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.

Daiku

The lock mortise routers certainly plunge 5 inches and use bits from 3/4 to 5/4 diameter but I do not recommend them for timber mortising.

Thanx for the help. Will try the extension. I plan on using 2 routers for each mortise. The first with a collar to dig up to 3 inches, then grab the heavy duty router to continue deeper. Plan to remove chips with air pressure, pop out the center (when practical ) with the grain using the chisel (after the perimeter has been removed.) Will also try to hollow out the center with 1" bit on 1/2 drill.

Will you be making round tennons, like a Hundegger, or will you chisel the corners? I think you'd be surprised how fast you can get cleaning up a chain-mortised hole with a chisel. Good luck to you. CB.

I especially like routing along the outside of housed dovetail pocket with a template and with one crack of a mallet having the waste come out in one piece.

I'm using a large Bosch router to finish 2 inch deep mortises and pockets with no problem.. This is in green Hemlock with a 2.5" cut 1/2" dia cutter. But I do two 2.5" drilled holes and a circular-saw edge cut where possible, and often chisel out the big chunks. The finish-up is about 30 or 45 seconds.

The MAIN thing is that the jig holds very close tolerances on final dimensions and the fit is excellent every time without fussing..

Even on big straight-cutout half-laps in 8by8 timber I use the router and a jig just making a 1/2" deep cut. There is almost no tear-out cutting with an electric chainsaw and a perfect guide for the cut every time. I do have a jig for holding the chainsaw nose on each half-lap cut, though, and that makes an accurate cut right down the routed line pretty easy. I smooth it a bit with the chisel to make myself feel good. But I probably digressed!

There's an interesting subject of jigs and tooling that I'd like to get into some other thread. Then there's the pickup-truck crane...

I am always leery of the "New and Improved". I often see it as coming from people who are relatively unskilled with their perspective Tools, be they Handtools or Power.

Tools require an Investment of time, as well as Capital -- Handtools generally requiring far more Time, far less capital, with the tool becoming more, and more accurate, as one's eye becomes more and more trained, the tool also becoming faster, and more efficient as one's muscles grow, as mostions become second nature, as, Finally, the tool and the Body meld, the right tool for the Job, and the right hand behind the tool.

There is less time which needs to be invested in Power Tools, but it is Still there, so much so that, OFTEN, instead of needing a new tool to acomplish a time worn task, what is needed is a little more practice, a bit more investment in skill, and an eye cast to seeing How the more experienced do things. What tools they use, how they use them, and in what order.

Notes from the field:

I have just recently been working on a frame for an addition to my house.
I have been intrigued by this topic and having posted opinions previously I thought perhaps I could test my theories and observations and/or learn something. (It could happen!)
Report as follows

Project: Thru motises-7 ½” & 9 ½” deep, cross sec-1 ½”x3 ½”

Material: #1 Doug Fir

Tools:
· 1 ¼” drill bit
· 3/8” drill bit,
· 1-1/2HP Router w/½” shank 2 flute bit 2 ½” cut length
· Reciprocating saw w/12” blade (don’t be frightened)
· Chisels and slick

Procedure:
· Layout mortises and score across grain
· Build jigs for router (dimensioned to index router base) and 1 ¼” drill bit
· Drill two holes 1/8”from both sides using site built jig
· Remove waste between holes w/saw (carefully) Starting at top and slowly moving saw to vertical
· Attach jig using screws where it won’t show, clamps where it will
· Set router to 1 ¾” –2” (depth not critical), remove material by “circling” around hole removing approx 1/16” per pass
· Set router to greatest cutting depth (3 ¼”) and repeat previous
· Repeat routing on other side of beam
· Drill 3/8” hole at corners of mortise thru material left at center.
· Remove remaining material and true mortise with chisels and slick

Thoughts and suggestions:
· I would suggest a larger router (in my case this was disallowed by a bout of budgetus interuptus),
· Keeping more than one bit on hand if doing production work.
· My plywood jigs seemed to be showing signs of wear, if long use is expected and the joint is standardized enough, perhaps metal jigs?
· A fence on the jig indexing the reference face (if doing square rule) might aid both speed and precision
· I a top bearing bit or a base mounted guide might allow for aligning the jig on a parallel plane with the reference face if it is on the opposite side of the member. This would keep the tool in alignment with the reference face. (Not incidentally this technique would work well for housings)
· Hearing protection for everyone within half a block. This is the loudest possible bit in a loud tool.

Overall I think the router could be a great tool for quickly cutting precise, standardized mortises after most stock has been removed by other tools. Used in conjunction with a chain mortiser I think that this could be a technique that could be very fast and quite precise.