This article is reprinted, with the permission of the author, by the Musical Instrument Makers Forum, an interactive forum for the discussion of musical instrument construction, design and repair.
Building a Woodturning Lathe
by George F. Farrell, Dollmaker
Page 2
Once the frame has been assembled, it is time to mount the
headstock spindle:
For the headstock spindle I chose a one-foot length of 3/4D cold rolled steel. It was taken to a local machine shop and threaded for 1.5 inches along one end to 3/4X16 National Fine. This was chosen because a search of the mail order catalogs gave (still does) the following information:
- Self-centering chucks -- AMT, Woodcraft and Penn State Industries.
- Headstock drill chuck to take 1/2D drills -- Penn State Ind.
- Face Plates -- AMT, Penn State Ind.
- Screw chucks -- Penn State Ind.
- I could not find a commercially made spur drive center. The Luna chuck (Woodcraft and Penn State Ind.) has a wide range of accessories, one of which is a spur drive center to fit their chuck. The alternative is having one made by a local machine shop.
- A 3/4X16 National Fine thread nut will also be required to assist in getting the tools on and off. This item can be found at local hardware outlets.
- Pillow blocks for 3/4D -- Woodworker's Supply
The axis of this spindle must be parallel with the
ways -- not only vertically but horizontally as well. Failure in this
respect will cause whatever is turned to come out elliptical instead
of round. The mounting tabs of the pillow blocks have slotted holes
allowing lateral adjustment. Vertical adjustment can be accomplished
with fender washers under the appropriate pillow block. This works
for a coarse adjustment. Finer adjustment means using a thinner
material as a shim. Tin-can material, precut to size and stacked
between boards, will allow drilling the mounting holes without
tearing. Tin-can metal is about 0.012 inches thick; bear and soda pop
cans are about 0.005 inches thick; household aluminum foil is about
0.001 inches thick. These should be enough thicknesses of shim to
test the patience of even the most persistent and diligent.
The best way to test and adjust for runout is to mount the pillow
blocks using hanger bolts. Hanger bolts are threaded on one end like
lag bolts and threaded on the other end like machine bolts. When
buying the 3/4D cold rolled steel shafting for the headstock spindle,
it would be best to buy an additional 3 foot length of it. When
mounted in the pillow blocks in place of the spindle, it will project
out over the ways by about 2 feet. This fact multiplies alignment
errors by about 3 making it easier to find a runout error. A dial
indicator set against the side of this extended spindle and run along
the ways on a clip that keeps the instrument along the inside of the
ways will give a measure of horizontal runout. Vertical runout is
measured with the dial indicator set against the underside of the
extended spindle and run along the ways.
Once the headstock spindle is aligned with the ways, it is time to make the tail stock and tool rest:
Return to Page 1
Continue to Page 3
Return to MIMF Links Pages
Return to MIMF Home
©George F. Farrell, Dollmaker, 2000, all
rights reserved, reprinted by permission.