Coping on a Shaper

For large quantities of base shoe and cap, coping ends on a shaper could be worth the setup expense. Here's a discussion of the fine points. November 10, 2006

We have a very big paint grade trim job coming up. The base cap detail will be coped throughout. Has anyone tried cutting a cope profile on a shaper? The general idea is to set up a tenoning-type jig with appropriate hold-downs and a reverse profile backer board, etc. Cope a couple hundred 6' or 8' lengths on one end and put a scarf joint on the other. Any thoughts?

Forum Responses
(Architectural Woodworking Forum)
From contributor W:
Great idea. I once had to do a number of copes on site in a large quarter round. I bandsawed and then sanded them to fit on a spindle sander. The one problem you may face is backing up the molding to avoid blowout.

From contributor J:
It seems like you would spend more on the shaper cutter than it would be worth, but I have seen a tool for grinding the cope into crown. You see it advertised in all the books and the bonus is all you have to do is make a pattern with your jig saw for whatever profile you need.

From contributor I:
I think it is a great idea and I don't see why you need reverse profile backer either. Why not just a flat backer? The only place that tearout would even show is at the very top of the cap. Even if the back side of the cap is back relieved, you'll get solid backing top and bottom, and only the top matters anyhow. Go for it! And while you're at it, mill the ends of all your stool on the shaper, too.

From contributor P:
I have done this quite a bit, and it works very well. Yes, you will spend a few bucks on a reverse profile knife, but with an efficient setup, you will fly through the copes. What I found most helpful was a near perfect backup board. If you can, keep the tear out on the back, but that may not always be possible unless you want to make two sets of knives. What worked for me was to make a negative cast of the profile. That being part of the backer, you'll have zero clearance and no tearout. Bondo works okay, but a cast made from West System epoxy with the correct filler worked like a dream. It must be clamped tight to work. I cut several hundred copes on a very detailed cherry crown this way. Not one problem.

From contributor W:
Or if the reverse profile knife is accurate enough, just use it to run a profiled backup piece out of stock thick enough to back cut so it in turn is not shattered by the knife.

From contributor I:
I am confused as to why you need to make a cast of the profile, or any special backer. The first pass of a vertical wood fence through the cutter will put the exact profile on it. And he can freshen it up whenever he wants by just sliding it in a little more. He only needs one profile for base cap - one cope on whatever end he prefers. There is always a door somewhere when dealing with base cap to start square and end square. And if there is no door to get into the room - who cares if it's got base cap or not?

From contributor H:
On most cap moldings, the cope leaves a very fine point on the end. I'm scared just walking from the saw to the room, let alone having a bunch all cut in a pile. You normally need to back cut copes. You also need left and right cuts, which would require a second setup. Hand coping a cap molding isn't a big deal. With a large job, you'll get good, fast and be able to do it in just a few strokes. Typical cap molding has an S curve. You make three, basically straight in, relief cuts, top, bottom and at the interchange of the curve. Then you just cope out between. I doubt that it takes a minute even with hardwood.