Profiling Fir

      Slower feed rates, sharper tools, multi-edge cutterheads, and very cautious climb-cutting can reduce the tearout and splintering that are common problems when profiling Doug Fir. October 4, 2011

Question
I used to run Douglas fir fairly often when I worked at a cabinet shop, but now that I have my own business, I have been trying to avoid it because of all the splintering and tearout. I have enough experience to read grain pretty well, but is there any tooling that makes running fir less of a hassle? I've been told by one of my potential door customers that it's a fir market, so I should count on doing the majority of my screen doors in fir. I'm planning on running everything with 1-1/4" cutters on my shaper. I'm leaning toward insert tooling, but the ones I've been looking at, Amana, are only two wing cutters. I realize HSS knives will be sharper than a carbide cutter, but what about 3 or even 5 wing carbide cutters - do they cut smoother than 2 wing insert heads?

Forum Responses
(Solid Wood Machining Forum)
From contributor D:
The higher the moisture content, the better it shapes. Poplar works better in terms of shaping smoothly without much fuzz or tearout. But I don't know if that's an option for you.

The carbide cutters only cut as smooth as one wing can, no matter how many (considering proper feed rate). 3 wings will work very well - good feed rate and good cut. More wings = more money and maintenance cost. A chip in one wing will leave a mark, and the other wings will not take it out. Sharping cost increases, and/or carbide replacement. Of course I'm assuming your cutter supplier has maxed out the best geometry on your cutters geared toward the softwood fir.



From contributor J:
Contributor D is telling it like it is with regard to multiple wing cutters. Nothing is sharper than HSS and razor sharp knives are what you really need to cut softwoods. VG fir is your best bet for consistent molding and profile milling. Climb cutting may also minimize splintering and tear out (but can be hazardous to your health).


From the original questioner:
Thanks for the replies. Since I have one vote for carbide and one for HSS, I guess I'll have to go with my gut. To me, a sharper cutter makes sense. Does anybody make a 3 wing insert head? I've tried searching for it with only results for panel raisers/backers.


From contributor N:
On small quantities, HSS is fine. It dulls quickly though. Either way both cutters need proper feed rate. You'll get that annoying peel up if you run too slow, or the even more annoying chip out running too fast.

A few months back I was on here not advocating climb cutting, but the fact is I do it all day every day, just on a CNC. I think fir is an exception, though, and would go through the setups on a shaper each time to do a final cut climbing. Usually a relief cut on the table saw is the safest route for removing most of the stock first - smaller rabbet cuts on a shaper blow out more. Smaller diameter cutters in general blow out more. Coping with backers is not perfect with splintery fir - we always oversize in anticipation of blow out, doing crosscuts and copes, then ripping and profiling.



From contributor R:
For nearly defect-free fir profiling, my recipe includes a stock feeder and climb cutting. It just doesn't get any better than that.


From contributor O:
After years of helping customers avoid tear-out running fir and hemlock on our moulders, my thoughts are:

a) Basis of problem is weak boundary layer between early/late growth of relatively fast growth tree.

b) Reduced cutting forces (i.e. sharp tools, slower feed rates/more wings) will generally reduce the problem, but these can be a compromise since slower feed rate causes faster tool wear, which will then increase tear-out.

c) Safe climb cutting is a proven solution. On a moulder we just climb-cut the profiling spindle and make sure the out-feed rolls control the finished profile and an out-feed guard captures flying projectiles!



From the original questioner:
Thanks. I was thinking when using a shaper for climb cutting, in addition to using an out-board fence, it would be a good idea to have a guide fence on the outfeed side to help keep the cutter from pulling the piece into itself, just in case the power-feed rollers don't hold. Is that overkill? Will just the powerfeed do a good job?


From contributor J:
The only thing that's truly overkill when it comes to controlling a climb cut is an out-of-control climb-cut. This can definitely "overkill" you. You must make it virtually impossible for any stick to ever become a spear, and then stand well clear. Is that crystal clear?


From contributor O:
A climb-cutting tool has a tendency to push the work piece away from the tool and in the direction of rotation with considerable force... So the work piece must be controlled securely for your safety, and the safety of others nearby.

On a through-feed moulder I normally recommend keeping the climb cutting portion to a minimum, and complete it with a vertical spindle so that the work piece is firmly between both inner and outer fences while fully controlled by the main (steel) feedrolls. I would not recommend climb cutting in a pushfeed moulder, because of insufficient control.



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