Member postings for John MC

Many years ago I acquired a large quantity of 8BA screws, cheese and hex. head and varying lengths, probably a life times supply. As might be expected, they are never the right length! So I take the next longest, screw on a nut, cut it to length, then touch it on a fine grinding wheel to tidy up. This is fine when only a few need shortening but tedious for the 50+ I need for my next project.

Any ideas to make the job easier?

Thanks, John.

I've enjoyed the recent discussion here about the BSA/Triumph 350 that may have saved BSA if the banks had not pulled the plug. The Edward Turner designed twin, ETED1, always much maligned and the subject of bad press. I would speculate much of the bad press was as much about the man as the bike. Many myths seem to have become facts regarding this bike. One popular story is the unreliability of the crankshaft, frequent failures. Yes the crank broke across one of the pins. This was after something like 25000 miles of being thrashed by some very fast riders. I believe Percy Tait did the performance testing at Mira, it's performance on a par with a Bonneville!

After the crank failure stress analysis experts found the problem, a subtle change here and there sorted it. This crank then when into the later Bandit/Fury design.

Turner's bike did not get the development it needed before politics got in the way. So, what did the later redesign that is recognised as the Bandit/ Fury do for the bike? It had a 5 speed gearbox, Turner's had a 4 speed. Some work was done with the 4 speed to get 5 speeds out of it, that in itself is a fascinating story. The bike gained an electric starter, necessary to compete in the market place. It also gained a lot weight 70 - 80lbs, thus losing it's sparkling performance.

Turners brief was to produce a bike that would be competitive in the American market, the 350cc class was the big seller at the time. The bike had to be low in cost to produce and easy to maintain. This was broadly achieved compared with the later version.

I could ramble on about the bike but it would better coming from the "horses mouth" so I am going to try and persuade one of the BSA guy's who was seconded to Turner's design team to get the story written down.

John

I have a Fowler-Bowers internal micrometer, 0.50" to 0.62" range, the type with 3 expanding pins. While it is accurate to the various setting rings I have, the scale on the thimble does not quite line up with the scale on the sleeve, if that makes sense, enough to cause a reading error unless I am careful.

On an external micrometer this type of error can usually be corrected by moving the sleeve axially with a tiny C spanner.

I've looked at the manufacturers website, it explains resetting the thimble to a gauge but not resetting the sleeve.

Its bound to catch me out one day so I would like to reset the sleeve,anyone know how?

John

"Phil Irving tried to get the British vertical twin manufacturers to change to 90 degree cranks many years earlier and got laughed out the factory gates. It was a long-standing and enduring prejudice I guess."

Yes, Phil Irving (one of my engineering hero's) was keen on the 90 degree crankpin spacing for a parallel twin, an attempt to reduce vibration by utilising the best of both arrangements? Its now accepted that Irving made one of his very, very few mistakes in suggesting 90 degrees, as has already been said, 76 degrees, or near would be better.

As for prejudice and "not designed here syndrome", plenty of that, look what happened to the BSA/Triumphs last gasp attempt to stay in business, the Bandit..........

John

"Briggs and Stratton engines use aluminium bores with no coatings but they run a plated piston ( can't remember if it was silver or nickle or tin )to stop any galling ."

I believe Villiers did the same with a lightweight range of small engines. As has been pointed out, Aluminium running on Aluminium does not work well. I'm not too sure about stainless steel and Aluminium, galling is not unknown with that combination.

Whatever combination the OP decides to use then I would suggest the first step in considering the clearance would be to consider the relative thermal expansions and go from there.

John

Impressive work! I've had a spot welder in the workshop for many years, its a very basic machines for which I had to make some parts for to get in to a usable state. Well worth the (little) effort. I used Copper electrodes initially, they would last for 10 -20 weld before needing to be reshaped. I then bought some proper electrodes, (Copper/Chrome alloy?), these will hold their shape a lot longer but still deform because they get so hot. The obvious way forward is to water cool the electrodes.

Joe, have you considered cooling the electrodes? What material are your electrodes made from?

I've just completed a job that required nearly 400 welds, it took all day, allowing time for the electrodes to cool and only 2 reshapings of the electrode!

John

Today I shortened 200 M8 bolts and used a Coventry die head to put a 5/16" BSF thread on the remaining plain part of the bolt.

This got me thinking, is a die head an obsolete piece of workshop equipment? Obsolete as is a shaper or planer in industry but never the less still useful for the model engineer. A local engineering business very occasionally borrows mine, having not replaced their worn out head some 30 years ago. They much prefer to use a throw away tip tools running at normal turning speeds for threading. last time they used my die head was to cut M10 threads on a part using the only "conventional" lathe (non-CNC) they now have, the reason being all the CNC lathes were busy!

