Member postings for old mart

LM is what I use, and avoid overpacking. At least 50% airspace should be left when assembling.

If there is room, you could put a nylon plug under the locking grubscrew to prevent the scarring that locking screwsusually cause.

I had a look at the belt system on the Atlas. Keeping the 5 1/4" motor pulley will give a maximum speed of about 1980 rpm. This fits in quite well with the speed of 2080 rpm on the speed label. The difference might be between 50 and 60 Hz.

So I decided to replace the 2" motor pulley with the 3" one, they both share the same 8.5" shaft spacing. The pulleys are fitted together with Loctite 638, and I am part way through adding four 5mm screws for luck.

We will still have to move the door to clear the 5 1/4" motor pulley.

I get the impression that the whole set of speeds for this lathe will be from 10 to 20% faster than they should be. The guard door is having to be lowered and moved rearwards to clear that 5 1/4" motor pulley. Fortunately there is plenty of clearance around the upper 7.5"-9" pulley to do this. The motor is in working condition to test the range of speeds, the last owner had simply fitted a plug to the cable from the motor. Not exactly my idea of a proper way of running a machine tool.

I could keep the 2" pulley and reduce the 5 1/4" as the motor pulley is one piece and machined from plate, not a casting. It would be easy to mount it on a faceplate if some tooling holes were drilled in it.

The list of options available to me has now reached three. I am starting to lean in the reduction of the larger motor pulley size as suggested by Robert, as being my easiest solution.

More measuring will be done tomorrow.

Edited By old mart on 18/06/2021 20:33:14

Edited By old mart on 18/06/2021 20:35:45

Edited By old mart on 18/06/2021 20:38:16

Edited By old mart on 18/06/2021 20:55:59

Here are a couple of pictures of the laser, from ebay, which comes with a variety of mounts, and a useful remote switch which is shown fitted. The bit of white paint on the end is the target for the reflection. There is no optical adjustment, but after I cleaned both sides of the end glass, the focus is as good as the other laser that I was thinking of using.

Edited By old mart on 17/06/2021 18:24:38

It is common for grease to be used, unless the seals are very good as it is less likely to leak out everywhere. If you use grease, make sure there is at least 50% air space otherwise the head will overheat. A lithium based grease would be ok, don't use moly grease with ball or roller races.

A 5" vise will be about 1 1/2" higher than a 4" one before adding a swivel base.

Since there were several pulleys knocking around in the junk boxes, I thought I would try out a likely candidate. First, I measured the pulleys. The motor pulleys are 2" and 5 1/4" and the layshaft ones are 7 1/2" and 9". It is the 2" one that is too small. One of the single pulleys was 2 3/4", and when I tried it, it was too small. There was also a triple made by Picador and the centre pulley was 3", and was exactly right. I was surprised that the small 1/4" diameter increase would make such a difference.

I shall be machining both pulleys and fixing them together, it will cost nothing.

Edited By old mart on 17/06/2021 18:02:51

I tried googling your vise and there were a few pictures of a base which looks like being an inch high. I,m not sure if it could be retrofitted, however.

The pullys are in the same configuration as the photos, yours is in low speed I will take a picture tomorrow. Buying a belt to fit the mismatched sizes will save me a lot of time and effort. I'm thinking that the larger of the motor pulleys is bigger than it should be. It is a bit of a mystery, as Mike bought the belt and it matched the size in the manual, and the higher speed is the one that works, the small motor pulley is too small. The belt guard door is having to be lowered 20mm and moved rearward 25mm to make room for the drive system.

It will be interesting to find out just how fast top speed will turn out to be.

Edited By old mart on 16/06/2021 22:05:25

You only have to do it once, therefore a top quality job is well worth it.

Pete you are a genious, that is the easiest solution by far.

Making the tool is quite easy, as the laydown inserts are an equilateral triangle. I got the tilt angle from measuring bought tools. Recently I bought this little 3" vise which has two axes of rotation with tilt in between them, just the job to make custom tools like that even easier. The scales are in 2 degree increments, and can be read easily to 1/2 degree.

Glad you have got it, now for some very careful setting up. I would shim the tip height about 0.005" above centre. I hope the tool is long enough for you to comfortably disengage the nuts, I made it just long enough for the nut length I wanted, but I have the easier left hand threading away from the chuck. I have relieved the lower part of the insert because the helix angle is greater with that small diameter to pitch ratio. If you need to turn the insert, you shouild also use a diamond file to relieve the lower edges of the next edge. There is very little chance of blunting the insert cutting bronze. Make as many nuts as you like. You could even produce a test nut made from a bit of aluminium, if you do, use WD40 or equivalent to lubricate things.

I have checked out HPC gears and have bookmarked them in my favorites, they could be very useful.

Edited By old mart on 16/06/2021 18:31:11

You were lucky to get away with that crossed belt!

Exeter St Davids has a new one also, somewhat bigger.

We have a problem with a 2speed pulley system on the Atlas 12 X 24 lathe. The first set of pulleys from the motor is paired for two speed operation. The high range pair is satisfactory, but the smaller pulley on the motor is smaller than it should be, and is outside the adjustment range for the belt tension. I think the motor pulley pair is not the correct size and it also looks out of place being machined from solid rather than the rest of the pulleys which are castings. The drawings for the machine are no help as only a single speed is shown at that point. There is room inside the casing for a double pulley system from the motor.

The undersize pulley could be machined off and be replaced with larger to keep the spindle centre distance the same in both speed settings if I could calculate the size. I could even make one if I knew the diameter,any help would be appreciated.

Edited By old mart on 16/06/2021 18:04:56

I will have to see if there is any improvement to be made in the laser, actually one of those sights that can be fitted to airguns. I have a small spirit level with a built in laser which has a much finer focus which could be used. Despite only reflecting off a window, the return beam is very easy to see.

RDG tools also have 100mm and 125mm three jaw scroll chucks which have the 1 1/8 Myford thread. They have shipping rates on their website.

**LINK**

I fitted a laser on the side of the museum's drill mill, it reflects off a window about 9 feet and back to a white target next to the laser. It is accurate to 0.002" and could be better if I got hold of a laser with a better focussed beam.