Member postings for old mart

Arc have a Chinese 125mm three jaw self centring chuck with both sets of jaws and backplates with the 1 1/8 Myford thread. The backplates have to be machined on their fronts to match the rear of the chuck, and the screw holes drilled.

I have one of ARC'S 125mm, 5" vises which is right at the limit of size for the large drill mill, and too big for the Tom Senior. I have only had it on the TS in line with the X axis for a particular job. The ARC site is good because the dimentions are listed, and you can cut a cardboard template to put on the mill bed which makes choosing easier. I thought about the limitless type of vise, but they have to be used in line with the Xaxis and an old hand told me they can warp the bed and make it hard to move.

Edited By old mart on 10/11/2020 15:01:10

Because the ACME, and trapezoidal threads have sloping sides, they are easier to produce. In the lathe leadscrew application, the nut is engaged radially and the sides of the threads should touch before the threads bottom out. This allows adjustment for minimum backlash and wear. The ammount of engagement of a square thread will not change its fit, and it can only get looser with wear. Square threads have the lowest axial friction of any thread but that is their only advantage as far as I can see.

Great luck to have kept the invoice, perhaps you should order a spare set while you can.

I would get a new four jaw independent chuck first, the PB is not worth restoring. I made a set of screws for the museums 6" lightweight PB and then discovered other faults when it was stripped down. I was lucky to get hold of a NOS Toolmex which was better than the PB had ever been. To stop risking damage to the screws, never use a cheater on the key, and using a strap wrench to unscrew the chuck is better than using a hammer on any part of the chuck.

I bought a 100mm four jaw independent for my 7 x 12 home lathe, it is Chinese and not at all bad for the price. You would probably need a slightly bigger one for your Myford.

We have had smart meters for electricity and gas for a couple of years now. I was not impressed by the kid who fitted them, just the minimum of training to be certified, but not any sort of proper fitter. The silly gadget they give you to monitor the consumption is sitting unused in a drawer. The only possible advantage could be that the meters we had were very old and that we don't have the meter reader needing to be let into the garage periodically.

I'm impressed by your attention to detail, well done.

All of the LN dewar flasks at work were stainless steel, from the 500ml to the 50L ones, the big ones had a large lid which was insulated with polyurethane foam. Glass would not have lasted long in an industrial enviroment.

Edited By old mart on 09/11/2020 15:07:37

I remember the pipeline section of the Scottish six days trial that featured every year in Motorcycle News. That was an off peak pumped storage power station.

Could you make a drawing and post a picture of it?

It should be ok as long as you keep alert for signs of distress from the motor, particularly when it is at the lower end of its speed range. The Align model intended for the Bridgeport Z axis has 760 inlb, but the weight involved must be three times as much as the TS. I wish I had taken some measurements of the knee mechanism and the length of the housing that the Z leadscrew dissapears into. I would like to put a 1" thick plate between the base and the main body to give a little extra Z height.

If you are using imperial measurements, then a thread of 7/16 or 1/2 UNF has 20tpi which is 0.050" per turn. For metric, there are taps available in 12 x 1 and 10 x 1mm pitch and the bolt can be easily made to fit.

We had to drill stainless steel for a pop rivet to lock parts of a springbox used in the tail of the Hawk trainer jet. The best method was slow speed and high pressure with a sharp drill. It was done dry, as oil would contaminate the assembly and make the drill swarf difficult to remove.

We had liquid nitrogen at work in a small vertical dewar flask around 3 feet diameter by 5 foot 6 inches high. The take off pipe inside ran close to the bottom of the tank and the valve and flexible pipe was at the top. The nitrogen was always at its boiling point, but kept at about 20 psi. This was to make it self discharging when the outlet valve was turned on. There were two safety valves, one designed to periodically vent pressure over the 20 psi set, the other set slightly higher. There was also a safety burst disc, a concave thin stainless steel, about 3" diameter which if it started to blow out, came in contact with sharp cutters which would rupture it.

Our works manager came up to me one day and said he was taking the rep from the firms insurance company past the nitrogen tank when a sudden blast of gas made them jump. I said to him that the safety vent did that several times a day and not to worry.

Edited By old mart on 08/11/2020 20:45:08

Just google "train crash whale tail", all of the pictures and story is there.

I made two for the Smart & Brown model A and the wear at the left end of the prismatic bed measured 89 degrees, the unworn right end was 90 degrees.

I have seen the pioctures of the accident taken from above. The end car is suspended above water, which is not visible in the original pic.

Perhaps you haven't tried inserts made for aluminium for finishing cuts on steel. A 0.0005" depth of cut is easy with these inserts and the best thing about them is that the cheap Chinese ones are not nasty any more.

Edited By old mart on 08/11/2020 16:04:08

Having both the TS and a large Taiwanese drill mill at the museum, I can say that the TS is nicer to use, but slightly smaller in capacity, and the end results are about equal. Neither can compare with a Bridgeport, which I recon is the ultimate home shop machine.

I may have to get another bit of gunmetal if I decide to make a new nut for the Y axis of the TS, I have a feeling the leadscrew is 3/4", too small for a 17mm starting bore. That particular nut was the best of the three on the machine, probably only 0.007" backlash.

I would not polish, I can get a finish on most steels that looks like ground if needed, and with carbide inserts, I never use HSS on the lathe unless it's a twist drill.