Team Thrifty /Fifty Build Diary for Bitza

**psycho_fling** · 17th June 2011, 15:29

my sponsors do all my ti stuff i think grade 5 will bend with ti if it bends it will if its designed not to then it will crack

easiest way to cut is on a guillotine but ive used angle grinder before

to bend it my sponsors use a piece of equipment to do it you can get exact angles best way id say

alex

**PJ-27** · 17th June 2011, 18:30

Cheers for the advise.

Will it bend, that is the question?

**PJ-27** · 23rd June 2011, 00:27

What is the best way to attach a pulley to a motor shaft?

Just bought a brushless for my Beetle, it has a shaft diameter of just over 3mm and is completely smooth. The timing pulley just has a pilot hole.

The motor is an outrunner, and Ewan advised bolting onto the casing (since that also rotates) but I could do with some more detail.

Any suggestions?

Thanks,

PJ

**typhoon_driver** · 23rd June 2011, 02:54

drill the pulley out to 3mm. Drill and tap a grub screw hole to intersect this hole. File a very small flat onto the motor shaft. Mount using the non rotating face of the motor, slide the pulley on and tighten the grub.

**Mouldy** · 23rd June 2011, 05:45

Id say do what gary suggests.. If you dont have any drills and taps small enough for a grub screw, get some high grade loctite, and loctite the pulley onto the shaft... I did this for the gears in 360's first stage disc drive and it worked fine... thats putting much more tourque through the pulley then you will be able to generate... It just makes removing the pulley a pain.

I wouldnt suggest mounting it of the rear of the motor if you can help it- its asking a lot of the bearings in the front plate of the motor over that sort of distance.

As for the ti- try it... the term grade 5 is pretty open.... put it in a vice, try bend it over with a hammer, if it cracks, try heating it

... you will need to get it cherry red until the point that the surface of the titanium looks like its gone flakey before you will be able to bend it easy.... Wear some welding gogles if you've got some while heating it.

**typhoon_driver** · 23rd June 2011, 06:10

Don't use cobalt drills on titanium. They're best used on hardox and steel. Use regular HSS drill bits on titanium with plenty of lubricant/coolant

**PJ-27** · 23rd June 2011, 11:09

No to Cobalt? They went through a dream! Although I did use a lot of lubricant.

It's TA6, which I believe is the British name for Grade 4 (Not Grade 5 which is Ti-6A... you can see my confusion...). The Verniers come up at 1.6mm, so I'm hoping it'll bend without heating. But I'll test it on an un-needed bit first.

Unfortunately I don't think we have taps that small, but I'll check. If not then I'll try the Loctite idea.

Thanks guys.

**typhoon_driver** · 23rd June 2011, 11:56

even if it's an M3 tap going through it should be fine (sets usually go down to around the M2 mark). Or you would probably be able to pick up a cheap tap on ebay.

I should have quantified the drill bit statement. On sheet, cobalt drills will be fine, however when it comes to thicker sections you're best using HSS bits (a wee tip for the future there). I can't remember the exact reasoning but it was advice from a very reliable source on the subject of machining titanium.

If my memory serves me right, grade 4 should be bendable to a certain point. Grade 5 and upwards are the ones that are more likely to snap although don't quote me on that one!

**PJ-27** · 23rd June 2011, 12:39

Cheers for the advise.

Apparently we do have some small taps, so I'll see what I can find.

Also Grade 4 does bend without heat. Dan just turned up with it all done!