Part built Allchin 1.5 inch

[KWILParticipant @kwil]

The screws were presumably there to hold parts during original silver soldering assembly. As such they merely held the flanges etc in place and take no real part in the boiler's integrity.

Edited By KWIL on 16/08/2019 14:21:52

[derek blakeParticipant @derekblake72550]

Hi KWIL

So even though they are brass, there's no risk of an inspector failing the boiler?

Kind regards,

Del

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[derek blakeParticipant @derekblake72550]

sorry I just meant it had hydraulic and passed, but a boiler inspector is another level?

[JasonBModerator @jasonb]

Do any of the screws go through into the water space?

[Jeff DaymanParticipant @jeffdayman43397]

Hi Derek, if you plan to operate the tractor in public at a club, who is the boiler inspector at the club? I'd talk to that inspector before doing anything with the screws, or worrying too much about it.

If you are using the tractor only at home and it has passed a hydraulic test, I don't think you have much to worry about. The only remaining concern MIGHT be loss of zinc in the brass screws over time if they are under the water line in the boiler. However this could take years to cause any issue and in many cases never happens – it depends a lot on your local water. If your house faucets don't have punky brass / de-zinc issues your boiler probably won't either.

Just food for thought.

[derek blakeParticipant @derekblake72550]

Afternoon all,

could someone advise where you can buy copper shims, I need to fit my steam fittings but need to space them as they won’t screw in and line up.

i can find one size washers but not ones in a different thickness like 0.2mm, 0.3mm etc etc.

any help would be great.

thanks

Derek

[JasonBModerator @jasonb]

Most of the ME suppliers who sell steam fittings will do packs of washers in nixed thicknesses. Reeves do them in various diameters here

[Jeff DaymanParticipant @jeffdayman43397]

Hi Derek, you can also make your own shim washers. One way is to get some small sheets of copper in various thicknesses. Figure out your OD and ID needed. Drill the ID's in the sheet about 1.5 x the OD apart. Cut squares with the ID centred in them with tin snips. Snip the corners to make octagons then snip the corners again to make them roughly round, a bit bigger than the needed OD. Mount all these blanks on a bolt that fits the ID, and use washers and nuts to tighten the stack of blanks. Make the bolt long enough to hold all the blanks and leave a good bit of the thread for chucking in the lathe. Chuck the bolt and stack of blanks in the lathe and turn the OD of the whole stack and the end washers. Dismantle after turning and there's a drawer full of shim washers (and a sad looking set of end washers plus a bolt with iffy chucked threads – no extra charge for the last bit).

PS you can also punch the ID's if you have a hand punch or gasket punch if you'd rather not drill the copper sheets

Edited By Jeff Dayman on 20/08/2019 04:25:10

[derek blakeParticipant @derekblake72550]

Many thanks Jeff, so I have another question.

Sorry to keep asking everyone but I'm looking to line up the cylinder on the boiler and have positioned where I think it should be.

however my piston comes out the end of the bore, I've checked the lengths of the piston rod, piston and all seems perfect or near as dam it.

I'm not totally sure how much gap you need to leave each end of the bore, should piston end up a couple of mm in from the end, or go right to the end?

I did know id struggle with this part of the build, if I get one end of the travel correct it seems to hit the cover the other end.

Regards,

Del

[JasonBModerator @jasonb]

You should aim for an equal amount of clearance from the cylinder covers each end when in steam so a little less at the back (chimney end) when setting it cold.

Drawings show cylinder 2.094" long less front cover spigot 0.062 gives 2.031" clear cylinder length

Piston 0.406" long + stroke 1.500" = 1.906"

2.031 – 1.906 = 0.125" divided by 2 gives 0.062" or 1/16" clear from covers at each end.

Therefor when hot piston should be 1/8" in from the chimney end and in 1/16" in from crankshaft end. Doing it cold I would say something like 0.107"  (45 + 62) from chimney end and 0.080" from crankshaft end

 

 

Edited By JasonB on 22/08/2019 10:53:08

[derek blakeParticipant @derekblake72550]

Excellent explanation Jason, many thanks it should get me much closer than I was.

Regards,

Derek

[derek blakeParticipant @derekblake72550]

When setting the chimney end do I need to add the back cover spigot length onto the 1/16th clearance that end? or will the 1/16th clearance take this into account.

sorry for the dumb questions but this part was always going to be hard, and I obviously want to get it correct before drilling holes.

Regards,

Derek

[JasonBModerator @jasonb]

Derek, I'm just going to alter what I posted, got the cover without a spigot the wrong way round.

[derek blakeParticipant @derekblake72550]

that's Ok Jason, when I say spigot I mean the 1/16th lip that sits inside the bore on the chimney end cover.

[JasonBModerator @jasonb]

This should make it clearer for cold setting.

Once in steam as the boiler expands the cylinder will move away from the crankshaft so everything moves to the left but the piston does not so the 45thou gap will increase and the 80thou gap will decrease and hopefully end up equal.

[derek blakeParticipant @derekblake72550]

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

[derek blakeParticipant @derekblake72550]

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.

[derek blakeParticipant @derekblake72550]

[derek blakeParticipant @derekblake72550]

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

[derek blakeParticipant @derekblake72550]

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

[JasonBModerator @jasonb]

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.

[derek blakeParticipant @derekblake72550]

I will set up and take a picture Jason

[derek blakeParticipant @derekblake72550]

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.

[JasonBModerator @jasonb]

Yes

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