Shaper Cutter Choices

A small shop owner who has just purchased his first shaper gets advice on his cutterhead options. December 1, 2005

I own a one-man custom furniture and cabinet making shop. I've just purchased my first shaper and I'm very pleased with the step up from a router table. I have a 3 HP General International with interchangeable spindles and 1/2" & 1/4" collets. I also got a 1/4 hp power feeder.

I've done a number of test cuts using router bits and they came out just fine. I also built a raised panel door (poplar R&S with ultralight MDF panel) and it worked fine. As I look to the future and building a stock of shaper cutters, I'd be interested in comments on my strategy, and/or specific recommendations.

It seems to me that a very common usage will be straight cut and/or rabbeting, so I thought a good rabbeting cutter would be in order. I do a fair amount of work with teak, so I'm looking at carbide (already have carbide knives on my jointer and planer, having eaten up my share of HSS knives). In particular, I am very impressed with the insert rabbet cutter head from Inifinity. I like the reversible replaceable carbide knives and the fact it has 4 spur cutters as well. The only downside is, with a 4" diameter and 2" height, I won't be able to drop it all the way into my table (max 1 1/2"), but all things considered, I figured for those occasions I need less than 1/2" high rabbet, I can throw a 3/4" melamine "sub-top" on the table. Does anyone have comments in general, or on that specific cutter?

I have a number of Jesada and Infinity router bits and they are very, very good. An addition to the strategy question: for many cutters there are a number of different options - bore, cutter diameter etc. depending on manufacturer, and sometimes even from the same manufacturer. My thinking is, in general, if given a choice, go with 1-1/4" bore and largest diameter head. If I understand correctly, a larger diameter head makes for a shallower entry/exit and cutting angle, which makes for a smoother cut and less tearout, yes? And the larger bore means less chance for spindle flex?

My second purchase would be for one of those multi-insert heads. CMT, Freud, Elite, Dimar all make one. I'm leaning towards the Dimar because it's available locally, and reasonable priced. Again, 1-1/4" bore, 3-5/8" diameter and 1-1/2+" height (and CMT has a number of 2" knives as well that fit). I would get a few different profiles that would be common use kinds of profiles. The head is aluminum, although a number of the makers offer steel as well, and the knives are HSS. Carbide doesn't seem to be a reasonably priced option for this scenario, so if I have to run this set on teak, I'll just have to live with the dulling. Does anyone have any thoughts or comments?

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
You might want to look into a dual angle cutterhead - maybe a 12-20 degree or similar angles. Use the 12 when you have tearout problems. You should expect less footage off the 12 degree. Use the 20 degree for everything else (longer footage). That way, you are covered in any situation.

From contributor B:
We all have such different needs as woodworkers its hard to recommend what shaper cutters to buy. I have a powerful shaper with a large powerfeed on it but I still use my router table a lot. I find my router table to be easier to set up for the smaller cuts that router bits make and I have a lot of special featherboard designs that hold small moldings against the fence and against the table in ways that a power feed is just too clumsy for. The large motor on the router has plenty of power for even my largest bit so I donít see any gain in using my shaper for them.

I let my work dictate what to buy. If I land a job that requires an operation that would be best done with the shaper and with a cutter that I donít have, thatís when I buy new tooling. The shaper is a must in my shop for cope and pattern door frames as well as panel raising. I canít advise you on the shaper heads because I run most of my crown molding and custom molding on a planer style molder. They are very fast to set up and the power feed is built in and always set up. Since you said that this is your first shaper, be aware that operations that require you to run material on a bearing are some of the most dangerous operations in woodworking. Be careful not to come up shorthanded.

From Dave Rankin, forum technical advisor:
From what I understand about your post, I would not recommend the use of a corrugated head at this time. It sounds to me like you would like to stay with the more common profiles. If this is the case, I would look into LRH, Freud, CMT and this type of tool. The other choice is to use a Universal insert head and have custom knives and backers made. For your application, I think that the standard cutters will meet your need.

From contributor D:
If you consider buying a rabbeting head I suggest that you buy a design where the knife is vertical in the head. There are designs where the knife has a shear angle to it also. I tried using one of these to joint the edges of stock for edge gluing panel blanks together. The problem is that the shear angle causes a slight convex shape to the edge of the lumber and makes it impossible to get a tight joint at the surface of the panel, not to mention a flat panel, and causes a weaker joint.

