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: What lathes have you had?|
Got a bank loan at 18 to buy a Zyto lathe for £45. I recall making some cardboard dials for the cross slide.
Sold it and got an ML7. Sold that for £750 to buy a Super 7 for the same price! Still have it; I went to Nottingham to buy a gearbox and QC tooling several years ago.
Unimat 3, which seldom gets used other than mounting the head on a post on the Myford cross slide.
Boxford 280, which is a lovely machine, very under-rated. Designed by the same chap who designed the Harrison M300, I understand. Plan was to sell the S7 to pay for it, but a windfall meant that I could keep them both; it’s just a bit of a squeeze in the shed now. Great to have an Imperial and a metric lathe.
|Thread: Dangerous 2" Scale BB1 Boiler|
Some years ago I bought a part-built 2" scale Fowler BB1 ploughing engine to John Haining's design from the estate of a deceased model engineer. He'd bought it from somebody else. The workmanship wasn't brilliant, but the boiler had been commercially built in about 1975 and came with a certificate, saying it had withstood 175psi without leakage or distortion. The boiler itself looked lovely, so I was quite happy with the purchase. It was always going to be a long-term project, so I was in no hurry to get on with it. (Ignore the bloody great hole in it in the picture below!)
There were a lot of further leaks from stays (screwed and silver-soldered) so I applied more Comsol. A couple of days ago I pumped it up again, and it withstood 150psi with only some very slight weeps from the odd stay. One or two responded to a bit of gentle caulking with a hammer and punch. Then a small leak manifested itself in what was apparently a plain section of boiler barrel, just in front of the firebox. Curious... I lightly tapped the area with a hammer and the leak became a torrent. I filed the area and a brass colour became exposed. The barrel had been brazed to the firebox, and then smoothed over before copper-plating the boiler to disguise it.
That piston ring was only serving as a location for brazing the two halves together!
These are the two sections of barrel/firebox wrapper removed by hole-sawing - and the braze had given way during the operation.
The whole thing had been a potential bomb. The scary thing is that if the joint had been only a few percent better than it had been, it wouldn't have leaked and I would have been blissfully ignorant of the potential. And it's a ploughing engine - it's not just pressure stresses on the boiler, but driving it over rough ground imparts who knows what additional loads on the joint?
There were other concerns as well, such as very thin fire tubes - they'd have worn through very quickly - and the internal pad under the cylinders was not in the right place (or too small) so the front ring of cylinder bolts were only tapped into 2mm of copper.
I'm not prepared to disclose the name of the maker. Technically I can't prove anything because there is no marking on the boiler or certificate. Suffice it to say that he was later bankrupted. And I hope he had a really miserable time of it.
At least there's no chance of it being used - it's well cut now and I shall weigh it in for scrap.
Moral: Take care when dealing with older boilers built by unknown "professionals", and look at them very carefully before parting with your money. If a boiler has been copper-plated, walk away from it. It's hiding something. And always, always test a boiler you wish to use.
|Thread: Forging brass; how easy would it be?|
If it's brass bar, then it's probably CZ121, in which case you've little chance of forming it as you want to do. It just doesn't anneal like brass sheet and stays hard after you've heated it. You can usually anneal the generally-supplied grades of sheet. Mostly due to the zinc content!
Just try it out on a small piece of brass rod first - so you don't waste both gas and brass - and after bopping it cold, try battering it hot, to see what Guy Lamb means about it being "hot short". Phosphor bronze rod can behave similarly.
|Thread: Bespoke bicycle making|
I built a bike frame in Reynolds 531 back in 1978 - and I won a road race on it! I used a 5-pint paraffin blowlamp to silver-solder the frame - before I acquired a Sievert outfit. The frame is a rather sad-looking rusty affair hanging up in the garage now, because it needs a new down tube and a new bottom bracket shell and it isn't worth the effort - but I can't bring myself to throw it away!
|Thread: Is it bad practice to lock my Myford lathe using the slow speed lever|
On my S7 I have marked one of the two possible engagements of the little flick lever which gives the solid drive rather than back gear, so I always ensure it is only engaged in this one position. Hence when the spindle lock is engaged, my headstock spindle is always in a certain orientation. Having engaged the spindle lock, and properly fitted a chuck, I have then drilled a little dimple in each and every headstock spindle-mounted chuck such that the dimple points upwards. These dimples are painted black. Hence I can easily spin the chuck to rotate the headstock spindle more or less the correct orientation to engage the spindle lock.
