Hi-Tech, Low-Tech

D&W mortiser

Charles S. making mortises on the D&W

My old Davis & Wells horizontal boring machine is a great platform for making mortices, using machinists’ end mills, and boring holes in doweling and other operations. Knowing that the end mills like a little higher rotation speeds than most drills, I swapped the drive pulley a while back for a larger diameter one that would gear up the motor’s 1725 rpm output to a spindle speed in the 3600 rpm range. This improved the mortising, but my drill bits didn’t like it.




Boring on the D&W

Boring holes on the D&W

I decided to create a best-of-both-worlds solution by converting the machine from single speed to infinitely variable speed, using a 3-phase motor and a VFD (variable frequency drive).


D&W with VFD

The old D&W with 3-ph motor and VFD

Saving me the trouble of a trip to Apache Reclamation to scrounge for an inexpensive small 3-ph motor, my neighbor produced an old GE 1-HP 3-ph 1725 rpm motor that even had exactly the right mounting foot for the D&W mortiser.  The next step was to pair it with a VFD of the same specifications, and for that I went to Dealers Electric in New Jersey. There I found a Westinghouse-TECO VFD rated for 240v single phase input, three phase 1-hp output, with constant torque output, for about $130.



D&W with VFD

The new VFD in place

Wiring these is pretty easy, and once they are set up you have to go through a series of keypad commands to set the VFD’s parameters to match the motor’s capacities exactly, shaft rotation direction, etc. Once done, you have (in my case) an infinitely variable, 0-3600 rpm speed control at constant torque.


D&W with VFD

The new VFD

The LED readout on the VFD is in hz rather than rpm, so I have to do a bit of interpolation to hit precise speeds, but ballpark seems to work just fine. If I’m mortising with the end mills, I run in the upper ranges (depending on the diameter of the mill, hardness of the material and general feel of the operation). If boring holes with drill bits I’ll be in the lower ranges, with the same caveats.

I may even get a drill speed chart one of these days! 🙂


This entry was posted in Uncategorized. Bookmark the permalink.

9 Responses to Hi-Tech, Low-Tech

  1. Jonathan Giard says:

    I have the same machine and would like to do mortising like you do. Do you use 2 or 4 flute end mills, HSS or carbide? Also do you move the work into the mill or use the foot pedal to plunge the cut? I’m curious what setup you use to plunge the cut and move the work side to side for the mortise. I have a picture of Krenov doing it freehand, and even some folks using an x-y table. I am retired and enjoy designing and building.


  2. Dave F says:

    Hi Jon,

    A lot of the end mills I have were bought used from machinist’s supply houses, I have both 2- and 4-flute mills (no real preference on my part). A few HSS, a few carbide. A while back I bought a graduated set (3/16 to 3/4)of 4-flute, HSS mills from Grizzly for a very reasonable price, and those have been holding up nicely. I also have a set of European-style ‘birdsmouth’ mortising bits for deeper mortises.

    As far as I know, Krenov never used an x-y-z table. His massive Stenburg saw had a fixed arbor and a vertically-adjustable (z-axis) table, and that was it. The College of the Redwoods shop was fitted out with two Davis & Wells horizontal boring machines, similar to mine but later models, again with no x-y-z table. So he (and we students) did it all manually — marking out the mortise carefully, setting the bit height with the table and moving the workpiece back and forth by hand and eye, gradually increasing the depth of cut with each pass. We cut close to, but not right up to the lines, and the last two cuts were plunging cuts right on the line, setting the length of the mortise.

    That’s still the way I do it when using my D&W. The variable speed I added really helps (it does me, at least). I don’t use the foot-pedal plunge when mortising, just advance the depth gradually by hand. In my shop I also have an old Inca 259 tablesaw with a nice little x-y-z table, and I use that for most of my ‘furniture-sized’ mortise work.

    Hope that helps — Good luck with your D&W, they’re great old machines, and thanks for the interest.


    David Fleming

    • Jonathan Giard says:

      Thanks David,

      Your detailed response is very helpful. Also, I am grateful to find your site and you sharing how to add variable speed at a reasonable cost. This used to be a real problem, what a great solution. Thanks again.


  3. Terry Jorgensen says:

    read your article with interest…have 50 year old davis wells giving to me by my uncle. don’t dowel much anymore in my cabinet, furniture making. Wanted to incorporate loose tenon jointery into some projects thought the boring machine would work for the mortise…Is the speed of the original machine going to be suffiecent for the back and forth motion of cleaning up the moetise. I’m searching for a chuck to convert from the screw on bit..could I chuck in spiral router bits as well grill bits to make mortises. Thank you, Terry

  4. Dave F says:

    Hi Terry,

    I would say that the speed of the machine as originally ‘geared’ is sufficient, generally, for all-around boring and mortising. The ones one use at the College of the Redwoods have not been modified, and have produced by this time thousands and thousands of mortises. I simply wanted to be able to fine-tune the output speed of the bit (drill or end mill) to more efficiently suit the work at hand — bits of various diameters and types, and materials of varying density and hardness. Adding the 3-phase motor and VFD solves that problem. The Jacobs model 36B ball bearing chuck (3/16″-3/4″ capacity, 3/4″ x 16tpi mount) or the Jacobs model 6316 plain bearing chuck (same capacity and mount) will fit the machine. I have the 36B, and switch as needed between that and 7/16″ x 14tpi threaded shank drill bits from Morris Wood Tool Co. I have not tried a spiral router bit in the machine — they are designed to run much faster than the D&W can turn them, but they might work OK. For mortising, standard HSS 2-flute or 4-flute machinists end mills work pretty well. Thanks for the inquiry, good luck getting your D&W set up!



  5. Brian Moran says:

    Hey David, Thank you for the info on the D&W boring machine. I just bought one. Does the single screw on the back of the pulley cover control the removal of the cover? It doesn’t see to want to unscrew. I know is a simple one but your thoughts. Thank you, Brian

  6. Dave F says:

    Hi Brian,

    My machine doesn’t have a pulley cover, so I can’t say for certain but I think you have to be right about the function of that screw. My neighbor has a later model D&W that I’ll look at tomorrow. Not sure if it has a cover or not, but if so I’ll report back here.

    Thanks for the inquiry, hope you enjoy your machine


  7. Bill says:

    How is the Jacobs chuck mounted on the spindle? Can it be removed easily?

    • Dave F says:

      Hi Bill,
      Many, many apologies. Your question slipped completely through the cracks here in the backend of my web site, and I’ve only recently discovered it one year after you posted it 🙁

      On the assumption that late is better than never: The spindle end of the D&W mortiser has both internal and external machine threads. The internal is for threaded drill bits and the like (7/16-14). The external thread is 3/4″-16. The big Jacobs 3/4″ 36B chuck has internal threads, 3/4″-16. So the short, though embarrassingly year-long-in-coming answer is that the chuck screws on and off the machine easily. I constantly switch back and forth between using the chuck (for mortising, mostly) and threaded shank drill bits (for boring). Regards, David

Leave a Reply

Your email address will not be published. Required fields are marked *