Author Topic: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine  (Read 5641 times)

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #105 on: December 06, 2019, 05:04:44 PM »
Maybe you should let them know that it will be used to carry a set of Chuk 1 Castings early next year and Surus has got wind of the potential delivery  :facepalm:  :pinkelephant:

Jo
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Online Bluechip

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #106 on: December 06, 2019, 07:15:46 PM »
Maybe you should let them know that it will be used to carry a set of Chuk 1 Castings early next year and Surus has got wind of the potential delivery  :facepalm:  :pinkelephant:

Jo

Whose 'them'  :noidea:  The insurers ??  Baffled  :headscratch:  What's the castings got to do with them ?? 

Signed by a 'Confused old Codger'

Dave

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #107 on: December 07, 2019, 03:11:16 PM »
"Them" is the insurers: I think I may have mentioned that Surus has taken to pouncing on the post lady or any delivery drivers when ever castings are due to be delivered :facepalm2: Their screams of terror is a clear indication that they tried delivering something and he got there first....

Maybe I shouldn't have mentioned this before you try to dropping off the castings for me in your nice new vehicle  :-X

Jo
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Online Bluechip

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #108 on: December 07, 2019, 06:39:59 PM »
"Them" is the insurers: I think I may have mentioned that Surus has taken to pouncing on the post lady or any delivery drivers when ever castings are due to be delivered :facepalm2: Their screams of terror is a clear indication that they tried delivering something and he got there first....

Maybe I shouldn't have mentioned this before you try to dropping off the castings for me in your nice new vehicle  :-X

Jo

They will be delivered to yourself with my usual decorum.    :LittleAngel:

'Dropping off'  indeed. Perish the thought that I should be so wanton ....  ::)  Rest assured I shall treat your property with the same contempt care as if it were mine own.  ;D

Dave  .. ( At the moment trying to gouge Red Oxide Primer out from under his fingernails ....  I'd forgotten how gobby the damn stuff is      :rant: ).
« Last Edit: December 07, 2019, 06:43:19 PM by Bluechip »

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #109 on: December 10, 2019, 02:53:31 PM »
Having roughed out the piston I decided to mill out the slots for the two bolts on the power piston centre. This was a bad move: Only after turning the outside to size and adding the cavitation grooves did I remember I should have also drilled the tapping holes for the six screws that will hold on the brass Top Ring.


A slightly thicker than shown on the plans piece of brass sheet was found and had six clearance holes for the screws added. This then allowed the offcut of brass to be attached to the piston so it could have its outside turned and the inside bored. Before milling the slots for the power piston centre bolts. Having done the final machining of the power piston it could finally be turned round and the indent for the nut added.


Somewhere along the lines the piston seems to have grown and it now does not want to slide in the cylinder  :headscratch: This is not a problem it just provides a bit of material to conduct the lapping with.


I was trying to work out why the power piston had that odd brass plate: It seems to have originally been used to hold in place a leather cup ring but on the model it would cause too much friction so the recommendation is to use Teflon plumbing packing. I decided I would order some silicon "O" rings of 51mm diameter to see if they proved to be better  :noidea:

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #110 on: December 12, 2019, 10:52:52 AM »
The outside of the piston was a little too tight so I mounted it on its centre and rubbed a stone on the outside of it until it once again slide nicely into the cylinder. Of course the piston being aluminium it clogs up the stone so that need to be cleaned off as does the oily gritty mess caused by the lapping before assembling everything.

The power piston is held in place with a nut which uses a pin spanner but as I don't have one the right size two drills in the holes and a tommy bar between does just as well ;)

So looking at the fit:


 :thinking: That will do for now, it will wear in with use.

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #111 on: December 12, 2019, 01:29:08 PM »
To position the Displacer piston in the right place the instructions say it should be 2.5mm below the power piston when the beam is level  :headscratch:  I decided if I first level up the beam and then put a G clamp on the displacer piston rod, I could remove the piston assembly and would know where the power piston needed to be relative to the displacer rod when mounting the displacer piston while tightening it up  :ThumbsUp:

At this point I decided to try putting some heat under the hot end (displacer cylinder) to see if anything happened. I used my usual candle power... Candles have the advantage that they do not make lots of noise but still provide sufficient heat. What this proved was the Hot end had a leak  :wallbang:

So it was necessary to repair it with some more silver solder and after some coffee and remembering to add a gasket I can give it another twirl over the candle :)

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #112 on: December 13, 2019, 11:04:16 AM »
You will recall yesterday was trying to run the engine on a candle. Having thought about it the displacer piston is a huge piece of cold steel and I thought it is probably cooling the hot air before it can do any good at the power end, so I decided to try a gas burner to apply a bit more heat. A couple of seconds later and I heard a pop and the plate came off the end of the hot cylinder  :toilet_claw:

This morning I have silver soldered it back on and I will have to think further on the displacer piston cooling before it warms up problem  :thinking:

Jo
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Offline scc

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #113 on: December 13, 2019, 11:33:28 AM »
Oh dear :thinking:   A facet of engineering that I'm ashamed to say  I know nowt about.

Offline Jasonb

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #114 on: December 13, 2019, 04:07:17 PM »
How big a gas burner did you use :o

Or was it just a poor solder joint to start with, you need tenacity 5 or HT 5 for stainless as easyflow won't remove the chrome oxide that forms on the SS

Offline Alyn Foundry

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #115 on: December 13, 2019, 04:24:47 PM »
What I was concerned about is the why it " popped " off? Surely the pressure should have started to move the power piston in an upward direction?

Cheers Graham.

Offline bent

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #116 on: December 13, 2019, 04:35:26 PM »
Wouldn't think you could develop much pressure, the fit's not that tight?  Could be thermal expansion of the end cap created enough shear to break the braze/solder joint?  Break out the Tig welder?

Offline Vixen

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #117 on: December 13, 2019, 04:54:47 PM »
Hello Jo,

I cannot be sure from the photo, but the silver solder joint looks to be very crystalline and therefore structurally weak. You can get that sort of effect if the silver solder melts with the torch flame before the rest of the cylinder is up to red heat. It can also be caused by a flux which is not aggressive enough to clean all the oxides off the surfaces. Try to get the surfaces red hot to melt the solder rather than the flame. The solder should flash into the joint when the temperature is right.  As a matter of interest which grades of silver solder and flux are you using?

Mike
« Last Edit: December 13, 2019, 04:57:53 PM by Vixen »
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #118 on: December 13, 2019, 06:22:56 PM »
The hot end is only 1mm thick so it takes very little to get it red hot, which is above the temperature of the silver solder joint. Soldering up used B6 and Tenacity No 5 which is the flux I always use on stainless the existing silver solder was very well attached.

The book of words says it takes 10 to 15 mins for the engine to heat up prior to trying to run it: I assume this is to do with warming up the displacer cylinder... So will be going back to using candle power.. The heat shield may help to keep the heat in.

Jo
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Offline Jasonb

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #119 on: December 13, 2019, 06:33:29 PM »
If you got it red hot then whatever burner you used was way too aggressive, if using your Sievert then just crack the knob open and play a gentle almost orange flame under the engine not a full blast. Small camping burner would be ideal or a ceramic burner both with a fine regulator.

Some hot water through the plumbing will help warm it up if you can't wait that long.