Safety and climb cutting
Safety issues involved in climb cutting with a shaper. January 21, 2003
A friend of mine makes high-end house doors and climb cuts everything that goes through his shaper using power feed. I know that to get a decent finish with a router I have to climb cut first or I may ruin the whole affair. How many of you also climb cut using your shaper?
From contributor R:
I climb cut everything I don't freehand. It's no big deal - you just have to be careful.
Climb cutting is a great technique for certain kinds of cuts under certain circumstances. It can also be extremely dangerous when used indiscriminately.
The problem with climb cutting is that if everything is not set up perfectly, then it's possible for the work piece to be forced from the shaper at great speed by the action of the cutting tool. Of course this is possible under any circumstances, but far more likely to occur when climb cutting.
Climbing through a heavy cut (large profile panel raising operation for example) is, in my opinion, not desirable. The cut is so heavy that itís easier for the cutterís action to overwhelm the feeder, causing the work piece to become a dangerously fast-moving projectile.
In any case, a large heavy feeder should be used, all feeder settings should be carefully checked and operations that remove large amounts of material may just not be good candidates for climb cutting.
You should be an experienced shaper operator to use the technique. Any advice to use it without a clear description of its dangers is, in my opinion, inappropriate.
Freehanding and curved work with power feed should always be done via conventional cut. Climb cutting is great for delicate and sharp detail profile that any chipout will impair. Light cuts are the ticket, as heavy cuts can be near deadly. Sometimes I do final clean-up with a climb. Sometimes my first cut is a climb only. It's experience with the shaper that gives you the edge. The only firm rule with a shaper is safety.
A coworker of mine who had 5+ years experience with big 10hp shapers lost his hand in one doing a climb cut. This method is no joke - please be very careful.
I have always had excellent results cutting any species with very squirrelly grain if I take a cut of at least 1/8". The cutter head seems to cut way ahead of what would be tearout if taking a lesser cut. In my shop, we never climb cut with shapers.
If you have a hefty shaper with large cutters, no climb cut would be needed. Smaller shapers with small cutters go slower, and have more vibration. You are more likely to get tearout on some woods. I do an 1/8" deep climb cut on the first pass to prevent tearout on something like stile and rail cabinet doors. Never do any climb cut free hand. When doing curve work free hand, use several different size bearings when making deep profiles, or you may just watch your work shatter.
Climb cutting with a shaper is like falling off a nine story building - it concentrates the mind wonderfully.
From contributor R:
Where is the danger if you use a power feed? Might be hard on the drywall! But seriously, you have to take care when setting up the power feed.
From the original questioner:
That's my take - as long as no one is in the line of fire and using power feed, what's to lose? It does bring to mind the 30 degree backbevel doors we used to do 30 years ago. I used to cut that back bevel on the table saw and the garage door behind me would have these sticks shot like arrows right through it.
We used to do a lot of climb cutting with a power feed. Mostly for grooves and rabbets in square edge doors. Here are some tips to avoid climb cutting and throwing sawdust and fingers on the floor.
A heavy duty shaper does make a better cut. Use the shaper like a molder and take the whole edge off. Do this by using the fence like a jointer or an outboard fence. When doing grooves or rabbets and it is not possible to take the edge off, we have found the Leitz insert rebating and grooving cutters with spurs make a really clean cut without climb cutting.
Power feeders don't contribute a lot to free handing curved parts. In addition to good heavy uty shapers, be sure you pay attention to sharp tooling.
Jon Elvrum, forum technical advisor