Part built Allchin 1.5 inch

[Paul KempParticipant @paulkemp46892]

Derek,

Ooops! Sadly a hazard of the hobby. I don't think I would bother with another casting but get a lump of cored bronze of the right proportions and chew it out of that. You can get cored bronze in various O/D – I/D combinations and it will almost certainly be cheaper than a casting from a model supplier. I have bought from metals4u in the past, they sell by the inch. Doubtless there are other sources. I think I would bore the block first and then turn the liner to suit, needs to be a good fit so steam can't leak from the anulus, you probably need around a thou to thou and a half interference fit on that size.

Paul.

[derek blakeParticipant @derekblake72550]

I think Jason said Sa660 is a good bronze to machine, so I will look to get a piece ordered.

Thank you

[JasonBModerator @jasonb]

Agree with Paul it will be better to use hollow bronze, M-machine are another source and Macc who advertise down the right of the screen

[derek blakeParticipant @derekblake72550]

Thanks Jason, will the SA660 be ok as I’ve found sound.

Regards

Derek

[JasonBModerator @jasonb]

Yes that's fine for cylinders and liners as well as your other small items, the LG2 from M-machine is OK for the liner

Edited By JasonB on 08/01/2019 08:22:03

[Keith LongParticipant @keithlong89920]

Just a thought after reading this thread that might help Derek.

As you've now got to machine a liner from scratch, would it be feasible to machine the cylinder casting right through at the bore of the designed annular space, and then machine the liner with ends that fit the larger bore but with the centre part waisted down a bit to make the annular steam space. Having a uniform bore through the cylinder casting would be easier than trying to machine the recess and machining the liner od down locally is just straightforward turning.

[derek blakeParticipant @derekblake72550]

Hi keith

I think I'm with you, basically put the annulus onto the liner.

the width for the liner should be 1 1/4 inch so increase this by 1/16. then turn a annulus in the liner 3.1750 approx. deep all the round obviously.

Regards,

Derek

[derek blakeParticipant @derekblake72550]

it does sound a much simpler way of doing things.

[JasonBModerator @jasonb]

But it does mean the cover stud holes are being drilled right on teh joint line rather than going into solid metal.

Annulus is 1/16" each side so would need to be increased to 1 3/8" which is the same as the PCD of the studs

[derek blakeParticipant @derekblake72550]

do you think this would weaken anything? id imagine as the liner is a tight fit in cylinder the fixture would be pretty tight.

[derek blakeParticipant @derekblake72550]

Hi Jason

So are you saying liner would need to be 1 3/8 wide instead of 1 1/4 but with the 3.2mm deep annulus.

I would them bore the cylinder to 1 3/8 to match liner ends.

[derek blakeParticipant @derekblake72550]

3.2mm deep annulus on the liner obviously, with a straight 1 3/8 bore on cylinder block.

[JasonBModerator @jasonb]

Ends of liner would be 1 3/8" diameter, middle of liner 1 1/4" diameter so it is no thinner than original Cylinder bored 1 3/8". It is just the stud postions on the joint that are not ideal

[derek blakeParticipant @derekblake72550]

Hi Jason

Well to be honest you are the experts, if you think it’s risky then I will stick to drawing.

I think the idea actually makes sense and is a much easier way of building that part of the cylinder, the screws would I guess be half in the liner and half in the casting.

I will go which ever way works without causing an issue to reliability,safety etc

Many thanks

Derek

[derek blakeParticipant @derekblake72550]

Hi Jason

Would it be safe to use Loctite 638 on the liner to assist the screw fixings?

its temperature range is way above what the cylinder would ever get to i think.

The liner material will be here soon, so id like to be sure i know which option to machine.

Many thanks.

[JasonBModerator @jasonb]

I tend to use 648 for liners, bit higher temp to be on the safe side.

[derek blakeParticipant @derekblake72550]

Many thanks Jason

[derek blakeParticipant @derekblake72550]

Sorry to keep on guys I just want to be 100% sure before ruining bronze and casting.

The new idea and larger liner I will increase from 1 1/4 to 1 3/8 and into the liner I add the annulus at a 1/16 depth all the way round? For some reason I was thinking I’d have to double the 1/16 but that’s not the case looking at the drawing.

I just need to leave both ends of the liner 1 3/8.

I think I’m right with all that.

I will let you all know how I get on, many thanks

[derek blakeParticipant @derekblake72550]

material arrived so tonight is the night, I've drawn up what needs doing so hopefully all goes well.

i will post a picture of the finished liner hopefully.

Thank you for everyones help and the idea to machine this way.

[derek blakeParticipant @derekblake72550]

Evening all.

Liner finished, hopefully new improved version.

[Jeff DaymanParticipant @jeffdayman43397]

That's looking great Derek! well done.

[derek blakeParticipant @derekblake72550]

Many thanks Jeff, and thank you to Keith long for the initial idea and Jason for answering my questions.

[Paul KempParticipant @paulkemp46892]

Derek,

Well done. Excellent progress. In less than 2 weeks you have gone from looking for someone to machine the cylinder for you to being almost halfway there. That includes overcoming the issue with the dodgy casting for the liner and sourcing a replacement and a bit of out of the box thinking as to how you can overcome the limitations of your machine capacity. I bet that's a lot more satisfying than paying someone else to do it and the bank manager will be happy too!

The really great thing about this forum is seeing people achieve things with a little advice they didn't think they could do. Well done indeed.

Paul.

[derek blakeParticipant @derekblake72550]

Many thanks Paul, you are right I feel much more confident but that's thanks to people like you on the forum who support me and help without making me feel stupid.

So many thanks again.

Derek

[derek blakeParticipant @derekblake72550]

Hi All

Not a very interesting picture today I’m afraid, but cleaned up the boiler kit buy ready for packing away if worse comes to worse and my original boiler is scrap

That’s one part of the engine that needs a specialist let alone good equipment so this will be something I will need to definitely send away.

Next job will be to work on piston, and water pump as until I get my boiler and Hornplates back I’m on a stop really.

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