Member postings for old mart

If your chuck is imperial, it will have a scroll pitch of 1/3", so a no3 jaw in a no2 slot will be 0.111" too deep. If the chuck has a metric scroll, pitch 8mm, then no3 jaw in no2 slot will be 2.66mm too deep.

First try out the jaws in the chuck body. Then measure the one that fits carefully and make a note of the teeth pitch. There are a huge number of chuck jaws out there, but very few vendors have any idea of how to measure them and often quote the serial numbers mistakenly thinking they are part numbers. Genuine jaws may cost more than the price of a complete chuck and then there is no telling how worn your chuck body is.

If you have milling or grinding machinery, you could modify a jaw to match them up. The error is 1/3 of the scroll pitch.

Iwould do it the same way as Alan's suggestion.

If you aren't already a member, it would be a good idea to join a Landrover forum, they could advise on the optimum oil to use in the rebuilt box.

The seal which overheated was a common size and I made the housing dimensions to fit it. I thought the overheating was due to excessive preload of the bearings and even resorted to setting zero preload before finding that the seal was the source. The overheating occurred at 2000 rpm which was inside the projected 3000 rpm for the spindle.

Tom Senior seemed to make some changes to their designs from time to time which can be confusing. The drawing does not show the oil seal, for instance, and the position of the gear on the spindle varies. Do you know whether oil or grease is used in the head? If it is grease, then a common lithium high melting point would probably be ok. Moly grease is not recommended for ball and roller bearings, as it can make the surface of hardened rolling elements brittle. I used a double lip oil seal without the garter spring on the TS light vertical R8 conversion along with lithium grease and it overheated. The only solution was to completely remove the inner half of the seal, which was ok with grease and the outer lip keeps the swarf out of the bearings.

I would align the workpiece first and then carefully bring the fingers into contact, using a dti to make sure that a minimum of deflection was present. If the work needed turning at the point where the fingers were going, I would attempt to turn a portion near the chuck and then turn the workpiece around if possible. I made a set of fingers with little ball races for less friction and no wear. As already mentioned, a collar could be used to run on if the marking was not desirable. A piece of card should be cut to form a barrier against swarf getting stuck in the fingers.

Even with medium hard steel and rollers, marking is likely, the steady marks show on this spindle, but do not matter, fortunately.

Pratt Burnerd used to make specialist soft jaws for some of their smaller chucks from nylon, you would have to be careful not to snap off the scroll teeth.

A couple of years ago, we took a 1/2" Elliot chuck apart because it was stiff to turn over the lower half of the range, and cleaned every part and carefully greased it and it was exactly the same afterwards. That one is the only Elliot drill chuck I have ever seen.

The same picture as Steviegtr's hoping for better definition. I got this from the Denford forum, hope they don't mind. There is no sign of any shims for preloading.

Edited By old mart on 03/02/2021 18:04:34

Is there room for 8 positions, but leaving alternate ones unused for general use?

I don't see any shims on the shaft, or anything marked under the end covers. 

It doesn't make sense exactly, since the central part seems like it should be clamped tightly using the missing tube and the outer races shimmed for the preload. Your spindle is different from the drawing, the gear is offset from the centre. I think the lower race outer is held tightly and the upper one moved to give the preload.

Edited By old mart on 03/02/2021 17:07:36

Edited By old mart on 03/02/2021 17:27:09

Pure aluminium rivets would be the easiest to fit. I think you are going to strip the model right down to the bare chassis before tackling the work. Every extra part will just get in the way.

The current Jacobs chucks are made in China and are not reconed to be of the same standard as the UK, or USA products. I have been lucky and have picked up a NOS 1/2" British made one. The best running chuck we have at the museum is an R8 integral shank 1/2" Cutwell keyless one. You may be lucky buying a cheap chuck, they all seem to vary in runout, even the expensive ones. My favourites are the Kawasaki keyless, they will run in reverse if needed.

Edited By old mart on 03/02/2021 12:16:17

Those rivets look like copper on my screen.

You will have to make a variety of cantilevered dollys to hold in a vise while doing the work, and having assistance to hold the model in place would be welcome.

Edited By old mart on 03/02/2021 12:04:01

I had mine at 10.30 today, Pfizer. I asked for strawberry flavour, but they only had vanilla.

Thats a good result. I have some pics of a Mitutoyo showing what they are capable of. (when I get them in the album, that is)

Edited By old mart on 02/02/2021 20:29:17

We were left a set of Lidl Parkside brand drills and taps in a legacy, and they are quite good. They are all hss and the drills are split point. I have used them sucessfully on mild steel, cast iron and aluminium. If you see a set there, have a close look at it.

APT is a very good firm, they also supply some carbide inserts singly for those who don't want to buy a box of ten.

Edited By old mart on 02/02/2021 16:46:16

I'm just under 72 and therefore in group 4, so North Somerset must have reached this far as my jab is tomorrow.