Tools: Paint Shaker by Woody Mitchell

Woody Mitchell shared on the Groups.io's S-scale list a description of his paint-shaker creation. This page captures his information about how he did it.

Please note that links to external web sites are only intended for reference, i.e. clarification as to which products to get. You may already have those parts at home, or you can buy them at your favorite retailer; the links are not intended as promotions.

WARNING!

If not properly constructed, this tool can cause some damage. Woody and the NASG cannot be held responsible for anything that happens to you should you follow these instructions. Use at your own risk! You assume all responsibility.

Introduction

Woody provided this brief video of the paint shaker in action.

There are two things that are interesting about Woody's solution:
a) it is relatively simple to build;
b) it can accept just about any of the model railroading paint bottles.

Description

The unit consists of a surface (table) to which a de-stabilized/vibrating motor and the paint bottle are mounted. The springs keep this table attached to a base, but yet allow it to vibrate.

Parts

one: 1/4" plywood section or similar (sturdy but lightweight)
one: 1/2" or thicker plywood section or similar (strong)
one: 12-volt vibrating motor
four: #10-24 flat-head machine screw: 3/4" (longer than the thickness of your base) (e.g. Lowes )
six: #10-24 flat-head machine screw: 1/2" (longer than the thickness of your table) (e.g. Lowes )
six: washer for the above machine screws #10 (e.g. Lowes )
four: 1-inch compression spring (e.g. Amazon)
one: stainless steel hose clamp, larger than the diameter of your largest paint bottle (e.g. Lowes )
one: stainless steel hose clamp, larger than the diameter of your motor
threadlock (e.g. Lowes )
JB Weld (e.g. Lowes); Woody recommends not using 5-minute epoxy (too brittle).
12-volt, or lower, power supply (wall-wart, trainset power supply, etc.; see Operation note below)
rheostat (current and voltage rating depends on the power supply you use).

The springs should not be too soft, nor too stiff. You want the table to move with the vibrations of the motor, but not wildly so.

The springs need to have an interior diameter appropriate for the machine screw nuts. The nut must be, at least, a little larger than the inside of the spring coil so that you can engage the nut within the spring's coil.

Construction

Cut or prepare the table and the base sheets.
Place the table and the base sheets on top of each other in the desired position.
Drill four matching holes for the machine screws in the two sheets of wood (the base and the table).
Determine where the bottle and the motor are to be located on the table.
Drill one hole for each for the machine screws.
Use a Dremel tool (or something similar) with a cut-off disk installed to remove a link in each of the hose clamps, to accommodate the flat-head screw's shaft diameter. Be sure not to compromise the clamp's continuous side straps when cutting the link out. Alternatively, you might be able to drill out the link; use whichever method works for you, but you need to be able to get the screw installed into the clamp.
Install the hose clamps by inserting the machine screws from above through the opening you just created, and attaching the washer and nut under the table.
You might want to apply some JB Weld to the connection between the screw head and the hose clamp, to make sure it stays.
Solder two wires to the tabs on the motor.
Install the motor in one of the hose clamps, and tighten.
Mount the screws into the base, from the base's bottom; the screw should be protruding out the top of the base. The screw's head should be flush with the base's bottom.
For each of the four locations, place the spring over the protruding screw, and install the washer and nut such that the nut grabs the spring's last winding.
Use the threadlock adhesive to install those nuts.
Use something like JB Weld to glue the spring-and-nut connection in place (very important). (update: Woody mentioned that he actually applied JB Weld to the nut and the spring first, and let that cure overnight; this may actually make it a bit easier to install.)
Mount the machine screws into the table, with the screws protruding out the bottom of the table.
Attach these to the other end of the springs already mounted to the base, in exactly the same manner as done to the base.
Install a wire clamp to keep the motor wire from getting in the way of the vibrating table.

Operation

Clamp the base to a solid surface.

Try the paint shaker first without a paint bottle, to make sure that it works. You may want to protect yourself (including your hearing and your eyes) and your surroundings, just in case something shakes loose.

Install the paint bottle and tightened the hose clamp. Make absolutely sure that the cap is on the bottle very tight! Woody was even able to use the old Floquil square bottles. Be sure to check all attachments before turning the unit on each time, just in case something wiggled loose.

The larger the paint bottle is, the lower the voltage should be. The reason behind this is that the mass of the bottle at too high of a speed may break the hose clamp or the machine screw's connection.

A bottle he hadn't used in 30 years was ready to go in about a minute of shaking. If you are using a larger bottle, at something like 5 volts, it will take a bit longer for the paint to be shaken. For really thick paint, Woody found that he needed to run the 5-volt shaker for about 10 minutes.

Model paint; shaken, not stirred!

Woody's Experience After One Year of Use

Woody used a transformer with a rheostat to power his paint shaker. This allowed him to vary the speed of the shaker as appropriate for the size and weight of the bottle. Even the placement of the bottle in the shaker affects the motion of the bottle. The more off-center the bottle is in the hose clamp, the more aggressive will be the action and he finds it necessary to adjust the voltage via the rheostat. You can use these physics to your advantage!

What is required is a modicum of good judgment. Does it look like it is shaking too aggressively? Then you risk the possibility of a destructive failure. Woody uses the off-center position in the shaker for a long-settled bottle so that the end of the bottle with the settled paint describes a larger angular moment but not at a frequency that would suggest it is too aggressive; if it is visually a blur, then it is too fast.

The size of the bottle, weight of the bottle, amount of paint in the bottle, and position in the clamp all affect the effect. You can only control the frequency of the shake by varying the voltage with a rheostat or, if appropriate for your motor/power source, perhaps a potentiometer.

Woody says he uses his paint shaker a couple of times a week. During the past year of use, one of the springs broke at its mounting point to the shaker table. It is good to stay with the shaker while it is operating, as he could immediately detect the change in the sound that something was wrong; it was louder/noisier.