Treadle Runners and Carpet Protectors
Here is a picture of the most recent version of treadle runners I made… they raise the treadle above the carpet enough to allow free treadling, keep the treadle from imprinting the carpet, and allow you to slide the treadle out from the wall smoothly. To fit the standard, most common treadle, the dimensions are: start with a 2 x 4 (3.5" X 1.5") , cut to a length of 20.5". Using a Forstner bit, drill a 2" hole .75" deep. These holes should be centered side to side and centered 17.25" apart (this will put the centers about 1.75" from the ends… actually just a teensy smidge less, but it is not all that critical as the 2" hole allows for some slop).
Note: measure on YOUR treadle… even make a cardboard pattern. Recent posts indicate that there is some variation among treadles, even within a brand.
Further Note: The question was asked, "So what's a Forstner bit?" A Forstner bit is a special drill bit for drilling large holes that don't necessarily go all the way through the piece. Any hardware store has them in various sizes. Another alternative is a spade bit. These are generally cheaper, though they tend to come in sets. They are a little trickier to operate and do not give as smooth a hole.
Using a belt sander, smooth all edges and the ends. Here is the big "secret"… really sand a curve into the front and back bottom edges… I mean really sand a curve… make it look like the front of a sleigh or toboggan. With good deep holes, this will let you slide the treadle out from the wall and push it back quite easily. As to wood, I used cedar, clear grained, and sanded it quite smooth. Red oak would have been nicer, but an oak 2 x 4 is only moderately less expensive than sending a child to college, and I had the cedar. If you use pine, be sure to do a good sanding job, and stain and finish it so it looks decent. Pine is subject to splitting and splinters and this can catch in the carpet, defeating the purpose.
If you have the very old treadle, or the more modern one from the 1930's, you will have to make adjustments… the very old one is a bit bigger in stance. The 1930's one is smaller in stance, and has shallower feet, so you can't make the hole as deep. In fact, you will probably want to use a 3/4" board instead of the 2 x 4 and make a shallower hole. Also, obviously, if you have a different brand of treadle, you will need to determine your own measurements.
I did not treat Moby Treadle to this extra. Industrials are designed to be screwed or bolted to the floor. They have flat feet with bolt holes in them instead of wheels. I just made a pair of runners out of 3/4" oak and screwed the treadle base onto them.
If you have access to a lathe, you can also just make round carpet protector cups. Here is a picture of a set of runners made from 3/4" oak boards, for one of the later 15-88 style treadle cabinets, and also a pair of carpet protector cups (two are shown... obviously, you need four).