Member postings for old mart

I have started on the new nut for the knee Z axis. The length of leaded gunmetal, sae 660 has the bore opened up to 0.8" as the starting size for 1" X 5 ACME. I have to make a tool to hold the IR22 5 ACME insert. The tool is being made of an unidentified bar of something that looks like a high tensile stainless steel. The angle of dip for the insert is 14 degrees and I have left the helix angle at zero as the tool may be used for right handed threads as well as the left hand thread I will be cutting. The actual helix angle for 1" X 5 ACME is 3.65 degrees, I might have to give the insert a little added relief before cutting the thread. This is a time that a rotating base for the vise comes in handy. The bored gunmetal was parted off with a little added support from the tailstock and I used a 26mm 2mm wide Kennametal blade with an A2 insert. Gunmetal is one of the easiest alloys to part off. The threading tool will need some slight mods to fit the bore and I have to wait until the internal threading insert arrives from APT. Being a left hand thread,I can use a righthanded tool and thread away from the chuck which is much easier.

Edited By old mart on 04/11/2020 19:33:25

Edited By old mart on 04/11/2020 19:35:25

You would need to do a few tests and select the combination that gave the best finish. I have only done internal TPG on chuck jaws, which are an interrupted cut, so the lathe spindle was running quite slow. I now have a long shank pneumatic die grinder which has performed very well.

Be careful when holding something that is short relative to the vise jaw width at one end of the jaws. Many types of vise will require an identical width block at the other end to stop their jaws tilting.

The trouble with buying from down under is that the postage can be even higher than from the USA.

Edited By old mart on 03/11/2020 20:00:31

A little bit of rubbing on the shanks of the cutters with a very fine diamond lap would improve the grip in the collets. Remember to hold the sharp end in some old rags to protect your fingers.

The adjustment of the belts is one of the most frustrating and non intuative parts of the design. I did know how, but have forgotten and would have to learn it all over. The primary belt on the museum's machine is one of the linked types. It ran out of adjustment some years ago and Mike managed to extract it through the aperture where the speed control is screwed on. This was on the MK 1 and Mk 1.5 central control which is in line with the motor. The Mk 2 must have a remote linkage, so reaching the belt could be even more difficult. Mike removed one link and it has been ok ever since, I bought a metre of 13mm link belt just in case but it has not been needed yet.I have just got hold of a complete Norton gearbox and both leadscrew and feedscrew for the model A The casing is cracked, but could be repaired and nobody wanted it on ebay, so I got the lot for £45 including postage for 37 Kg of old iron.

Edited By old mart on 03/11/2020 19:36:25

Hi Mark, welcome to the forum, it's not the dark side you are succumbing to, but the hard side, (as opposed to the soft side). When I was working, we had a gigantic Wadkin horizontal mill, the bed must have been 8 x 5, feet that is, with a BT50 spindle.

We have a Mk 1.5 at the museum, it has the older type of backgear mechanism which I have improved. If you have a choice, get a Mk 2 with the totally revised and improved backgear. You can tell the difference at a glance, as the three speed gearbox control in the Mk 1 is in the middle and at the right hand side in the Mk 2. Another vital check before buying is to lift the belt lid and remove the cover to the right of the pulleys. The bronze gear must have a reasonable ammount of tooth depth on it. These are as rare as hens teeth, I have only seen one for sale ever.

The 1024 would be a better choice being slightly bigger as long as the spindle bearings are ok.

Do look at the "lathes UK" website before deciding. Remember the lathe weighs 3/4 of a ton.

Edited By old mart on 03/11/2020 15:11:50

They sound like spotting drills, all the solid carbide twist drills I have look like regular hss drills.

I bought a 4" steel backplate on ebay with the 1 3/4" x 8W thread for Smart & Brown, it got fitted in the centre of a faceplate, and works fine, although I always keep the spindle end lightly lubricated. All the others except the opener for male stepped collets have been made in CI. I have bought backplates with the 1 1/2" Boxford thread to rework to S & B size as long as the boss diameter is nice and thick. It saves a lot of machining mess.

You might find that the MT2 used a 10mm or 3/8" drawbar which passed through the 12mm thread in the adaptor. If you can shine a light down the spindle and use a mirror to look up the adaptor, if you are lucky, some threads will be visible. Then a length of 12mm studding could remove it.

I have a slitting saw arbor in MT2 which fits in an R8 MT2 adaptor and the pair are held in the spindle with a 10mm drawbar. The 7/16" standard R8 drawbar thread is still present in the adaptor.

Flats are often put on MT centres for lathe tailstocks. Putting a spanner on and giving it a sharp tap with a copper hammer will usually break the taper.

Edited By old mart on 02/11/2020 21:41:52

The bush idea would work well as long as the assembly could be separated after each pass to completely remove all traces of swarf. Grinding the ACME form is not enough, it should be honed for the sharpest possible edge. Also, the cutting tip should be aligned exactly to match the helix angle of the thread.

I would agree with Clive, it might have been part of an optical comparitor, but I didn't see any scales next to the handles.

Have you tried a similar test with the X and Y locks? It is common for the locking action to move something, even a thin film of oil can be squeezed thinner. You only need to take something like that into account if the tolerances expected are tight. It would be normal practice to lock the axes which are not going to be moved before cutting metal. I always lock the quill before taking a cut also.

Use some blocks of wood to rest the knee on and possibly a prop to stop the weight of the bed leaning forward and straining the knee screw. Or centralise the bed and use larger blocks to support either side, watch out for the Xaxis screw.

I would run solid carbide drills at low rpm into hard materials and use light hand pressure to feel the drill cutting.

The govenment might have given a bit longer notice, a fortnight would have been sensible.

It sounds like it needs a tiny centre in the free end and a little centre to support it.

I mostly use carbides as I am frightened of making HSS blunt and then being unable to sharpen them. I do use hss on aluminium with lubricant. Something to be careful of when handling carbide, they will be damaged if you drop them on the mill bed and the ends can chip if you touch down on steel when stationary.

Midnight, Wednesday 4th November. I will only get one day to take anything I need at home back from the museum. This time I will remember all the batteries for my Parkside tools.

Smart & Brown use a low profile design, with the locknuts pretty much flush with the surface. A tubular spanner is used on the nuts and a screwdriver or hex key is used on the gib screws.

The only tapered gib on the S & B model A is for the sliding leadscrew nut.