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Member postings for Nigel Bennett

Here is a list of all the postings Nigel Bennett has made in our forums. Click on a thread name to jump to the thread.

Thread: Training school auction
06/08/2020 12:49:52

Gosh! There's a hell of a lot of stuff there. With so many identical bit-too-big for the average model engineer lathes for sale, I can imagine they'll go for peanuts and then be shipped overseas. I do wonder about some of those cupboards plus contents, though; if you bid and won one, how much of the contents would you actually get?

Thread: Starting Small Holes
30/07/2020 09:56:21

I've had a job of drilling 1/32" holes in the end of 1/8" dia brass bar, in the lathe. Normally I would start with a centre drill but the smallest centre drill pilot is to large.

Why is it too large? It isn't necessary to make the centre drill open up the hole to its full pilot diameter; all you need to do is to make a small dimple, slightly smaller than the hole size you want. (Same with spotting drills.) If you make the dimple slightly larger than the final size, you'll be left with a tiny countersink around your final hole size.

Thread: Bar clamp
25/07/2020 15:36:24

Hello Tony

What's the application? Is it something you will adjust frequently or is it a fit and forget job? How much time and effort do you need to spend on making it?

Slitting the "dark" is a good way but be careful if using cast iron outer and the bar is a loose fit as it may break when you tighten it up.

There are quite a lot of ways of "claiming" the bar; I suppose the simplest was of clamping is a grub screw or similar. However unless you take precautions it will mark the bar, and it will also tend to force the bar slightly out of axial alignment - how much will depend on the clearance between the parts.

I imagine by your "2 part cotter pin and bolt" that you mean those split clamp affairs. They're good, and give excellent clamping. They don't mark the bar, but again they do tend to force the parts out of alignment as the grub screw does.

Another way is some kind of collet arrangement; tightening this up will give an excellent grip and maintain concentricity if you've made it correctly.

Thread: Making sense of big numbers
25/07/2020 09:28:08

I liked the story about a chap (It may have been a story on Monkey Cage) who was explaining to his audience that the sun was going to envelop the earth in a few billion years.

One chap stuck his hand up and asked, "Did you say billion or million?"

"Billion."

"Oh - phew! Thank goodness for that. I was sure you'd said million."

Thread: Interesting bike ride today
18/07/2020 16:58:39

No bat-related, but I had an amazing incident with a Red Kite when I was out pedalling the other week. I was happily tootling along and I was about to make a slight diversion to avoid a bit of road kill in the road in front of me, when "Whoosh!" a Red Kite swooped from behind, about six inches above my head, dived down to the road an unfeasibly small distance in front of me and scooped up its lunch! I actually heard its talons scraping on the tarmac as it gathered in the harvest. How I didn't run over it I'll never know.

Edited By Nigel Bennett on 18/07/2020 16:59:03

Edited By Nigel Bennett on 18/07/2020 16:59:24

Thread: Statfold railway
16/07/2020 09:47:55

I've been. One of the Club members told me to go, and said that if I wasn't happy, he'd personally refund me the money. I took my good lady and we had an excellent day. I think there were eighteen steam locomotives running, plus the electric tram, and I lost count of the number of other locomotives on view awaiting restoration, sawed in half (sorry, Gertude!) or just sitting looking pretty.

If you have the slightest interest in narrow-gauge steam and Diesel locomotives, Statfold is the place to go for a surfeit of them.

Enjoy it, when you go!

Thread: Tailstock Bore regrinding
16/07/2020 09:39:23

I've had a Boxford 280 for a while now. When I bought it, the tailstock 3MT bore was badly scored a little way down. There was a reasonable amount of surface left, but it annoyed me and I was concerned that it would not provide the grip for larger sized tools. I contacted Boxford a few days ago to see if they had a spare, but they don't any more. (If I'd wanted a new Myford one, it would have been a lot easier!)

One option would have been to fit a shortened 2-3MT sleeve and permanently batter it into the bore with Loctite, but I had a fair amount of 3MT tooling which would have then been useless.

(One interesting point was that when I had the barrel in my hand, part of the outside diameter hadn't cleaned up properly when it had been originally made. I realised then that the finish-ground taper bore must have been created first and then the barrel mounted on a special 3MT male spigot for the OD to be ground true to the bore. I imagine the keyway was then machined.)

I was therefore left with the option of leaving it or doing something. First attempt was to buy a 3MT finishing reamer. (It was a fairly inexpensive one, and probably made in an extremely well-populated country some miles away from here.) I tried it - and failed to remove any material at all as the barrel is hardened and the HSS reamer wouldn't touch it. My mind boggled at the imagined cost of a solid carbide 3MT reamer...

I did wonder about how I could grind the bore myself, but quite frankly I just didn't have the kit to stand a chance of obtaining a satisfactory result.

I searched on the net for local grinders and sent off several email enquiries. I only got two replies - one apologised and said it was beyond them, and the other said to bring it in and they'd probably be able to do it.

I went over on Monday and it was ready for collection the following day. Brilliant job; they showed me the 3MT test gauge they had used to check it and it blued up absolutely fine.

No connection at all with the company - B Kemp Grinders in Liversage, West Yorkshire - other than a satisfied customer.

**LINK**

Hope the information may help somebody out there with a (relatively) rare problem lathe.

Thread: Boxford 280 spindle nose runout
22/06/2020 19:35:50

On my Boxford 280 I have drilled a little dimple by one camlock mounting hole and corresponding dimples on the chucks so that they always go back in the same orientation.

