bear with me, Jeff & all you other PM viewers, this is going to be a re-hash of much posted before.
Jeff-
It really depends what you intend to do with the shaper, and how comfortable you are with making vs buying tooling.
For slotting/rabbeting & straight heads, there is a lot of merit to indexible tooling. But if quantities and hourly use per year is low, solid body with Tantung tips will be cheaper to source. Tantung is superior to carbide for most wood except manmade board such as plywood & MDF; & tantung can be sharpened with normal AlO wheels instead of diamond.
Solid body cutters for slotting are good in carbide, because they often end up being used on plywood, but diamond wheels on the T & C will be needed to sharpen them.
After that, hand making and sharpening profile bits is how it was done for most of the first hundred years of shapers and moulders & is still viable today. Ultimately it's a personal comfort thing. I started around 1975 with a Belsaw planer and used it as advertised to make mouldings. Bought the first few profiles, then just started making my own. Other than a few carbide round-over cutters for plywood products, I have never bought another shaper or moulder profile cutter since, and make all my own cutter bodies.
An essential element of cutter body design is the geometry of the cutter approach to the work (hook angle, basically) but it can also include things like shear, how the profile is divided among knives and spurs, etc. The reason I started making my own cutters was originally parsimony. Industrial cutterheads cost $thousand$ and light commercial duty common 3-wing carbide and tantung tip cutters usually have an all-purpose geometry that is seldom ideal for the stuff I was making or replicating.
In the late 70's and early 80's, we started to get more flooring work including wideboard floors, which back then were not commonly available. I built these heads because the industrial versions of MTP (milled to pattern) lug bits and cutterheads was close to $3,000 at the time. These create a slightly longer tongue and groove, and it is parallel rather than round, for wider boards, so the tongues do not pop out in times of dryness. Ideally, I should have incorporated carbide slotters into the head; but they work as made, and all that's necessary to sharpen them is a pass across the face and occasional indexing. Of course a few years after making these, custom flooring became available everywhere at a cost less than I could buy the lumber, counting waste and offcuts.
These are insert slotters I made, they can be stacked for straight cutting up to 2" tall, or interlocked for variable thickness slots, or stacked with spacers to create tongues. Also shown are smaller slotters made with brazed carbide for narrow slots.
It is certainly possible to buy carbide or tantung tipped solid body tools with all the profile on one face. To me, the geometry is poor, and I prefer to build industrial style stacks or cutter bodies that separate functions into different spurs, cutters, and inserts for both faster and smoother cutting.
I mentioned starting in '75 with a Belsaw. Their system of holding single knives in a cutterhead balanced with various weight gibs (aluminum or steel, at various lengths) encouraged me to experiment to extremes in that machine with ever larger and more complex knives. When my Advance double spindle shaper came along a few years later, Belsaw was advertising a different version of their planer that used a 1-1/2" shaft, onto which separate heads could be slid and fixed, for making mouldings. They ran at around 4,500 rpm, so I figured the same heads would be safe for at least that rpm on the shaper. My shaper had 1-1/8" spindles, so I bushed them as you describe. They worked fine, and I still use one for large knives. However, it is somewhat difficult to balance one slot heads, so I quickly began making my own with 3, 4 and eventually 2 slots; incorporating various gib styles including the more common (compared to Belsaw) pocket and wedge gib styles.
I don't use corrugated back cutterheads mostly because they were too new and hence too expensive when I started; and have never used a typical bevel edged shaper cutter set with slip knives. Again the issue for me is not so much safety, as cost - there's a lot of expensive steel beyond the cutting edge to hold a knife in the collars; and the bevel edge steel is a premium cost. But they are an effective solution for a lot of typical work. Especially with integral ball bearing rub collar and lock edge steel for safety.
Grinding knives is a lot simpler and easier than most people imagine. The problem beoomes what cutterhead to hold it in, and what is a safe speed to run that cutterhead? Making your own, there are a lot of unknowns. I was fastidious when making early cutterheads and calculated loads, built in big safety margins, and even once calculated frictional forces for a few gib systems and "scenarios". Having gotten older and dumber, I now regress to "experience" for my own work. If you set off down this road, 2 books are useful. _Knife Grinding and Woodworking Manual_ by Charles G. Monnett, JR is a compendium of knowledge from the early 20th C about cutter geometry, grinding, and moulder set up and principles. _Chisels on a Wheel_ by Jim Effner includes more theory for modern practice & pictures of modern cutterheads. It has many relevant formulas, if you can search them out in the chapters. A basic college physics text has useful formulae.
One useful concept to grasp is that the only configuration of cutting knives that is ever in perfect joint is a single knife head on a spindle with high class bearings. IOW, a single knife head is the "perfect" set up for best work. Except that the problems are balance, and feed rate for the work. Some other posters touched on this. The point is the number of wings is only to enhance speed of feed, and perhaps balance, it has no effect, or can have a deleterious effect on cut "quality" if the work feed speed is faster than one knife cutting supports*. Of course too much out of balance has bad effects and can be dangerous however many wings.
It is impossible for me to buy most profiles off the shelf since much work here is replication. I've used this project as an example many times in the past. There are something like 9 moulding profiles of various sizes, inside and out of this window & jambs. The profiles needed to be run on a shaper since most include both a straight run and a curved run. All were cut with one knife (except a few cut with a shop made 2 wing router bit) and hand ground profiles, in various geometry heads.
Other work throughout the years before 1995, much including shaper work.
Plenty of big mouldings have been run over the years, but I have hesitated to post them because the single knife, non-corrugated heads could be an issue without experience and baseline references. I'd hate to seem blase about saying "here, this works for me all the time, just try it" Like any craft, there is a lot of subtlety, nicety, quondam calculation, and practice that are not obvious.
This used to be a good seller to other shops for kitchen bulkheads (behind the planes & section of 1860's US Treasury floor)
Another crown version.
If there is any summary here, it is that cutterhead choice depends on work and purpose. Grinding profiles is accessible and easy with a small amount of practice and good wheel choices and dressing. The choices to start might be one of the Euro kits because they are designed for shapers and with safety in mind. Or a set of conventional slip collars with a lock edge feature and ball bearing. Or appropriate size moulder heads bushed to suit. Beyond that, get a Charles GG Schmidt catalog,
http://www.cggschmidt.com/ and preferably some industrial catalogs such as Yates
http://www.yatesamerican.com/tooling.html for examples. The books mentioned would be valuable if the notion strikes anyone to "roll their own".
Shapers are dangerous machines. Besides cutterhead theory, there is a ton of stuff to learn just about set-up and guarding. I trust everyone knows at a minimum that contour work requires a starting pin. Instruction would be ideal. Full guides and fencing are even better than a starting pin. Whenever a feeder can be used, it probably should be. Carry boards are effective patterns and safety enhancers. Feeders can be used a lot more than might first seem probable. Sometimes that takes adaptation and modification, too.
There is not much out there on the use of shapers. _Shaper Handbook_ by Eric Stephenson is a good basic text & overview of the subject, and it promotes safe work practice. Almost nothing on the use of feeders, though, except that they exist. Still, not a waste of money for review and reminders even for advanced operators.
smt
*Industrial multi-wing heads are made for high speed feedrates, are installed on taper spindles, or have hydroloc collar or other centering systems, and are jointed to profile right on the machine under dynamic conditions.
