Choosing and Setting Up Insert Cutters for a Shaper

A woodshop owner gets advice on how to make insert tooling work properly with his equipment. July 11, 2007

I recently purchased a shaper and want to get the best quality raised panel cutter for making doors. What will give the cleanest cut, an insert cutterhead or brazed cutter? Another option is a 3 wing brazed cutter or a 5 wing brazed cutter. The insert cutter is also 3 wings. Any suggestions as to feed rate and such would also be appreciated as to what will give the cleanest cut with minimal sanding.

Forum Responses
(Cabinetmaking Forum)
From contributor H:
I don't see any difference in the two while the cutters are sharp. The inserts stay sharp longer and are easily replaced. No changing the setup to allow for smaller cutter due to sharpening. This isn't critical with the rp cutters but certainly is with most others that I use. It's cheaper to resharpen a cutter ($40+-) than replace 3 tips ($30+-each), but you can't resharpen forever either. Once you have the body, you can use different profiles in the same head, within reason. It's easy to have backup in case one is damaged. Bottom line - it's faster.

From contributor J:
I've used both and have settled on insert cutters for a couple of good reasons... First, as mentioned above, they will hold their edge longer. Probably the most important reason to me is that once the brazed matched sets are sharpened, they rarely match up like they did when they were new. The inserts will always match up with a new set... plus, if you break a piece off you just replace it instead of trying to get it repaired.

From contributor L:
Almost all new tooling in our shop is inserted, same reasons as above posts.

From contributor P:
What kind of shaper did you get? Insert heads need a good solid machine. My RP insert head is 6" diameter. When I used it in my Delta 3hp I got a lot of cutter runout.

From contributor L:
You need a shaper with a 1.25" spindle and large, heavy quill assembly to swing larger heads. More money but worth it in the long run.

From contributor T:
It appears that we have established that the insert tool is the better tool. So I will address your other questions. Increasing from a 3 wing tool to a 5 wing tool will increase your finish quality provided you can feed it fast enough. It will burn your wood at too slow of feed rates.

Let's say you are running at 7000 RPM's and a brazed raised panel cutter is 5.500" in diameter. For a fine finish we will figure a chipload of 0.030". A 3 wing would need to be fed at 52.5 Ft/min. A 5 wing would need to be fed at 87.5 Ft/min.

Something else to consider is alloy tips or inserts. Alloy holds a better edge than any carbide and has a higher tolerance for high heat. It is a very good choice for raised panels as the cross grain cuts are far superior to that of equivalent carbide cutters.

From the original questioner:
Perhaps I made a mistake by purchasing an insert cutterhead for my 3 hp Grizzly shaper. I got it with bushings to fit a 1 inch spindle. I of course ordered it before anyone mentioned that a 6 inch cutter may not run properly on a smaller shaper such as this. As for feed rate, someone else said to run it at about 12 fpm. A bit slow according to contributor T. I assume that would build up too much heat. Now what do I do? Try the insert head when I get it or just send it back and get a smaller brazed head? A larger shaper is not a possibility right now.

From contributor T:
Feed rates are dependent upon your RPMs, chiploads, and number of wings. Most shapers run about 7,000 RPM's so my calculations were based upon that and the other information you gave. If your RPM's are slower, you will get a slower feed rate.

Based on the feed rate that someone else gave you and the standard 7,000 RPM's, you would get a chipload of only 0.004", which for a cutter is way too fine. It would lead to burnished or burnt surfaces.

As to the insert tool's diameter you may be alright as long as the tool is balanced properly. The problem most people run into is on the 3/4" spindle shapers. I would give it a try. Most manufacturers will accept returns as long as you do not damage or modify the tool.

From the original questioner:
My shaper runs at 10000 or 7000 rpm. I plan to set it to 7000 rpm. As for the spindle, the machine came with interchangeable 1/2 inch, 3/4 inch, and 1 inch spindles. Would it make a difference if I ran it on the 3/4 inch spindle or 1 inch spindle? If so, I will be sure to bush it down to 1 inch and not 3/4 inch. I do appreciate the advice. I have been making raised panels on my router table for 3 years now, averaging about 30 doors per kitchen and want this to go as smoothly as possible. I used to make raised panels on a shaper at the shop I used to work at and couldn't wait till I could afford a similar setup.

From contributor T:
The actual spindle size is not the problem, but the size of the bearings used to support it. Now that you say that your spindles are interchangeable from 1/2" to 1", you might want to be careful. You might encounter vibration issues with your insert head if the bearings are not fairly heavy duty.

From the original questioner:
Just an update. I got my cutterhead today complete with the bearing, undercutter, and the necessary T bushing to make it work. I installed it all onto the 1 inch spindle on my Grizzly 3 hp shaper. I set up the new stockfeeder and adjusted the fence and then I shut my eyes and pressed the green button… It sounded pretty good so I then fed an extra panel that I had run through with the rest of the job. That cutterhead made the sweetest cut I have seen in a long time. I had my doubts with all the cheap Taiwanese equipment running it, but it worked out perfectly. Thanks to everyone who helped make my mind up to get the insert setup. Even though I paid as much for the cutter setup as I paid for the shaper. Even after running 36 raised panels, the cutter was still cool to the touch. That is amazing to me. Thanks again.