Climb cutting and why not

Climb cutting on a shaper with feeder--safety and procedure issues. September 19, 2001

Although I frequently climb cut small profiles on a router table, I have never attempted this on my shaper with power feeder (for such items as raised panels). I am assuming that if the feeder is put into its reverse mode to feed into the direction of the climb cut, there is no way it will keep the lumber from being shot past the cutter and through the concrete wall of the shop. Should the feeder be set up to feed in the proper direction and then the lumber pushed through the shaper against the feed of the rollers? I figured it would be better to ask than experiment.

Forum Responses
From contributor M:
First off: climb cutting is dangerous. There's no way around it. You must be sure of your setup to attempt it. The material is fed through the machine with the rotation of the cutterhead rather than against it, so your assumption that it can be "shot past the cutter" is correct.

I would only climb cut materials or profiles that are particularly troublesome to cut in normal feeding mode, those that might chip and tear with normal cutting. Even then I'd never cut a large profile this way.

I donít see a reason to climb cut a raised panel profile. It's a shearing cut that usually yields a chip-free surface and my feeling is that climb cutting won't help you here. It's also one of those heavy cutting situations that are quite a bit more dangerous to climb cut. My advice: donít do it.

Climb cutting a cabinet door edge profile or a typical cabinet door stile profile can be effective. It will usually eliminate the chipping you get as the cutter exits the panel groove.

Again, Iíd reserve the technique only for relatively light cuts and even then Iíd think twice and make sure the feeder is locked down solid, the feed wheels are clean, unglazed and set below the level of the stock appropriately.

One more thing. I'd only attempt a climb cut with a heavy-duty feeder, at least a 1 hp, 3 roll.

If you think the process makes me nervous, you're right.

I once spent a day trying to learn how to climb cut using a 1hp co-matic feeder w/8 speeds and a 3hp Delta shaper. I was unable to get satisfactory results. Some people claim to do this on a regular basis. I cannot.

From contributor E:
Do not climb cut raised panels. To effectively profile panels in one pass you'll need a shaper with at least 5 hp and a power feeder. I make doors every day but would never consider climb cutting panels. The other problem of tearout on sticking profile--all you need to do is oversize your 2 1/4" stiles and rails to 2 3/8". This will eliminate that problem. I have considered climb cutting rails and stiles, not for cut quality but cutter life (between sharpenings).

Could you explain how wider rails and stiles allow you to eliminate tearout on the sticking profile?

From contributor M:
For what it's worth, we consistently reduced our chipping on stile grooves to near-"0" using climb cutting. There were also edge profiles that caused trouble occasionally and rejects here can't be tolerated since they are on completed doors. We achieved a "0" reject rate here too as well. If the part is fed smoothly, there is no difference in finished surface quality.

I can't understand how chipping can be cured by making the stiles wider. I suspect we're talking about two different kinds of "chipping".

From contributor E:
To say I completely understand why, I'd be lying, but when I explained my early tearout problem to the guys at LA Weaver, this is what they came back with. And unless the stock is really wild, that suggestion has corrected the problem.

From contributor M:
So you're simply making the rough part wider and just machining deeper?

While I am a fan of climbing moldings and the like, I consider climb cutting a raised panel too dangerous. The large surface area of the knife generates too much push. You are better off cutting in two passes, doing the cross grain first, of course.

From contributor B:
Climb cutting and back fencing are effective ways of wood processing. You need to know what you are doing and have the proper setup but they can be done safely and efficiently. I would agree that the small feeders are not suited for this operation. Raised panels are tough because of the cut size, as already pointed out. You don't need to cut the full depth in the standard feed direction on the first pass. Make three passes if necessary--this would help to minimize tearout.

I was visiting my local custom house door maker and he does all of his shaper work as a climb cut. It scared me to watch, but he told me that it is the only way not to blow out an expensive panel on that last pass. He has his four wheel heavy duty feeder set in reverse and it keeps his large work under control.

