General Description

  The housing for the lap is constructed from 8" x 1" dimensional Poplar lumber.  The top is constructed from 3/4 inch Lexan since it is a very rigid and stable material, though my primary choice would have been tool grade aluminum plate.  Price was the main consideration for choosing Lexan which I ordered from McMaster-Carr.  I purchased the motor and speed control from Surplus Center and the Lexan from McMaster-Carr.  The lumber and other hardware came from Lowes. 

Construction

                                           The poplar wood base (pictured to left) is is 17" x 11.5" using 8" x 1" lumber.  The 4 sides of the base are held together by 3 inch and 4 inch metal reinforcing angles screwed into the wood panels.  The smaller angle braces on top will be used to attach the Lexan top while the larger lower braces will be used to mount the leveling feet.  Once the base box was assembled completely and tested for squareness, the wood surfaces were sanded smooth and the corners were rounded over with a router and sanded smooth.  A cutout was made in the front panel to access the switch and control panel that will be mounted from the inside.  The edges of the cutout were rounded over and sanded smooth.  The entire outside of the box base was stained and sealed using several coats of MinWax PolyShades. 

The Lexan I used was clear so I made it a bit more opaque by sanding it with fine sandpaper on all sides.  The top was drilled and countersunk in alignment with the holes predrilled in the upper corner brackets.  I decided to make the splash guard non-removable and chose to use the top several inches of an inexpensive white plastic round wastebasket for the guard.  I routed a narrow circular slot in the top of the lexan panel centered on the spindle hole and used epoxy to mount and seal it.  A short piece of white PVC pipe was similarly adhered to the center to keep water out of the spindle hole. 

The motor was drilled in 4 locations around the front flange and mounted through a small piece of Lexan acting as a spacer to accommodate the bearing extension on the front of the motor.  The top Lexan was once again drilled and holes countersunk to match the mounting holes in the motor.  The bolt heads were covered with silicone adhesive to seal them watertight.  The splash guard and spindle dam were also both sealed at their attachment with silicone just in case the epoxy had gaps that would leak.  A hole was drilled and tapped to fit a 1/2 inch PVC pipe to tubing nipple which was screwed in from the underside of the Lexan panel.  A piece of 1/2 clear vinyl tubing was attached and routed out a hole drilled in the rear of the wood enclosure to act as a drain. 

I also drilled and tapped the left rear corner of the Lexan top panel to fit a 12 inch long 1/2 gray PVC sprinkler head riser tube.  This tube screwed into the hole in the Lexan top and a cast iron pipe flange was screwed onto the top of the tube to serve as a base for the water tank.  The water tank which is epoxied to the top of the flange is a simple clear plastic Tupperware type container with a 1/4 inch brass swamp cooler supply valve threaded into a hole on its front.  A short piece of metal rod was bent and threaded to insert into a hole drilled into the PVC riser tube to guide and support the clear plastic water line. 

A basic wiring diagram is displayed at the bottom of the page.

Parts and Photos

0.75 HP 130 VDC 5,100 RPM 8 AMP McMillan Electric Motor model S335782768 permanent magnet motor with brushes from Surplus Center.

5K-Ohm Linear Taper Potentiometer, Radio Shack Part# 271-1714  used as the speed control

The Tachometer is not yet functional since I have not yet found a suitable encoder to drive it.  Also to be added is a flexible gooseneck halogen work light.  Since this lap will be used for faceting, I also need to decide on the type of faceting head I want to use and whether to construct my own or purchase a used one.  I had originally intended to use a Wyckoff Calibrated Jam Peg to start off with since it definitely fits within my current budget.  For the faceting head, I will need to cut a slot in the open area of the Lexan top to the right of the splash guard.  I will probably mount a slotted piece of aluminum flat stock on top of the Lexan to mount the faceting head mast into.  The aluminum should be sturdier and wear better when adjusting the masts distance from the lap.  I will post additional photos as the project continues to evolve.

Disclaimer : No liability will be assumed in the event an individual constructs a similar device based upon my photos, diagrams and descriptions. 

This is a basic wiring diagram showing how the board and  switches are wired.