Drilling & tapping the pinion gears for locking screws
 

Has anyone drilled their pinions for grub screws? We got our pinons from McMaster Carr and they don't have the keyway or grub screw hole. I am not sure if drilling the holes and taping them is easy or hard to do. Any procedures that I need to be aware of before moving forward.

Thanks

Justin, I personally find tapping to be very easy today, but 40 years ago it was nerve-wracking! :)

First you need to buy the right tap, plus the right drill size. (I don't have the experience of the names and sizes used in your part of the world, so I'll hope that a "local" fills you in).

For the small quantity of pinions, it could be more economical to take them out for someone else to tap, since a decent quality tap is not so cheap, and you are unlikely to need it again soon.

In this thread: Tapping threads into metal the discussion is more for tapping the rail screws, rather than the pinions, using power tools to drive the tap. For the pinions, you won't use a power tool, but the other comments there are mostly valid.

Hi Justin,

I was worried about tapping the pinions as well. As it turned out it was easier than I expected. Just set it up in your vise and away you go. I wouldn't give it any worries.

I had the same concerns as you and GregM above and I just tapped my pinion gears on Sunday. It was really a piece a cake and, given your ability as shown
in your photos, this will be trivial for you.

Here's a tap-and-drill guide for US sizes:
http://www.boltdepot.com/fastener-in...rill-Size.aspx

I've been watching (Lurking) your build as I'm about a month behind you.

Good luck! Can't wait to see the finished photos!

Cheers,

-Jeff

Hey Justin,

I bought the same pinions from McMaster. Tapping is not that big of a deal.

In fact, I screwed up (no pun intended) the first hole. I just rotated the pinion 180 degrees and proceeded with a new one.

You will see some discussion about tapping two holes for two set (grub) screws. Just for reference, I tapped one hole and used two set screws in the same hole. I have not had any problems with pinions coming loose. Just the way I was taught.

It finally clicked! "two set screws in same hole" . . . .

I have been used to working with 1" diameter pinions and just couldn't figure what 2 screws in one hole meant - but you are talking of bigger 30T pinions where the hole is deep enough to get 2 short grubscrews one behind the other. Good idea! (must admit that I had never seen or heard of it till now).

The ungeared, direct drive stepper motors from Oriental Motor have 2 flats on the shaft, 90 degrees opposed. The geared motors only have one flat. We are grinding a second flat (short) for 2 grubscrews to mate with the shaft. Backing them up with 2 more grubscrews (for the 30T pinions) should be extremely secure.

Pinions Drilled
 

Last bits & pieces to be done.

Pinions drilled and taped
 

Pinion gears were purchased from McMaster Carr. It is a Boston Gear with 35 teeth. The set screw is 6mm. They were very easy to drill and tap. I don't even remember why we were nervous about drilling them!

Thanks for the pics, Hennie & Justin

Justin,

Great pictures. They show the process perfectly.

Nice documentation.

WOW, you can teach an old dog new tricks. :p

...I can always rely on Greg to make me chuckle!