A friend mentioned to me recently that she wanted to own a home pottery wheel but was prohibited by the cost. They appear to cost between several hundred dollars and upwards of $1700. I expressed my surprise at the $1000 price tag given the simplicity of the device and she jokingly replied "Hey yeah, you should build me one of those!". I decided to take up the challenge. That evening I found VertDude's instructable and colemishler's instructable and decided this was the way to go.
I followed VertDude's instructable fairly closely with the following deltas (some influenced by colemishler's design):
- different pulley and mount
- wheel construction
- belt tension motor mount adjustment
- pedal based speed control
The steps below describe these differences.
Special thanks to my dad for the time, welding expertise and knowledge of all things mechanical that he contributed to this project!
Note: More photos can be found here
Step 1: Pulley and Mount
To save time I purchased the pulley wheel. With no access to a lathe, I used a tractor blade fastener welded to a 5/8" diameter shaft and two bearing units.
Pulley mechanism parts:
- Fixed Bore V-Belt Sheaves, Cast Iron 2.05" OD
- V-Belt Pulley
- V-Belt, 4L460
- UCF202-10 Bearing Unit (2)
- tractor blade fastener
Due to the height of the bearing units and the unfortunate need to balance an uneven tractor blade fastener, a support shelf was built to elevate the oil-pan splash guard. I additionally made the table a bit higher and installed a shelf to hold the pedal and various potter's materials when not in use. In retrospect, with limited access to precise cutting tools (i.e. only a jigsaw) and the desire for the additional shelf, I would opt for a design that keeps the front and back widths of the surface equal, allowing for primarily 90 degree cuts.
Step 2: Wheel Construction
I decided to try building the wheel exclusively from plywood. I haven't noticed any balancing problems with this (though they may exist and just be obscured by the uneven tractor blade fastener). I made sure to install the bolts in such a way that their weight was balanced. I used two layers of 1/2" thick sanded plywood were used to fasten the wheel to the tractor blade. I then glued a third piece of 23/32" thick plywood to cover the bolts. I finally applied several coats of a stain & polyurethane mixture.
Step 3: Belt Tension Motor Mount Adjustment
Instead of the hinge-based approach to adjustable belt tension, I installed the motor on runners. As belt loosens, the user can loosen the bolts attaching the motor, pull the motor back on the runners, and re-tighten the bolts.
The runners are separated from the frame by 5/8" thick spacers so the bolt heads have room between the frame and runners. The runner system is screwed into the frame.
Step 4: Pedal Based Speed Control
I purchased a broken Dunlop wah pedal on ebay, needing only the mechanical assembly and the gear mechanism. I kept the circuit board to make use of the 1/4" mounted input jack but disconnected any lines from the jack to the rest of the circuit by scratching away the pcb line connections with a razor blade and a screwdriver. The potentiometer was replaced with a 5K pot as described on most hobbyist sites and MC60 controller schematics available online. I wired a female XLR jack to the MC-60 5K pot connections and connected the pedal to this jack via a 1/4" jack to female XLR cable. Because I wanted the wheel to start at a slow speed with the pedal adjusted "down" and move to a reasonable high speed when fully "up", I had to:
1. Clip the resistor R15 to remove the "slow start" feature (link). This allows the wheel to start spinning when power is turned on w/o having to adjust the pedal to "0". This also allowed me to install the pot without needing to make sure that it could be brought to actual "0".
2. Install the pot such that the "down" setting started at a value higher than 0.
3. Use a screwdriver to adjust the speed multiplier on the MC-60.
I tweaked (2) and (3) until I found an acceptable speed range with smooth adjustment acceleration.
Note that if using the current pot mount and default wiring scheme is used, the pedal works opposite to that of a car pedal: depressing the pedal with slow the wheel down. This could be reversed by either installing a mount on the opposite side of the pedal or perhaps reversing the wiring and tweaking the speed multiplier on the MC-60. Once I present the gift I'll find out what the preferred speed and operation are and tweak accordingly.
Step 5: Electrical
I used a GFCI outlet and also wired in the 15 amp fuse that came with the power components of the treadmill. Instead of the knob and light panel, however, I used a single GFCI outlet with a power switch included (comlimented by the pedal to complete the features provided by VertDude's control panel). The light was not needed in this system because the "slow start" feature is disabled and the pedal's "down" position will still move the wheel.