Tommy bar repalcement

[Tiger]

I have a chuck which requires tightening by using 2 tommy bars. What makes it awkward is when you need to centre the workpiece and tighten the chuck at the same time, ideally you need 3 hands. Is there a way around this so you can somehow tighten the chuck with one hand only?

[wheelinround]

Tiger there is use the two closet holes for the tommy bars and nip together as much as possible

Or bring your tailstock up and use it to hold the work in place I use a timber scrap bit between so no damage.:2tsup:

[Cliff Rogers]

2 things I find helpful here.

1. Spindle lock or indexing attachment, you lock the spindle & then you can tighten the chuck while you hold the piece with the other hand.

2. A big gut. You stick one tommy bar straight out into your gut & lean on it & then you have a spare hand. :D

[Sturdee]

2. A big gut. You stick one tommy bar straight out into your gut & lean on it & then you have a spare hand. :D

Or put a long handle on one of the tommy bars or spindle spanner so that it can be locked in position with a normal gut.:D


Peter.

[tea lady]

Or put a long handle on one of the tommy bars or spindle spanner so that it can be locked in position with a normal gut.:D


Peter.or put it on the tool rest. Or if its long enough the lathe bed. :cool: I try and find the holes that are close together. :shrug: (The tool rest can give you more purchase especially when you want to UNdo something. )

[Tiger]

Thanks for the interesting replies.

So I can try and grow a big gut - shouldn't be hard to do, however downside is that it could be bad for health or turn another tommy bar with a longer handle... mmm...I think I'll go for the longer handle.

Cliff, I like the spindle lock idea but I have the basic entry level lathe, not sure how I can build one, but will investigate.

[bobsreturn2003]

these chucks were designed for people with 3 hands !!!and are easy to use :doh: . since giving up my job with the circus i just use the bars close together ,and tighten that way . the new chucks just use a key . this is because 3 handed buyers are getting hard to find . cheers

[RETIRED]

Post no 10 here:

Need information on chucks. (http://www.woodworkforums.com/f8/need-information-chucks-108876/#post1070518)

[Tiger]

Hi ,

I've read post no. 10 that you mentioned but I can't see how that helps. From Issatree's post, he has made up a couple of tommy bars but then says he only needs one tommy bar :?. I'm still not sure how you lock the spindle in place so that you only need the one tommy bar. As a Fish 'n Chip politician was heard to say, "Please explain".

[RETIRED]

The biggest problem I have is that they are both the same length and neither is long enough to wedge against your arm or wrist while you tighten the other.

You can use the tool rest as TL suggested.

If you make longer bars you can get past the timber and at least wedge that against yourself whilst you tighten the other.

I never have much trouble with them. I do as Issatree does and tighten the little ring by hand or if I can't I use the tail stock to hold the timber while I loosely fit the chuck. Remove tailstock support and check for concentricity and then tighten when right.

[Allan at Wallan]

Thanks for the interesting replies.

So I can try and grow a big gut - shouldn't be hard to do, however downside is that it could be bad for health or turn another tommy bar with a longer handle... mmm...I think I'll go for the longer handle.

Cliff, I like the spindle lock idea but I have the basic entry level lathe, not sure how I can build one, but will investigate.

I can loan you a bigger gut but you may need to hurry
... I have lost 18kg since September so offer is disappearing soon.:D

Allan

[Tiger]

I can loan you a bigger gut but you may need to hurry
... I have lost 18kg since September so offer is disappearing soon.:D

Allan

It's okay Al, I'll make do, but thanks for your generous offer.

[wheelinround]

I can loan you a bigger gut but you may need to hurry
... I have lost 18kg since September so offer is disappearing soon.:D

Allan

Your becoming gutless Alan :U:2tsup:

[brendan stemp]

What I have done is drilled extra holes around one of the rings so that there are more options to place the bars which means you will always find two holes that are close enough together so that one hand can be used to tighten or loosen the chuck. Does this make sense??

[Gil Jones]

Look for used scanners and /or printers. The steel bars inside that the light and ink run back and forth on are sometimes just the right thickness to use as Tommy Bars, and cut in half they make nice long bars (with more leverage).
Gil

[Tiger]

What I have done is drilled extra holes around one of the rings so that there are more options to place the bars which means you will always find two holes that are close enough together so that one hand can be used to tighten or loosen the chuck. Does this make sense??

Hi Brendan,

Yep, that makes sense and I may well end up doing that. Having read all the posts, I'm now leaning toward making an indexing wheel/spindle lock. The indexing wheel has always appealed and so now I have a very good reason to make one. I do have a handwheel already on the outboard side of the lathe so the indexing wheel/spindle stop will have to be mounted on the inside just before the chuck. Just need a nice easy plan to follow....

[issatree]

Hi Tiger,
Regarding " The Bars " , go to a Trash & Treasure Market, take a Tommy Bar with you, & buy 2 good quality lengthy Screwdrivers of the same thickness. Some of the S/D bend very easily
Cut the ends off, grind the ends sq. & you need to do this often, as it stops the Holes from going Oval.
Now you have 2 New Tommy Bars.
As Brendan said, Drill extra Holes in the Chuck Rings, very easy to do.
I'm thinking that the Chucks are "Black, Nova Scroll Chucks".
Be sure to use "Graphite Powder" in the Workings, to make the Chucks work nicely.
Also you may like to buy a set of 35 or 45mm. Spigot Jaws, as they hold on a lot better.
Regards,
issatree.
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[Tiger]

Thanks, Issatree, some good suggestions there.

[Allen Neighbors]

Thanks, Issatree, some good suggestions there.

Easiest way to fix this problem is to break a thin magnet into pieces; find pieces small enough to fit into the holed, and CA them in place. The magnets will hold the bars in, making it easy to use one bar while the other bar is against something else, like the ways, or another blank... at least you won't be having to bend over an pick up a fallen bar.

[Tiger]

Easiest way to fix this problem is to break a thin magnet into pieces; find pieces small enough to fit into the holed, and CA them in place. The magnets will hold the bars in, making it easy to use one bar while the other bar is against something else, like the ways, or another blank... at least you won't be having to bend over an pick up a fallen bar.

Allen, have you had a problem with the magnets flying out when the lathe rotates at high speed?

[Allen Neighbors]

Allen, have you had a problem with the magnets flying out when the lathe rotates at high speed?

Tiger, CA works wonders. :2tsup:

[Alastair]

Can't say I have ever had a problem with this.

Chuck body has 2 holes, scroll has 3, so at any time there has to be one of each within 60deg. One hand can easily span this, and the gripping power in ones hand is ample to tighten the chuck.

So:

Get chuck to near correct opening.
Hold piece in rt hand, and put it into, (or over for expanding) the jaws.
Spin scroll with left hand until in contact with piece.
Rotate piece and chuck until appropriate pair of adjacent holes in scroll and body are uppermost.
Insert 2 tommy bars. Gravity keeps them in place.
Rotate chuck and piece towards you, as you grip the pair of tommy bars in the left hand.
Press piece so it is seated in/on jaws, and SQUEEZE left hand to tighten.

Once held, you can use both hands to force it tight, (but can't say I have ever found it necessary).

To be fair, since I have had a spindle lock, I don't do it this way all that often. The exception is with big pieces, where there is a tendency for the chuck to unscrew when tightening/loosening against the thread, when I revert to the "one hand squeeze" method.

regards