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+--- Thread: New power finger file. (/thread-3884.html)
New power finger file. - toglhot - 04-23-2018
https://www.youtube.com/watch?v=OUm1D7hdt50
I wanted to use aluminum for this project, 10mm thick would have done the job but I had no idea where to souurce that size sheet from; however, I did have some sheets of 25 mm Delrin so I thought I'd have a bit of a play with that medium.
Delrin turns nicely giving a nice finish, but when grinding and filing the finish is quite rough. I expect some more work in this area to neaten the project up a little.
I cut a rough shape from a largish slab and set about shaping it with a finger file. The hole for the motor was turned on the lathe, this necessitated making the handle a little shorter than I'd like. As it turned out the handle fits the hand quite comfortably. I cut a slot just forward of the handle and tapped a hole from the top of the blank for clamping the motor in place. Next I mounted a small piece of Delrin in the four jaw and drilled a 10mm hole for the front wheel mount. After mounting the motor, I spun up a small piece of Delrin and sunk it into the drive drum and pushed the drum on the splined motor shaft. I was going to use some Delrin for the drum but thought it might melt so used a stell drum mounted on a Delrin Bush.
For the motor cover I turned a 12 mm thick piece of Delrin to fit over the motor and then turned down a piece of PVC to slide over that. The end is capped with another piece of Delrin I had lying about, yellow unfortunately. I mounted the swich in that.
The unit works nicely, but curiously the 18 volt motor I sourced from an old cordless impact driver smokes badly when run on 18 volts. On 12 volts it runs ok, if a little hot.
RE: New power finger file. - Roadracer_Al - 04-23-2018
That is a very nice tool! I've been contemplating building something similar using a disc grinder for motive power.
RE: New power finger file. - Vinny - 04-23-2018
(04-23-2018, 03:35 AM)toglhot Wrote: The unit works nicely, but curiously the 18 volt motor I sourced from an old cordless impact driver smokes badly when run on 18 volts. On 12 volts it runs ok, if a little hot.
The motor was more than likely designed to be controlled by PWM (pulse width modulation). The speed is controlled by varying the length of time the motor is receiving 18 volts and receiving 0 (duty cycle). This happens very fast so you don't notice it. You can hear the high pitch whine in some cordless drills. Anyway, the reason it doesn't smoke at 12 volts is because when running the drill at the same speed as you're getting with the 12 volts on your finger file, the duty cycle of the PWM's 18 volts averages to around 12 volts. A light dimmer operates much the same way, except with AC instead of DC. The brighter the light, the closer the duty cycle is to 100%.
Hope that made some sense.