Holes coming out to small with Mach3 post

[slaith]

Hello

I have a bit of an Fusion post issue, i wanted to run 8mm holes in a part to attach rare earth magnets.

But my holes come out at 7.47mm instead of 8mm.

I tried running the same with both Vectric Aspire and the built in wizard in Mach3, they all came out exactly 8mm.

I'm using a 3mm 1 flute carbide bit, there is no flex in the machine and i've run alla code twice just to be safe.

Which leads me to believe that this is a mach3 post error somewhere.

Altghought the odd thing is that the depth of the hole comes out perfect at 2.99mm, so it has to be somekind of XY error.

I use a edited Mach3 post, I have been using it before but haven't noticed any issues before.

Either I missed them or just haven't noticed before.

There was nothing majord done to it, just I have no home switches so my machine coordinates are invalid.

And some other minor things.

Did try just for reference to run a square pocket, both regular pocketing and adaptive clearing.

Both came out within 0.01mm.

I just can't see why a hole pocket would be an issue.

I'll attach the post processor I've been using.

I didn't make the modifications myself, got good help from this forum. 🙂

At the code post screen, I've set M6, M28 and use radius to no.

This is a bit of an issue of course, since it prevents me from running certain parts I need for projects.

I can bypass it by making the holes bigger and reducing the stock to leave, but that is as a last resort to me.

If anybody has any ideas, just to get the thouhgts flowing.

Please let me know.

Best regards

Patrik J 

[LibertyMachine]

Could you share the Fusion file you used to create the code?

File > Export > Save to local folder. Return to thread and attach the .f3d in your reply

[slaith]

Certainly!

I attached the file.

It's just a peice of round stock with a hole inside for testing when I discovered that somethings is up.

Thanks

[slaith]

Double post

[LibertyMachine · Accepted solution]

The toolpath you are using to make the hole larger; Adaptive. It is not designed or intended to be used as a finishing toolpath, especially for walls. Could you possibly go in with a 2D Contour or Circular operation and report back?

[slaith]

Absolutely.

I'll let you know how it turned out.

[slaith · Accepted solution]

Well I'll be damned, that actually worked!

I did circular first, that worked just great.

Turned out great at one or two hundreds of a milimeter under 8, but it was a great fit for the magnets!

The 2d contour worked just as well, although I was afraid it was going to miss in the middle.

It didn't and the magnet fit just fine here to.

Abviously this is operator error on my behalf. 

Would you care to shed som light as to what I've been doing wrong, and why regular pocketing didn't work?

[LibertyMachine]

2D Pocket is somewhat capable of bringing a feature to it's final size. 2D Adaptive is not at all capable, due to how it calculates it's cutting moves.

While 2D Pocket "should" technically give you the desired result, it's good habits to enable this checkbox in Pocket:

[slaith]

I always check the box and do at least one finishing pass.

Would you recommend doing a stock to leave with adaptive clearing and then a 2d contour just to clean up the sides?

Not so much in a curcular hole but in any pocket so to speak.

[LibertyMachine]

Absolutely. Use cutter comp if you can, that way you can creep into final dimensions

[slaith]

Will do!

I'll experiment this weekend.

Got a small batch of items I need done.

Thank you for the quick help.

I really appreciate it. 

Have a good weekend.

Patrik