Drilling out turning chucks for different threads

[=Adam=]

Hi guys!

I have been offered a couple of chucks by someone local to me but they have an m20 x 2.0 thread from an old multico lathe. The chucks are tempting but i was wondering if there was a way to get them drilled out and tapped to suit an m33 x 3.5 spindle?

The chucks are great value and I dont want to let them go and I would rather have them drilled out if possible as opposed to having a spindle adaptor.

Any input would be great

Cheers guys!

 

[CHJ]

Assuming there is enough meat in the chuck inner body it is obviously possible to machine out (not drill) and cut new threads.

This would need to be done by someone with a lathe at the upper end on size as far as a Hobbyist goes, or someone with a commercial workshop.
If that person is to be re-numerated sensibly for time and tooling it is probably going to cost more than the chucks in the first place, then of course there is the shipping costs to and from workshop.

Mike Fincher (antarmike on woodworkers institute would probably be able to give you a realistic quotation.

 

[dickm]

Second what Chas has said. I've re-threaded quite a few chucks now (in two cases, twice, having changed lathes!) using a Super 7, which is probably the size of lathe most likely to be in amateur hands. In fact, re-threading is marginally easier than making an adaptor, because there's only one thread and more importantly, one register, to get right.
But it's probably not something that it would be economical to get done by a specialist. Unless the chucks are VERY cheap, professional rethreading will probably cost you more than the extra to buy the right chuck straight off.

 

[antarmike]

Is the chuck on a backplate? One option would be to buy a standard ISO backplate in M33 x 3.5 and the machine the back of the chuck to matching register and to fix the chuck to the Back Plate with Allen Cap head screws. Unless you strip the chuck you will not know how far you can bore out the existing thread before you break through the central spigot and catch the scroll itself. Certainly the proposed thread is bigger my quite a margin than the existing thread and there may not be enough wall.

Backplate T38 is £26.75

A photo of the back of one of the chucks would help get you a sensible suggestion.

 

[CHJ]

Welcome to the forum Mike.
I wish all Woodworking Chuck Makers would stick to the standard ISO backplate system, currently we seem to only have the Versa Chuck from the ToolPost giving this easy change option now that Axminster has dropped the Option.

 

[antarmike]

Axminster still list iso backplates......They are used on their super precision chuck

 

[antarmike]

I am a bit confused since Multico is listed as M20 x 1.5mm Not M20 x 2.0mm

M20 x 2.0mm is normal for Tyme Cub or Gem.

 

[gregmcateer]

Welcome to the forum Mike.

Ditto from me.

Greg

 

[antarmike]

we meet again!

 

[CHJ]

Axminster still list iso backplates......They are used on their super precision chuck

Yes I have a couple of them, unfortunately Axminster no longer distribute the Super Precision, having gone for a new stainless steel 110mm design made in house.
The new ones are fixed thread and have various fitting problems as originally released which has lead to a whole draft of fitting options, admittedly some obscure ones to special order are now offered but none are mobile across machine standards and are an expensive none transferable option.

 

[dickm]

Welcome to the forum Mike.
I wish all Woodworking Chuck Makers would stick to the standard ISO backplate system

AGREED!!! But not holding my breath for it to happen.

 

[Aden30mm]

I would have thought if as Chas indicated if there is sufficient section to allow for a correct thread clearance drill or cutting tool access, and the chuck working parts are not affected by the enlargement, then I would go down the path of re-threading the chuck.

I have just used a local machine company to produce a collar for my lathe 1-1/4 X 8TPI, it cost me £10. They are going to re-thread my Multistar backplate and expect the cost to be similar (although I did provide the taps for the job as they are a very difficult size to source). You thread size is fairly standard and may be held by local engineering workshops.

Finally, find out your local machine engineering workshop (there out there), normally small outlets but disappearing fast as we consign to the skip our engineering history.

Kind regards

Aden

 

[antarmike]

M33 is 65% increase in thread size over M20. I have my doubts there will be enough metal to take this thread which Is why I suggested using a backplate.

Most engineering Firms charge £30 per hour or thereabouts. I think you got a very good price few other companies would care to match. £10 quid is a quid for the barstock, and £9 machining time. Someone was doing you a favour......

 

[Aden30mm]

What I have suggested is to encourage access to a machine workshop, as this may be a route to resolve the problem. You will not know if this modification is achievable until you obtain a professional to review the chucks. You could make it a condition of sale with the chuck vendor.

Did the chuck at anytime offer an initial sale with this thread size (m33 x 3.5)?

Finally, sorry to disagree, no one did me a favor I asked for them to do a job which they did and it cost me £10.

 

[antarmike]

Finally, sorry to disagree, no one did me a favor I asked for them to do a job which they did and it cost me £10.

Where abouts in Lincolnshire are you and which company did you use?

 

[Aden30mm]

Mike

Camberwood Engineering Services Ltd. Manning Road Bourne Lincolnshire PE10 9HW

They also surface ground some square bar down for me for a bandsaw mitre fence, again for a tenner.

 

[antarmike]

My only thought was a Teknatool chuck insert is about £20.00 and is CNC manufactured in big runs. If a company can hand make a one off for half the price, they either have to be very very quick at what they do if they can make a sleeve for £10, or they are working at a very low hourly rate.
It has to cost more to hand machine a one of adapter than to CNC produce them in bulk. You are getting an adapter at half the price of a bulk run CNC produced one, when in reality a hand produced one ought to cost twice a CNC one, I would expect a hand made one of to reasonably be £35 - 40.

I see they have CNC lathes. If the insert was programmed for CNC then yes I suppose they could still just turn a profit a £10.