Member postings for old mart

Taper taps do help to get the thread straight and a few visual checks as the first few turns are cut will also be worth doing.

Forget the AA cell, wire it up to a D size and it will run for years.

Welcome Red, it will be great having you contributing to the forum.

Seeing the photo of the large tool in the rotary broach makes me understand why the broaching was a failure. You would need tons of pressure and the broach is bigger than the shank of the tool. Think of the cutting end of the broach being rotated with the workpiece and moving like your finger would if you pressed it onto a surface and rocked it about in a rotary motion. The tip of the finger does not move about sideways at all. Iwould take the workpiece and the broach cutter, not the broaching tool to some local engineering workshops and ask them if they can do the job for you. The hex could be cut on a shaper if all else fails.

Edited By old mart on 05/07/2023 19:22:41

I did think about a lock, and one can be easily added at any time, it only takes a few minutes to remove the cross slide. One thing put me off and that was the gib is brass, and would be distorted by localised pressure on it. The possible way around that might be to have a hole in the gib where the locking screw is and to use a bronze pin against the dovetail. Those two large screw holes are simply existing holes in the steel block, they do not emerge in the wall, just too high and short. That piece of sheet aluminium is original and fixes to the rear of the cross slide to keep swarf away.

Edited By old mart on 05/07/2023 19:04:38

Edited By old mart on 05/07/2023 19:06:20

I used backgear on the lathe and plenty of tapping fluid for steel.

A set of very slightly larger diameter rollers might resurect the clutch, but getting some of about 0.05 to 0.015mm plus might be difficult.

I made my broaches out of silver steel, hardened them and then put them at the top of the gas oven at regulo 9 on a teaplate. They just about got tempered enough to use, but the plate cracked.

With help from the forum, I was able to get hold of a new 1/2x 10 LH ACME leadscrew length and a nut for the museum's Atlas lathe. Also there was advice on a resettable Myford dial which is superior to the original Atlas one. There was a block of steel of a good size to make a longer cross slide to replace the very short original and enable plenty of room to incorporate twin nuts for antibacklash. It is now finished and about 3" longer than the original, shown next to the new one. There are 6 gib grubscrews now instead of 4 and the height has been adjusted slightly to share the Smart & Brown tooling. The 12mm tools which I had bought for the lathe will need slightly thicker shims, and they can also be used on the S & B. The degree scale is part of a brass protractor glued onto the rear of the compound pivot point and lined up before the glue hardened.

When you design a rotary broach the exact angle and offset of the bearing housing must be calculated as well as the position of the null point where the cutting takes place.

This is what mine looks like, the null point is 87mm in front of the body, as marked. The angle it was made has been forgotten, but 1 degree would seem a good guess, hence the reverse taper on the tools to stop them fouling the hole.

We have two, one upstairs and one downstairs, great little cleaners and made in Chard, not China.

I made one with an er25 collet with a pair of bearings on a MT2 shank. The cutting end of the tooling must project exactly to the null point or the tool won't work. I marked the length on the body whan I made it.

Verdict lever type indicators have a shaped tip which reduces the cosine error over a greater range that other types can manage. I only use these for zeroing shaft runout and would only rely on fine accuracy over a short distance, say within 0.005" with the lever at right angles to the movement. The original length of lever also matters.

Normally the wiring details are inside the lid of the terminal block. A 12 pole motor would have very high torque for the rpm.

I would glue it with epoxy. Scrape back any external witness and repaint. The glue will be as strong as brazing if the bell cannot withstand dropping on a floor and you would still have to repaint it if it were brazed, and the external brazing would be much harder to disguise.

It might be possible to incorporate an ISO30 into your short MT5, then much better tooling than MT3 could be used. The drawbar for the ISO30 would hold both in and the steeper angle would not be likely to disturb the MT5 when changing tools.

That just goes to show what persistance and patience can achieve, well done.

On a smaller scale with a mower motor, my only option was to make a bolt together split steel holder to sit it under the hydraulic press. The bore was grooved with a threading singlepoint at the same pitch as the belt grooves. It looked like a thread inside. If you take it to a small engineering workshop,they may be able to help. If you don't want to reuse the pulley, then the easy way is to turn it off on a lathe.

Edited By old mart on 30/06/2023 19:07:00

Vic, there are masses of microscopes on ebay, many at very good prices. If Ididn't already have a nice one which is hardly ever used, I would be buying myself.