Timber Framers Guild Forums General General Forum Questions Routers for speed and precision

It seems to me that routers (in conjunction with homemade jigs) are an excellent tool for making almost any mortises we need. Clearly faster and more precise than chisels or chain mortisers. A deep mortise can be hollowed out by fashioning a steel sleeve and recycled shank together (mig welded and trued) so as to cut e.g. 6, or 7 inches deep. This sounds too easy and economical. Am I missing something?

try it and see...
there is certainly more than one way to skin a cat, or any animal for that matter.
Power tools have some drawbacks, in my opinion, particularily noise and the cost of electricity.
I like the balance between taking away most of the waste with powered tools and finishing quietly with hand tools.

I used a router with a 1/2" shanked straight flute cutter to mortise out a series of housings for stair treads in a set of stringers with great results. The stringer were 2" thick Red Oak. I went in from both sides to avoid blow out on either face while cuting out 2x10" mortises. Not real deep compared to some bigger timber mortises but the same idea.

I did note that I had to go in steps of only about 1/2" of depth at a time. Atleast in oak, you would need a very stout router to take a bigger bite.

I don't think they are really designed for such rigorous work and you may find that the tool won't last long if used extensively for carving out deep mortises. Adding a shank extension would add a lot of extra side load on the bearings and motor. Loads it was not designed for. Like Mark, I don't much care for the high pitch scream of the router myself...

Shaun

I am reading a timberframing book that shows the use of a router and homemade jigs for routing mortise housings...

Recently, a woodworking tool company came out with a router bit extension.

The first "mortise machine" I used was a Porter-Cable lock mortiser I adapted for timber framing. The major flaws were slow cutting and poor chip ejection. A deep mortising router would also have a risk of the bit bending, so a wider shank would be needed. I also believe that a router held free hand with such extreme bit exposure poses a control and safety problem.

My experience with routers tells me that they may be the perfect tool for shallower work such as housings
But for something like a mortise you will run into several problems.
The first being that the longer bits tend to cavatate esp. when fully extended
Most any long bit you find will be a core box with cutting edges parallel to the turning axis and with little cross sec perpendicular to the axis. This results in a tool that is chipping as opposed to slicing and which flexes when it meets resistance. (Yes I know that is the action of power planes but in their case the cutter is supported on both ends)
Another problem is that this type of bit is prone to heating up, which of course means it doesn’t cut as well and so heats up etc….
Lastly it will no clear at all which only adds to the above problems
Having sounded all those sour notes I would suggest some things:
One, look for a spiral cutting bit
Two: consider using the router to finish the mortise after have removed the bulk of material from the center by other means.
Three: don’t try any of this with less than a three horse router
Four: Keep the bit sharp and clean, scrape resin build up off the cutting edge and clean with acetone and touch the edge up with a diamond stone from time to time.

Can you provide the source of the tool (extender)?

Michel...

The extension is from MLCS.

www.mlcswoodworking.com

There is a model that holds 1/4" bits and a model that holds 1/2" bits. Both models are to be used in a 1/2" router. They extend the bit about 2". Cost $35 They are, or were, on sale for $25.

They also sell carbide spiral upcut bits. They have a 1/2" diameter, 3" long, 1-1/2" cutting length for $35.

I'd be very interested in how the router approach works for you.

Joel

Does anyone have a router with a plunge stroke travel of 5 inches or more? Stopping to take out/put in the bit extender each time seems pretty inefficient to me! Also, its going to get really hard to keep the shaft vertical (the base of the router horizontal) with a 5" bnit hanging down. Routers are great for housings, but if you really want a clean, deep mortise, look into a chisel mortiser. I know Hitachi makes one, but I'm not sure if it's still being exported. CB.