Drive motor options

[overkill]

Hi Ellis! You reminded me how slack I've been so I tried out some new drill on the drill gears. It worked brilliantly, see the details here: http://www.robowars.org/forum/viewto...?p=85652#85652

[Liftoff]

Nice work nick. Could be it was as you said Ellis, some type of sintered steel... strange material to work with!
It's also most probable my fault as well as I drilled them without coolant and the two that cracked clearly overheated!
That material has got some sort of case hardening tho, I could cut through the central part relatively easy with a black HSS drill and reamed to a good finish. The ends were a different story!

I was also drilling slightly larger holes than you were Nick, 6 and 5mm. The 5mm holes came out fine, but the 6mm holes were at the limit a 10T mod 1 gear can take!

20140207_090836.jpg

[overkill]

My gears look different to the ones in your photo; they have a surface finish that couldn't have come from any milling or turning method I know of and they were definitely hard all the way thru. Your gears would probably benefit from the carbide drills as well; I had the lathe set for 200 rpm and used a slow feed as I don't have and data for working sintered steel with carbide. The gears only got slightly warm.

[Liftoff]

My gears look different to the ones in your photo; they have a surface finish that couldn't have come from any milling or turning method I know of

Originally they looked like this:

HPI gear.jpg
I couldn't drill through it at that stage so I turned it on a lathe and cut a new face, that took the hardened piece off and I could just about drill it.
What type of drills did you get Nick, there are loads of different shapes carbide drills around! What worked for you?

[overkill]

Ah, now your gear looks exactly like mine. I used drills like this: http://www.mcmaster.com/#standard-drill-bits/=ql6bw5 and I am sure you can find the same thing locally in the UK or Europe. I tried facing one of these gears and only succeeded in ruining a carbide insert.

[Liftoff]

Could be they are different materials then, as I did face it with a carbide insert. I needed the gear 5mm wide so I cut it off with a Dremel type cut-off disc, no problems there either.
Good choice of drill on that website, thanks...

[Liftoff]

Gearboxes almost ready now. Have not tried them out with the motor yet, but they turn freely by hand. Had to do some modifications to the original design, namely introducing thrust washers to reduce gear rubbing on the side plates. Looks good enough though, considering its a precision part manufactured using hand tools a lathe milling combi would have come very useful! will have to wait a bit more for that...
Will try to find some time tomorrow to couple the motor to the box and give it a go...hoping it will stay in one piece - fingers crossed!

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[Mouldy]

looks good!

[overkill]

For a gearbox made with just hand tools, that is fantastic work.

[daveimi]

Is there any chance of getting a run through of how you got it so accurate with hand tools?

There is hope that mere mortals may be able to make something like this!