Part built Allchin 1.5 inch

[derek blakeParticipant @derekblake72550]

Thank you Jeff, that’s very encouraging words.

Regards

Derek

[derek blakeParticipant @derekblake72550]

Evening all,

so I have a small question, I’m looking to cut some studs myself as the commercial studdings seems to keep arriving with a lot of slop.

and the 4BA that arrives measures around 3.35mm, but I’m looking to be closer to 3.5

however when I try and cut studs on the lathe I get so much flex I can’t get a consistent thickness along the turning, I’m only sticking 16mm out of the chuck and removing around 0.5mm but one end keeps going 0.8.

obviously the bar is flexing and I think this is what you can run out, but is there something obvious I’m missing to make things easier.

Thank you in advance i

[Clive Brown 1Participant @clivebrown1]

What tool are you using for the turning? For that diameter of work, a very sharp tool is needed, well honed HSS or, if a carbide insert, then one with a ground finish, sold as intended for aluminium etc. The ordinary coated inserts for steel are not sharp and will cause too much deflection of slender work.

Incidentally, 4 BA spec. is 3.6 mm OD if you're making studs as tight as possible.

Hope that helps,

Clive

 

Edited By Clive Brown 1 on 03/09/2019 19:19:35

[derek blakeParticipant @derekblake72550]

Hi Clive

yes my tool probably not good enough, it’s an insert type.

every stud I’ve purchased has come in at 3.38mm or if lucky 3.42 so both have been wobbly in my holes so reluctant to use them.

i have some 4mm bronze on its way so I will try a new cutter and try again as I don’t need to remove too much material, and see how I get on.

thank you

[derek blakeParticipant @derekblake72550]

Cylinder fixed down, made some Stainless fixings in the end as they were a good fit.

if a Stainless is good enough on Jason’s Fowler it’s good enough for me, i guess we will have to wait and see if it’s sealed.

i used loctite 638 on the bronze studs of which there are 4, partly wish I had used red thread locker but hopefully it still holds ok, which I’m sure it will.

so I’d go as far as saying the lockdown of cylinder is complete, still nervous of leaks but I can’t do anymore than I have especially with my limit skills and knowledge, I will now concentrate on the more fun stuff like making steam fittings.

i assumed you must also seal the studs so I used what have on the other steam fittings and that loctite 542, i will upload more pictures soon for anyone who maybe interested.

[Terry Jessop 1Participant @terryjessop1]

I don't want to hijack this thread but I've recently acquired a allchin and started to look at a few bits. Has anyone been successful in making the square/acme thread on the brake?

[derek blakeParticipant @derekblake72550]

Hi Terry

hijack as much as you like, it’s nice to hear from another Allchin builder,

however I can’t help as the previous owner had made that part on my engine, do you have the build book as this goes how it’s done.

Del

[JasonBModerator @jasonb]

I screwcut the square brake rod thread for my Fowler and made a silver steel tap at the same time which I used to make the nut

[derek blakeParticipant @derekblake72550]

Evening all,

hope no one too disappointing with the cricket! Not a huge amount done on the engine but I did make a new piston as the last one seemed a little sloppy in the bore.

this one has a better shaped grove for the O-ring which brings me onto a question please, I have an O-ring for the piston rod, this instead of graphite yarn but how snug should the ring be on the shaft, should it be squeezed up.

i have graphite yarn fitted to all other areas, apart from the piston itself.

i just wrapped it around the rods a few times, and well tighten down the nuts more if I get leaks I guess but how do you deal with a leaky O-ring?

thanks in advance

[JasonBModerator @jasonb]

The fit of the ring is dealt with when the recess for the gland is machined as that needs to be made to a specific size to squash the ring around the rod by the right amount. If you did not do this then revert t graphite yarn.

[derek blakeParticipant @derekblake72550]

Would anyone mind advising if it’s OK to have the exhaust pipe made of bronze?

Thanks in advance..

[Jeff DaymanParticipant @jeffdayman43397]

Exh pipe for the Allchin in bronze should be ideal material, I would say.

