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Part built Allchin 1.5 inch

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derek blake28/09/2019 09:51:03
495 forum posts
130 photos

Thank you Ron, so I do have a question if anyone has time to answer.

when setting forward and reverse, as well as the valve do I move the die block to the extreme ends of the radius arm before setting the valve movement?

regards

Derek

Paul Kemp28/09/2019 18:02:02
313 forum posts
14 photos

Derek,

Short answer is no, not to the extreme ends, there needs to be a little clearance. Much longer answer explains why but trying to keep that short too, most traction engines have top suspended links which amplifies geometric error in the motion and is fairly inefficient, rail loco builders went to great lengths to support the link on trunnions on the vertical centre and the centres of the trunnions just offset from the centre line of the slot to give better valve events but even that does not overcome the fact the link is oscillating and not just rocking so it slides over the die block slightly and through the stroke of the valve the die block will slide towards the extremity of the slot. If you arrange your reach rod and reverser set up so it is already jammed against the end, it has nowhere to go.

That is probably not very well put and about as clear as mud! I am sure others can explain it better.

Paul.

derek blake28/09/2019 19:29:32
495 forum posts
130 photos

No that’s perfect Paul, I can now set the reach rod and set the valve as pushing to the extreme obviously changes the valve movement.

thank you

derek blake28/09/2019 21:55:43
495 forum posts
130 photos

Just a quick question please, when my valve goes full one way,and full the other across the port face I have just the slightest slit showing of the ports each end.

is this correct, or should my valve been slimmer so you can see the full amount of port each end when rotating the crank, the engine runs so I guess I’ve got it correct but I just want to double check I understand the setup.

thanks in advance.

JasonB29/09/2019 06:51:29
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Moderator
16451 forum posts
1741 photos
1 articles

You should be uncovering most of the port though that won't be at crank TDC and BDC.

derek blake29/09/2019 09:20:37
495 forum posts
130 photos

Right thanks Jason, I will double check today just how much of the ports get exposed.

derek blake01/10/2019 22:41:34
495 forum posts
130 photos

So I’m about to start the pipe work, however I can’t decide on the injector frown

when I purchased the engine parts, the previous builder had built the injector as per the drawings but not knowing much about these items I’m not sure if it would work.

there seems a lot of joints that could leak so I have considered plumbing in a commercial injector however there is the issue of the many types.

for an engine of my size what size injector is required, number 2 perhaps?

derek blake05/10/2019 19:57:27
495 forum posts
130 photos

Evening all, I hope all well.

today was a bit more engine work after week off with a kidney infection but blowdown cock made the best I can and trunk guide bracket made and fitted.

i was in two minds about drilling a hole in the boiler but looking at all the other holes your supposed to drill I thought one would be OK.

and guess what strengthening plate not where it should be so fixing only into outer shell, however the trunk guide is fitted very strongly to the cylinder so I can see that there is much force on this fixing, hopefully that’s correct anyway.

as you can see from the picture I added small stud, 6BA into boiler and 7 on the bracket this was to try and get a tighter fit in the shell, it’s sealed with 543 sealant so hopefully no leak.

derek blake05/10/2019 19:58:17
495 forum posts
130 photos

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derek blake05/10/2019 19:58:49
495 forum posts
130 photos

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derek blake05/10/2019 20:00:55
495 forum posts
130 photos

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derek blake07/10/2019 20:11:37
495 forum posts
130 photos

So no one screamed I’d made a mistake with the stud fixing so I will take that as it’s OK 😉

so next move will be to make the steam fittings, I have the blow down cock made but looking to purchase the injector for reliability reasons but trying to decide which one I think a 2oz one would be fine but please say if that’s wrong as they are not cheap.

I will then make the pipe work and we won’t be far away from a steam...

derek blake07/10/2019 21:30:10
495 forum posts
130 photos

Hi Jason

may I ask you a question please, in the past we spoke about my ports and the valve and the fact we may have to change things as per your CAD drawings.

my engine seems to have a direct leak up the exhaust when engine not running, is this caused by the regulator or valve not fully sat flat or something to do with the valve itself like the width of the exhaust space.

the engine runs so I don’t think anything is a show stopper but I’m interested to understand the process.

regards

Derek

derek blake13/10/2019 22:27:32
495 forum posts
130 photos

No updates full of cold so engine on back burner, still concerned of air going up exhaust but hoping this is a valve and regulator issue and nothing else.

im concerned about the plug that screws into the underside of the casting to block exhaust hole but I did loctite this in so I’d be surprised if it’s going through that.

im presently deciding how to fix ash pan assembly to horn plates, because of the badly made boiler the fixing holes don’t go into good meat so I’m thinking of making some brackets to bolt it to the hornplates instead.

not to drawing but shouldn’t be too obvious.

hopefully more updates in a few weeks.

derek blake13/10/2019 22:34:35
495 forum posts
130 photos

One quick question I do have is on globe valves, the Allchin has three, two of which are on the manifold and one on the blower.

i can’t see how I can make these but also can’t find anything that small commercially.

has anyone any ideas how I can replicate these or buy anything that size that I can either use or adapt to fit.

Regards

Derek

Paul Kemp14/10/2019 23:34:48
313 forum posts
14 photos

Derek,

If you have a constant blow up the chimney both the regulator and the valve are probably letting past a little. Try a smear of engineers blue on the face of both and slide them across their relative port faces and see what marking you get. This will indicate if the valves are contacting the port faces properly. If you don't get good marking try blueing a flat surface such as part of the lathe bed, surface plate (even a small piece of plate glass) and rub the valves over, scrape gently any high spots until you get a good marking right across the surface, then reblue the valves and try again on the faces. You can address any high spots on the faces in the same way until you get good all over contact.

Failing that you can try lapping the two faces together with a mild abrasive (eucryl smokers toothpaste powder mixed in a slurry with water is a good mild abrasive). As its water based its easy to remove too.

On the globe valves 90 degree ones are reasonably easy to make, in line ones are a little more complicated as you need to drill the passages at an angle. I can't remember where I have seen drawings for them, you might find some on here with a search. Or you could try steam fittings.co.uk they do various sizes at reasonable prices and I have used a couple in the past that have worked fine.

You are getting there now! Won't be long before you can light up!

All the best,

Paul.

Edited By Paul Kemp on 14/10/2019 23:37:42

derek blake15/10/2019 12:47:45
495 forum posts
130 photos

Many thanks Paul, I will check that out.

derek blake19/10/2019 20:35:44
495 forum posts
130 photos

Hi All

so only a small amount of work, I decided to be brave and drill the 7ba holes to hold the ash pan to the firebox.

i was reluctant to drill yet more holes in the boiler but as it’s in the drawings to do so I guessed I should just do it.

the drawing asks for 7ba bronze bolts but I’d have to make these, would I be able to use stainless steel instead?

Thanks

derek blake19/10/2019 23:02:43
495 forum posts
130 photos

Another quick question please, I have my boiler fixed onto the hornplates through the side stays with normal steel bolts, is this OK?

many thanks

JasonB20/10/2019 06:57:20
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Moderator
16451 forum posts
1741 photos
1 articles

Stainless OK for grate and ashpan.

Bolts should be fine provided there is not too much play in the hornplate holes, though I doubt you will be riding behind the engine that much which can see the fixings start to fret if there is play.

Edited By JasonB on 20/10/2019 06:57:47

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