Part built Allchin 1.5 inch

[Jeff DaymanParticipant @jeffdayman43397]

Derek you have a PM just FYI.

[derek blakeParticipant @derekblake72550]

Hi Jason

so what an evening, I’ve taken 1.5mm from piston rod and taken 0.3mm from each side of the piston.

the best I can do so far to your measurements are 1.3 one end and 2.3 the other, I’m pulling my hair out trying to understand but I knew I’d struggle.

do you think if I shorten the piston even more I will gain the extra gaps either end that I require?

Sorry for the questions,

regards

Derek

[derek blakeParticipant @derekblake72550]

Am I right in thinking if I take 1mm from the piston rod, this will give me 0.4 one end and 0.6 the other either end of the bore.

this would then give me the 2.7mm and 2mm you mention as being a good amount.

[Jeff DaymanParticipant @jeffdayman43397]

Derek you have another PM.

[JasonBModerator @jasonb]

I should think the 1.3 and 2.3 would be acceptable so leave it at that.

[derek blakeParticipant @derekblake72550]

Hi Jason

ok I shall take you advice and call this where my cylinder will be fixed, if for instance we find things need to change is there any tweaks that can be done even after cylinder is in its permanent position?

thank you very much for the help.

[JasonBModerator @jasonb]

Same as you have already done eg thinning the piston, altering rod length and you could add reducing teh front cover's spigot to the list.

Bear in mind that anything that has to connect to the cylinder/motion such as regulator rod and reversing rod will need to be a little longer so best to take the final lengths of these items from the engine.

[derek blakeParticipant @derekblake72550]

Right ok well that's good new, just one last question.

Piston on drawing says 10.3mm wide I have mine 10.1 how thin could I go without messing up things up and making the engine wrong?

Again thank you for your time.

[JasonBModerator @jasonb]

9mm would probably be OK, still enough meat either side of the rings

[derek blakeParticipant @derekblake72550]

Yes this would leave me 2.5mm each side of the centre which is approx. 4mm for the 0 ring.

Thanks again.

[derek blakeParticipant @derekblake72550]

Afternoon all, what a lovely day out.

so I tackled the job I’ve been dreading for months, drill the cylinder fixing hole.

now as you are aware I have no pillar drill or mill so I’ve had to do these by hand and a jig I made to hold the drill at the correct angle.

and other that the boiler blanking hole I’m all done, drilled and tapped.

however I’ve come across one issue which I hope isn’t a game changer, the previous boiler maker I think placed the strengthening plate slightly further round the barrel than he should.

im pretty sure it’s not my cylinder position or it’s holes, however 4 fixing holes have missed the plate and tapped just into the boiler shell! Now is that going to mean boiler ruined?

[derek blakeParticipant @derekblake72550]

[derek blakeParticipant @derekblake72550]

Its just the 4 top ones, every other hole seems to have hit the plate..

Edited By derek blake on 24/08/2019 14:34:53

[derek blakeParticipant @derekblake72550]

I’d actually say it’s probably my fault not the previous builder, looking in the holes I’m just hitting the edge of the inner

plate, if my holes were 2mm or 3mm further round boiler I’d of hit it, so maybe my cylinder saddle is too slim.

[derek blakeParticipant @derekblake72550]

Do you think it will be OK? It’s a real shame as everything was going well but I guess I’m worried so little thickness for the stud the grip will mean it strips.

[Jeff DaymanParticipant @jeffdayman43397]

One dodge that could be tried, to reduce risk of stud thread pull- out in the thinner sheet, is to fit a screw in from inside, rather than a stud from outside. This depends on whether there is room between shell and firetubes to get them in, held on a bit of wire dangled through the big hole. You would need to saw a screwdriver groove across the ends of the screws to wind them out through the shell with a jewellers screwdriver. Just food for thought.

[derek blakeParticipant @derekblake72550]

Hi Jeff

i did wonder about stud/bolt from the inside but there no room to get inside.

its actually a pain because all the drilling and tapping went well, especially as I had to use a hand drill.

the threads haven’t stripped yet, but I just wonder how tight they will go on final bolt down of cylinder and what I do if they do give way.

as the studs are in a line I did consider loctiting in the studs and adding nuts after, but not sure if this would strengthen or weaken the situation.

i guess silver soldering them in would be ideal but no chance I can attempt that

[derek blakeParticipant @derekblake72550]

Hi Jason

what would your expertise advise, just do the bolts up carefully as the thread hasn’t stripped yet or loctiting in some studs and use nuts?

regards

Derek

[derek blakeParticipant @derekblake72550]

I also considered adding two extra fixings in the space next to the boiler filling hole so I can get more clamping force without having to use the 4 bolts so much

[Clive Brown 1Participant @clivebrown1]

That's a real downer. You might just get away with it but at the risk of investing a lot of further effort only to find that the cylinder / boiler joint can't be well sealed. Also, a boiler inspector, assuming that he knew, might not be very keen on the departure from the published arrangement.

If you put in studs prior to mounting the cylinder, I think that you would find difficulty getting the studs through the cylinder flange unless you elongated the holes in the flange rather a lot and I don't see much real benefit.

My feeling is to consider drilling out the holes, say 6-7mm, countersink, and silver solder in 4 bronze bushes to be drilled and tapped. Not a too difficult job for someone who has boiler making expertise, and perhaps oxy-propane kit for localised heat. The bushes could be filed to blend with the boiler outer surface.

The existing threads need protection whilst soldering

Perhaps the local club has someone who can help. Best of luck.

clive

 

Edited By Clive Brown 1 on 25/08/2019 09:03:18

[Former MemberParticipant @formermember19781]

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[derek blakeParticipant @derekblake72550]

Thank you for your suggestions guys, unfortunately both wouldn’t work for me.

its been a year with my boiler away and I struggled to get it to where it is now so going out for soldering is a no no.

and looking inside the fixings I can’t get bolts in from the inside as the strengthening plate is in the way, when I tapped the holes it tapped into the edge of the plate, so one side has just the boiler thickness to grip and the other the boiler thickness and the edge of the strengthening plate.

this means I have no flat surface for an internal fixing.

its a blinking pain, I’m tempted to throw in the towel without sounding too dramatic, as this boiler has been the pain of my life for a year now

[Former MemberParticipant @formermember19781]

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[JasonBModerator @jasonb]

If when you make the Studs/bolts don't tighten the die down too much so you get as tight a fit in the thread as possible you may well be OK

Even if the head of a screw inserted from inside sat partly on the edge of the thickening plate that would not hurt so worth giving Jeff's idea a go even is it is a pain to get to you may want to try turning the tread off the then of the screw so you can poke the plain end through the hole before screwing it in (outwards)

[Former MemberParticipant @formermember19781]

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