Member postings for old mart

I cannot remember the length of the original TS nut, but I have enough gunmetal to make two 2 1/2" long nuts. The flange with the bolts in it and the lower part diameter will be finalised when the knee is removed. The flange might be screwed on and locked in place, it's too early to decide. Only one of the bronze bits has had the 0.800" bore done, the other remains 17mm, I might look at the Y axis nut, who knows?

The plug gauge that Ramon suggests is more accurate as measuring the outsides of something is always easier than the bore. I would make the front half of the gauge stepped 0.001" smaller than the exact size. That should enter the hole and the exact size not want to.

The ears on my old Mitotoyo digital calipers do actually measure holes accurately with practice and patience, but my Chinese copys will not. For holes up to 2 1/2" I would prefer a rocker telescopic gauge, over that my tube mike will fit.

Edited By old mart on 07/11/2020 18:31:30

If making SDS tooling, it would be sufficient to measure an existing one, the tolerances are not very tight. The material must be hardened to stand up to the striker constantly hammering the end.

I have a De Walt 3.3 Kj mains drill and a Parkside 1 Kj 20V battery one. I am particularly pleased with the Parkside, it is intended for up to 10mm holes, but could go to 12mm with a pilot hole first. It lacks the rotation stop function, but is really too lightweight for that.

I do hope it works ok, I would like one on the X axis of the museums mill, but the cost at the moment is putting me off.

The 5 ACME internal insert came from APT today, and I found my mistake when making the toolholder. It will have to be modified after lockdown as the insert hangs off the end by 3mm. I will have to move the housing 10mm to fully clean up, but the bar is plenty long enough. The bronze is 2 1/2" long, and there will still be 85mm to fit in the tooplpost.

If you get an SDS drill, it would be wise to keep a percussion drill and some bits for those soft walls where SDS can be extreme overkill. The plain shank masonary drill bits can be sharpened with a diamond wheel to make very servicable poor mans drills for hard steel.

The Smart & Brown model A at the museum was lifted up by the fork lift truck and a frame made from 4x2 hardwood was put underneath to ease my old back. If a short person ever uses the lathe, we can easily make some duckboards. The Tom senior mill also sits on 2" high wood with through studding glued into the concrete floor. You have to think of the machine stability when adding height and plan accordingly. With a small machine, there is no reason not to leave storage space underneath, and a clamping down system which allows moving the machine is sensible. Maybe you could use two rails of angle iron to make sliding sideways easier.

Edited By old mart on 07/11/2020 14:21:29

I bought one of the Vertex LED/ beep electronic types with the sprung loaded ball. It gets used at least twice a year. I must admit that I have never tested it's concentricity as Oily rag has mentioned. The glut of Chinese ones are currently on the market at 1/4 of the cost of my Taiwanese one. As the shank is 20mm, they will not be suitable for smaller machines.

You would have to be careful mixing the inserts, as even if the pitches were very similar, the different angle of thread and the width of the tip of the insert would not result in a very good thread if you got it wrong. I still think it would be a good idea to take the leadscrew to a machine shop to get the exact angle of thread checked, after lockdown, of course. The difference between 29 and 30 degrees would be difficult even fitting an insert in an unworn part of the leadscrew. There would be no hurry if your immediate concern was fitting ballscrews for CNC use.

Some of these units on ebay have a claimed torque of 450 inch lbs, they would be ok, but the others may be 135 inch lbs which would be fine for the X, but not for a loaded down Z. Maybe you could fit it to the X and use the motor that you have already fitted, possibly with further reduction on the Z.

Nick Hughes has an Align unit which is more powerful on his Z axis.

Edited By old mart on 06/11/2020 18:36:54

I would expect a broad arrow on it if it had ever been in the military.

You won't have any bother singlepointing a 1 1/8" diameter thread with a 4mm pitch thread, trapezoidal or ACME form. You would best get an `IR16 x 4mm insert (internal trapezoidal). I have started a 1" X 5 ACME which has a starting bore of 0.8" and because I cannot get 5 ACME in IR16, and have to go to IR22, I am having to make a holder for the job. Holders under 20mm don't seem to exist for the 22 size inserts, but you should get the choice of 16 or 20 mm in size 16 for your 4mm pitch.

If the unit would be ok at right angles in your case, you would not loose that vital Z travel. I am still worried about the low torque from most of these units, there is a slightly more expensive that has almost three times the torque. I think you will burn out the motor very quickly.

The reason I added that cranked lever was because of the high ammount of effort needed when the loading was high and the knee was low down.

Thats a big tap! Just as well you will only be cleaning up an existing thread. It might be easier to clamp the tap in a vise and screw the plate onto it.

Edited By old mart on 05/11/2020 19:37:40

I put a six pole three phase motor of Ihp and a VFD on the Tom Senior mill and set the limits from 25 to 75 Hz. Lower frequencies are possible, but I didn't think the rapid drop off of torque was worth it. The four speed ratios using the belt drive are still essential and worth the slight bother to change when required.

You could try degreasing the threads and blacken the spindle with felt tip. Then the tight parts will probably show up.

The Atlas also had 1 1/2" X 8 and that definitely had a 60 degree thread angle. I made one recently, and the register could also be different from Boxford. I am unable to check the Atlas sizes for you as the museum is not closed due to lockdown.

Edited By old mart on 05/11/2020 15:05:22

I have heard rumors that a nonstandard thread was used by some lathe manufacturers to save money on tooling. The only sure way to find out your particular thread would be to take the leadscrew to a sympathetic machine shop and get them to check the angle of an unworn section on a shadowgraph.

I cannot see exactly how one of those drives can be shoehorned into position for the Z axis. There is very little clearance between the chip tray and the knee at the lowest position. Also, one of the reasons I didn't make the long handle for the knee a permanent fixture was because it got in the way of the operator. I would love one on the Xaxis for the museum's TS.

My next door neighbor has a van that doesn't get used much, and he has a solar cell array stuck to the roof that keeps the battery charged.

Valve grinding paste is too coarse, even the fine, the taper reamer with a little oil is a better bet, just a bit at a time and using the blue until 90% clean up is shown. The test should be carried out with more than one MT in perfect condition and the average taken.