HSS bit, (Around 20 degrees) with a high shear relief. Then stick it in spindle of knee mill, lock spindle in low range, and use it like a broach bit. Work the tool up and down moving into part about .010 each swipe. Could also get and grind a broach to do this, but cheaper to use the lathe bit. I know this is REALLY old school, but hey.. it works

[jrmach]

You could do a variation of what Tony is suggesting.Tooling the same,but use the Lathe.This would be similar to how you broach internal splines in a Lathe. A Lathe in low gear will not rotate as easy as a mill quill.Also the hand wheel for the Lathe makes smooth quick work at it.The compound would be used for the cutting,the cross feed for the adjustment to dimension diameter.You would need a degree wheel for this.If you would like to explore the finer details of the set-up,let me know.

[Malish]

Thanks for the ideas guys. I think I will just program it by hand then. I was just hoping there was an easier and faster way to do it in Bobcad, but it does not appear so.

[The Engine Guy]

For stuff like that I normally use the rotary table/4th axis vertically and just use a couple of small diameter slitting saws/cutters, first one gets the sharp corners for the ramp end and the second with rads for the other end, works like a charm Only downside is making sure the cutters are well aligned to avoid any steps.

I have a box full of them dating back over 30 years, done lots of different jobs with them over the years Easy solution

I`m afraid the only easy way is to use the Rotary Table for sure

Regards
Rob
:rainfro: :rainfro: :rainfro:

[jrmach]

Thanks for the ideas guys. I think I will just program it by hand then. I was just hoping there was an easier and faster way to do it in Bobcad, but it does not appear so.

And what can you possibly do for this part,by programming by hand vs. using BoB ? ? ?

[Malish]

I will do a single slot along the X-Axis. I will place my end mill at the top of the ramp along the upper wall of the slot, offset by the tool diameter and then travel the X direction and the z direction simultanatously to make the ramp. It will leave a slight radius in the corner but that is ok. Then I will move X & Y to finish the slot and another ramp move to clear the bottom wall of the ramp out. Then I either use the rotary table to index the part 22.5 degrees or posibly use G68 to rotate the origin for the other 15 slots.

I was just hopign there was a way to import the solid model into Bobcad and mill the slots without haveing to do all this work. IT's not to hard, it's just really time consuming.

[jrmach]

OK,SO I guess that means you can deviate from print a little ?

I little time now,but I think I can point in the right direction.Thinking a 3D wireframe of the tool path you want.You will have to make the drawing taking the angle and radius of tool in account.I think what you are calling a slight radius is what I call a Scallop.So I think you have a grasp of visualizing how the end mill is going to cut.The feature I would use would be 3D Engrave.You only have to draw this once and do a copy/rotate.Tool path should be able to select all with one feature.I hope I got it right.Got to go.


BTW,,My thinking is a flat EM

[RAF.]

Would it not be possible to just machine it as norm in 3D and use feature like Rest Roughing with a Very small radius ball mill or just boundary the slope area and machine with a Very small radius ball mill. I would think there would be so little to file you probably need a mag glass to see it. And you would not even have to think Rotary Table.
Just a thought

[Malish]

So I got a single slot to program using the advanced rough, it looks pretty good in the back plot. Is there a way to copy the tool path around to the other 15 slots or do I need to program each one individually?

[RAF.]

Malish
On most my machine I can make a Sub Program of the one slot and do a rotate of 22.5 deg for the 16 slots most machines have this capability. I think it would be best to check your machine info to see how that would work for you.
One thing that I have noticed when programing the complete Geom at one time if you zoom in on the taper areas individually I can see that the tool path is not 100% to my liking with the Machine tolerance set to .0005 in the parameter. When changed to .00001 gets better but takes along time to generate Gcode.
It may be just as fast to just save the feature and Generate Gcode for each slots.
I'm posting a samples of the Gcode that can be zoomed in on at the slope areas. It is with Advanced Rough Strat and with Equal Dist Offset Strat for slope area.

[Malish]

I just did the advanced rough, used 2 step downs (0.120 each step to get 0.240 total) and 4 intermediate steps. I feel that will be percise enoguh for what I need on this part, doing the ramp as a seprate step would be overkill. It took me a bit to get the boundry to work a so that I wasn't cutting the entire part surface. I also had to upgrade to the latest release to use the rotate toolpath pattern, which is going to be handy.

I was looking into it on our HAAS TM2 machine and it will do the rotate as well, but it's a $1200 upgrade to turn it on.


Thanks to everyone for the help on this!

[aldepoalo]

I haven't read the whole thread, but this would be my approach.

1) You could create a 3D engraving tool path where the users offset for path for center line.

2 ) Use Z level finish

3) Use Advance rough

I measure a .092 width and a .06 corner radius. So Which ever tool path you use it up to you. By side note is I wouldn't program all the slots at once. I would program the 1 slot, bet it right and then create a tool path pattern to repeat it.