I just got a lathe off craigslist but the lathe came with a teknatool 4 jaw self centering chuck that only goes down to 1/2 inch, i would like to go as small as 1/4 inch so i can grip a 1/4inch mandrel.
what will I purchase so i can grip 1/4inch?

Jacobs Chuck 3/8-1/2' Get a bolt to fit the Threads and cut off the Head

Ridge,
I would suggest that you purchase a keyless Jacobs style 1/2 inch keyless chuck with the appropriate MT size insert on the end of the chuck.
i.e. MT1, Mt2 or ??

When working with small shafts, the use of the keyless Jacobs style chucks works very quickly and chucks up items very solidly.

Something like this one:

[www.lathemaster.com]

By the way, this same chuck will work very well for you if you want to drill a perfectly centered hole in a work piece. Simply take the chuck, and insert it into your tail stock and use it to hold a drill bit.

Then, to drill the hole, simply advance the tail stock drill bit into the spinning work piece.
A perfectly centered hole every time.

[www.rodbuilding.org]

Since the headstock and tail stock have the same MT2 size - the chuck will fit in either the spinning head stock, or the stationary tail stock.

Roger

X3 on the Jacobs chuck

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Super Tight Lines......Don

the tailstock has the 1/2 inch jacobs chuck. how will i connect it to the head stock?
i tried putting the jacobs chuck to the headstock but the metal thing that goes inside the headstock slipped.

BTA, $200 for the midi lathe, teknatool 4 jaw chuck and jacobs chuck, is it a good deal?

I use a 3 jaw micro chuck which screws onto teh headstock. I don't like the Jacobs in teh headstock, although it is a good option. I prefer somethign spinning at 4000 RPM's to be screwed in rather than friction fit.

By the way Billy, virtually all of the industrial drill presses use an MT or similar style base on their chuck.

It is much much easier to have a 100% true running chuck with an MT style base, than a threaded chuck.

I have an MT style chuck on my drill press. I commonly run the drill press up to 5000 rpm with no issues at all.

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Ridge,
Does your 1/2 inch chuck have an end on it with a taper on it that fits into either the tail stock or the head stock.
If is possible that you have a different taper on the head stock, compared to the tail stock, but that is not normally the case.

If you put the chuck into a tapered head stock, just give the chuck a good rap with a rubber mallet to seat it well into the socket to insure a non slip fit.

If you still have slippage or wobble, then it is likely that you do not have matching tapers on your lathe.

May I ask, what make and model lathe that you have?

For smaller shafts, my preference is always with a Jacobs chuck on the head stock.
The only time that I will use a conventional 3 or 4 jaw chuck is for the time that I need to allow the shaft to extend through the head stock for a shorter projection over the lath bed.

Roger

Go on Line and see if the jaws can be reversed so that they close smaller. I am not familiar with this chuck, but some do. It is a simple procedure if it is available on this chuck.

Penn State Industries has a 3-jaw that will chuck up 1/4" mandrels. The nice thing about a jawed chuck is the ability for the mandrel to go thru the chuck and then you don't have the entire length of your mandrel out between your chuck and tail.

I have 3 and 4-jaw chucks along with 3/8" and 1/2" Jacobs chucks. Each have their place. The 3-jaw is on the lathe 90% or more of the time.

I'll also 2nd Randolph's comments. I believe my 4-jaw has the ability to reverse the jaws. It also came with about 4 different sets of jaws.



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Better to have and not need than to need and not have.

You may be able to change out the jaws on your self centering chuck to allow you go as small as you want. A set of spigot or pin jaws should do the trick. What make is the chuck?

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Not all 3 jaw micros are hollowed out. Teh one tha tI use is not, I really dislike those because they have the tendency to allow teh mandrel to slide into teh headstock and come off of the tailstock, whip around and possible knock your teeth out or whale you in teh arm - you're lucky if all that happens is the mandrel gets bent into a V. If you are going to use a 3 jaw that is hollow, you need to use a live jacobs on teh tailstock, or some sort of stop to prevent the mandrel from sliding in.

Another reason why I like the 3 jaw chuck is I can grip mandrels up to almost 3/4" down to 1/16" drill bits. Like MAtt, mine stays on my lathe 90% of teh time, the only time I take it off is to put a 4 jaw to bore, or a REnzetti style 3 jaw to hold power reamers.

roger, the lathe is a rockler mc1018.
Tom, the chuck is a teknatool 4 jaw precision midi chuck.

the jacobs chuck goes to about 1/2 inch that is keyed, i tried to tap it into the headstock with a rubber mallet and it takes it, MT2.
but i dont want to use the jacobs chuck in the headstock because i want it int he tailstock, since it is keyed, i want it to grip the mandrel so it wont come flying into my face.
i need to find a stepd down jaw to grip 1/4, i like the teknatool because it is also keyed, i can tighten it so the mandrel wont fly.

Teknatool offers various jaw sets including pin and spigot jaws, for that chuck. They'll close down on a pencil lead.

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Ridge,
Actually, I have the same lathe:

[www.rockler.com]

I have found that it works very very well for anything that I want to use it for.
I like the additional bed extension as well. It is nice to be able to slide the tail stock down out of the way, when it is not needed.

I also had a friend modify backing plates for me for a 3 inch and a 4 inch machinist chuck. These larger machine chucks work well for some of the larger objects that I have used from time to time.

I agree with the other posts about purchasing additional jaws for your chuck. With the right jaws, you will be able to tighten the chuck nice and secure on the smaller objects.

Roger

I wouldn't buy different jaws just to grip a mandrel. Most jaws have 8 screws which you have to take off, then put back on. For $45 get the 3 jaw micro and take 5 seconds to unscrew it and screw teh other one on, or get another Jacobs. Both of these holds mandrels sufficiently with no slip.

The pin or spigot jaws only have to be put on once. They'll open up to hold about anything so you don't have to swap back and forth. The spigot jaws on my OneWay Talon chuck have never been removed since they were installed many years ago. I can chuck 2.5 inch square turning stock with them, or a 1/8th inch mandrel. So I don't even have to change chucks - one chuck and one jaw set does it all.

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But he has a Nova Midi, which will require him to interchange jaws. For rodbuilding, as far as I know the only reason to have a 4 jaw chuck is to bore square stock. If he's doing reel seats using pen blanks he might be able to get by with one set of jaws with the Nova. If he's using bigger blocks and turning handles, he will have to interchange jaws to go from teh boring process, to putting that same grip on a mandrel. AS opposed to unscrewing teh chuck and either screwing anothre on, or putting the jacobs in teh headstock.



Edited 1 time(s). Last edit at 03/19/2013 11:31AM by Billy Vivona.

I thought a photo might better illustrate what I'm describing.

[www.rodbuilding.org]

Once you make the change, you won't need to change the jaws again unless you're going to be doing some larger wood turning projects such as turning bowls. The photo shows the same chuck on a 1/4 inch steel mandrel and on a 2-1/8th inch turning square. They'll hold about anything and most chuck makers can even supply a center spur that fits into the chuck itself.

You'll just have to figure out how you'll come out best. It may be that a Jacobs type chuck is still your best option if it comes out to cost less than a set of spigot or pin jaws. Or, the Technatool chuck may not have enough total opening capacity to do all the things you need to do. You'll just have to consider your options and go from there.

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Nova is a product made by Technatool. They offer both spigot and pin jaws for all the Nova chucks. I think they're about $35 to $40 for a set.

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