Mach3 and Cam Bam discrepancy

[uspl]

Hi all

I am cutting (or trying to cut )two 5mm wide profiles, each is 2.5mm deep.

The first is along the X axis, basically a trench 5mm wide, 2.5mm deep and 100mm long. At one end of the trench I have a 5mm wide arc profile, scribing a 90 degree bend that is also 2.5mm deep. The cutter is a standard two flute 5mm end mill.

When I draw this in Cam Bam the two profiles overlap by 3mm to allow for under cutting at the very ends of each profile. What I want to finish up with is a trench 100mm long that then turns 90 degrees and continues for a further 50mm along the arc. All this looks great in both Cam Bam and in Mach 3 when I look at tool paths, cut widths etc. The end result is the trench and the arc are cut perfectly but they don't join; there is about a 2.5mm "under cut" where they should join.

Any thoughts ?

[cheetahcnc]

Wouldn't you do a 5mm wide path with a narrower mill bit, so you can climb cut both sides? Just a suggestion, as the software, and machining process, might not like the large cutting contact at the radius/end.

Jim

[nate]

Sounds like cam bam is simplifying the cut. why not post the code as 2 seperate programs, run one and then the other. that way cam bam does not use any "logic" to determine what you want to cut. i think cam bam is thinking too much and has decided that you intended something that you have not...

Just a guess...

[nate]

also, what is you tool size set to? sounds like this might be a cutter-comp issue.

[uspl]

Wouldn't you do a 5mm wide path with a narrower mill bit, so you can climb cut both sides? Just a suggestion, as the software, and machining process, might not like the large cutting contact at the radius/end.

Jim

Thanks Jim

I would use a smaller cutter but my JGRO setup means that tool changes are painful and inaccurate; the rest of the job needs much bigger profiles and pockets and some 5mm holes need to be drilled as well so a 5mm cutter does all the parts.

I suspect some sort of cutter comp or inside/outside radius issue is at the heart of the problem as I also have a similar problem on another job where two trenches meet at 90 degrees and I have to force the vertical one way past where it should end in order to meet the horizontal one.

[uspl]

also, what is you tool size set to? sounds like this might be a cutter-comp issue.

Thanks Nate

The tool size is 5mm in CB and it is cutting the right widths on all my profiles and pockets, it is just the junction/overlap issue I cannot seem to fix.

I'll try your suggestion on two programs and see how that goes.

Cheers

[uspl]

0.9.8H Square pockets are squashed ovals - HELP ??

It wasn't Cam Bam, it was Mach 3 and it was something I never would have thought of.

Just like poor old HAL9000, I gave Mach 3 two conflicting instructions; keep a CV of 600mm but don't exceed the acceleration threshold. It did what it could and the result satisfied nobody.

Hope this helps some one else.

Regards

David