A Marine Condensing Engine

Thanks Tug, what you say about the slip joint clearance & JBW was what I had imagined but it was nice to have the confirmation having not done it yet.

Re the bores I was thinking maybe if acute attention was paid to the turning then honing may not be necessary, I hope so!

Cheers, Chris

Hi Chris,

Both cylinders were done with a boring bar hand ground from a piece of 10mm HSS. Nothing special just a normal cutting edge but with a decent radius. As said the finish was better than anticipated, no doubt down to the meehanite material.

I took several spring cuts with the tool cutting on the back stoke - this helps eliminate any tendency to produce a taper. Given the pistons will be fitted with an annular gap and PTFE impregnated yarn seals any slight variation there may be (not detectable using telegauges) will be accomodated by the seal hopefully for a very free and frictionless fit.

Regards - Tug

Hi guys - just to say it's finally in one piece

It always looks a bit messy at this initial bonding stage but it will soon clean up with a bit of fettling. Further additional parts - gussets, flange bosses etc will get done later as well as improving the fillets. Just four 8BA c'sunk screws on top and four on bottom to keep it all in alignment whist curing. Very 'solid' end result.

Hope that result will be of interest

Regards - Tug

Much appreciated by me! Although I'm unlikely to make a model like this, the way you went about it is most valuable: I've been thoroughly cross-fertilized, and it's always good to learn new tricks!

Thanks for sharing.

Dave

It is very impressive, the detail that can be created from bar stock & JB Weld! I must try harder...

Well I'm not quite sure my intention has ever been to cross fertilise somone Dave but I think I know what you mean.

Dr Dave - this is one of those processes that you can take as far as your imagination and patience will allow but it is a matter of breaking the item down into component parts and using the JBW as a structural part as well as it's adhesive properties where possible to get the best effects. For instance, where I have a fillet I create a decent chamfer between parts underneath to give more contact area for the JB.

The cylinder head has now been fettled and is ready for the HP inlet cover to be attached before the final machining ops can be made.

Thanks for the comments guys

Tug

Edited By Ramon Wilson on 03/03/2021 23:02:07

Just thinking some more about drain cocks, in a lot of full size practice things like this discharge into a copper funnel, which then has a pipe to who knows where. The point seems to be that you can see the discharge so that you know it is working. This is of course especially important with things like gauge glass test cocks, where you want to know if it is discharging steam or water. With the drain cocks, when you are warming the engine it is good to be able to see when it is hot enough inside that it is discharging steam rather than a mixture of steam and water.

regards

John

Hello John, Thanks for the further input.

I can see the logic of what you are saying though when I was doing the Corliss engine and studied lots (and lots!) of images I could find no evidence of that on stationary engines. Virtually all that I can recall just disappeared into the foundations and I presume either eventually to atmosphere or into the exhaust system post condenser.

The Lydia Eva engine previously mentioned is a triple expansion engine built originally by Crabtree & Co of Great Yarmouth. I have no way of knowing if the piping as previously described was original or done when the vessel was restored but would hazard a guess that if it were not then all six pipes would have been sent to the 'sump' (as it was referred to).

Though I have more or less decided to follow that set up I will look into it a bit further. I have just received a DVD with literally countless old maritime books to peruse plus a very lucky find of Volume 2 of the Verbal Notes for marine engineers - must surely be something in there.

Hope to have some pics of latest progress at the weekend

Regards - Tug

Hi Guys, a little later than hoped for but the major 'casting' parts of this project have now been accomplished. It's taken two days to rid the workshop of the patina of black dust that had got everywhere and hopefully the hands will begin to freshen up too!

Last op was to mill the valve face flat - 6mm cutter with 5mm overlaps to give a flat if not visually attractive surface.

All the parts for the final make up. The two cylinder heads are not quite finished as yet with webs to put in ......

........ and the cylinder head assembled. Holes in those side flanges will be dealt with later as will the outer diameter of the piston valve chamber.

That's it for this stage - I'm going to take a break from it now as the garden will take precedence over coming weeks and there are other matters that require attention too.

Back sometime then but definitely not next week!

Thanks for looking in - hope you've found the method of interest and enjoyed the pics - there are more in the album of course

Regards - Tug

Edited By Ramon Wilson on 12/03/2021 22:56:13

That’s looking brilliant. Will you be spot-facing the mount bracket holes?

