AAAARGHHH!

[tel]

Spent a couple of hours today cutting a 48t 24dp gear in bronze. All went well until the last two teeth, which I managed to completely bugger up. Going to attempt a salvage tomorrow - as much in the interest of seeing if it can be done as anything else. Watch this space.
:wall: :wall: :wall:

 

[Maryak]

Tel,

Hope your better at brazing than I am

Good Luck, ;D

Regards
Bob

 

[Kludge]

All went well until the last two teeth, which I managed to completely bugger up.

Could you be a bit more specific? Are they off pitch or did they not quite fit or is the shape off or ... ?????

Come on, TELL, Tel!!

Best regards,

Kludge

 

[tel]

OK Kludge, 'ere's wot happened.

The blank was held on an arbour, in a 3 jaw chuck mounted to the rotary table. Not the most solid of arrangements, but the best I could do on the X2. Cutting with a single point flycutter. Now to get room for the cutting head between blank and chuck the arbour was not fully seated in the chuck, and the hammering action of the cutter was sloooowly pushing the whole thing back into the chuck jaws, to the point where the cutter clipped one of the jaws on the third last tooth, everything looked ok, but there was a tiny burr on the cutter that I failed to spot - continued on and - disaster.

I plan to cut out the whole bad section, silver solder in a piece of material, turn it to the original diameter, then try and pick up the postion and re-cut the bad section. Will it work????? Dunno, but I hate giving up on something I've spent so long on.

The cutter and setup were/are fine as an aluminium test piece works just fine against a commercial 24t gear.

 

[Maryak]

Tel,

I had your problem once and to make the job rigid enough for single point fly cutting, I drilled 4 holes through the blank and supported it using T nuts in the table slots, a length of thread and a nut each side of the blank.

Couldn't move. Of course 4 holes in the blank may not be acceptable to you. :

Anyway good luck

Regards
Bob

 

[tel]

You mean do away with the chuck and mount it directly on the table? That's not a bad idea, and if the holes were a problem they could always be plugged.

Things were going well

... until

This time I'll insert a slug behind the arbour to stop it moving back.

 

[jack404]

bugger!.....

good luck eh

jack

 

[Maryak]

Tel,

Yes, no chuck - a stub mandrel fitted into, (in my case 2mt), the RT centre, and a small 1/4" bolt and washers at the back as a puller to sheet home the mandrel in the RT bore.

Regards
Bob

 

[Kludge]

OK Kludge, 'ere's wot happened.

Okay, got my sharpened finger & forehead all ready.

I plan to cut out the whole bad section, silver solder in a piece of material, turn it to the original diameter, then try and pick up the postion and re-cut the bad section. Will it work????? Dunno, but I hate giving up on something I've spent so long on.

Okay, let me fall back on what I know again, watchmaker's practices. What you've described & shown shown is pretty much how it's done. They go outboard of the damaged area and cut in toward the hub like you show, though some cut in deeper than others - a practice I'm not sure is necessary. A few others would take it outboard at least one more tooth, the thinking being that breaking the teeth on a watrch wheel takes enough force that the adjacent teeth were probably damaged as well. That isn't the case in this situation.

From the picture, I think you want to move the right hand cut one tooth further. It looks like it's the one where the initial flycutter damage was done. It's "different" anyway and, in this case, different is baddity bad.

BEst regards,

Kludge

 

[tel]

Now that's a winkle worth keepin' in mind. I got more to do later and I'll certainly give it a try. No MT socket in my table tho' - just a bit of plain 'ole - but it would be OK for locating purposes (or porpoises Kludge)

 

[baldrocker]

Tel
This link may help.
http://home.iprimus.com.au/stevor/gearrepairs.htm
BR

 

[greenie]

That link you just posted, that Yours?

regards greenie

 

[tel]

Thanks blokes - I've made a start BUT now I've had to pull the set-up down, be at least a week before I can get back to it. :wall:

 

[baldrocker]

Greenie
No the bloke who owns it has an Advance lathe same as mine
I just dredged it up from my memory
BR