Having engaged the spindle lock, each chuck was unscrewed very carefully until it just disengaged with the thread. Another dimple was drilled in each chuck at the vertical position at the point of disengagement and the dimple filled with red paint. Hence I know when the chuck is about to unscrew - or it has one more full turn to make - so I can take hold of it before it unexpectedly releases and smashes down on to the lathe bed. Also I can orient the chuck correctly to start it on the spindle threads (with the spindle lock engaged) so that again, it engages immediately and doesn't fall off when I release my grip on it.
I did the same thing with my ML7 years ago but I dimpled the spindle so I could orientate that correctly for chuck-changing as above.
I did this because I did something similar with M42 screw-mount lenses many years ago when I dropped a 400mm lens on to some concrete due to it not being in the correct orientation to start engaging the threads.
The spindle lock is provided for a purpose - use it and don't end up with a dentally-challenged lathe and a stupid expression on your face.
|Thread: Historic Frogs|
Boggy the Frog in Into the Happy Glade and By A Silver Stream. Written by Trevor Dudley-Smith, aka Elleston Trevor, who is more well-known for his "The Flight of the Phoenix".
Bit obscure, but true!
|Thread: Making High Speed Steel Injector D Bits|
Hardening D-bit reamers usually resulted in banana-shaped curiosities for me. So having been inspired by an article about injectors by Basil Palmer, I ground some HSS injector reamers using his idea of triangular section. (Would be likely to give more even results in silver steel as the section is more uniform and symmetrical, so less prone to distort.)
I mounted a Quorn head on my Boxford 280 to grind some HSS and it worked out quite well. Note that if you want a 9 degree included angle, you DON'T grind the faces with the top slide at 4.5 degrees but at about 2.2 degrees - it depends on the diameter of the grinding wheel.
I made the mistake of grinding some Chinese-sourced HSS 6mm dia, only to find out when I tried to use one for reaming an injector cone that the stuff wasn't hardened. After trying it, the pointy end of the reamer came out looking like an oliver off a Showman's engine! I then dug out an old HSS tap and ground that instead. I did get a working injector, but it needs more time and attention than I have at present to get the working pressure range I want.
Despite covering up all of the lathe I could with newspaper, it still took ages to clear up all the horrid mess after grinding - so take care!
|Thread: Noise Cameras|
When I was a child of about two, my uncle showed me how you turned the ignition off and back on again to create a very satisfying bang. It was perhaps predictable that I thought I would see if I could make it go bang, too. It was perhaps unfortunate that Uncle was doing about 70mph when I tried it. It went bang, all right - blew the bloody exhaust system to bits! And it was his own damned silly fault for teaching me how it was done...
|Thread: Internal grooving help required.|
For reasons that escape me now, I once did a small job where I bored the groove OD into the bore with a slot drill, and then pressed in a little turned slug to create the groove. It depends on how much load you will have on a pressed in slug if you go that way.
|Thread: Boiler issues juliet|
Silver-soldering studs into a boiler with any sort of soft solder in it is a Very Bad Plan. Don't do it!
Fitting studs into your boiler should be possible if there's a reasonable thickness of material and the studs aren't too big in diameter. You need good threads in both boiler and stud, and some Loctite 542 will provide an excellent seal.
Once you've fixed it, do a hydraulic test on the boiler to one-and-a-half times working pressure by pumping it up with the hand pump to check all is well before lighting the fire.
