How do I disassemble an LFA chuck?

have you a photo that you could post, and a size for the chuck, as the numbers that you have supplied do not mean a thing to me. and if posible a manufacturer for the chuck.

If you are talking about one of these;

The outer sleeve (the key engages) is a press fit on the split nut that drives the jaws.

Find a tube that fits the sleeve diameter at top of the picture, and in a vice or press push the sleeve (in downward direction per the picture above) an the thing falls apart.

Extract jaws by pushing all in, then drawing one out, etc.

On reassembly make sure jaws are in order and trial assemble split nut to see they move together (in synchronous) then push sleeve back on.

P.s. you don't need to remove the arbor for this maintenance, just find a longer tube.

I hope this helps.

If it is not this type of chuck - post a picture.

Here's the procedure for a jacobs chuck

http://wiki.owwm.com/%28S%28bfdfie55namjaa55f55zihvi%29%29/Default.aspx?Page=JacobsChuckRebuild&AspxAutoDetectCookieSupport=1

I wouldn't press on the jaws myself, I'd screw them in until flush

you can make up something with all thread & a couple of steel plates

Totally agree - Definitely do not press on the jaws.

Perhaps this one was so rusted that the jaws could not be retracted. Even so they should have used a tube pressing on the body.

It is a recipe for fracturing the nut (which is hardened - brittle) or shearing the rack on the jaws.

Also do not use a hammer to reassemble - unless absolutely unavoidable - use the press you took it apart with. Hitting as shown, can damage those teeth

_{(The use of a hole in wood is a give away I'd say)}

You may not have to dissassemble the chuck. If your problem is getting the jaws to close properly and the chuck is on a reversible drill it may simply be that the screw in the bottom of the chuck has come loose. These chucks are threaded onto the drill spindle and to stop them unscrewing when in reverse they have a screw in the bottom.

So to know how to answer your question we need to know if the chuck is threaded or fitted to a taper. And what the nature of the problem is.

You haven't told us what sort of machine the chuck is attached to. If I assume it is a drill press, then the arbor probably has a morse taper into the quill and a jacobs taper into the chuck. In that case you can tap it off. I made myself a taper wedge that straddles the arbor. With this I can drive the chuck off the arbor.

First check by opening the chuck as far as you can and look inside to see if there is a socket-head capscrew securing the chuck to the arbor. If yes, this screw will have a left-hand thread. Remove the cap screw with an Allen key.

At this point the chuck may be secured by a jacobs taper (in which judicious tapping should dislodge it) However, it may be screwed on. This would be more common in hand tools. In that case, though this be blasphemy, I insert the chuck key and whack it with a hammer. It should have a right-hand thread.

He did say the extraction jacking screw was broken off in the chuck therefor it is a taper jacobs mount not screwed on.

Speacial attention is needed for dissasembly otherwise the jaws will be damaged. I have an instruction sheet but cannot manage to copy a ledgible size to this site, very frusrating.

I hope folks notice you mentioned the left hand thread on the screw, that will drive you nuts. Probably how the screw got broken off in the first place.

If the chuck is just contaminated with junk, I would try plenty of rinsing, blowing, and running the jaws up and down until it's clean before I broke it trying to take it apart. Ultrasonic cleaning may help.

The chuck model number is LFA 85b-9A. This a taper mounted chuck (MT3-J4 arbor) It is in mint condition except for the fact that the jaws tend to jam up at one point on every rotation of the sleeve. This is more pronounced when closing the jaws. I suspect that when the broken arbor extraction bolt remnant was drilled flush with the back of the chuck cavity, some swarf found its way into the mechanism.

I hope all will be well after disassembly and a thorough cleaning and re-lube. I tried heating the chuck in the oven to 225° and then plunging the arbor into ice water to remove it but no joy.

The chuck is for my King PDM 30 vertical milling-drilling machine. Unfortunately, I've been unable to set it up because of the damn goose sh*t green wall to wall carpet in our apartment's master bedroom (my workshop). Everything has been in storage for the last 14 years or so. Currently, all I have to work with is a 12" drill press and a cross vice. I'm hesitant to drill into arbor extraction bolt to use a screw extractor because I have no way of securely holding and centering the chuck under the drill due to the arbor. I really think this would be best done on a lathe in any case.

By the way, the store that I bough the chuck from denies any knowledge of the transaction and insists that I must have bough it somewhere else. Problem is, they were the only place I was dealing with 15 years ago. I'm not all that surprised. They took me and now they just want to wash their hands of the whole fiasco. I can't prove a damned thing because I no longer have the invoice. Oh well.....

By the way, just to set the record straight, I'm female.

I agree, something is wrong with the assembly. Maybe when somebody was trying to drill out the broken screw, they held the chuck too tightly in a vise and bent the outside. Rotate the chuck slowly with a dial micrometer checking for runout in all directions. You may find a slight bend. Re-clamping it may bend it back. Good luck.

The additional information is helpful.

