Member postings for old mart

Chris H, your post relating to the fit of the centre axel with the Morse taper in it on your 4" brought to mind some suspicions I had relating to the 6" Soba table I have. I think that the axel has moved downwards very slightly. It cannot be a taper fitting as it would parted company with the top straight away. I would think it is an interference fit and when I get round to it, I will take it to bits to find out. It could do with a wash and re lube anyway. If it turns out to have moved, the only way I can think of at the moment without actually having a proper hands on, would be to drill and tap an axial hole on the joint line and fit a grub screw. Assuming the centre was not too hard to tap, the top will be cast iron and ok.

I like the fire blanket suggestion, you would certainly have a good size to cut up.

Just buy the cheapest possible and throw them away regularly, it is a harsh enviroment for a brush.

Thanks, Journeyman, following your instructions and unticking the text only worked perfectly in Firefox. I am now at 150% on my 27" screen and everything is hunky dory.

I do hate the use of percentages more than 100, don't people understand what the word "percent " means?

I get it with Firefox, but trying edge, it is ok.

Fibreglass cloth works to some extent, it is used by plumbers as the superior asbestos cloth has been outlawed for many years. A fierce flame from a bolwtorch will melt the glass fibres, but you do not say exactly what sort of flame will be present. Repair kits for car bodys have various types of fibreglass in them. There are also types of kevlar cloth which is fireproof.

Carbide silver solders and brazes very easily. I have made lots, mainly hand scrapers out of some of the odd shapes from cheap job lots on ebay. I have also bought 12mm ground carbide stock and silver soldered the ends of steel 12mm indexable boring bars on for solid carbide tooling. Because the carbide is brittle compared to steel, they have a special clamp which spreads the toolpost screw pressure. Also, the chipped and otherwise worn out inserts can be repurposed on steel shanks, brazing saves time rather than screwing them down.

You might find some fine threaded screws to make into grub screws with a screwdriver slot cut in with a junior hacksaw, just like they used to be in the old days.

Having three slots in the RT makes it a piece of cake to mount a three jaw chuck to it directly with tee nuts. Just look at the rear mount holes, and you will see that they can be drilled through to make front mounts. Several of my chucks are modified to front mount, there is often room for 6 holes for specific purposes.

I made two for the museums Smart & Brown model A, the genuine ones on ebay are stupidly expensive. The first was a little Chinese one with a 50mm bore mounted on an aluminium adaptor which fits the lathe bed and sets the centre of the bore on the spindle axis. The second one is a bigger hinged one with a bore of about 3 1/2", also with an aluminium base. I made a set of roller ends for it, so there is a choice in addition to the original bronze fingers. The bigger one can fit either side of the base centre line for greater versatility. Of course, I was lucky to have a mill to do the work with.

It is always worth being wary of ebay listings, there are many traps for the potential buyers out there. One ploy is to end a listing if the auction price is looking lower than the seller would like, despite a low starting price. Pictures can be deceptive,and descriptions wrong. I have had well over 1000 successful purchases and only one problem with a Chinese seller in all that time. Most problems can be worked out, such as a seller with two lathe backplates, who sent the wrong ones to me and another buyer. It was eventually sorted simply by the seller making a donation to charity and the other buyer and myself just posting the plates to each other.

If you know a good engineering firm that will do one offs, you could get a shim plate made. If the tilt was measured as 0.002" across the same width as the base joint, then a piece of gauge plate could be surface ground with the same angle of tilt. You could buy a suitable piece, and drill the holes yourself. Slightly longer bolts would be needed, but the mills Z height would be increased by the thickness of the plate, a useful thing on most small machines.

You would need a left hand tool that uses size 11 inserts. Those that I have, came with a job lot and have an insanely sharp tip, that is why they are more use for engraving lines than turning. I also have other variants with larger radius tips which are more useful for turning.

This site is worth bookmarking for understanding carbide inserts:

http://www.carbidedepot.com/formulas-insert-d.htm

Edited By old mart on 15/12/2020 14:24:26

I have a toolholder for VCGT 16 which is too sharp tipped for normal use. The inserts for it are so sharp tipped that I used them for drag engraving the new cross slide dial for the lathe. The toolholder is 20mm which might be too big for you, but there might be 16mm to fit that size of insert. I think the tip radius might be 0.25mm. There are several sizes of VCGT inserts on ebay.

Edited By old mart on 14/12/2020 20:38:05

Edited By old mart on 14/12/2020 20:44:10

Carefully designed way wipers will help to keep abrasives out. If the saddle has them left and right, it would be a good idea to provide a way of getting oil into the area between them.

Smart and Brown model A lathes have a positive oil feed to the cross slide and the saddle from the reservoir in the apron which has a pump which works as the saddle moves. In their manual, it says never use compressed air for cleaning.

For fine cuts down to 0.0005" for finishing, get the inserts intended for aluminium, they work well on steel and stainless steel,

N D I Y' s wife has the perfectly concise answer.

When we got the drill mill for the museum, it was a basket case, having been stored in bits under a tarpaulin in somebodys garden for three years. Everything had to be cleaned up and a lower spindle bearing was fitted. The round column was hollow and it still had a coating of foundry sand inside. I gave up trying to remove every grain of sand which kept falling off and found a large cork plug to fit in the bore. The cork had been a NOS part for a helicopter, I have no idea what it was for, but it stopped any danger of the sand grains getting into the joint between the column and the base as they were fitted together. The Taiwan made mill has never had a tram problem, luckily. I would guess that even 0.001" shim on one side would make a big difference and more worrying that the cast iron would be stressed badly by uneven clamping.

You have to have a lathe with a feed to the cross slide, not all do.

What a strange way of producing a thread rolling die. The three "rolls" must be syncronised before they are locked, possibly by having a sample threaded rod in place. If you want to turn them to an unworn part, then the syncronisation process has to be repeated. It would be sensible to make a mark on each roll face, pointing inward to know where to index them. As mentioned, an extra length incorporating a lead in taper would be the best way to start a thread. Iwould use an extreme pressure gear oil as lubricant.

Starting with a slightly undersize rod would be best and gradually work up using a tapped hole in a test piece for a gauge. Different alloys vary in ductility, some are not suitable for thread rolling unless hardened and tempered after the threads are produced.

Edited By old mart on 14/12/2020 13:54:10

Edited By old mart on 14/12/2020 13:59:55