Drawbars

evening all, Im getting to the stage where I can actually use my mill (electricity arrives at the weekend :) so my thoughts turn to the drawbar. The mill is int 40 taper, and the drawbar that was in it is marked unc. needless to say my collet chucks are M16... (its never simple). My guess is that as the taper isnt a driving taper, there are two big dogs for the drive the drawbar only has to hold the tooling in place, and not with a large amount of force? I have some M12 studding (the drawbar nut is M12) and a couple of M16 bolts. thus the correct threads are already done :) but on 2 separate bits :( My plan is to unite these parts and hey presto drawbar. As I see it I can either drill and tap the M16 bolt for M12, or drill and cross drill and then pin the M12 studding in, or possibly drill through and rivet/weld over the end. Obviously the threading option is strongest, but also the most PITA, esp as I dont have an M12 tap, but would the cross pinning (quicker?) be strong enough? Or, where do I get a drawbar that doesnt cost an arm and a leg, which is M12 on 1 end, M16 on the other, and of the correct length for a TOS mill?

thoughts and opinions please

cheers

Dave

Reply to
dave sanderson
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Buy a metre of M16 studding, turn down one end to 12mm & thread it. Does it need to be an M12 nut on top? Any reason why it can't be M16 all the way through? On my Elliott mill (30 taper) I use a length of M12 studding with a big purpose-made brass nut on top, with a locking nut. That way I can easily fiddle the length for different tooling.

Tim

Reply to
Tim Leech

Are you in the right hobby/job?

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Reply to
Emimec

The spindle only has a small hole in the middle, M12 will fit, but not much bigger, the original unc drawbar wont pass upwards. The original drawbar nut is M12, that and having some M12 studding are the reasons to use it, nothing more. I thought of turning down M16, but its quite long, about half a meter, and it seems like the hard way...

Dave

Reply to
dave sanderson

Hmm, well its a thought I suppose ;) not really what I had in mind tho

Dave

Reply to
dave sanderson

(electricity arrives at the weekend :)

...ah... Mr Faraday coming round at the weekend ?

AWEM

Reply to
Andrew Mawson

do it from scratch

get a chrome vanadium socket extention bar ...and thread that ... will make an excellent very strong drawbar ..

thats how im planning to make them for my fritz.

all the best.mark

Reply to
mark

When the thread on my Bridgeport clone drawbar wore out to the point it wouldn't hold in the collets anymore we just cut it off, sawed the threaded bit off an appropriate UNC bolt and welded it on. It's been fine like that for ten years or more. If the only thing wrong with your drawbar is the thread at the bottom then hack it off and weld some M16 in its place. If you hold the bits in the chuck and tailstock chuck of a lathe it'll keep them nicely aligned while you weld them.

Also I'm not exactly sure why a drawbar would be threaded at both ends. Usually the thread is at the collet end and the top is just a big flanged hex which bears on the top of the quill.

Reply to
Dave Baker

Is this after you have used the bed shears with a 4 pound lump hammer as a bending brake ?

He explained two or three threads earlier that this machine has a stepped drawbar and only has a 12mm hole up the spindle but needs 5/8" UNC or 16mm for the tool holders hence the need for a nut on the top

Reply to
John Stevenson

Reply to
Andrew Mawson

Often enough, they have threaded stubbies that can be replaced. So the chuck might have M16 inside, but the stubby standing out might be UNC. They don't cost a lot. Changed some tools from M16 to S20 (Deckel speciality) that way.

Nick

Reply to
Nick Mueller

Yes, with a huge bucket of special 3 phase electrons :)

Dave

Reply to
dave sanderson

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