Increasing Shaper RPM for Use With Router Bits

A discussion of modifying a shaper to work effectively with router bits, versus shop-rigging a router table or integrating a router into a re-purposed shaper bed. February 14, 2010

Has anyone out there increased the speed of their shaper to maybe 15,000 rpm or more so it would be more appropriate for small cutters? I use router bits in my 3 hp shaper every so often (especially for simple/small edge details or when duplicating a molding when it doesn't pay to grind a cutter). 10,000 rpm is not good enough. I do not want a router table bouncing around the shop - I already have three shapers. Not only that, but a router table setup can cost more than a cheap shaper. I know there is a safety issue involved, but if a guy doesn't know what rpm is appropriate for the cutter, than he shouldn't be using the shaper. And no, the side table of my tablesaw will not work - I have a support column in the way. Any input will be greatly appreciated.

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
Do you know of any woodworking machine that turns at 15,000 rpm? I don't think the bearings will handle the speed and heat. You will eventually cook the bearings. Anyone who has tried to run a router bit in a shaper learns quickly that 10k is not fast enough. Grab a piece of 3/4" plywood and mount your router to it. Clamp it to a table or even your shaper if you want to use the power feed. We haven't used a real router table in 12 years.

From the original questioner:
Yes I do - a router. Whether or not it would cook the bearings is a question for a technician, I suppose. I would never allow anyone in the shop to rig up a router that way. My question is whether or not anyone has modified their shaper to increase rpm. In your case the answer is simply "no."

I think this is a problem worth pursuing. Most shapers with replaceable spindles come with router collets, so someone must be using them. If a manufacturer sold a shaper with high rpm potential, I think it would be a huge success.

From contributor O:
Donít know if it is possible to modify your existing shaper, but most late model European shapers can run at those speeds. Martin, SCM and some of the others can do up to 12000 RPM. Plenty fast for a router. Some of the newer HSK equipped ones might be faster. The trend in shapers now is to be interchangeable with CNC router tooling. Felder has an optional router-shaft for their shapers that turns 16000 RPM.

From contributor J:
My two concerns would be cooking the bearings and the possibility of bending the shaft. Shaper cutters have their cutting force exerted laterally since the shaft runs through the cutter and is supported on the top and bottom. A router bit is only supported on the bottom with the collet and I would be concerned that at a higher speed the shaft may not be designed for the centrifugal force and lateral force that would be exerted with a high speed router bit running at proper speed. As mentioned in an earlier post, some companies are engineering shapers for high speed router bits; I suspect the shaft support and bearings are engineered a bit different than a regular shaper. I may be wrong.

I have the router collet for my shaper (a Grizzly) and find when I do use it that a really slow feed rate gives me good results. Have to match the feed with the spindle speed and bit size. Yes, I do get the occasional burn, but that is the only way I can get a decent cut.

From contributor E:
I'm going to agree with the others here - bearings are made to fit a certain speed and load range. If the bearings on your machine are rated to go up to 15k rpm, then you'll be fine. If they're not, they're going to be much more expensive to replace than just making up a simple router table.

Routers and other universal motors are high speed; induction motors are rarely so. Two different beasts that operated differently. I believe when contributor A said "woodworking machine" he was referring to machines with induction motors. I would also consider anything with a universal motor a tool as opposed to a machine, but that's probably just semantics.

I've got 2 shapers and a shop built router table and use them all. My router table was built from shop scrap, as were most of the router tables I've seen in pro shops. The only guys I see spending a lot of dough on them are hobbyists who don't know any better. I do see it as an invaluable tool for my shop anyway.

Lastly, the speed a router bit needs to run at depends on the size and type of cut. I occasionally run larger router bits in my shaper at 10k rpm with no problems. Generally if they're large enough that I don't want them in the router table, they can cut well at slower speeds. Sounds like you're experienced enough to know what speed you need for your cutters though. Contributor O mentioned 12k rpm and that might be possible using larger pulley drive without pushing the limits of the bearings too much. Of course it also depends on what type of shapers you have and the quality of the bearings in them.

From contributor N:
The Felder spindle for router bits has the bearings as part of the spindle, so when one switches from shaper spindle to router spindle, the bearings go with it. With the variable speed option on a Felder shaper, the router spindle will go over 20k. I get fine results at 15k with all the bits I have tried.

From contributor F:
Very true about purchased router tables. If you don't have or can't get a shaper that turns fast enough, a shop built router table with a powerful router is a very nice and versatile tool. Your comments about not letting anyone in your shop do that to a router surprised me.

A router table in its most basic form is simply a router motor and base fastened underneath a piece of sheet stock with a straight piece of lumber for a fence if required. I built my own table about 25 years ago. I laminated the top both sides and edged it with hardwood. I used a large variable speed Porter Cable router (still works great... lot of hours) and built a heavy stand with 4x4 fir sized for my height. The unit is on casters and has storage in the base for all bits and everything else related.

However, I have saved the day on quite a few construction sites by making a router table with a piece of scrap plywood, two by four fence, a couple sawhorses and about 15 minutes elapsed time to make a difficult task possible.

Last summer I made a table saw from a skill saw with the same technique. If you know what you are doing, these tools are as safe as anything else. Sure, a portable table saw is a better choice, but if time is tight...