I'm sorry to hear about your health issues - I hope you can sort the Juliet out and get it running again.
|Thread: Minnie 1"|
Check the bar litres of the boiler. A Minnie is very small and likely to fall within the “smaller boilers” category specified in section 11.7 of the regs, where only one water feed is required.
|Thread: Cast Iron For Boxford Change Gears?|
If you've set yourself the task of doing it, fair enough, but this chap advertises plastic ones on eBay and I had a couple off him for my Boxford 280. Usual disclaimer; I've been very happy with them.
I can't find exactly what you're looking for, but here's a sample:
Suggest you contact him and ask for a price for what you need.
|Thread: Servicing a Myford 254|
I've no knowledge of the Myford 254, but in the Boxford 280 manual I have it suggests very strongly that you don't faff about with the bearings, but leave it to their service department.
However, they say - if you must...
"Pre-load condition may be checked using the cord & spring balance method, when a steady pull in the region of 0,68kg (1.5lb) for new bearings or 0,34kg (0.75lb) for used bearings should be obtained, with the cord wrapped round the spindle nose and all gearing disconnected from the drive."
I imagine the two arrangements are very similar - adjustment by fine-pitched collars to set the preload.
I changed my spindle bearings on my Boxford, and it's not a task to be undertaken lightly.
|Thread: 2" Clayton Wagon help|
Quite a few folk (including me) have omitted the feed-water heater as it causes more problems than it solves. My steering wheel is fine relative to the regulator. Are your boiler feet set too low? Or is the steering column a tad short?
|Thread: Bought a Boxford...|
Thanks for the introduction, and welcome to the fold! I built a 531 bike frame back in 1978. I won a road race on it the following year, and the rather sad-looking frame is still hanging up in my garage, rusty, cracked and with a stuffed bottom bracket shell. Can't bear to throw it away...
Good luck with your steam project. Tubal Cain, aka Tom Walshaw, published a couple of books on "simple steam engines" and they're well worth acquiring for the gems they contain as to how to go about it. I built his steam crane "Hercules" for my nephew and it was a very interesting project.
|Thread: Removing a grub screw|
One method I've sometimes used with success is to batter in a Torx bit - it needs to be a tiny bit bigger than the hex socket, but not so much it swells the screw and binds it more tightly. The action of battering it in helps to loosen the grub screw, and then hopefully there's enough grip to unscrew it.
|Thread: Jacob chuck jaws|
I don't think they're unusual, George - they look like perfectly standard sets of replacement jaws for No.34 chucks. I can't see a size on the packaging, but I'd guess 0 - 1/2" size. The rusty ones might clean up.
Edited By Nigel Bennett on 30/03/2019 11:34:59
|Thread: Hydraulic test set up|
Make sure, if you've got a valve in between the pump and the boiler, that you don't kid yourself into thinking that the boiler is leak-free, when all you're actually doing is to pressurise the pipe between the pump and the (closed) valve...
|Thread: Can opener - the holy grail in engineering?|
Karen came back from a "Pampered Chef" party (Sort of Tupperware but rather better) with a can opener. It's excellent as it cuts the side of the can and forms it over so that there are no sharp edges. Absolute gem of a design.
|Thread: Bending cast gunmetal|
Heating up gunmetal to bend it is probably the problem. I recall trying to" bump up" a piece of drawn bronze bar, and heated it up first as if I were a blacksmith battering a piece of steel. The hot bronze fell to pieces when I hit it. Reading up about it after the event, it appears that bronze is (or my bit was) "Hot Short" which means it doesn't like being bopped when hot. It's likely that cast gunmetal will behave similarly.
If I was trying to unbend a GM casting, I'd try to bend it cold. If it broke, I'd silver-solder it back together in the correct position. Whether it's worth heating it up a bit after you've successfully bent it to stress-relieve it, I don't know as I'm not a metallurgist. A quick Google search on" stress-relief of cast gunmetal" suggests 300C for a while.
Hope that helps
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