Thread: Mystery boiler
11/06/2020 09:37:10

Like Jon, I thought LNER too. It's similar to a Maisie, but with a different tube arrangement. The firebox is also quite a bit longer than Maisie, but overall boiler length is about the same. Maisie does have a sloping throatplate, It might therefore foul the trailing wheelset of a Maisie chassis. Good luck with whatever you do with it!

Thread: Method of joining for chuck key?
28/05/2020 14:01:24

We used to make carriage door handles at work by casting the brass around a steel spindle with suitable chunks chewed out of it to provide a positive drive and location. The pattern was "handle plus spindle"; the pattern was removed and a steel spindle carefully positioned and aligned in the mould. Very simple bearings on most older carriage door locks; just a 3/4"BSW thread to provide axial and radial bearing surfaces.

To veer off-topic slightly, the handles on the BR Mk.3 doors were interesting; initially they were stainless steel, threaded 3/4"BSW, but they suffered misalignment problems. Later ones were fitted with plain journal bearings attached to the lock. Fitting the lock-plus-handle assembly involved first wangling the handle through the hole in the door, before securing the lock on the inside of the door with screws. Early handles - a lever type - suffered from twisting, due to the massive inertia caused by the handles whipping when the door slammed. (It is a rack-and-pinion arrangement which gives a positive visual clue to the door not being latched shut.) We had to change the material to a heat-treated grade normally used for turbine blades. The balanced dickie-bow type on Mk.2 and earlier stock didn't suffer from the problem, and a lower-spec stainless could be used.

And don't ask me about providing inside handles to slam door locks on Mk.3 stock...

Thread: Issue machining driving wheels
26/05/2020 20:41:42

With the wheel still in the chuck as you machined it, can you get a feeler gauge to slip between the back of the wheel and the face of any of the chuck jaws? It might just be that you haven’t seated it properly or perhaps there is a burr or piece of swarf trapped.

Thread: 2" Clayton Wagon
19/05/2020 17:12:45

Hello Jon

It was I who described the Clayton 6-wheeler and I built it that way so there was more room on the back for me to sit on without making it an artic. If you’re going to run it, then you need the 2:1 reduction gearing to make it usable. If I was building another I would go for the taller boiler. When all’s said and done, it’s a small engine, and it has to be thrashed if you’re driving it on grass. You’re forever firing, injecting and steering as well, so you can’t leave it for ten minutes to have lunch! It would be a lot better in 3” or 4” scale...

I would check availability of rubber tyres for it at an early stage; I heard they were difficult to get hold of.

Good luck with the project; I had a lot of enjoyment building mine.

Thread: Where do you put your chuck key?
08/05/2020 20:30:13

Just leave my shortened one in the chuck all the time, held in place with some duct tape so it doesn't fall out when the lathe's running.

No of course I don't. Two woodscrews into a piece of chipboard on the wall behind the lathe. Allen keys in a block of wood screwed to the chipboard. Two round-head screws carefully spaced allow QC toolholders to drop over them; a small chunk of wood stops them falling down.

Thread: Cutting a slot in a turned piece
27/04/2020 13:43:05

Couple of points; using a small slot drill, you will need to take very small cuts to avoid expensive pinging noises. Don't expect to do it all in one pass. High speed is good.

A slitting saw would be better, but it needs to run slowly; you're not using a circular saw on wood. (I recall one chap asking what he was doing wrong with a slitting saw on steel as all he got was sparks and broken teeth hurtling about...)

Thread: Lawn weed and feed. How much is 35g?
21/04/2020 17:34:25

Whatever you do, don't spread it in such a cavalier fashion that the top comes off the container and you splatter the entire contents over a very small area. If you do this, the grass dies and it takes a lot of effort to regrow it. Don't ask me how I know this....

Thread: Capacities of Eclipse T-handle tap wrenches
18/04/2020 09:46:26

I've got a set of 141, 142 & 143 Eclipse tap wrenches, circa 1975, so genuine, and well before the Chinese fakes. I find that there's a big gap in capacity between the 142 and 143; there's no way some taps (about M6 size IIRC) will go into the 142, but the 143 won't hold them properly. They won't enter the small part of the 143 jaws, and the large part won't close down as the threads disengage. Very irritating, so I have to rely on my apprentice skool made solid wrench for certain tap sizes!

Thread: Concorde model maden flight
13/04/2020 16:33:52

Very impressive indeed. But what about those utter lunatics who were standing at the side of the runway within feet of the thing taking off and landing? It would have done a lot of severe damage indeed to the aircraft if it had crashed into one of those onlookers. At 1/6 full size, that Concorde is about the same size as a typical light aircraft...

Thread: Brass or Bronze for boiler fittings
11/04/2020 14:55:39

I would never use brass in a boiler. I've had brass fittings dezincify and snap off! You say it will only be fired a few times, but what happens after you've gone and somebody else starts to use it?

Cost isn't really that different; it's just a bit more difficult to machine, so I would sternly advise bronze.

As a boiler inspector, I would refuse to certify a boiler with brass bushes in it.

Thread: Steel tyre suppliers
07/04/2020 19:57:57

I got some from Malcolm High at Model Engineers Laser. Obviously the current virus situation will affect any purchasing decision, and I don’t know if he is still able to supply.

Thread: Removing (decorators) paint from Myford Panel
02/04/2020 12:52:31

I too had a car covered in paint spots - they were painting the car park where I'd left it. And where was this?

Paignton.

I scraped them off with a finger nail. Took a long time.

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