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: Myford Lathe Chucks|
CJ - See Arc Euro catalogue. You're looking at a 5" 3-jaw (30mm bore) - but that's a bit big for a Myford as they're very heavy - and the Chinese ones are £65. Not fond of the Chinese chucks, as their jaws are very heavily chamfered so that you can't grip thin things with them. Buying TOS or Bison would be more expensive. The 5" Burnerd one on my Boxford 280 is 35mm bore, by the way.
Hope that helps!
Edited By Nigel Bennett on 22/01/2020 12:35:34
Edited By Nigel Bennett on 22/01/2020 12:35:58
|Thread: Buying metal - caveat emptor.|
I bought some 100mm cast iron from a well-known supplier. It was for some cylinders for my loco. I started machining it, thinking, "This is funny cast iron swarf!" I cut off a small piece of the bar and put it in the vice. I hit it with a hammer. It bent through 90°. In all fairness, they quickly replaced the steel bar supplied with the correct material, but I do wonder sometimes with commercial purchasing, which involves Certificates of Conformity, how often the C of C is incorrect...
|Thread: Windows 7 support ends|
If one migrates to Win 10, does that mean that the older (2006 in my case) Office programs of Word and Excel stop working? And does that mean you have to cough up an annual fee for the new Office versions?
|Thread: Soft soldering on a finished copper boiler ??? ... advice needed :-(|
Loctite 542 hydraulic sealant is also effective. Do not use brass screws to affix your retaining angles - make your own in bronze. Any brass subject to pressure below the boiler water level will de-zincify over time and become a horrid spongy mess. I'm sure I recall LBSC suggesting "a smear of plumber's jointing" (Boss White or similar) to affix screws into boilers, but I think we've moved on since then.
Take care when tapping the threads! Good luck, and hope all goes according to plan.
|Thread: Boxford X10 lathes|
Their website still seems to indicate they're selling spares:
|Thread: Holding screw-end end-mills/slot-drills|
In our machine shop at work they have an ISO 40 female holder screwed to the bench. Tooling is popped in there, tightened up with the appropriate ER spanner (the bloke goes "NNNNINNNG!" like they used to do in the Beano) and the cutters simply do not come out. If you're trying to tighten the collet chuck in the machine, you may not get them tight enuff. I have a similar bench-mounted fixture at home for my ISO 30 tooling - and I've not had a problem with cutters coming out.
|Thread: Fusible plugs for model loco boilers|
Who recommended that? Particularly on a Britannia, accessing it every year or so to change it would be a real pain. It's not usually a mandatory requirement that you fit one; if a bush has been provided, I'd just fit a plain solid bronze bush and forget about it.
|Thread: Tom Rolt cylinders|
Admittedly mine's 3.1/2"G, so I had to do my own thing, but I went for a brass fabrication with cast iron liners. Fabricating from steel with CI liners would be another option. Much cheaper to fabricate!
Provided you ensure it's well lubricated after a run, CI is the way to go - especially as you can then use CI piston rings in both the main cylinders and the piston valves.
|Thread: EN3 bowing after machining|
You can also heat up the bar to a nice red heat, hold it there for a couple of minutes and allow to cool slowly. This redistributes all the locked-in stresses created during the drawing process and distortion should be reduced.
|Thread: piston rings|
I'm not particularly into IC but there aren't many IC engines I've seen that use O rings. This is probably because of the heat involved. IC engine pistons can get quite hot, particularly if close to the piston crown.
I suggest you use cast iron rings. Making your own is quite straightforward. The idea is that you turn the rings to be a good fit in the bore, split them. and then heat-treat them by heating them up with a suitable piece of material in the gap. When the rings cool down, the gap is maintained and they behave in the same way as a bought one. You make sure, of course, that you make a couple of spares! An article by G Trimble in ME in 1984 V153 No. 3735 p 210 Heat Treatment of Piston Rings is a good start.
|Thread: Help with loco build please|
It would be usual to position the outside crankpins at 180 degrees from the adjacent big end. This is for balancing, as the coupling rod assists in balancing out the connecting rod. Not something you can do with an outside-cylinder engine! You may also find that the balance weights on the driving and coupled wheels are very differently positioned to each other. See photos of the full-sized locos.
|Thread: Lathe chuck guards - how many folk use them?|
My Boxford 280 has a chuck guard, which used to be interlocked to the "Run" circuit. It now just remains open, because for most of the time, especially when using a larger and hence longer 6" chuck, the job isn't covered by the guard anyway and the swarf flies off where it wants to. It's only any use when I'm cutting very near to the thinner chucks, and I sometimes drop it down then. So no, I don't use it much, and neither do I stand directly in line with things when swarf is pinging off everywhere! I also make a point of wearing safety specs. (I did have a good hunt round once, but I can't seem to find that spare pair of eyes anywhere...)
Just take care, people. Use common sense...
(editid four spelin)
Edited By Nigel Bennett on 31/10/2019 15:19:23
|Thread: Silicon piston ring|
With an O ring, the important thing to achieve sealing is for the radial gap between the bottom of the piston groove and the cylinder wall to be a little smaller than the O ring section. How much "nip" you decide upon for your O ring is probably best determined by reference to the manufacturer's data sheets. I'd say about 0,13mm or 0,005" would probably be OK.
If you fit a small O ring and stretch it over a groove, then the cross-section of the O ring will reduce slightly; per contra, squashing an oversize O ring into a bore means that the material has to go somewhere, and your "nip" figure may need to be adjusted slightly to cater for either case.
