3 Jaw for Flexispeed

I mentioned in another thread that I was purchasing a small 3 jaw chuck to fit my Flexispeed lathe. Here it is with a 14 x1 mm thread: No mention of origin anywhere on the documentation but Ketan said the chuck is Chinese.

First I took a steel dog end and turned it to about 1/2" to be concentric with the Myford spindle

Then mounted the new chuck, in reverse, on the stub. I measured the run out here and the TIR was 3 thou.

The body of the chuck was tough but machined OK so I turned away the 14mm thread and and opened the hole out to 3/4".

Another dog end was mounted in the Myford chuck and the OD turned to be a light press fit in the new chuck body. The Flexispeed spindle nose is 1/2" BSF (16 tpi) so I partially screw cut that, finished off the thread with a tap and then cut the 1/2" register before parting off.

The insert was annointed with Loctite retainer and pressed into the chuck with the bench vice.

24 hours later I mounted the chuck on the lathe

Run out on this 1/2" endmill was a shade less then 1 thou TIR. Checking with 3/16" and 1" mill shanks, the TIR drifted out to 3 thou in both cases. I'm happy with this as being within specification - I don't expect a 3 jaw sc check to be collet accurate.

I hope this helps some others needing chucks for their Flexispeeds.

Rod

Nice work, Rod

MichaelG.

Rod,

Thank you for this guide. It will be very useful in time as I shall want to get a new chuck and, probably, a four jaw version as well.

Regards,

James.

Well done Roderick, nice work

I hope you don't mind if I semi-hijack your thread with another possible mod which turns a 50 quid chuck into a 120 quid chuck

I used the Unimat a lot a few years ago with the finger bars and ageing fingers can become stiff and sore if you do a lot of chucking on these types

This is a keyed chuck

It may be possible to mod a finger bar chuck into one of these by making a ring with the cog teeth and fitting it to the back part of the chuck with 3 pins into the finger bar holes, then make the t-key

Quite a technical challenge I know, but a keyed chuck is far easier on old fingers

Edited By Ady1 on 12/08/2015 09:31:23

Hi Rod,

Looking at the picture of chuck, paperwork and packing, it is definately Chinese. The makers mark is also on the chuck.

It would be great to see what is available and acceptable at the cheap end, along with comparisons with an Indian origin version of this chuck.

Good write up of hands-on experiance. I too hope that it will help people, especially those who have no idea of what to expect from these type of chucks in this price range, even though ARC does not sell them at present

Ketan at ARC.

I need to do the same for mine,the one I have has a 14x1.5 thread. I was wondering what the chance of re threading the chuck? Where did you get your chuck from Roderick,or would I be better off doing the same as you?

Regards Mark P.

Good write up Rod. (Thinks: Bah! Would have made a good 2-pager for MEW...)

One thing some potential purchasers of this style of chuck may not realise is that the jaws are usually reversible, so although the you only get one set, they can be used as internal or external jaws.

Neil

Mark,

Aim tools on ebay. I chose this particular model because of the good illustrations and drawings on the listing. Similar chucks are available with a 12 x 1 thread (but not from Aim). You should be able to clean a 12mm thread out to 14 x 1.5 but you would have to be confident you could cut the screw and register in some pretty tough material. I took a little bit of a risk with the chuck I bought but I reckoned that if the worst came to the worst I could use my Dremel as a toolpost grinder to open up the hole for the insert (maybe!). In the event the body of the chuck was soft enough for turning but similar chucks from other suppliers may be different.

HTH

Rod

Edited By Roderick Jenkins on 12/08/2015 17:14:35

Nice work Rod. I have to do the same sort of thing for my Pultra. I could adapt a 10mm collet to hold a chuck but that increases the overhang. The Pultra 3 jaw doesn't have any leverage additions at all, just uses finger friction on the rims of the chuck. Rather than use the keyed type I feel I would just make some longer levers.

I wonder if the chuck has a hardened scroll plate and heat treated jaws? One of the problems with the larger chucks in the past has been a soft scroll plate that can strip easily. Some of the cheaper quality chucks get round this by making the parts in a sort of chunky fashion and still heat treating them.

ARC/Ketan might like to note that for some reason 80mm versions of these chucks are hard to find as are light weight 4 jaw independents of this size. The Peatol one is a solid block of metal. 50mm 3 jaws are all over the place but I feel they are too small even for a Pultra.

John

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Sorry! Sometimes the lure of instant communication is just too tempting.  You're right about the jaws.

I hope you've got yourself set up for the Perseids. It's clouding over nicely here in sunny south

Rod

Edited By Roderick Jenkins on 12/08/2015 17:12:24

Nice addition to the Flexi Omnibus, Rod. Many thanks, Hugh.

Roderick,

Do you think that the Flexispeed itself will be sturdy enough to use to turn out the thread in the chuck? I am tempted to buy one of these chucks for my own Flexispeed.

Regards,

James.

Hmmmm...

I really don't know. A boring bar with cgt type insert would give you a pretty good chance but I would be worried about the overhang on that rather slender Flexispeed spindle with 2 chucks hanging off it. Are you in the UK? I'd be happy to do it for you if it tuned out not to be possible, the postal service is still pretty good (if a tad expensive).

Rod

You can also get these inexpensive lever scroll chucks with a 3-screw fixing. I have one and I've made an backplate to fit my new adept spindle. I will turn the spigot in place once the lathe is functioning.

Neil

Rod,

Thank you for your reply. I had the same apprehension regarding the overhang. I have considered a temporary lathe spindle, just using a length of 1/2" bar, and turning the temporary spigot on that, clamping the new chuck onto it for boring. However, I am not sure quite whether that may upset the headstock bushes for when I refit the proper spindle.

I am in England, in Bucks, and may take up your offer, if you do not mind.

Neil,

I confess that I have only found small chucks with the thread bored into the chuck body. Do you remember where your bought your chuck with the backplate? I am happy to have a go at turning a backplate myself instead of troubling Rod, if I can avoid doing so.

Regards,

James.