Member postings for old mart

A matching pitch thread chaser would be of great service with a slightly tight thread, and excellent for removing that difficult pressed in swarf that defies wire brushes.

I bought one from Tracey tools to finish the X axis nuts for the Tom Senior light vertical. Having tried the tap in a bit of scrap with the correct starting bore, I decided to partially single point the thread on the lathe and finish with the tap. Their ACME taps are very long with a single taper, but I wasn't prepared to risk breaking it in gunmetal. The finished thread had some backlash on the leadscrew, but I had modified the design for two nuts with backlash adjustment, so that didn't matter.

I have seen pictures of extra long ACME taps with two stages of threading, they would produce a thread in one pass without the extremely high torque.

There is some information on exactly what I did in the manual machines, Tom senior threads.

Edited By old mart on 31/07/2021 19:23:07

Edited By old mart on 31/07/2021 19:24:23

Probably not what you want, but lathes UK have a printed manual for £45.

**LINK**

As the forces will be minimal and the minimum of friction is best for that type of motor, if possible, the shaft in the bush should be made a very light push fit at first and then polished down with 1200 or finer grit paper used with light oil until it fits with no friction at all. Every stage would need washing in solvent before testing the fit to avoid getting abrasives in the bush.

Wonderful precision work. I couldn't see the photo's when I first visited the thread, but now I am logged on, they all work as expected. I have never had that happen on this forum before.

Picture 2 made me chuckle, instead of wearing a 2 inch bar, the anvil would be a good substitute.

Edited By old mart on 28/07/2021 20:22:09

I looked on the H & K website, but unfortunately there is nothing listed and no sign of any of their legacy tools. If you like, I could post a link on an American website that I am a member of to spread the search wider.

You could try lapping them together as they are nearly the same size, using fine compound and light oil. It would be a help if you could post photo's of them.

You could look at sintered bronze bearings, available in metric and imperial, self lubricating and already made to size.

You may be able to get a thinwall sleeve from a bearing supplier for the needle roller to run on. I fitted one on a motorcycle gearbox shaft to repair it.

https://simplybearings.co.uk/shop/Bearings-Needle-Roller-Bearings-Needle-Roller-Inner-Rings/c3_29_35/index.html

Edited By old mart on 27/07/2021 17:12:53

I'm with Jason here, a light coating of lacquer. But it would also look great in a suitable regional livery.

Not cycling, but still in the olympics:

**LINK**

The "levelling" when used in relation to a lathe is a poor way of simply making sure that runs true whatever length of work is machined. As I mentioned earlier, it is best to do test turning as your lathe bed may be fine as it is

At the museum, we are working on a 12 X 14 atlas lathe on a welded up stand. Instructions for the lathe include leveling and the only way to achieve that would be to include some sort of adjustment. I fitted an aluminium block under the headstock to raise the lathe about 40mm. That enabled adjustable mounting bolts to fit at the tailstock end. We haven't finished the lathe yet, and I'm not sure my Moore and Wright level is sensitive enough to be used directly. As mentioned in my earlier post, leveling can be tested by a test turning.

Edited By old mart on 26/07/2021 15:32:00

Some mills are purposly set slightly off level to allow better drainage of coolant, so I wouldn't worry too much. A large ball bearing sitting on the bed would be a cheap way to level, or an ordinary spirit level in both axes and double checked by turning it round.

For the lathe, it would be best to have a 20mm brass bar sticking out of the chuck about 100mm and take a very light skim and compare the diameters of both ends of the machined diameter. If the end furthest from the chuck is less than 0.010mm bigger, then you might as well forget messing about with leveling.

I cannot see what the difference would be except for expense of arbor and chuck if using a 16mm plain shank or a blacksmiths drill. It is the MT1 taper that is at risk.

 Reducing the rake angle of the larger drills and predrilling a pilot would help. I managed to break the MT2 taper twice the other day with a stepped shank 26mm drill in a 16mm chuck in steel. Changing to a slightly smaller drill about 24mm with integral MT was the solution. It just meant a little more to bore.

Edited By old mart on 25/07/2021 21:01:22

When using the Smart & Brown model A at the museum years ago when it had a very worn cross slide screw and nut, everything which was faced off had pronounced ripples. Since replacing the leadscrew with a new one and having two nuts set up for antibacklash which is set at 0.001" the ripples have dissapeared. I doubt whether that lathe could produce the quality of facing that yours can to reveal that rare effect.

A modern cnc lathe would have some compensation for tool speed, cutting radius and feed rate.

I wonder if the effect would still be there if a little WD40 was used during the facing?

Edited By old mart on 25/07/2021 17:26:03

Edited By old mart on 25/07/2021 17:27:09

Edited By old mart on 25/07/2021 17:31:00

The Wikipedia link by Thor is well worth studying. There seems to be very little sense in just how tapers are derived. Morse tapers are all different angles and the B type are truncated Morse tapers.

Having a 16mm chuck on a MT1 taper will require very careul use with larger drills, a MT3 shank is a better match for the torque required.

It is always a good idea to check the runout of the backplate when the opportunity arises, especially when it is only fitting properly for the first time. I would bet on the spindle threads being innocent of any faults unless there is visible damage. Unlike most of the experts, I have a choice of 12 items which screw on the threaded spindle of the museums Smart & Brown model A and the register fits are from 0.0005" to 0.020" and as if by magic, they all repeat perfect runout every time. Martin Kyte is one of the few people who understands this.

Well done, you will find that in the real world, the fit is better when it is a bit on the loose side. You should remove the chuck from the backplate and screw the backplate on and off the spindle several times to settle it into place. Then check the runout of the front face outboard of the step and skim that part true if needed. Then refit the chuck.

Most of my spotting drills have a 90 degree point, but I have got one with a 130 degree tip. It stays in its tube, as I found its drawback, you don't get a good view of exactly where the end is. I also have some centre drills with the 90 degree flank rather than the standard 60 degree. Not much good for use with a centre, but good for when a drill is to be used.