[derek blakeParticipant @derekblake72550]

Thanks Jeff

[derek blakeParticipant @derekblake72550]

Evening all,.

now my next question has been asked many times and I’ve done my best to work this one out myself, however.

if my piston is central in the bore, should my valve slide be central as well? I’ve set my eccentrics only by eye at the moment and I can get the valve to move across the ports equally if I reduce the length of the rod which makes sense as I had to reduce the piston rod length also to get that to a good position.

if I know the piston position relative to the slide valve I could check if I’m in the ball park, I have read all the posts about TDC and 90 degrees and read the book but mathematics is not my strong point, is there a real basic way to position the eccentrics on the crank,

kind regards

Derek

[JasonBModerator @jasonb]

Looking from the flywheel side.

Set the crank so that the piston is towards the front of the engine, this will put the crankpin at 9 0'clock.

The thickest part of the forward eccentric should then be about 10 degrees past noon. Just a sit is on drawing No6

The thickest part of the reverse eccentric should be at about 10 degrees before 6 o'clock which is hard to see on drawing 6.

[derek blakeParticipant @derekblake72550]

Hi Jason

Many thanks as that seems a simple explanation, just checking if I look from flywheel side and move piston to the front of the bore towards the chimney would that not put the crankpin at 3 o clock? I’m obviously not questioning your correct I’m just checking I understand it correctly,

regards

Derek

[derek blakeParticipant @derekblake72550]

Sorry Jason, I can see it’s 9 o clock now I have engine in front of me, I shall give it a go today.

thank you

[derek blakeParticipant @derekblake72550]

So I had my first go at setting the eccentric with Jason help and a few pictures, it seemed pretty good.

however when I push the linkage to the top which I’m not sure is forward or reverse the lifting arm badly rocks forward and back.

but doesn’t in the other position, slightly odd but is probably clear to someone that something is out.

i will have another go tomorrow to make it more accurate as I’ve obviously not got it correct yet…

[derek blakeParticipant @derekblake72550]

So I had another go at setup, probably a weird way but I printed a circle with the degrees added and attached this to the gear on the crank.

i move both the eccentrics the 10 degrees as told, and I’m pretty sure they are in the correct position now or at least the best I can do, I do still get rock on the lifting arm but when I held this tight with the push rod it stopped so maybe this is normal.

moving the eccentrics didn’t seem to help the rock so I’m assuming it’s maybe something else or just how the mechanics works, this week I will make a new rod for the slide valve as the other I cut slightly too short.

and see how the movement is, my intention will be to run on air to see how things go, hopefully this week would be nice.

probably just with a foot pump for now, and if the engine comes alive not only will I feel a sense of accomplishment I will spend time making the steam fittings, I will change that into attempt to make the steam fittings…

[JasonBModerator @jasonb]

Things will move about if the whole linkage is not in place back to the reverser, can't seem to get the embed code to post video of mine but so here

[Ron LadenParticipant @ronladen17547]

Excellent Jason, I am getting lots of information from that video, seeing how things run, fit and how they look.

Edited By Ron Laden on 17/09/2019 09:43:59

[derek blakeParticipant @derekblake72550]

Many thanks Jason, that's great

[derek blakeParticipant @derekblake72550]

So to add a little variety to the engine build I’ve decided to attempt two extra model, a living van and trailer scratch built from pictures.

very early stages but a bit of fun, if they end up looking half decent I shall sell them to fund engine parts.

[derek blakeParticipant @derekblake72550]

[derek blakeParticipant @derekblake72550]

Only progress on engine is a new valve rod, as other one was too long.

piston rod and valve rod have had to be made shorter, I’ve lost around 2.3mm on length of boiler if I was to copy drawing exactly so it’s possible this is the answer to why I’ve had to shorten both rods but hopefully this won’t make any difference to the running of the engine.

I am presently blanking the steam fixings to attempt to run the engine on a foot pump as the book suggests, she will either come alive, not run, or leak like a sieve.

i think I have set the eccentrics correctly from Jason’s help and the movement on the valve looks reasonable so let’s see.

if we have life I shall take a short YouTube video.

[Author]

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