How to cut flat sided holes for Globe and Door motor

[Max Lobovsky]

How have teams cut holes in their sprockets and gears to interface with the flat sided shafts of the Globe and sliding door motor? Even with mill, there is no way to cut the edge between the curved and flat parts of the motor. Leave that edge with an oversize fillet? Would a circumscribed rectangle work? Is there any way to do a sloppy job if you can't get to a mill?

[ajlapp]

circumscribed rectangles work just fine. the flat part of the shaft is what holds the assembly from spinning. if you have a cnc than you can mill the pocket to the correct shape. i've done it both ways with absolutely no trouble.

[Tytus Gerrish]

use a waterjet, a laser, a small endmill, a file, anything can do it

[Biff]

Originally Posted by Max Lobovsky

How have teams cut holes in their sprockets and gears to interface with the flat sided shafts of the Globe and sliding door motor? Even with mill, there is no way to cut the edge between the curved and flat parts of the motor. Leave that edge with an oversize fillet? Would a circumscribed rectangle work? Is there any way to do a sloppy job if you can't get to a mill?

The Machine shop that donated work for our team last year did it with a wire burner. He was able to cut the proper hole for a globe shaft in a 9 tooth #25 stainless sprocket, that started with a 1/4" bore. We had no issues with that sprocket hope to visit him again and get another one or two made for this year.

[Joe Johnson]

For the Power Sliding Door motor we have had very good success with an 11mm Trantorque.

They run about $30 from McMaster, but we love them. No changes to the motor (which is good if you burn one up and have to switch) and a simple hole (22.5mm if I recall) in the gear you want to attach to the motor.

As to the Double D on the Globe, I know some teams have modified a standard round broach to put in the flats. I THINK the Globe has a 3/8 round shaft with flats, so if you buy a 3/8 broach and grind in the flats, you should be all set. I have not done this myself, but have heard good reports.

Joe J.

[Max Lobovsky]

Why not use a trantorque or some other clamp for the Globe also? On a related note, do either motors shafts need support if using them for chain?

[Bill Gold]

Originally Posted by Max Lobovsky

Why not use a trantorque or some other clamp for the Globe also? On a related note, do either motors shafts need support if using them for chain?

I've used trantorques on both in the past. Yes, the globe shaft needs support. It cannot handle sideloads.

[ShadowKnight]

neither can the mabuchi motor (look in the FIRST guidelines and they highlight the globe and the mabuchi on this). Motors in general don't like side loads so I would be supporting all of your motors so that they do not experience this.

[sanddrag]

What we have done for both the Globe and Van Door motors in the past was this. Take a piece of steel shaft say 1/2 inch di. Face the end of it in a lathe and then drill a hole into the end of it that is just slightly larger than the di. of the round part on the end of the motor shaft. Then take the shaft and lay it in a vise on a mill. Tighten it snug but don't smash it. Then mill a slot right into the end of it. Slide it over your motor and use a shaft collar to clamp it on.