Member postings for old mart

Glad to hear you got a good result. As there are no marks on the mating parts, it would be a good idea to check the run out in all three positions and put permanent marks on the best one.

How would you measure a gap of 0.004mm, my feeler gauges only go to 0.001" which is 0.025mm.

Should you end up deciding to change to a 3 phase motor run from a VFD, then there is a choice of basic types. At 50Hz standard mains frequency, the choice is as follows:

2 pole @ 3000rpm

4 pole @ 1500rpm

6 pole @1000rpm

8 pole @ 750rpm

The price increases with the number of poles. They all can be controlled with a VFD and the torque values are good between 25 and 75 Hz, (0.5 to 1.5 times their standard speed). Lower frequencies bring a steep dip in torque.

Don't forget that a little lubrication is essential when machining aluminium as it will weld itself to the cutters when cut dry.

I use them a lot and have twice made a donation as I think they are a worthy cause.

I opted for er25, it goes up to 16mm. If you intend to use er collets on the lathe with a mounting plate as well as on the mill, then er32 would be a better choice for both machines to share.

If you can afford the Vertex, it is made to a higher standard than Soba. I have a 6" Soba, bought privately, but in new condition, and the first thing I had to do was ditch the central needle roller bearing and turn up an aluminium bush. This was because I noticed a large ammount of radial play when the table was unlocked. I did not think 0.010" movement was reasonable, and who needs a needle roller bearing for the speeds at which a rotary table achieves. Now it works ok. As the table has four tee slots, a four jaw independent with front mounting is easy to fit. I have drilled and tapped holes for a 5" front mount Pratt Burnerd three jaw scroll chuck. This requires some thought, I made the mistake of drilling one of the holes into the drilling for lubrication, and had to re align all three. Now the holes are in the right place, fitting the chuck is easy, and with a test bar in the central Morse taper, and the chuck jaws lightly clamped on it before the screws are tightened, the chuck is centralised to about 0.002" tir which is good enough for my purposes. Having some short grub screws to put in the holes when the chuck is not fitted keeps the muck out of the works.

https://inverterdrive.com/group/AC-Inverter-Drives-230V/Schneider-Altivar-12-ATV12H037M2/Here is the link, the VFD is suitable for a 1/2 hp motor and this model is one of those which IDS include a quick start guide. I bought a larger model for the Tom Senior mill together with switches and a potentiometer for remote control as the switches on the VFD are not intended for normal machine use, just for setting up and are too small to be safe to use in an emergency.

Edited By old mart on 21/11/2020 14:42:22

Look no further, the Inverter Drive Supermarket also provide a printable quick start guide which is worth its weight in gold, its so easy to understand.

**LINK**

It looks like an ordinary garden fork to me, whatever did you expect. Iv'e replaced a few handles in my time, usually replacing the rivet with a nut and bolt. You usually have to whittle down the new ash handle to fit the fork. The Spear & Jackson fork and spade in my shed are stainless and the handles are either plastic or plastic coated metal.

Why not treat her to a new fork for Christmas, they also do a smaller size.

Edited By old mart on 20/11/2020 20:38:33

It has to be the threads centring each time, there is no other explanation. I would usually check a backplate on its own when the chuck is off being cleaned, and have never had to correct any runouts. The only threaded spindles that totally rely on that register are Raglan, I believe they use square threads. I have had to remachine the square end of backplates and that is when the front face would need a skim.

One thing that annoys me is when a figure of over 100% is mentioned. Even the power of gas turbines is often a figure over 100%.

That type of bomb is not made from stable isotopes.

A picture would be useful if possible.

You might post some drawings of the leadscrew and nut with dimensions. There is a possibility that a leadscrew and nut from another make of lathe could be made to fit.

The crossslide leadscrew and nut for the Museum's Smart & Brown model A was worn out, pretty long and 1/2 X 8 LH ACME. I managed to get one similar which was new and it had two bronze nuts with it. I was rather dissapointed when I checked the pitch and found it was a 3mm trapezoidal thread. When I contacted the seller, he generously refunded the money and said keep it. I ended up using it and having both nuts for antibacklash. Then a new scale had to be made with 0-118 on it rather than the original 0-125. There is a slight error between 118 thousandths of an inch and 3mm, but its not noticable in normal lathe use.

Smart & Brown use a 1 3/4" X 8 thread with a 1 3/4" register. We have about 8 chucks and faceplates with clearance between the spindle register and the bore of the backplate from 0.0005" (0.0125mm), to 0.020"(0.508mm). They all tighten up and repeat perfectly for concentricity and face flatness. The important thing is that the rear face of the plate is in tight contact with the corresponding face on the spindle. The most difficult chuck to attach to the lathe spindle is the one with the tightest fit.

I admit to being a hoarder of spare parts for the museum's Smart & Brown model A lathe, it is over 70 years old, so you cannot just go out and get the parts. My latest haul is a complete Norton QCGB with a cracked case, nobody else wanted in on ebay despite it being relisted twice and being cheap. I do keep a few of the safety links made to drawing for the leadscrew drive. The machines at the museum do not use any tufnol gears, but if yours does, some spares are a good idea as already mentioned. For many lathes, a length of the link type belt is useful to keep, and it doesn't mean removing the spindle to fit. Mini lathes have a fuse which tends to blow if the spindle stalls, when drilling, for instance, spares are worth having.

Good news, it's nice to hear of a successful result.

We have some large pieces of Stainless steel laying about at the museum, I avoid them as the swarf comes off like razor wire, only sharper.

Stainless steel varies in its magnetic properties and very much in its machinability. I have to tap a 4.5mm thread in a piece of non magnetic SS and even with a brand new British made tap, I'm not looking forward to it.