Author Topic: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine  (Read 8644 times)

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #75 on: November 24, 2019, 12:03:58 PM »
A piece of stainless was found for the displacer cylinder which was 5 mm too short  :facepalm: But I think I can loose this shortfall in the base casting  :-X

The bottom of the tube has to be filled and I chose to cut a bit off of a piece of plate and to turn it round. With the three pieces available it was time to silver solder it up. I started by spacing the ring up off the bottom of the tube by 6mm using 4 8 nuts and silver soldering it in place. It was the thin cap that gave me most trouble and took three attempts  :facepalm: the first attempt left such a big hole that it pretended to be a watering can. The second left a little black line that did not have any solder on the inside so I poked it with a scalpel and it went through  :Doh:

Finally the displacer cylinder was complete and it was time to look at mounting it to the platform. At this point the difference in the diameters of the hole in the platform and the end of the displacer was HUGE  :o

The platform was mounted up in a vice and the centre of the hole found. This allowed the 6 holes to mount the displacer cylinder to be drilled and tapped. With the displacer cylinder in place it was time to pop the displacer piston in and look at all the clearances: which also look big. The good news was that the horrible looking piston that came with the engine once cleaned up proves to be made to the drawing but I am not sure I am happy with the clearance  :noidea:

Jo
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Offline Roger B

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #76 on: November 24, 2019, 12:36:30 PM »
I like your live centre for cutting the disc for the end of the displacer cylinder  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #77 on: November 24, 2019, 03:17:58 PM »
Thanks Roger, I needed an extra washer as the point was a bit long.


Back to the yoke, what a pain, shaping it up was a bit like playing twister  :Doh: I managed to form the two bosses on the arms by supporting it with a spacer between the arms and providing a centre on one of the button screws. Then the rotary table helped form the other two but the shape of the yoke was not easy and it still hit the body of the BCA on either end. Thinning down of the flat arm had to be done in a vice...

Finally a bit of filing and use of a sanding drum in the Foredom left me with a possibly acceptable yoke  :) . Which even mounted on the engine allowing a bit of round and round/up and down testing: 


Ok so the displacer piston is rubbing  :facepalm2: but as it is not connected up yet that was to be expected.

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #78 on: November 25, 2019, 04:43:27 PM »
The Displacer Piston Rod End is a round knob. To make one of these we have to dig out our ball end turner. For those of you who may not have used one of these lets go through how to set up and use one:

The end of the rod need an undercut just beyond where the ball is going, for this part the drawing is perfect and gives us a 11.1mm diameter at the back end of the ball.  (Mr Silky is a collet lathe, this means his nose is the ideal shape for ball turning, if you use a standard chuck you will have to stick the metal you are turning your ball on further out to gain clearance for the ball turner. )

We now need to mount our ball turner on the tool post. The tip of the cutting edge has to be right in the middle of the bar, to set this we can position the tool on the top of the bar - this also sets the radius of the cutter for cutting the ball. Now we wind the saddle along and we bring it up and touch the tool on the end of the bar - this now positions the saddle for cutting the ball and we are going to lock the saddle. We now wind out the cutting tool and can start using the ball turner handle to pass the tool over the bar cutting our ball. Simples  ;D

The ball on its stub can now be held to have two flats milled and the central bore drilled and reamed (or bored if like me you don't have a reamer the right size  ::) ). The last trick is the ball is still on its stub.... so we can used the stub to hold the ball inside the collet to drill and tap the hole in the stem of the rod end before parting it off.

My engine now has a brass knob on it  :embarassed:

Jo

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Offline bent

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #79 on: November 25, 2019, 05:40:50 PM »
Lovely work Jo.  I was admiring the time and effort to put the circular bosses on the yoke piece...then you go and whip out a brass knob... :embarassed: :lolb:

Didn't know I wanted a ball cutter until now, that's a neat bit of kit.  Oh and your explanation for the yoke drilling makes sense, I too get too busy to take pictures sometimes.

Is the ball end practical or just decorative?  Still trying to picture the linkage for the displacer (from the photo back on page 1 of this log), I assume the hoop that attaches to the yoke can also pivot around the yoke ends?