John

The photo I have hopefully uploaded is similar to the OP's "mandrel". I wonder if it cold be of a similar purpose? This one is the spindle that held the hob on a Dowding gear hobbing machine. It has a 4 morse taper, the thread adjacent to the taper is for extraction, I think. The other end has a center hole for support and a thread arrangement for clamping the hob. It has been some time since I acquired the spindle so the detail may be a little "off". I had three of them, various lengths, useful for the 4MT.

John

Graham, rather than making a gear why not buy a manual AR gear and modify that to carry the AT device? Not easy but you will be using a gear with properly generated teeth rather than the less than adequate formed teeth.

John

Never had a problem getting my optician to relense a frame, as long as the frame is in good condition. Will probably need to buy a new frame next time, the current pair have had couple of repairs now. I use a local (to me) optician "Haine and Smith". The frames are "Mobsen", the lenses are marked MO-1F-CE.

John

92T 32DP, 20deg. PA, 16deg. LH helix. Top dia. 3.063", Ptich dia 3.00", Root dia 2.922", all+0 -0002".

Hope this helps.

John

Edited By John MC on 31/12/2017 12:36:33

A good friend of mine is occasionally asked, because of his gentle and sympathetic nature, to dispose of deceased model engineers workshops. He has, over the years accumulated a number of tools that have not sold, a few boxes of screwdrivers, spanners, small drills etc. With the rise of the "Mens Shed" movement he thought donating the tools to the cause would be a good idea. There are two in our area, we went along to have a look. The first one was appalling, the place was a mess, a quick look around and we both concluded it needed shutting down! Then, as we headed to the door someone starts arc welding on a bench covered in sawdust and with no eye protection and no warning they were about to start welding!

The second shed was superb, well organised, clean and tidy. Has attracted donations and help from industry. A credit to those who set it up and a valuable asset not only to the individuals who use it but the community at large. Guess where the tools went.

John

I wonder how many model engineers wear their prescription glass lensed specs in the workshop? I need glasses for reading. When I need a new prescription (seems to be every time I go to the opticians!), I have a new pair of plastic bifocal lenses made for my safety glasses. Not cheap but justified on the amount of time I like to spend in the workshop.

John

I've been using a clip on/flip up lens on my reading glasses for a couple of years now, very cheap from Ebay for the small fiddly bits. Even my optician is quite impressed "optically" with them. They are getting a bit scratched now so was thinking upgrading to an Optivisor. I'm slightly concerned over the size of the Optivisor, I can quickly flip down the lenses I have to, say, accurately position a centre punch on fine lines, then flip them out of the way, can I do this with the Optivisor? Will they get in the way of safety glasses?

I am also concerned that the genuine Optivisor has, I believe, glass lenses, not the best thing in the workshop environment from the H&S point of view.

I would also like to reinforce the point that good lighting is also a great help with elderly eyes.

John

"John Mc one moment you say you are surprised that the polystyrene was where it is and ask if B. Regs were consulted and the next you suggest I look at the Building regs which show both and say you chose the opposite, If you had looked at the regs in making your choice they why were you surprised at the construction?"

I qualified my first set of comments with "30 years". For my second set I took a quick look at the regs to see how they had been developed, quite considerably as it turns out.

John

"Again I will say it. This is standard building practice slab or beam and block, layer of insulation, screed."

This depends on whether a "warm or "cold" construction (check the building regs), I chose " warm" construction after considering the possible loads in the workshop ares. looking at "cold" construction now, a more complex route to follow.

"Can't you just build a proper shed instead rather than put it in the house?"

I built my workshop as an extension to the house, insulated floor, insulated cavity walls and insulated ceiling (a foot of insulation!) so it could be heated with the house central heating, lovely to work in looking out at last weeks snow!

John

I assume that the polystyrene layer is for insulation, I am surprised its on top of the load bearing slab, 2 to 2.5" of screed(?) will have no strength in this context. Were building regulations consulted before the floor was laid? When I extended my house, admittedly nearly 30 years ago, insulation requirements had been extensively upgraded. The floor had to consist of 50mm insulation, the DP membrane, 100mm of concrete (load bearing) then 50mm of screed. Unless regulations have changed over the years then it seems to me the floor has not been constructed properly.

Part of the extension to the house is the workshop, so I (discretely) increased the load bearing layer to 150mm and slipped in some reinforcement in anticipation of heavier equipment arriving, which it did!

John

Listened to a radio news report on the prop shaft leak this morning, the shaft is 7metres diameter, is it? Repeated an hour later so must be.

What sort of seal is it? One of those rubber ones that is lubricated by the water around it? The name of these escapes me at the moment.

John

I have used, for many years a felt tip pen, one with a big fat tip, usually blue but sometimes red or black, whichever comes to hand. Bought them from Staples years ago for next to nothing. One thing I have found, to work reliably they need to be stored upright tip down.

I assume you mean marking out blue rather than "micrometer blue" for checking fits etc.

John