From contributor B:
Industrial shapers are shapers (not routers). They have large and heavy spindles and are not meant to operate at extremely high RPM. The use of router bits attached to the spindle is (and always has been) a bad idea. Trade in one of your old shapers for an even older pin router. The older cast iron versions are built like Sherman tanks and usually have big tables. You might consider an inverted model if you don't like the standard overhead unit. Either way, these things can scream along at 20,000+ and can do it all day.

From contributor P:
First, tell us what make shaper you have. Many of the Taiwanese shapers use bearings that are rated to run 12 to 15K rpm. Most manufacturers are not going to rate their machines to run at the bearing max, however. Open bearings or bearings with a wick-fed oil will run at a higher rpm than sealed.

The biggest problem you will encounter is that the shaft assembly supported by the bearings is not dynamically balanced to 15K. If your machine is rated to run at 10K, the shaft was probably balanced to 12K, but you will never know.

I did modify an import to run at higher speeds many years back. I added an additional pulley to both the motor and shaft assembly. The pulley greatly affects the balancing, thus the means of mounting should be done in a machine shop. After all my fiddling around, I just bought a big router and mounted it in a router table. Much better. Sold the import shaper and bought a real machine.

Still, 99% of the time I prefer using shapers with shaper cutters.

From contributor F:
To me, the shaper, the router table and the handheld router are all important, and experience teaches you which is fastest and/or best in any given situation.

Reminds me of a funny experience I had in a shop. I worked a few years for a man who made a catalogue full of small wooden things for preschools (Montessori). The bulk of the products he made and sold used small finger jointed boxes in one form or another. He had a part time worker that had been there for years after school, on weekends and school summer vacations, etc. The vibrator sanders in the shop were Porter Cable 505's and were all used upside down on the sanding table. The worker held the boxes or whatever object was being sanded in his hands instead of holding the sander itself. The sanders were all resting upside down on shop made holders and it was the perfect way to finish sand these small items.

Since I had cabinetmaking experience, the owner decided to have me design and build some small preschool classroom bookcases to add to his product line. I will never forget the day I came into the shop and saw the part time worker holding a 12" deep x 30" wide x 32" high Baltic birch bookcase in his hands while attempting to sand it on top of the sander sitting upside down on the bench. He simply had never seen a finish sander used while the sander was held in the hands.

From the original questioner:
Thank you, everyone. I do not promote a construction site environment in the shop. That is the reason I have a shop. I'm not saying a piece of plywood wouldn't work in a bind, but that's not the long term solution I'm looking for.

I'm looking into the Felder option and the pin router. The shaper I was hoping to use is a Powermatic 27. I think it's a 2002 unit, so I'm not sure if it's Taiwanese or not. Has the Made in America sticker, which I don't think means a thing.

The main reason I don't want a router table is that in general they lack the beef of the shaper. With a shaper I can mount the powerfeed in several locations and I know the fence can handle the force of the powerfeed. I have considered gutting an old shaper and having the top machined (by my very generous brother) to accept a router motor insert. This is just something I've had in my head for a while and thought it might be worth putting out there.

From contributor U:
That is what I did - took an old shaper and had plates made to mount the router. Works great.

Click here for higher quality, full size image

From the original questioner:
Now that's what I'm talking about.

From contributor A:
A router is not a woodworking machine; it is a portable power tool. I think it would be great if you could find an old shaper and modify it to accept a 3 1/4 hp router.

From contributor R:
You can increase the rpm of a shaper with a three phase motor and VFD. If the bearings can do 10,000 rpm, they should be able to run at 15,000 rpm. A variable frequency drive can increase the rpm of a motor. Best price and tech help on VFD's is Speaking from experience, not armchair theory.

From contributor B:
I still might suggest trying out a real industrial pin router (as well as your very nice shaper/table mounted unit). Believe me, there is no comparison between your Porter Cable hand router and my 3-phase, high frequency, 230 volt industrial pin router. My own table-top Porter Cable would (and has) flown to pieces using some of the same cutters that I routinely run on the pin router.

I believe my old Onsrud machines are rated at 9hp continuous duty and the high frequency operation makes them truly unstoppable. The big cast iron table travels up and down about 15" as well as tilts. I bought one at auction (about 15 years ago) and paid less money for it than for a new 3 1/4hp Porter Cable. I had to get some new bearings for it, but that was it. These older routers are especially easy to pick up now since most are being traded off for CNC machine centers. In my opinion, a traditional pin router is still the most versatile machine in the shop and I wouldn't be without one.

From contributor K:
Man, that looks great. If you have some more pictures of that thing, please post, especially if you have some that show how the power feeder is adapted. Great idea!

From contributor U:
Here is a top view of the converted shaper.

Click here for higher quality, full size image

From contributor L:
I bought a Delta shaper from our high school and it had a 3ph motor. The guy at the Delta repair shop put a Delta vs control unit off a Delta lathe. It works okay but I haven't used it much for router bits even though I do have the spindle for router bits for it. Not sure what speed it turns, but I have used it a few times with small router bits - rail/stile bits - and had no trouble.

From contributor K:
Add ceramic bearings to your Powermatic 27 and you can run at 20,000 rpm, no problem.