Re: Chuck Jaw Issues Unimat Selecta

#54698

Hi
A couple of things. Are the jaws in the correct slots, they are numbered.
Do the jaws have any sign of wear.
Could you show us some photos of the chuck so we can get a better idea.

Chuck Jaw Issues Unimat Selecta

#54697

Hi there I've just gotten myself an old unimat selecta mini-lathe, with the standard 3 jaw chuck installed. I seem to be having quite a bit of trouble 1. getting things centred and 2. getting the jaws to hold my part properly. With soft aluminium of course, the non-centred thing isn't so much of an issue as I just start bigger and work my way down in size, however when it comes to machining steel I can't for the life of me take virtually any cuts without the part catching the binding up the motor, and then coming out of the chuck jaws. I must note I've changed the motor from the standard 70-watt one over to a 150-watt electric scooter motor. Is it possible to do something to my chuck to make it centre parts better and be able to hold on to them easier or is it a case of getting a new chuck. 4 Jaw perhaps? I am using some cheap carbide lathe tools off eBay if that helps at all (I've ordered some indexable carbide tools with the tcmt tip on to replace these in the hope this helps me out a bit)
Any help is greatly appreciated as this is a whole new world to me and I'm trying to learn as I go.?

Thanks Dan?

Re: 3-Jaw Chuck

#54696

开云体育

I’m a relative beginner but I would say as long as the chuck is correctly fitted, tight is good. ?The 3 jaw chuck that came with mine secondhand moved freely and I had difficulty getting the precision I wanted. ?I acquired an apparently as new one that is very stiff to move, and have only ever gone back to the original when occasionally I have wanted to mount something head and tail. ?(I use the lathe as often for lining up as I do for turning.)

Show quoted text

On 6 Apr 2020, at 15:14, Aron <Tugtower@...> wrote:

?My original 3 jaw is still very tight to move by hand, I’ve oiled all the parts and the jaws themself and it’s only reduced a little, honestly I don’t have issues holding material I only get push and pull during cuts if I haven’t done it up right, honestly tight jaws can be a blessing as your less likely to get slippage during operation, but to be fair that’s what the tommy bars are for on the original 3 jaw.

you may also have the jaws not set correctly in position, it maybe worth rotating them out and putting back in correct position. This can help a lot, I found that’s reversing the jaws for larger work the manual was no bloody help at all, and you have to insert 3 into 3 2 into 1 and 1 into 2 in that order to work...

if your problem is tapered cuts from the 3 jaw it could be a number of things like headstock isn’t running true, so adjust the head, the bearings are shot ( really bad chatter during cutting with a sharp bit) or the lathe is not actually level. Believe me it’s easy to correct the lvl issue!

the other tapering issues could be too long a work piece in the jaw so it flexes during cutting...

ive said all that and honestly haven’t read all the posts but these have been my personal findings since owning a unimat that I’ve had to overcome, but mines now running very well after addressing these issues.

Re: 3-Jaw Chuck

Aron

#54695

My original 3 jaw is still very tight to move by hand, I’ve oiled all the parts and the jaws themself and it’s only reduced a little, honestly I don’t have issues holding material I only get push and pull during cuts if I haven’t done it up right, honestly tight jaws can be a blessing as your less likely to get slippage during operation, but to be fair that’s what the tommy bars are for on the original 3 jaw.

you may also have the jaws not set correctly in position, it maybe worth rotating them out and putting back in correct position. This can help a lot, I found that’s reversing the jaws for larger work the manual was no bloody help at all, and you have to insert 3 into 3 2 into 1 and 1 into 2 in that order to work...

if your problem is tapered cuts from the 3 jaw it could be a number of things like headstock isn’t running true, so adjust the head, the bearings are shot ( really bad chatter during cutting with a sharp bit) or the lathe is not actually level. Believe me it’s easy to correct the lvl issue!

the other tapering issues could be too long a work piece in the jaw so it flexes during cutting...

ive said all that and honestly haven’t read all the posts but these have been my personal findings since owning a unimat that I’ve had to overcome, but mines now running very well after addressing these issues.

Re: 3-Jaw Chuck

#54694

G'Day Matthew!