I assume that this is a 5/8 chuck. You have removed the arbor from the quill using the taper key. Now you want to remove the arbor from the chuck. You are certain that you have a J4 taper into the chuck. You have had this thing off before. How am I doing?

I have doubts about the arbor extraction bolt but if you have used this before to pop off the chuck then that's it.

The arbor should have a tang on the MT3 end. Cut a piece of pipe into which the arbor will fit in length from the chuck to the shoulder of the tang. Clamp the tang in your vise so the thing is horizontal. Wedge using a couple of cold chisels or blade screwdrivers. Tap the wedges alternately. Give the chuck a couple of judicious taps from time to time.

I have made myself a couple of wedges out of mild steel for this purpose. But the cold chisels will probably work.

Don't get crud on the carpet.

Dear Baffled. It is a 1 1/32" chuck and was purchased with the arbor already installed. As I mentioned previously, I was quite surprised that the J4 end of the arbor was not visible at the back of the chuck cavity when I bought it. Unfortunately, I allowed myself to be mislead by the salesman who claimed that the chuck would pop out if the jaws were fully opened. The chuck was in storage as bought for 15 years.

I recently checked with the manufacturer. LFA taper mounted chucks have a threaded hole in the web that separates the floor of the J4 taper and the back of the chuck cavity. The arbor is removed by threading suitable bolt (3/8-16 in this case) into this hole and tightening it which out the arbor. This is the LFA "arbor removal system".

In my case, this extraction bolt had been broken in the hole. This was covered up by drilling the bolt remnant flush with the back of the chuck cavity. This left me no way to remove the arbor.

I love your idea about using wedges. I'm a bit concerned about possible distortion of the back of the chuck and/or the arbor though.

If the extraction bolt has been broken off inside the chuck, drill it out so that you can be sure that it is not still retaining the chuck to the arbour.

then as suggested use a wedge to force off the tapper. a car ball joint splitter may be more appropriate as it has two pronged wedges on one handle.

You should be able to drill out the old retaining bolt on your pillar drill by using the chuck jaws to center the center drill first and then by opening up the holes gradually until the tops of the threads can be seen. at this stage the remaining thread may be prised out as if it was a spring. Or it may need to have a tap running through it.

If you have a good feel for drilling you should be able to feel when you have gone deep enough. Take it slowly and be gentle.

Good luck.

Hi Perfectionest, Well I can copy a link for you even if I cannot post the picture. Most important re position of jaws as I previously posted . You can leave your arbor in and use a piece of tube long enough to allow the arbor and part of the chuck to enter and press it off with a press or woodworkers vice if jaws open wide enough. http://www.jacobschuck.com/drill-chuck-repair.asp Hope this helps.

Follow the instructions in the link provided by garthh and as he also suggests don't push on the jaws. Wind them all the way in, or at least until they are below flush. The teeth on the jaws can dent the scroll/nut/split nut. In fact that may be the problem you have. The chuck may have been dropped on its jaws or been used to push something, as in using the drill as a make do press.

If you want to remove the broken screw try this.

1. put a L.H. 5/16 drill in a lathe chuck.

2. put the lathe chuck on the drill press table with the drill bit sticking up

3. lower your LFA chuck over the drill bit and hand tighten onto the drill bit

4.. lightly lift the lathe chuck with the drill press and put back down.

5. clamp the lathe chuck in this position

6. totally loosen the LFA chuck and raise

7. put the drill in reverse and lower the LFA chuck onto the L.H. drill bit by using the hand lever i.e. don't use power feed.

8. proceed to drill the broken screw.

As it is a left hand drill part way through the drilling process the brocken screw will undo. Most often this happens just as the drill bit 'breaks through'. NOTE; Removing the LFA chuck from the arbor won't help to dismantle the chuck.

No JIMRAT - when the jaws are fully in, their tails will prevent the sleeve removal.

yup

flush is the best

I wouldn't remove the chuck from the arbor unless it was absolutely necessary.[broken screw or not]

You should see my link in post 15 it fully describes the method of removal with the jaws half way out , Thats why I posted the link. If you think the information is wrong please explain.

Jacobs would be the experts, can't say as I disagree

http://www.jacobschuck.com/drill-chuck-repair.asp

just remembering what I would do, rebuilding fairly large capacity chucks that had been badly abused, sometimes combining the used parts from several to make the best one possible.

very important to make sure the jaws close properly before the final pressing together, the inner gear is meant to be broken in 1/2 so it matches up & has a good fit. Carefully remove any nicks, burrs or other deformities that prevent smooth operation, inside the body where the jaws slide is especially important.

I like to use never sieze for lube, as it doesn't seem to attract the chips & filings the way grease or oil does.

I don't think the information my name sake [garth] provided is wrong

Just read the Jacobs instructions.

I stand corrected.

Stiiiil i would wind the jaws in to just under flush. Especially with an old one that might be very tight.

Cheers

Jim

Either way

Don't push on the jaws

a socket can be used to just push on the body

I was using an electric/hydraulic press, so things happened very quickly

I had more than one oh shyt moment, launching parts across the shop