Member postings for old mart

I made a versatile guard from a cheap TV mount which has a drawbar through it to use the tee slots in the table. As we have a supply of 6mm polycarbonate sheet at the museum, a variety of QD guards fit on the arm.

I bought an ARC 5" with the removable swivel base and it geta used for the larger jobs where the 100mm Bisons are too small. It has the hemispherical bearing which helps with the jaw lift, a Stevenson mod which is well worth having.

As far as I know, the tall boys and grand slam casings were manufactured in the USA, as the UK didn't have the capability at the time.

2ba is hardly going to be able to hold any type of jaw extensions onto your existing jaws. The holes were probably drilled freehand which would explain the oddly positioned one. I would not trust less than three off 2ba fixings on each jaw to hold work securely, even on a small chuck like yours. Evwn then I would go for 6mm with 12.9 screws.

If you visit the ROTAGRIP website, they sell soft jaws for these small chucks at just under £30. The code is EJB and the exact dimensions are listed, as there are so many variations with chuck jaw sizes. I have bought lots of the much commoner soft jaws for the 5" size chucks on ebay, in various remaining ammounts of usability. Even when a totally used up set was included in a job lot, they got turned into base jaws for aluminium and brass tops.

If you can mill down the jaws illustrated to be level with the lower step, then they have potential for making base slot and tenon jaws to hold a variety of tops.

Edited By old mart on 12/10/2020 14:00:08

I get grumpy when I cannot do things that were easy once due to old age and arthritus.

You seem to be learning the machinery perfectly well, it it always a good idea to think of ways to double check why something is not right, rather than accepting the first conclusion.

I have one threaded shank Clarkson adaptor for 6mm FC3 cutters, I believe it is the 16mm fitting, so if you got hold of one, it would work in er25.

Edited By old mart on 09/10/2020 18:30:08

The apprentices at work were given the task of removing tooling lugs from titanium aircraft parts part way through their milling. They spent the day cutting them off with the toolmakers vertical bandsaw. This saw is kept spotless inside and out by the toolmakers, so when it burst into flames, it had to be the titanium. It was put out using CO2, the same way a magnesium fire would be. That was the only titanium fire I saw in 17 years there, but magnesium was alight every couple of years.

Minutes,you say for 638, I would not use it on anything that would take more than ten seconds to fit together. And even less time if the parts are even a light push fit as I recon even a little localised friction warming the joint can cause tears.

They are a very good option. The exact size to make your shaft should be included with the sleeve. It could be made a sliding fit and be sealed with Loctite, or if you go for a press fit, then an assembly tool will have to be made, as the sleeves are fragile.

Edited By old mart on 06/10/2020 13:57:06

The latest I could find out is that the number of fire crews is being reduced, they have won the battle, good work.

Peter Cook's suggestion of thr er16 collet chuck is worth thinking about, as it gives you the extra precision to hold very small work. Your lathe is already very compact and might benifit from some good additions made to it.

638 Loctite is primarily a sleeve and bearing fit, you are right not to use it when screwing in those sleeves, as it has a very short cure time. I had to find a product to secure the halves of a milling machine spindle which had a combination of threads and sleeve fit. I chose Loctite 620 which gave me plenty of time to screw the parts together and tighten them. 620 is also a sleeve and bearing fit, but as the joint is never going to be unscrewed, it will be fine.

Looks like you got a good one. I have drilled and tapped some 6mm holes in the faces of ours to hold balance weights to help when odd shapes are turned.

Threaded sleeves will reduce the strength somewhat. If you have a mill and rotary table, it would be safer to drill and tap another set of holes for the pins. Another option would be to get M10 x 1 helicoils and a tap and convert the existing holes without loosing any strength.

Threaded sleeves in the chuck body would be satisfactory.

To check how good the chuck is, clamp the jaws tight onto a bar of soft aluminium which has been turned and the witness marks made by the jaws will tell tales.

Edited By old mart on 05/10/2020 15:52:24

Edited By old mart on 05/10/2020 15:57:21

You may well have the answer there, Tim, iron rust and aluminium are a bad mix, that is why aluminium is banned from coal mines.

The downside of the er32, is the limited length of the larger diameter tooling that it can handle. I chose er25 which holds up to 16mm, and we have a full set of R8 collets which will hold longer tooling deeper, except for the 20mm one which is limited by the size of the R8 design. Above that diameter I have a 25mm indexable with 3 APHT 16 inserts with the shank turned down to 20 and 18mm in steps according to how much projection is needed. Then its shell mills, 40, 50, 63 and 80mm.

I like the use of a bench grinder being used, most people have one and many have an old one dumped under the bench.

It's a mystery to me exactly what is burning. If oil was a component, I would expect the smoke to be black. If there was a lot of plastic in the pile, the smoke would be black also. Magnesium does emit white smoke, but the quantities of it relative to the more common metals is small and those piles of metal would have been separated magnetically before piling up prior to being loaded into ships. Putting water on burning magnesium is not the correct way to control it, but fire services will have extremely limited options with such a large fire.