Showroom 6DOF Build (Bodine Motors, Sabertooth, FlyPT Mover)

There are no threads on this motors shaft. It is 5/8" keyway by 3/4" shaft. Unless I'm missing something in your explanation.

@bruce stephen you are correct. We're you able to hand turn your motors?

That little hole

Ah ok it's not threaded but could be tapped.. It's about m3.

@BondeX yes with leverage. Once I put the levers on it isn't too difficult to turn the motors

Damn, good eye @shannonb1 lol. @bruce stephen that's what I will do. Just waiting on 5/8" couplers.

For the Alliance!

Are you going to weld a lever on the side of the coupler then? My thinking in the above post was to weld a piece of flat bar steel for a lever on the end of the coupler. Then you could do as I said previously using a 5/8” drill bit put thru the coupler to find the center point thru the lever, then finish drilling the size you need to attach a bolt to clamp one end of the pot coupler to.

I think you will find the motors shaft does not have a hole on the end but just an indentation at the center where it was attached to a lathe when turned. If so you will have to drill it deeper, tap it, and then the rod you thread in could still turn unless you thread lock it into place.

the hole is 4mm deep on my test motor. it will need to be drilled deeper and tapped.

this is a coupler with a piece of flat bar welded to one half

EDIT: this is a collar not a coupler as @BlazinH points out below.

@BlazinH I will be doing what you had suggested earlier.

I might do what @shannonb1 is suggesting just to setup hall sensors for feedback if my MMs don't arrive on time.

I see you are using a locking collar @bruce stephen so you wouldn’t be able to weld a piece of flat bar to the end and still lock it down. BondeX stated he ordered couplers and they just use setscrews. I think the use of a locking collar may be a better way of doing it vs. a coupler though. Due the fact that we are constantly reversing our motors setscrews have a tendency to work themselves loose. If they get a little loose it will start wearing the corners of the key out when the coupler starts moving around too causing more play to develop. I suppose it will depend if the stresses in BondeXs case are enough to start working the setscrews loose or not. Or maybe some thread lock here too.

@BlazinH I was thinking the same thing and am also worried about the coupler getting loose and falling out.

So I was thinking of drilling a hole through the coupler and the motor shaft and securing it with a clevis pin. I think this would work, wouldn't it?

I always use loctite on metal to metal fastener's you dont want wigging loose....once the threads are "gummed up" that screw aint going no where.

Drilling and cutting hardened steel can be trying. Use cutting oil and a carbide bit. Carbide tipped will work but solid is better. Also keep the speed low and add enough oil that it doesn't run dry.

Been there, done that! I used a bolt instead of a clevis pin though. In my case I had two holes and two 5/16" bolts but the stress I put on them even sheered the bolts. I even tried grade 8 bolts. But I was heaving 300lbs so you won't be putting anything close to that amount of stress on yours.

What would work best though is if you cut your couplers length shorter than your motors shaft by about 3/4". Then weld a piece of 1/4 flat bar on the end of the coupler. Use a 5/8" drill bit and drill all the way thru your lever thru the coupler. Now you can slide the whole assembly on the motors shaft with 3/8" of the shaft left sticking out the end and with 1/8" clearance on the other end so the coupler doesn't drag on the gearbox. Weld the lever to the motor shaft and your done.

I use cobalt or titanium bits on hardened steel with lots of oil and a slow cutting speed.

The shaft is only 3/4" long

I found this info on drilling different types of steel.

HSS Drill Bits - Work well up to the 50ish RHC
Drill - Mild steel, Some tool steel, Some Spring Steel
No Drill - Hard Plate, Anti Drill Plate, 404c Stainless Steel
Pro - Good in Hand Drills and most drilling applications
Con - Has limitations in hardened steels

Cobalt - Works up to 58ish RHC
Drill - Mild Steel, Some Spring Steel, Some Tool Steel
No Drill - Hard Plate, Anti Drill Plate, 440C Stainless Steel
Pro - Good for hand drills and most drilling applications
Con - Has limits with hardened steel

Carbide Tipped - Will drill almost any steel, Hard, Stainless or Mild.
Pro - Drills all steel
Con- Blunt tip requires extreme pressure to produce cuttings. Drill bit is hard to start on all steels.

Diamond Coated Drill Bit - Cuts on most steels(Not Hard Plate) just not for long.
Pro - Will Drill most steels (Not Hard Plate)
Con - Cutting stops quickly after diamond grit has warn off, Then behaves like HSS bit

Solid Carbide Drill Bit - Cuts all steels.
Pro - Sharpened points wont "walk" like carbide tipped bit. Cuts all steel
Con - Sharp tip and fine edges can chip easily and ruin drill bit. Not for hand drills. Expensive!

If the shafts are hardened steel then it not the best idea to weld them. I doubt they are though on such a low power motor.

Whoops! Didn't check that.

Best to just weld the lever on and omit the coupler altogether then (assuming it doesn't have plastic or nylon gearing).

All metal gearbox

Ok I am an electron by profession and you guys are getting way too advanced in the Mech world

I like @Nick Moxley's idea of loctite

@BondeX are you still planning on doing the testing on these motors? It would be good to know stall and amp draw. Right up the electrical engineers alley so to speak.