Hi Doc, yes, this is just the initial stage in establishing the casting shape(s). There's quite a few holes that need spotfacing including some reverse ones on the base. First up will be getting a coat of primer on to see if any of the fillets need improving/fettling.

There's a web that needs adding to the base - missed that first time! - and various bosses to be added.

But, as said that will be a while before I get back on it. Very pleased with the outcome so far and looking forwards to dealing with the remaining work

Thanks for looking in

Ramon (Tug)

That is impressive: thank you for showing us how you assembled the raw parts to make the "castings". I have learned a lot of the Black Art of cast iron & JB Weld!

Dave

Ha from the residue left 'Black Art' is indeed an apt description Dave

Glad you have got something from it, I'm sure it won't be everyone's cup of tea but it is, to my mind, a viable way of ending up with a 'casting' that not only looks a reasonable rendition but is functional as well.

I'm surprised no one has questioned its potential to withstand the forces involved. For myself I'm more than content that it will but like most posting on building anything many look in but so few comment.

Anyway thanks for your comments - it will be a while before 'phase two' begins but I will continue to post once back on it again

Regards - Tug

Maybe like me they have seen your previous proof of JBWelds holding power and enjoying just quietly following along. Maybe if you showed your soft jaws that may draw a few comments

Nice work Tug - most impressive construction for the cylinders. Not only have you made the lot look like a real casting, but I am sure the JB Weld used will hold well and is a good construction material. I know you want to run the engine only on air, so heat doesn't come into it, but even on steam I fell sure JB Weld would be good.

I would hazard a guess that most model engineers, running this engine on steam, would only use steam at about 150psi max; (though probably a bit less, 100-125 psi maybe, maybe as low as 80psi) at 150psi the saturated steam temp is only around 350ish deg.F, (358 to be pedantic at 150psi!). Given that the Original JB Weld is able to withstand 550 deg.F and even at 200 psi the saturated steam temp is only about 380deg.F, so there is a fair degree of leeway in there temp-wise, even allowing for a fair degree of superheat, so yes, technique used is good to go!

Know what you mean about garden work, on the case myself, but looking forward to your next instalment whenever that is.

Chris

Edited By ChrisH on 15/03/2021 14:01:00

Jason - Strange you should mention the soft jaws as after extensive use since modifying them, one jaw has finally 'given' very slightly. The amount of work done however certainly made it worthwhile exercise and I shall remill and fit new pieces in the same way for more extended useage. I think I will put a small pin in this time to resist the radial pressure on the JB Weld which appears to be the reason for the slight movement.

Chris - as said I do only intend to run this on air but I agree with all that you say with regard to using steam. My thoughts that it would withstand any forces under steam are based on the same conclusions as yourself. The likelyhood of running this on anything greater than 80-100psi is minimal at best so the JB will stand up to that with a good safety margin if done properly.

Some time back I did a test piece with three flanges identical to the parts intended for the job itself. Just JB'd into respective bores - no other means of retention - and left for a few days to fully cure. I pressure tested it to 300psi for a good 20-30 mins without any loss of pressure then repeated it at the same pressure but this time with the part under constantly boiling water for the same period.

That may possibly be of interest to a wider audience so I'll make a new post on it.

Tug

Edited By Ramon Wilson on 16/03/2021 10:54:52

Tug - you mentioned two phases in your last post that I missed when I commented on using JB Weld - "if done properly" and "fully cure". They are the important bits!

Chris

Hi Guys, after far too long an 'aeromodelling distraction', pleasurable as that has been, I finally have set some time aside to progress this engine a bit more.

Began by setting up a base and making a couple of bearers from mild steel (just behind the mic on the shelf behind) but these didn't look right for some reason so decided to use hardwood instead.

With the front columns made it was possible to see if it all lined up - pleased to say it did as there is a lot of holes that have to be in the right place.

Here are a couple of pics of work so far this week - intention is to stick with this until the end of Feb at least, next up is the crank and main bearings

I found that piece of 12mm dia. precision ground mild steel for the shaft - just too short to make the three main pieces - looks like the centre portion will have to be turned from 1/2"

Back when that's done I guess

Regards - Tug

Edited By Ramon Wilson on 16/12/2021 23:02:58

Good to see you back progressing this one.

Thanks Jason, always good to hear from you and besides, it's nice to think there's at least one of you

Starting on that crankshaft this afternoon - decided not to use the PGMS and machine to size instead

Back later - Tug