Enlarging pinion holes

[sim]

Drilling out pinion holes. I just tried drilling the hole on an aluminium pinion from 1/8" to 5mm and didn't have a drill press, so I just eyeballed it and boy did it come out bad. I worked my way up from the smallest bits to 5mm. I think the final hole was slanting at least 4 or 5 degrees from the original. (I'm trying to mount a pinion and a tranny on the same 5mm shaft, to make a custom tranny).

It might be my excuse to get a drill press but I'm not sure how accurate they would be. Anybody tried drilling out a pinion hole with a drill press before? How did it work out?

Oh ya, it's a 48 pitch pinion, so I'm trying to be as accurate as possible.

Thanks for reading this.

[RockSuperStar]

For just a little more $ over a good drill press, you could get a cheap lathe. I have drilled many pinions on my lathe with great results. Plus, you would have the ability to do many other things with it.

[sim]

Wow. Now you've gone and tempted me. I thought I'd just get into the hobby with a hacksaw and a metal file, build a crawler and spend all my time driving it.

Hmm, ok will seriously consider the lathe. What should I be looking out for?

I am working on my first of many scratch-built crawlers and I find most parts can be built by hand or gotten around by alternate mounting methods, but the precision rotating parts are a real pain in the *** since I have to find things that fit in the same bearings, on the same diameter shafts, etc. With a lathe, I should be able match-make all sorts of gears from various donor cars. Yay.

[DiscoCool]

I thought I would post what I did to mount a pinion gear on the output shaft of a stampede tranny.

First I took out the differential.

2nd - tossed all of those gears and pins in the diff

3 - Took a 1/8th inch piece of steel and using my standing grinder, ground down the metal to fit all the nooks and crannies of the larger plastic 1/2. Was fun and didn't take too long.

4 - Placed piece in diff. found a 3/16 drill bit and carefully drilled a starter hole with the drill press. Removed diff body and finished drilling hole. 5 mm drill would have been best. Using the smallest Dremal cutting tool I could find, cut a notch in this hole - so it looked like a keyhole.

5 - Found a steel hex head 5 mm 3 in screw that has a 'shoulder' on it. 5 mm is the size of the bearings. Cut off head, smoothed down threads to take the ‘edge off’. Using a dremal cutting wheel, put a 1/2 lengthways rut into screw. This will fit the smallest woodchuck key I could find.

6 - Threaded modified shaft through my metal plate. Fitted woodchuck key and mixed up a small batch of JB Weld. Goo'd it all together and placed it in the diff. Placed diff in the tranny body so that the threaded part of the shaft did no touch the bearings. Align and let dry.

This allows me to:

7 - Using a drill press get a 1/8 in drill bit and clamp the pinion gear into a vise. Run the drill down through hole, until you hear or 'feel' the metal not touching. Clamp firmly. Replace 1/8 drill with 3/16 (or 5 mm) drill and very slowly - oh so slowly - drill the hole out to 5 mm.

8 - Place enlarged pinion on modified shaft (leaving about 1/4 inch of screw left) and screw the setscrew down, firmly. Unscrew. Remove pinion. Grind a flat notch in shaft where setscrew sat. Replace pinion. Set screw. On threaded end, place a dab of loctite and a 'nut condom' (a nut with a cap on it). Tighten nut firmly so that it lines up everything and bam - one pinion gear on a pede tranny.

The pinion gear will wobble a bit due to the inability to drill the center out perfectly, for my use, this is fine. I will mount the tranny on tension springs so that it forces the pinion gear onto the larger gear.

Whew - I had to get that out.



Disco out.