Member postings for old mart

If I am right about the studs passing from one side of the bridge to the other, it would also explain the nut length and sequence. The nuts would have to be extremely tight, and would cause a large amount of tension stretching of the studs. This could be measured in inches rather than fractions of an inch. A long nut of three diameters or more would be safer to tension than the standard length of nut, and the short nut is probably just there to use up the remaining length of thread, and not as a serious lock nut. It also looks the part to casual onlookers.

A bit off the original topic, but try looking at street view of Old Basing, Hampshire, UK, 51-16-22N, 1-02-39W. I ducked when riding a motorcycle under this twin track railway bridge, it is marked 7 foot 9 inches.

It looks to me that they are studs passing through the entire width of the bridge. Forces are distributed through the brickwork which will be at least 10 feet thick for a single track. The other bridge was displaced off its bearings.

I believe that the 68 pounder was the largest made, and sailors referred to the weapon as the smasher.

It could be used if an additional means of locking was added to it. A back up tee nut and block would not be hard to make.

Edited By old mart on 03/12/2019 20:34:52

Edited By old mart on 03/12/2019 20:35:22

So do a lot of lathes, including Smart & Brown, they rely on the collets being perfect.

How about this:

**LINK**

Having a tight tapered fitting is fine in theory, but allowing a small amount of radial adjustment means you can fine tune the runout to zero.

For photos, you have to have some already in the pc, then you go into "ALBUMS", and add the pics of your choice to your new album. Then when you post, just click on the camera icon, and select the appropriate jpeg. I find that keeping my camera set at its lowest resolution makes it easier to get the pictures onto the album. I use 2 megapixel photo's.

Welcome, Bob, from a model A user, the S & B's are a step up and more from any Myford.

It can be very difficult to figure out where the cracks end, and even then, only the surface part shows. I wonder if there is room to skim the underside and screw on a plate / plates that side?                                                                     That observation that the weld might be a bodge done by the manufacturer seems plausible.

There are some signs of bodges done by Senior to blowholes in the castings of the Light Vertical mill we are doing up.

Edited By old mart on 02/12/2019 15:58:47

I have just come across a type of lathe I have never seen before. It has a sliding bed to allow different lengths of gap.**LINK**

Why not ditch the 29 degrees and keep the compound parallel to the axis? It is so much less complicated for beginners. The finishing cuts should be only about 0.001" and should not be too much even for a small lathe. Proper threading inserts are sharp and do not cause undue stresses on the machine.                                                                 The other advantage of going in straight is you can use the scales to measure the exact thread depth directly, which is found in decent thread charts.

Edited By old mart on 02/12/2019 14:38:47

Torque wrenches are for tightening bolts, not for undoing them. On a typical application such as a cylinder head, the bolts will be done up to a lower torque on the first time round, and then to the full tightness finally. The final tightening should be done in one continuous movement per bolt. If the tightening is interrupted just before the final torque is reached, the bolt will not be fully tightened when the torque wrench is taken to the set torque.. As soon as the tightening stops, the friction increases greatly before the bolt starts to move further. This is why it is common for taking some heads down to a lower torque, and then finishing by turning through a predetermined angle. On some older engines, the head was retightened after running to working temperature and then cooling. Then the way to retighten, was to slacken off each bolt, one at a time, before final tightening in the original sequence, to eliminate the "stiction". It is important to adhere to instructions regarding lubrication, or not.

One of the jobs at work was to bolt together the propeller hubs of C130J Hercules, before final machining. The 18 threequarter inch UNF bolts were tightened with a torque wrench in a predetermined sequence to stretch them from 0.012" to 0.015". Torquing alone was not considered accurate enough.

I was taught to heat to dull red and then quench in water. Another point is that removing sharp corners from the outside of the area to be bent and smoothing the surface, reduces the likelihood of future stress fractures.

Look up "seasonal cracking of brass"

Edited By old mart on 01/12/2019 21:20:51

That insert in the picture is for turning not threading, try some threading inserts and a holder.

Be careful with getting the right screws, their heads have a taper, probably 60 degrees.

It is a fairly large thread, so should be easy to pick up visually. Just set the pitch and take out any backlash by turning the spindle, by hand if you want. Then bring the threading tool into mesh with the spindle stationary. Have a piece of white card behind to make it easier to line up. Start with the usual light cuts, and after several passes, the tool should just be touching the original thread, and you are close to the same size.

I added 4" of 3/4" X 5 ACME to a mill leadscrew with no bother. The other day, I had to make a 32 tpi thread on an R8 blank arbor to fit an optical sight which had an ISO 30 fitting originally. The actual pitch should have been 0.8mm, but 32 was near enough for a short length of thread. The tip rad was too big, so I had to change to a finer pitch insert. Even at 32 tpi, it was not difficult to get it re aligned.

Dead right, Pete, I would just get used to a diameter in inches reading. I fitted a 3mm pitch cross slide leadscrew to the imperial Smart & Brown model A and made a 0-118 dial for it. Since most turning involves creeping up on the last bit, the tiny error in 0.118" verses 3mm is of no consequence.

I have three magnets by the machines at the museum, one on a three foot handle, and two little telescopic ones. They are invaluable, as I have difficulty reaching as low as the floor.