I also have a problem with the use of aluminum heads. I have a tendency to over-tighten set screws in my cutter heads and I worry about the stress over time on the threads of an aluminum head. In the absence of torque specifications, I wonder if there is a risk of eventually tearing away the threads on an aluminum head?

From the original questioner:
To contributor A: I'll give the multi-angle approach some consideration, but at first glance it appears it may be overkill for my limited needs.

To contributor B: I will still have a router table, but as you said, I expect it will be just for the very small stuff. And I do expect to purchase special need cutters as the requirements surface. But I'd like to have a lightly stocked inventory of common profiles, thus the universal insert cutter-head approach. Regarding your comment about bearing/rub collar use, what would make that more dangerous than the shaper with a fence, or router table with bearing use, other than the general increase in risk due to the normal shaper vs router table considerations?

To Dave Rankin, forum technical advisor: I did look at the corrugated and others, and as you said, a bit more than I need, I think.

To contributor D: I don't plan to joint (I use my jointer) but find your comment interesting. My experience with my big rabbeter router bit with the shear angle has been good, particularly with a veneer edge. However, the Infinity cutter I referenced above (and just noticed CMT makes virtually the same one) does have a straight vertical cut profile, but I'm guessing the spur cutters take care of the clean line on veneers. Regarding the aluminum head, I share the concern. Also, I always thought that momentum was a good thing - evens out any stress bumps, kind of like a big flywheel on an engine. However, thus far in my research and discussions, the consensus seems to be the aluminum is not a problem, as long as you don't strip the screws, and the lighter weight is an advantage on a smaller shaper, such as my 3hp.

From contributor B:
On the issue of the danger, when you are running with a fence, a power feed is typically used which covers the knives and becomes a guard. When running on a router bits bearing, the cutters are relatively small and the wood being removed is small and the cut is more easily controlled.

However, when you start running shaped raised panels, you have a very large diameter cutter that is removing a lot of material. Panels can sometimes blow apart and the operatorís hands can move quickly towards the panel knife. There are a lot of tools on the market to make that type of work safer and I recommend using them. Back in the old days we just pushed the bare wood panel onto the bearing and made the cut. Some of us got cut. A friend of mine lost his whole right hand.

From contributor E:
I would definitely stick with carbide for the MDF and HSS for the solid wood. We run both carbide and HSS knives per profile. We run a lot of the same profiles (as opposed to shorter runs) in both MDF and different species of wood. We tried all carbide and had breakage in hard knots, etc. We find we get more production and therefore for our money this way. As well, we use 12 degree heads for hardwood and 20 degree heads for softwood and MDF. Again we tried every other idea we could think of to save money but this is what we came back to. With all due respect I am a little confused about the gentleman who runs a Weinig grinder. I read on his web site that the 12 degree for hardwood and 20 degree for softwood is a myth. In the Weinig books that I have they say that every species of wood has it own cutting angle and that they lump the woods into the two cutting angle (heads not knives) categories. I run moldings five to six days a week and I do this the Weinig way and I find that the two different angle heads (or a dual angle head that was mentioned) works great. I tried running everything at 20 degrees at first and sometimes it worked and sometimes I ended up wasting a lot of wood and time.

From contributor A:
To contributor E: I wanted to comment on your post about your confusion. Salesmen for years have sold customers who were milling all hardwoods all 12 degree cutterheads, and all the customers who mill softwoods 20 degree heads. My point is that you sacrifice footage with 12 degree heads, as well as throwing away the 12 degree knives long before you do that with 20 degree knives. You also suck up about 15% more horsepower on your motors. Some customers have small horsepower motors and kick the circuit breakers with bigger cuts. If the 20 degree hook angle works with no tearout, all is good. If not, you have the option to switch hook angles. But to say 12 degree for all hardwoods and 20 degree is for all softwoods is truly a myth. Poplar is a hardwood and I have never used a 12 degree cutterhead on this species.

From the original questioner:
To contributor B: I suspected that's what you were referring to. While I'm not really afraid of any tool in my shop, I have a very healthy respect for all of them. I was actually a bit afraid of this new shaper, but with some use that too is subsiding into a very healthy respect.

To contributor E: Thanks for your response. My situation is very limited runs, so doubt I can justify the leap to the more specialized equipment. I'm probably looking at something that is less oriented to industrial production, and doubt I would have the luxury of specifying cutter angles.