Building a Leather Sewing Machine for Shoes With a Drill

My domestic Bernina sewing machine is wonderful but isn't strong enough to sew through anything thicker than light leather. I wanted something to sew leather uppers for shoes but I'm planning to move overseas in June and didn't want to invest in anything too expensive, in case I can't take it with me. Industrial machines are also heavy, noisy and take up a lot of space. It's not easy to find one suitable for leather locally in New Zealand for a reasonable price.

I purchased an old Singer 99k from 1953 very cheaply. It is a small portable model, only weighing about 10kg and designed for domestic use. The lady I purchased mine from kept it as an ornament and never used it. It was so dirty that when I turned the hand crank, it made an awful crunching sound like there was sand stuck inside it. I cleaned it with an ordinary metal cleaner first which did little to shift the layers of baked on dirt and dust. At my Dad's suggestion, I used WD40 three times and it came up really smooth and shiny.

Even though it is small and domestic, the machine is very strong. The outer is made from cast iron and the parts are steel. This model was made with both motors and a hand cranks, I planned to fit it with a new motor and replace the sewing foot with a wheel attachment. Alphasew motors are readily available (around $50) from China, but some complain about the quality. VDK are Taiwanese motors that seem to be superior (approx $70) but are only available for American voltage and would require a converter for use in New Zealand. Both motors are around 0.9 or 1 amps and from my online research I'd need above 0.75 amps for sewing leather (most domestic machines are 0.3 amps).

While visiting my Dad in Sydney he suggested we build our own motor from an ordinary cheap drill, having more than enough power at 2 amps and costing around $20. Apparently electrical engineers like to use drill motors to power all sorts of unlikely things...

The first step was to cut off the handle, we then cut off the switches to make them into a foot pedal switch so the speed can be varied like in a normal sewing machine (something you wouldn't get in an industrial machine). Dad cut the wires to the motor and soldered them to a cable, to create distance between the foot pedal switch and the motor which will be attached to the machine itself. 

We then used plastic builder's shims or spacers, a hinge and the spring from a clamp to make the foot pedal. This was actually the second pedal we made, Dad didn't like the first one. If you look closely at the finished pedal, you can see holes in the plastic we recycled from the first version.

 We soldered the drill switch to the other end of our cable, when we first did this we mixed up one of the inputs and our motor started to smoke... Take care to read the switch diagram carefully on your drill! The plastic encasing the drill switch had to be cut away first so it could be mounted on it's side without restricting the movement as the pedal is pressed.

Dad removed the original drill switch that controls direction and soldered on a new switch and mounted it to the side of the pedal for forward and reverse stitching. (Possibly not the most practical placement but I don't expect to use it very often)

We didn't have time to build a box around the pedal but I may add that on to it later. We made a belt pulley from bolts and washers slotted into the drill chuck. I brought my new motor and pedal back to Auckland and was left to work out how to mount it to my Singer without Dad and all his tools. As it turns out, we picked a large drill to mount to a small machine and small motor belts aren't so easy to find in Auckland.

I ordered a cheap motor belt from Ebay that is specific to the 99k model (part no. 196386). I have read that some of the standard sewing machine motor belts are not long enough for the 99k and a short belt would have made things even more difficult because I would have to attach the drill higher up. The belt seems to be made of a hard rubber with ridges on the inside for grip.

I decided to attach the drill away from the machine, to avoid interrupting any function of the Singer and because the cast iron body is very curved from all sides so attaching anything to it would have been unstable. 

I drilled an aluminium plate onto the back, aligned with the wheel and motor belt and secured it with an L bracket underneath. Drilling holes into the wood of such an old machine felt like blasphemy, I had to keep reminding myself that it's only the wood and not the machine and I'm giving it new life! 

For additional stability, I packed the space underneath the drill with rubber to absorb the vibrations. The drill was held to the aluminium plate with cable ties at the right tension. The tension can be adjusted by moving the drill across the plate, away from the machine (I packed some rubber here too because of the shape of the drill). 

Was it worth the struggle? Probably not but it was fun, educational and economical. I only hope that the belt has enough grip to power through thick leather without slipping. Testing and front wheel attachment to follow.