best cutting strategy for pine triangles

[ron_churches]

I have a need to cut some isosceles triangles in 1.25 x 12 Southern Yellow Pine and am wondering what you guys think would be the best way to go about it. I am concerned about tear out, as I need to have sharp corners and "jointed" edges. I am hoping to accomplish this with bits I have on hand, but the only bits I have with a 1.5" depth of cut are a well used .5" 2-flute straight bit, and a new .375" Centurion compression spiral. Any advice is appreciated.

BTW, I have a PRT 9648 Alpha with a 3.25HP P.C. router

Ron

[pkirby]

The .375" compression spiral will work great for this. I would keep the pass depth between .25" to .375" and also make the first passes in climb leaving an onion skin and then come pack and do a cleanup pass in conventional.

[ron_churches]

Paul,

Thanks for the quick reply. Any suggestion of what move speed and RPM at .375 pass depth? Also, do I need to use an allowance in the Partworks profile toolpath setup on the climb passes?

Ron

[pkirby]

I also have 4x8 PRT not Alpha but 4G w/ 3.25 Porter Cable. I run that bit at 13,000 RPM and cut speed of 4.7 ips in pine plywood with a pass depth of .375". Do a test cut, and if it bogs down or loses steps, then decrease the feed rate or increase the RPM. Also your holddown might prove to be challenging because solid wood tends not to lay down as flat on a vacuum table. Also, you don't need an allowance because the climb cut will deflect to the waste side of the cut.

[srwtlc]

Can you rotate/flip your triangles enough to nest a bit tighter and have less waste? As it is, you have two corners that will have short grain and be susceptible to chipout.

Also, in the toolpath setup, uncheck sharp corners. You'll still have sharp corners on your part, but the toolpath will roll around the corner instead of come to a sharp transition around it. I've found that this greatly reduces corner chipout for profiles.

[ron_churches]

Can you rotate/flip your triangles enough to nest a bit tighter and have less waste? As it is, you have two corners that will have short grain and be susceptible to chipout.

Also, in the toolpath setup, uncheck sharp corners. You'll still have sharp corners on your part, but the toolpath will roll around the corner instead of come to a sharp transition around it. I've found that this greatly reduces corner chipout for profiles.


Unfortunately, I can't rotate the parts. I need to have the grain running as shown. The triangles will be glued back together in the form of a square with the grain radiating from the center. Thanks for the tip on the "sharp corners".

[bobmoore]

Do you have someone local to kiln dry the yellow pine? If you are buying from a lumber center that wood will be green and could move or split after cutting.
Bob