Try the chuck ways for fit with chuck disassembled before lapping and if it is the same, try lubricating and if that helps, use chuck as it is, it may work its way by itself after a period of time.

One of my Unimat 3, three jaws chucks was very tight and after few months being stiff after lubricating it started behaving. ?

Cheers, Dushan

Show quoted text

On Mon, 6 Apr 2020 at 15:13, Matthew Trump <mjtrump@...> wrote:

My jaws are very tight.? I will have to lap each one of the a little bit.? Equal amounts off of both sides. ??

Re: 3-Jaw Chuck

#54693

Lapping should be a last resort imo. I've ruined a chuck in the past trying to true up the jaws.?

I would imagine your problem is elsewhere, I doubt it would have left the factory all those years ago with tight jaws, they did have some degree of quality control. ?

Are the jaws tight in the slot? If it is the slots it might just be burred corners.?

Re: 3-Jaw Chuck

#54691

My jaws are very tight. ?I will have to lap each one of the a little bit. ?Equal amounts off of both sides. ??

Re: 3-Jaw Chuck

#54690

I use a very light grease sparingly. The canned spray on type you might use for a bicycle. Swarf and chips getting into it are inevitable im affraid.?

Re: 3-Jaw Chuck

#54689

1. The jaws should be a snug fit/ they should slide fairly easily but they should not rattle in the guides/ ideally there should be no slack at all.

2. I would avoid all oils, since they are going to get sprayed around once the chuck starts turning. Fine swarf will stick to grease, so I'd avoid that too. I would look at dry lubricants, like graphite powder. If it flies around it doesn't do any harm. Then again I have never lubricated a chuck, and never needed to.

3-Jaw Chuck

#54688

Good evening friends,
I have recently disassembled and cleaned my new to me 3-jaw chuck for my DB/SL. ? I have two questions.?

1. ?Before I reassemble and lubricate the chuck, how easily should the jaws move in their appropriate channels?

2. ?What lubrication do you like for your 3-jaw chuck? ? Bearing grease? ?Gear oil? ?Motor Oil? ?Thicker Nano Oil?

Thank you. ?I look forward to your responses. ??

Matt

Re: 3-jaw chuck as dividing head

#54687

Thank you for the picture.

Dick

Re: Wheel turning (RP25 & similar)

#54686

--
Lio, France - Unimat SL x 3

Re: 3-jaw chuck as dividing head

#54685

Dick, it is a simple "CNC" pulley , like this one for example

--
Lio, France - Unimat SL x 3

Re: 3-jaw chuck as dividing head

#54684

Nice work, Lionel?
Is the aluminum part a timing pulley?
Dick

Re: 3-jaw chuck as dividing head

#54683

Hi
My "DIY" :

???
?

?

--
Lio, France - Unimat SL x 3

Re: Wheel turning (RP25 & similar)

#54682

Hi
The Forhman Tool , and a copy "DIY"? ;-)

??

???

--
Lio, France - Unimat SL x 3

Re: Plan for chuck plate please

#54681

Thank's Roman
--
Lio, France - Unimat SL x 3

Re: What do you guys make?

#54680

Paul, I really appreciate your blog (i made several visits there), thank you for all these shares !
--
Lio, France - Unimat SL x 3

Re: SL U-90 Motor Wiring

#54679

Thank's Pat for these details , i will check it all
--
Lio, France - Unimat SL x 3

Re: SL U-90 Motor Wiring

#54678

Just a heads up to those that open up their u90 motors. The only time I have had one pop a line circuit breaker was a short in one of the leads caused by rubbing against the rotor. I posted on the other web site how to make a suppression capacitor if you can’t find one. The caps (3) are there to reduce the arcing of the brushes and the noise that feeds back onto the mains. The motor will run fine without it, however your significant other or the neighbors may complain about the electrical noise on their TVs and stereos, your brushes will wear faster and you will pit the commutator segments .
Now if you reassemble the motor and it runs backwards you will need to swap the brush leads. Oh and the motor will run fine on DC current as well so if you desire to use up a bunch of 12 volt batteries have at it.

Pat