Tough gears

[Chippie]

The gears I purchased for my little engine project are as hard as ****…..I need to drill them at least for the camshaft and crankshaft.
A hss steel drill won’t touch them…I haven’t got a carbide drill, and as such to ream them to size my reamers are has too.

So, I assume they have been hardened….if I heat them to red heat, will this soften them?
Can I re harden them afterwards?

Im think yes, but would like some reassurance…please..

 

[frank horton]

I'm sure u will sofen that way......but when rehardening it'll be a bit of a witches brew.....
u may get lucky.....
do u need to modify both.....?
if it's just a toy engine perhaps get one of the gears made from Tuffnal......

 

[tom2207]

would they spark erode [edm]

 

[Chippie]

I'm sure u will sofen that way......but when rehardening it'll be a bit of a witches brew.....
u may get lucky.....
do u need to modify both.....?
if it's just a toy engine perhaps get one of the gears made from Tuffnal......

Toy engine? Really? Work of art….

I have some Kasenit(e) equivalent that I can use….

Spark erosion costs money….I’m a poor pensioner..

 

[RWD3M]

Cobalt tipped drills?

 

[Agroshield]

...if I heat them to red heat, will this soften them?
Can I re harden them afterwards?

Where did you buy them? Is there any information available from the seller concerning material and heat treatment?

Just heating to red hot to anneal them may not work. I think you need to heat until they become non-magnetic, let them soak at that temperature for a reasonable period of time and then cool very slowly. But it is hugely material-dependent, hence the need to know of what steel specification they are made.

Re-hardening could be more challenging than annealing.

What tooth count and specification are the gears? Then we could try to find some economically priced, machinable alternatives.

 

[Chippie]

I bought them from a seller on eBay, guess I could ask him about the matl. specs,

They are all metric mod. 0.8, 12/22/24 teeth.

 

[Chippie]

Cobalt tipped drills?

Dont have any, and they need to be reamed to size…and don’t have any cobalt/carbide reamers..

 

[RWD3M]

What size?

 

[Milkybars]

Given you location maybe a trip to the @doubleboost establishment ??
how small are we talking, could they be clocked and bored in the lathe ??

 

[Chippie]

Given you location maybe a trip to the @doubleboost establishment ??
how small are we talking, could they be clocked and bored in the lathe ??

I’m sure John would/could help but I’d rather sort this alone with out intervention if you know what I mean…

 

[Richiew]

Could you use a boring bar on a lathe

This.

 

[Chippie]

Not sure what happened there, I missed the post by ‘o Thames’, sorry m8….

But no, boring bars I have are too big, I have an 8mm and 12mm shank tools….
I fear anything smaller wouldn’t be rigid enough…especially hss.

 

[Pete.]

Make a miniature boring bar freom a broken carbide end mill. I use them all the time.

 

[Agroshield]

They are all metric mod. 0.8, 12/22/24 teeth.

HPC Gears have them but are expensive.

The only other place I could find alternatives for all three sizes, anodised alloy, 32DP, is this:

RW Racing Pinion; Hard Alloy 32dp - 12T (RW3200-12) - SC Models

SC Models - RW Racing Pinion; Hard Alloy 32dp - 12T (RW3200-12)

www.scmodels.co.uk

It is hard to find 12t 0.8MOD. Most stock gear sellers only go down to 15t. 22t is not a stock size - the range generally goes 20, 24, 25.

 

[Chippie]

I checked HPC gears, was my first port of call….but too expensive..
Not sure 22 tooth gear could swapped because of the centre distances of the other two…

 

[winchman]

Gears are machined as green gears ( Still Soft) then hardened after, once managed to bore one out for a reverse steer bike it wasn't easy.

 

[Agroshield]

Not sure 22 tooth gear could swapped because of the centre distances of the other two…

32DP is for everyday use the same as 0.8 MOD.

If the three gear axes are co-linear, it means 22t is the minimum you can use. Any tooth size bigger than that can be used as an idler but you would have to displace its axis sideways. So it could be swapped but would mean a design change. You could draw up or calculate how much it would have to move if changed to a 24t.