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #80 on: November 25, 2019, 05:55:57 PM »
Thanks Bent  :)

Is the ball end practical or just decorative?  Still trying to picture the linkage for the displacer (from the photo back on page 1 of this log), I assume the hoop that attaches to the yoke can also pivot around the yoke ends?

The Ball end was on some of the original engines. From what I understand the engines varied.. a lot  :facepalm:

The hole through the ball is for the pivot which bolts to the two arms (Displacer Piston Rod Yoke) which have two pivots on their ends which pivot around the yoke ends  :thinking: It might be easier if I make those two arms tomorrow as it is much easier to see than to say.

Jo
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Offline bent

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #81 on: November 25, 2019, 07:11:13 PM »
I follow your description, sounds like what I thought Jo (pivot at the ball, pivot on the yoke ends, so that the displacer piston rod moves through a fixed sleeve up at the top of the cylinder?)

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #82 on: November 26, 2019, 11:16:58 AM »
That is about right Bent  ;)

I have just finished off the top pivot. It has been made out of 304 Stainless, so that it is relatively hard but will not corrode and damage the brass pivot. It is a piece of round bar which has had two flats milled onto it and had two threaded holes for the vertical links.

Now it is time for those long vertical links. The first thing I have noted is that one of the measurements is wrong and while most of the engines I have seen are all different... I will be deviating from the drawings to make ours more authentic  :)

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #83 on: November 26, 2019, 04:32:49 PM »
The displacer piston rod yoke (two long arms) are made in three pieces: a steel part to join to the pivot through the brass ball, a length of 4.76mm square steel and I have chosen to make the bottom loops out of brass. These three pieces need to be silver soldered together to make the arms yoke.

The top steel part began as a 12.7mm by 4.76mm length of steel which had two holes drilled in it for the two bolts. Then I sawed it in two and packed it with two pieces of 1.6mm to enable it to be held in a collet and turned to 11.1mm diameter. Over to the mill and the two sides had scallops taken out of the sides before milling a slot for the square bars.

Two pieces of square bar are needed which have a 25mm ID bend on the end. It is easy to bend this round another bar cold but it  will be necessary to leave it over length so that it can be clamped for bending. Once cut to length the two ends can be silver soldered on and it cleaned up.

Jo
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Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #84 on: November 26, 2019, 04:39:27 PM »
A similar process is used to machine up the other end of the yoke except that these are filed round after silver soldering on the end of the rods.

Having put the yoke on the engine it became apparent that it is no longer possible to do any more round and round testing without adding the cylinder liner or the power piston as that acts as the guide for the piston rod  :(

So four pics of the crankshaft in each position to show the position of the arms and to check nothing jams up  :)

Jo
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Offline bent

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #85 on: November 26, 2019, 05:55:50 PM »
Getting both pieces to come out square and true after silver soldering is the tricky part...for me  :Lol: 

Still following Jo. :popcorn:

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #86 on: December 01, 2019, 01:07:11 PM »
I have been given a barrel to go with my engine  :thinking: And a piece of seamless steal tube and a bit of Brass. So I can now finish off the engine  :whoohoo:

Thank you Dave  :-*

Jo
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Offline Jasonb

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #87 on: December 01, 2019, 01:24:13 PM »
Do you have to empty the Barrel first or did Dave helpfully do that for you?

Online Jo

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #88 on: December 01, 2019, 01:31:07 PM »
Dave was very generous in this regards ;)

Jo
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Offline Bluechip

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Re: Camden 3" scale Rider-Ericsson Hot Air Pumping Engine
« Reply #89 on: December 01, 2019, 02:15:06 PM »
Do you have to empty the Barrel first or did Dave helpfully do that for you?

That barrel has been loooooong ago emptied ...   I remember where and when and by whom it was emptied .....

The place was RAF Eastleigh  Nairobi  Kenya.

Time was Christmas Day 1964

Rob. C, Roy. S, Phil. V and me .... The first 3 names abbreviated to protect those who were undeniably guilty ...   ;D

Dave

Edit:  Actually 1964  -- corrected   :old:
« Last Edit: December 01, 2019, 08:42:37 PM by Bluechip »