From contributor M:
Once again I'll say that not only is raised panel climb cutting dangerous, it is unnecessary. The kind of defect that climb cutting prevents is not a problem when machining nearly all raised panel profiles.

If the ends of the panels are machined first and then the edges, there is no tearout problem most of the time.

From the original questioner:
I apologize for the confusion. My original post was meant to get information about the proper way to climb cut on a shaper with the feeder. I guess panels were a bad example. I should have stated profiles in general. Are you supposed to rely on the feeder to control the stock and let it feed into the climb cut or let it feed against the climb cut and push the stock through manually?

From contributor B:
The feeder will do ALL the work. No manual help should be needed.

I too take about 1/8 off of my stiles when I cut the profile and tearout has never been a problem.

I don't see any reason to climb mill most parts. You will find that the diameter of the shaper cutters being larger than the router makes a tremendous difference. My one suggestion if you do climb mill is to make sure you have good insurance because ER trips get very expensive.

P.S. Don't get any blood on your new shaper.

The fingers don't grow back, and you only have so many toes to transplant. But hey, I can still count to 9 1/2 with both hands.

It seems no one answered the question . The feeder will hold the cut just fine. I have been woodworking for many years and have all my fingers. Many machines are designed to climb cut for the simple fact that it is the best way to cut wood. It's just that humans cannot hold against the force. Set up your feeder opposite the normal way. Tilt slightly towards the fence this time, going with the rotation of the cutter. Get your height set right, turn your machine and shaper on and have fun.

The above has it right. Set up the machine and feeder correctly and you will have no problem. We have been doing it for a long time and have had no problem. Just make sure your knives are sharp and the feeder is set up correctly.

My friend recently lost his hand to a 10 hp 3 phase shaper while trying to climb cut large crown moulding. Please be aware that climb cutting is probably the most dangerous operation in woodworking. Be safe.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
Until very recently I used only the conventional feeding direction for making rails and stiles, but eventually noted that feeding was hampered by what seemed to be glazing of the feed rollers. So I tried climb feeding, realizing that this would facilitate feed. The first time, I fed a short stock, stood back and prayed. It worked well. Then I ran my good stock and the result was the same. Again, the only reason for trying climb feeding in the first place was poor feeding otherwise. (Now I'm looking for a rubber conditioner that will rejuvenate the roller surfaces so that I can go back to non-climb feeding, which is definitely much safer.) (Jet 3 HP shaper, STEFF 2038 feeder, hard maple.)

Comment from contributor R:
When cutting mortise/male profiles we often over-width rails and stiles for the first pass through a shaper. Then if there is tear-out we edge-sand or saw a little of the excess off the molded side and re-run the profile. It does a finish cut (only a little off) and 99% of the time, no tear-out, plus it cleans off any that was there from the first pass.

Climb-cutting with a good feeder works fine with a cut under one inch. The greater the resistance from the blade, the more danger. Wide cuts such as wide molding or any cutting with dull blades or any cut with two wing-blades or an out of line set (where only one cutter edge is really doing the work) will send things flying.

When wood fractures in cut it really becomes dangerous, so climb cutting should never be done with highly figured wood, stress cracked or checked wood or wood with weak growth rings like Zebrano, cedar, lacewood, and others. Very dense woods like Jatoba and many others should not be climb-cut.

Climb-cutting panels requires pneumatic hold-down devices with proper bumpers, rub collars and sufficient weight/inertia. So it should not be done in a shop that can't afford this sort of thing.

I sure hope that the poor fellow who lost his hand wasn't feeding the shaper manually!

Comment from contributor C:
A shaper is not something to experiment on. If you're not sure, don't do it. Climb cutting can be very effective making stile and rail French Doors out of VGDF. Use a fence on the other side of the piece you are running. With the power feed rollers angled to the fence, make sure you have at least 1/4" of pressure to hold the piece down. Never walk in front of the piece as it is coming out. Always make sure the feeder locked down tight. Climb cutting works on profile cutting, s4s, and some mouldings. Not panel raising or crown moulding. Again, you have to know what you are doing.