Reversible chuck on the Opti TU1503 lathe

[Gert HattinghParticipant @gerthattingh94166]

Hi

I have recently purchased my first metal lathe, and since I make small things, I opted for the smallest model, the TU1503. It was advertised (worldwide) to ship with a reversible jaw chuck. I have managed to take the jaws out, re-insert them in the correct way, but if I want to reverse the jaws (i.e. to grip a larger diameter stock), I cannot get it past the initial hook. I am obviously doing something very wrong.

Any help?

[Gert HattinghParticipant @gerthattingh94166]

[JasonBModerator @jasonb]

If I remember right on my Unimat3 you have to put two of the jaws into different numbered slots when reversing them so the Opti may well be the same

Best thing to do is look at the teeth on the underside of the jaws, the one with the tooth nearest the end you want to face the lathe spindle goes in first, then the one with the tooth a bit further back and finally the one with the tooth furthest from the end goes in last. Probably end up fitting in an order like 1, 3, 2 rather than 1, 2, 3

J

[HopperParticipant @hopper]

Can you post a pic of the back sides of the jaws, showing the "teeth" that engage with the spiral scroll in the chuck?

On reversible jaws they should have a convex curve on both surfaces, or at least pretty straight-ish.

See pic downpage here **LINK**

and more noticeably here **LINK**

Normal non-reversible jaws have a distinctive curve to the teeth that clearly is not reversible.

[JasonBModerator @jasonb]

I just looked at another members photos in this thread who has the same lathe, looks like you should have a second set of jaws in the box with teh teeth that only fit one way.

Hopper, looks like Brian has two sets of jaws on his one.

[HopperParticipant @hopper]

Yes, Jason, the pictures in Brian's first post you linked to certainly appear to have the distinctive "one way" curve of non-reversible jaws. Whether all the Optimum 150s have the same chuck as Brian's Australian-market model, who knows? Pics of the OP's jaws would show what's what.

I haven't heard from Brian in a while but last I heard he was still happily making various kit engines on it and doing rather well. Goes to show, I guess, once sorted they are a good little lathe.

Edited By Hopper on 12/01/2018 09:50:21

Edited By Hopper on 12/01/2018 09:51:35

[Howard LewisParticipant @howardlewis46836]

If it is a 3 Jaw Chuck, (self centering), there should be one set of jaws for internal holding small diameter work, with the longer stepped part of the jaw towards the centre, and and another set, for larger diameter work, with the longer stepped part of the jaw on the outside, away from the centreline.

Each jaw should carry a number, 1, 2 or 3. Each numbered jaw should only be fitted into the slot in the chuck body with the same number, starting with No. 1, then No. 3 and finally No.3. The trick is to look into slot 1 and rotate the chuck key until the start of the scroll just becomes visible. Insert jaw 1, and rotate the chuck key, until the start of the scroll becomes visible in slot 2, insert Jaw 2, and then repeat with slot 3. This applies whether the Internal or the External jaws are being fitted. If you pick up the scroll in the wrong place, the three jaws will not meet in the centre. You cannot reverse the jaws in a 3 Jaw Self Centering Chuck.

For a Four Jaw, Independant chuck, you merely remove the jaw, reverse it and reinsert into the slot. The adjusting screw only operates that particular jaw; which allows you to do at least three things.

1) Hold work more accuately centred than in a 3 jaw chuck. (Virtually no 3 jaw chuck will centre work as accurately as you can in a 4 jaw. But you will need a Dial Test Indicator to allow you to reduce the eccentricity to a minimum)

2) Deliberately set work off centre, to allow drilling, reaming or boring off the centreline of the workiece.

3) Hold irregular objects with required centre point on the centreline of the lathe mandrel, (spindle)

H T H

Howard

P S You will get lots of help on here, from folk much more knowledgeable and skilled than I.  Don't be afraid to ask!

Edited By Howard Lewis on 12/01/2018 15:37:11

[Gert HattinghParticipant @gerthattingh94166]

Thank you, I am overwhelmed by the quick responses. For my late reply – I apologise, we had a bit of trouble with internet at home this weekend.

I had a good look at the jaws, and came to the conclusion that the arcs on the screw teeth would not allow me to turn the reverse insert the jaws. (The light bulb momnent when I realised that there must be another set of jaws). When I finally got online last night, I had a look at a new chuck (It is the KS-11) I noticed that they ship with two sets of jaws. With this info, I went back my chuck, and I think my extra set of jaws have been left out of the package.

Thank you very much, I got some really good info here! And I will post the images even if it is for academic use.

[EmgeeParticipant @emgee]

Posted by Howard Lewis on 12/01/2018 15:34:56:

You cannot reverse the jaws in a 3 Jaw Self Centering Chuck.

H T H

Howard

Howard, on the early Emco 5 3 jaw SC chuck with the drill type chuck key the same jaws served inside and outside configurations, as Jason said the jaw numbers were changed, I have the number to use listed but not on this computer, anyone wants them just have to ask.

Emgee

[HopperParticipant @hopper]

Gert, you should contact your lathe supplier and get the extra set of jaws they owe you.

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