You do need superb surface finish on your bore to accommodate O rings; otherwise you'll end up wearing them out very quickly!
Personally I'd use metallic piston rings - preferably cast iron - but that depends on your cylinder material.
(And yes, Alain's right - Silicone with an E. And Viton not Vitron...)
Edited By Nigel Bennett on 26/10/2019 15:22:31
Edited By Nigel Bennett on 26/10/2019 15:22:45
|Thread: Boiler build abandoned !|
Sorry to hear of your woes!
If you can find a fellow club member who is well versed in boiler-building, and who has access to oxy-acetylene or oxy-propane, the boiler may be rescuable. See what your boiler inspector says!
One thought; you've not been dumping the boiler when it's still very hot into the pickle, are you? That can easily cause massive thermal stresses which result in leaks.
Also, if the boiler is generally sound but just has the odd weep, then don't discount Comsol to caulk it up - but you won't be able to do any silver-soldering on it afterwards!
|Thread: To Pin or Not To Pin|
I had the wheels come off (well not absolutely off, you understand) my 5"G Edward Thomas a few years ago. The Loctite gave way as a result of some over-large stresses caused (I think) by a hydraulic lock and as a result, the motion ended up in an interesting arrangement of angles and unsurprisingly it Wouldn't Go. I removed the coupling rods and ran it as a 2-2-2 for a few laps, rather than waste the nice bright fire, but it sounded a bit off-beat.
Later investigation showed the quartering on the driving wheels was about 120 deg not 90. I fitted some axial pins once I'd got it all back together.
The load on the Loctite had obviously gone far beyond expectations - but I've never relied solely on Loctite after that for sticking wheels on to axles. Crankshafts would, I imagine, be prone to similar unexpected stresses when in use.
I suppose it's down to where you want the weak point to be - did the Loctite failure on my ET wheels save me knocking a cylinder cover off or bending a rod or two?
|Thread: Just bought an ML7, what should i do first?|
Whereabouts in the world are you, Shaun? If you're anywhere near me in Leeds I could pop over and have a look at it and perhaps offer some advice. For instance, engaging backgear on an ML7 is not obvious and requires a specially-shortened Allen key to slacken and move a little gear segment fitted to the bullwheel. Good luck with the restoration, anyway!
|Thread: Steel axleboxes|
No problem at all with steel axleboxes with either gunmetal or cast iron horns, but they need to have a proper bearing for the axles. This could be with needle roller bearings or pressed-in bronze bushes.
You could even use steel horns with steel axleboxes, as the movement is slight, but you need to pay more attention to the lubrication.
Steel-on-steel does not work well as a rotating bearing as it's prone to "pick up" and seize.
|Thread: Long tender means the controls need extending|
I could lend you a hacksaw to shorten your tender...
I've seen quite a few contrivances to operate loco valves from the rear of the tender. It usually involves a number of controls attached to a cross-plate secured to the tender. The controls are usually rotary (for steam valves) and generally involve a long operating rod provided with a couple of universal joints. The "loco end" of the long operating rods also need some kind of bearing/support.
There needs to be some provision for changing the effective length of the rods as the tender and loco negotiate curves. This could be a pin through one part of the rod and a slotted tubular section on the other. Water valves can be sited at the rear of the tender so that their operating valves can be sited where it suits you.
It depends on how you feel about your loco; if you want it to look realistic when you aren't using it, then it would be an idea to have all the jiggery-pokery removable - but that will add to the complexity of the design.
It does need very careful thought to make the regulator control safe; you don't want to be faced with the loco running away and you being unable to shut the regulator. Hence give a bit of thought to fail-safe design of the linkages so that if the loco-tender coupling parts, then the loco will coast to a halt.
You've got a big task to operate a pole reverser remotely, but a screw reverser might be susceptible of remote control.
My advice is to stay away from electronic/radio operating devices and use something mechanical.
|Thread: Jim Al Kahlili : Revolutions|
I think you're just trotting out the tired old cliche of "parasitic cyclists" again. Why do you say cyclists are "parasitic"? Is it because they don't have to pay vehicle excise duty? Well work it out for yourself. VED is based on the amount of pollution caused by the vehicle. Electric cars pay no duty - but the carbon effect of generating the power in the first place is hardly negligible, and the road damage caused by them is no less than an IC vehicle. So as cyclists cause less pollution than electric cars, then surely then they should be paid to use the roads?
So let us assume that cyclists have to pay a proportion of that paid by petrol or diesel cars - £145 currently for a typical car. The only fair way to do that is to base it on vehicle weight as the effect of damage by the vehicle to the roads. Bikes weigh say 10kg. Cars typically weigh 1500kg. So that's 96p a year. Then you have to consider that the cyclist is barred from all motorways, so to be fair, that would further reduce it to about 60p.
Are you going to be able to instigate a viable tax system whereby you can ask cyclists for 60p a year? No, I didn't think you could.
Cyclists, pedestrians and horses have a RIGHT to be on a public highway. Cars do not - they only have permission.
I forget the exact figure, but I think it was in the 90% or so of adult cyclists who also tax and own motor vehicles.
Personally, I use my bike to keep myself fit and reduce my need for the overstressed NHS. I commuted to work when I was working because I hated being in long queues of cars when I did have to use it. And it was often quicker, and taking the canal towpath occasionally kept me off the roads altogether, thus freeing it up for nincompoops in cars.
I often find that people who moan about cyclists do because they're just too fat and idle to ride a bicycle.
Parasitic? Don't talk rubbish.
|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.
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