Part built Allchin 1.5 inch

Excellent, thanks Jason I shall give that a go later and see how it all lines up.

Hi Jason

so I set my cylinder as per drawings, and with crank full over as per picture piston sticks right out of the end of bore as seen in other picture, to correct this I’d have to move cylinder right up against smokebox.

very odd I wonder what’s wrong as all the measurements seem correct to drawing.

I have noticed my cylinder saddle is 4mm too wide but I still have to put cylinder out from being central to make it fit, maybe that’s fine,

regards

Derek

4mm towards the smokebox to get piston in correct position 🤔

How does the cross head run in the trunk guide with the piston in those positions, if the cross head comes too far towards the crankshaft the piston rod may be too long.

I will set up and take a picture Jason

Because my Hornplates have bigger fixing I managed to pull the boiler forward by 2mm, I now seem to be just 2mm from centre over steam hole, do you think this will be ok?

The crosshead seem to come to a good position at both travels, as I guess as long as the piston travel is correct the cylinder can be slightly forward or back on barrel?

i appreciate the help.

Yes

Derek you have a PM just FYI.

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

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.

Derek you have another PM.

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

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.

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.

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.

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

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

Thanks again.

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?