mill table auto feed

[th62]

This is my auto power feed I built for my small BF20 mill. The motor is a two speed windscreen wiper motor for which I made some aluminium brackets to mount it to the left side end of the mill table. I made two 20 mm blocks to mount to the table end brackets and a mounting plate for the motor which bolts to the two block. To mount the assembly to the table end plate, I milled the end plate flate, drilled four holes to mount the block and then mounted the motor plate to the end of that.
To attach the motor to the table I machined a clutch system. First turning up two drive bushes, one for the motor the other for the table lead screw.
The motor shaft is a splined tapered shaft. The leadscrew drive bush is also aluminium which is a neat fit over the leadscrew. I removed the key as a safety feature.
Both drive bushes have four 8mm slots milled equal distanced around the circumference of the bushes
The clutch system relies on a four prong sliding bush.The prongs are 6.2 mm brass pressed into a 50mm round aluminium bush.
The clutch bush slides along the leadscrew drive bush to engage the motor drive bush.
Initially I had the switchgear mounted on the rear 20mm block, but decided that was awkward, so I made a plate to hold the switchgear and mounted it between the mill headstock and control box.
The switchgear is comprised of a two way rocker switch for speed selection, a DPDT rocker for reversing and a momentary on push button switch for activation.
While I was at it, I made some small brackets and mounted a couple of DROs for the table. One is a Vevor, the other a no name brand. The no name brand DRO works fine, but trying to get the Vevor DRO to work presented quite a few problems. EMT making the readout fluctuate.
The fluctuations varied greatly, from slight to the read out going completely haywire, dependant on the cable routing. I finally found a route that gave the least amount of interference and attached some clip on ferrites but they didn’t work at all.
The Vevor DRO fluctuates .01 to .02 or .03mm continually, not a great deal, but annoying just the same. I’ll give it a try, if it’s not workable I’ll buy another no name DRO and mount that in place of the Vevor.

[brianr47]

A nice project - it should be very handy.

Regarding the Vevor DRO reading fluctuating, if it is dc-fed, similar to a no-name one I fitted on my lathe then it may help to connect an electrolytic capacitor, say 100uF, across the supply as near to the DRO as possible. This may help by absorbing incoming induced voltage spikes.

[bruce.desertrat]

There was a similar project in Home Shop Machinist, "Mini-Mill Power Feed" by Ted Hansen HSM Vol. 43 No. 1 Jan-Feb 2024.

One thing his design had was a limit switch to automatically turn it off if it reached the end of the table travel. It used a surplus automotive seat adjuster motor, which probably provides more power than a windshield washer motor, but the overall design was quite similar.

[mr mikey]

Nice build, I had similar issues with my dro set up, what I did was purchase a roll of aluminum duct tape and cut a strip the length of each cable and about a half inch wide. I wrapped each cable completely then before you reached the end insert a wire 18 or 16 gauge or whatever you have. Strip the end about 2", make sure its touching the foil side. I have three separate gauges, so you crimp all three wires to a single wire then attach to any screw or bolt on your machine. make sure your ground is clean (no painted surface). This made a huge difference, my gauges are now flawless.