Some Machining

[Pinski1]

I'd like to get some HTD 3mm pitch, 9mm belt width pulleys, like this could be bored out with a 0.75 inch hexagonal hole so that they could fit on these.

I'd love to know if you can do that and how much it would cost, ideally I'd want a minimum of 4, possibly 6 so I have some spares.

Thanks.

[Eventorizon]

It is almost impossible to bore a hexagonal hole. Why can't you use a grub screw/keyway and a hole?

I will also point out, 3mm pitch is to small for a featherweight if that is your intended use. 5mm is far better.

[Pinski1]

If you've got a broaching set-up hex is easy, if you've got a CNC machine hex is definitely possible. I don't want to trust a grub screw and I don't really have a shaft to put a keyway in.

The GR02 doesn't have a long shaft, especially when you have 3mm of aluminium bulkhead and a bearing block to go though. I wanted to use the Banebots hub to extend the shaft as well as allow me to use the same wheel & pulley setup on both driver wheels and driven wheels.

Also HPC gears seems to think a 28 tooth, HTD 3mm pitch, 9mm wide belt is okay up to 134 Watts, which is 105 RPM at the GR02's rated stall torque of 12.1Nm.

[Eventorizon]

In combat the belts and parts will experience things far beyond what they are spec'd to on the data sheet. You will find that things never quite meet expectations as they are never used in the circumstances they are designed for. It is better to over spec something rather than discover that your design is built around parts that can't survive the forces and shocks.

[Pinski1]

I agree, which is why the belt is good for 105 RPM at the stall, i.e. when the motor is stopped, torque of 12.1Nm. Or to put it another way, roughly 1300Nm at 1 RPM.

I'd love to be able to bolt the pulley to the wheel and the wheel to the GR02 shaft via the GR02 shaft mating hub but unfortunately the SHF 12mm has it's bolt holes 36mm apart, whechi s larger than the pulley which is only 32mm in diameter.

[Eventorizon]

Then go up in your size of pulley. That is easier than trying to do all this machining and modification. If you do it right then you wont actually change the distance between your axles ie. you change both pulleys and the length of the belt.

[maddox10]

The GR02 hub ain't available atm.
And I shortened the axles of the GR 02's for Nebelwerfer and the GR 01's in Hannibalito 4.

In any case, whatever you want mated on a GR02, I can do. PM me for more involved talks.

[typhoon_driver]

I haven't read any of this thread but i'm going to assume that being a hex hole you are talking about the bane bots wheels and hubs on a regular drill shaft etc. If so these can be fit together. Look for my thread on boner. I mated a banebots wheels with a hex hole and hub using only a thin piece of copper. I'm drunk over xmas right now but pm me for more details if you fancy.

[Ellis]

I don't really understand. All you'd gain by making the bore of the pulley a hex is moving where you have the setscrews. The Banebots adapter attaches with just setscrews, so, why not attach the pulley in the same way, directly? And, by burying one in the toothed portion of the pulley, as well as its boss, you could have a much sturdier pair of grubs than the BB adapter gives.

Or, probably the best method in terms of balancing work/cost, is a 19mm steel hex piece turned to have a hex portion for the wheel, and a round portion with a large flat onto which you can setscrew the pulley. Much, much easier to machine.