Chipping on exiting edge

[Bob Eustace]

Trying to put 1/2" face slot/rebate in very brittle oak. Problem is tearout and splintering on exiting timber. Using a pocketing tool path slighly longer than the trench in Aspire 3.5. Is there some way of tricking the software into starting from both ends to stop this? Zero problems on the entry side. Making "fines" boxes for Rotary and they have to be spot on!

Sorry for the dumb question but I'm a mere metal machinist!

Thanks

Bob

[tmerrill]

Hi Bob,

It sounds like you are using a single pass with a 1/2" diameter bit to follow a vector line?

If so, you can use Node Editing to cut the vector near the middle and change the end nodes as necessary so they are both start nodes (green). Then select both lines at the same time and set up your toolpath, being sure the box is checked that says "Use Vector Start Nodes".

Some other things to try:

Use a downspiral bit.

Instead of drawing a line, create a rectangle the length you want but only 0.001" wide. Still set up a profile toolpath and this will bring the bit back to the starting point before it retracts. You could even take this a step farther and use node editing to place a start node on one of the long sides which would start/stop machining in the center.

Tim

[Bob Eustace]

Thanks Tim

Using a 1/4 down spiral in a pocket toolpath! Is this daft?

Bob

[tmerrill]

Sorry, that's what happens when you post before that first cup of coffee.

How are you setting up the pocket toolpath?

Have you tried raster with profile cut first?

You could also use node editing to create a start node midway down a long side and use a Profile Inside toolpath with small lead in/lead out. This will keep the bit away from the outer edge when plunging or retracting. See picture.

Tim

[bobmoore]

I don't know what your part looks like but you may just be able to clamp a piece of scrap wood to your part on the exit edge and route into that.
Bob

[Brady Watson]

Trying to put 1/2" face slot/rebate in very brittle oak. Problem is tearout and splintering on exiting timber. Using a pocketing tool path slighly longer than the trench in Aspire 3.5. Is there some way of tricking the software into starting from both ends to stop this? Zero problems on the entry side. Making "fines" boxes for Rotary and they have to be spot on!

Sorry for the dumb question but I'm a mere metal machinist!

Thanks

Bob

Hey Bob,
Just draw a line and do a profile 'on' strategy to drive the bit from the 'exit side' into the material about 1/4" or so. This will relieve the problem of blowing out on exit when you run your pocketing toolpath. Also, you may find that you have to use climb if the material is still pulling out...it's the way the bit rotates and grabs the grain.

-B