Cole jaw.

dubtom

Just wondering if any turners use cole jaws for those over sized bits and bobs.I'm in the process of making a banjo,which involves turning the rim,which is about 11'' in diameter outside and about 91/2 inside, I've considered just using a glue/hot glue setup but I need to recess both inside and outside of the piece. I know cole jaws are generally recommended just for finishing etc, so with that in mind I was going to attempt to round the rim with a router first,then do the recesses and finishing on the cole jaws.Hold wise are they up to the job. Making the rim has been a bit of a task,laminating 18 pie shaped pieces into three rings which are then glued together to form the rim and hopefully finished on the lathe,I could do without a throwout. Here's a pic of what a finished rim looks like,at about €400 you can see the saving by making my own.BTW,Goughs have a cole jaw for I think €90,good price?

Alun

I have a set for my SuperNova chuck, and to be honest don't use it that much. I bought it primarily with the idea of using it for tidying up the bottoms of bowls, but the standard rubber thingies on the jaws are a little on the small side (i.e. not quite deep enough) to grip the rims of most bowls I have made. Now, it is, of course, quite feasible to make your own jaws to attach to the system as shown here under "CUSTOMISING THE COLE JAW USING WOODEN JAWS" or you could just make replacement wooden grips and cover them with something grippy to make them extend further.

My concern though, even if you did manage to mount your existing frame on the lathe, would be that of centering it properly in the case that it's not 100% round, both inside and out. If this is the case, I suppose you'd have to grip it on the inside first, round off the outside, and then grip from the outside and round off the inside (if that's important).

However, if it is 100% round, and all you need to do is create the two recesses, and leave the rest as is, then you'd probably be OK.

Generally they're OK, but you do have to quite careful when using them. Keep the revs low, take very small cuts, and be very careful not to get a catch, and try not to apply any pressure away from the headstock otherwise the piece will pop out of the jaws quite easily.

BTW, if this is a one off, and you're somewhere near me, you're more than welcome to borrow my jaws if you like. Let me know if you do.

P.S. just noticed on the Teknatool website that the maximum attainable sizes for the SuperNova2 chuck are 9.291" external and approx. 11" internal, so gripping the outside of your piece would be a problem without custom jaw pieces.

dubtom

Thanks Alun for the info,and offer.Unfortunatly I think that the chances of me getting the pieces perfectly round with the router and lined up 100% to not need any work on the lathe is slim,with that in mind I don't think it's worth the risk.I have two nova chucks,I wonder would it be possible to get an oversized set of jaws made for it. Normal rim making is usually done on a metal lathe with huge 3 jaw chucks,using the cutter in the same way as cutting metal,mm at a time with the hand crank thingy, so much more precise than I could be with a chisel.I'll have to do a bit more browsing to see what I can come up with.
Thanks again for the reply.

Alun

Hi Tom, there's nothing particularly special about Teknatool's Cole jaws .. they're just 4 metal quadrants with some holes drilled in them after all! If you Google a bit, especially in Google groups rec.crafts.woodturning, there are references to people who've effectively made their own version of these using plywood.

Teknatool make a pretty expensive Ornamental Turner, see here which can (with additional accessories!) do limited machining type work. See http://www.youtube.com/watch?v=y9OGI4xEs0E

loz

Tom,

Good luck with your project - and more pics when done please.

I dont use cole jaws, i normally just jamchuck bowls for bottom finishing, but am in the process of making a donut chuck as a little proect.

this PDF has lots of alternative reverse chucking methods

LINK to PDF


Loz


ps - if any of you kind skilled guys fancy making me the longworth in that pdf - then i would pay for parts etc - anyone up for it ?

dubtom

Loz, thanks for that link,that longworth chuck certainly looks interesting,if it is indeed self centering it would save me a headache or two. I'll do a search on a how to,if it looks manageable for my humble skills I'm sure I could muster two.

loz

You're welcome.

I'd try myself to make one but as i dont have a router i'm stuped on how to cut the grooves perfectly.