Member postings for Howard Sutcliffe

Hello Michael / Neil

I must admit that I'd never before heard of the term "barring engine", but it sounds a good idea because I could then avoid trapping my fingers between the flywheel and its pedestal which I do often when spinning it by hand!

Thanks

Howard

Thank you for the comments regarding oiling. I run my engines for only brief periods on air and usually introduce a little oil into the air inlet beforehand (as mentioned by Joey) in the belief / hope that the airflow will carry sufficient of it to the cylinder. In between times I frequently turnover the engines by hand. This seems to be satisfactory since they each spin smoothly at present.

Howard

Many thanks to all of you who have helped with suggestions / advice / info.

I've now got some idea of the psi / cfm ranges to bear in mind in my compressor search.

Thanks again.

Howard

Gary, Geoff, Thanks for the replies.

I did try an old aquarium air pump. It was most impressive doing its original job, but - as Geoff found - it wouldn't even start either Stuart engine!

Clive, Thanks. That's another name to look out for on eBay. Fingers crossed one turns up for collection that's local.

Michael, Thanks. To be honest, I've never heard of a Mamod oscillator - I'll read up about them.

Howard

Ian - thanks for the info about water / rust in the bore, even on air - I must say, I hadn't thought of that .

I guess a compressor that can maintain up to about 30 psi should be quite adequate for the purpose.

Howard

Gary, Jason, Stewart - thanks for the replies. It's probably more convenient for me if a compressor is not too far from the engine, so I think that means I'll have to look for one of the "silent" type. I'll keep checking on eBay.

Thanks again,

Howard

Thanks for the reply. To be honest, I'm not sure of the range of psi required to run these small engines. I guess that there's a minimum psi needed to simply make the piston move - to overcome the inertia of the components plus all friction - and then the cfm dictates the engine's subsequent rpm depending on the volume displaced by the piston - or is this too simplistic?

Thanks for the info Jason. I've had a look on eBay and in Machine Mart. I didn't realise these small compressors were so expensive! I'll keep looking for one of the ones you mention. Thanks again.

I've never run my Stuart stationary engines (James Coombes and Victoria) on steam because I'm concerned they'll rust internally with infrequent use. Instead I've used occasionally a small, old, noisy compressor which isn't really up to the job. I'd be grateful for any suggestions regarding compressors from other folk who have used compressed air rather than steam for their engines. Is an air-brush compressor a possibility?

Many thanks to all for the advice and tips in response to my original post.

Dusty – to answer your question - after my initial problems I obtained some more pieces of the original tubing.  After viewing your photo, I realised that I forgot to mention that the finished tube (2¼ inches long, 3/16 OD, 1/8 bore) is threaded 40 TPI for 1¼ inches at one end and 3/16 inch at the other, leaving only 13/16 inch unthreaded.  After I’d die-threaded each end of the original plain tube, it seemed to me that I wouldn’t be able to grip it for boring out in the lathe chuck without the certainty of damaging the threads.  I decided to hold the threaded brass tube in some thin walled, 3/16 inch bore aluminium tube, slit lengthwise.  This did protect the threaded portions, but the final bore had the problems I described initially.

Before trying once more, I’ve bought some new drills including 1/16 and 3/32 stub and 1/8 inch slow spiral (apparently recommended for brass), although I’m not sure of the rpm to use with this one.  

I think I’m going to try reversing the tube in the chuck (as suggested by Ian S C and Andrew Johnston) and bore it out at higher speed, so I thought I’d best re-check my 30 year old Super 7’s alignments, as brought to mind by Dinosaur Engineer’s comments.  Using my 2MT test bar I got the following results on the bar’s 4½ inch long parallel with my tdi on the cross slide:-

In headstock taper – tdi on front side of bar facing me, zero out end to end - I appreciate this only means undetectable with my tdi.  Rotating spindle by hand - about 1/5 thou out at the right end, zero out at left end.  With tdi on top of bar, ½ thou out end to end – I’d not thought of checking this previously.

In tailstock taper – zero out end to end.

Test bar held between centres in headstock and tailstock – zero out on front or top of parallel.

Headstock spindle register face – zero out.

Test bar gripped by part of its parallel in lathe chuck – about 2 thou out end to end; rotated by hand – 3 thou out near chuck, 5 thou out right end.

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