Author Topic: Strictly.... “ Hot Air “  (Read 21910 times)

Offline Jasonb

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Re: Strictly.... “ Hot Air “
« Reply #15 on: January 09, 2018, 03:49:36 PM »
Lets hope he has not bought quick drying paint for it :Lol:

Looking good, have the boys made any more progress on their RLEs?

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #16 on: January 09, 2018, 04:05:41 PM »
Hi Jason.

Hmmm.... trying to find a warm place to spray without upsetting mama is the problem.

Alan's about a third of the way through and Mathew about a quarter. I'll try to post some photos on the R.L.E. thread that Jo started.

Meanwhile, a few pictures showing the complexity of patterns and core boxes for " JUST " the engine platform.

Cheers Graham.

Picture 1.

Showing all the parts. The big plate makes an impression for the platform outside core. Picture 2 shows the platform pattern now split to allow removal from its box. Picture 3 showing the air passage and displacer cavity core box. Picture 4 showing the water jacket core box and " Robinson Patent " cores.
« Last Edit: January 09, 2018, 04:12:38 PM by Alyn Foundry »

Offline Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #17 on: January 09, 2018, 06:19:29 PM »
I started working on castings for the Robinson hot air engine last October.
Graham suggested that I add some pictures of a platform casting that I have been working on. Some defects called cold shuts only became apparent as I milled the upper surface of the casting and there is a porous blowhole underneath.

I started off milling the underside of the platform casting flat.
WP_20171106_10_37_17_Pro by Andy, on Flickr

I could see a depression to the left of the casting but it didn't concern me at that stage...
WP_20171106_12_48_09_Pro by Andy, on Flickr

Ready to mill the top of the platform flat
WP_20171106_13_10_37_Pro by Andy, on Flickr

Then the cold shuts were revealed....
WP_20171106_15_51_38_Pro by Andy, on Flickr

I filled the air passage in the casting with thinners to test for porosity and it leaked like a sieve...
WP_20171108_12_17_23_Pro by Andy, on Flickr

Graham agreed the casting was scrap and he would resurrect the patterns so we could have some more cast.
I have continued to work on the other castings

Cylinder, I started by milling the base flat.
WP_20171104_12_35_43_Pro by Andy, on Flickr

Then boring it out
WP_20171106_13_25_43_Pro by Andy, on Flickr
WP_20171127_11_28_43_Pro by Andy, on Flickr

Lapping the cylinder using fine Timesaver compound
WP_20171230_15_32_21_Pro by Andy, on Flickr

Machining the displacer cylinder insider and out then forming a groove for a large O ring seal...
WP_20171231_15_56_14_Pro by Andy, on Flickr
WP_20180103_15_42_33_Pro by Andy, on Flickr
WP_20180103_16_04_20_Pro by Andy, on Flickr
WP_20180103_16_19_56_Pro by Andy, on Flickr

This is the engine as at yesterday afternoon
WP_20180107_19_41_31_Pro by Andy, on Flickr
WP_20180107_19_43_33_Pro by Andy, on Flickr

I'm expecting Graham to pick me up on the use of screws to hold the flywheel on the crankshaft, they will be replaced by discreet grub screws........

Andy


« Last Edit: January 09, 2018, 06:32:10 PM by Chipmaster »

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #18 on: January 10, 2018, 11:40:18 AM »
Good morning Andy.

It’s your engine, your prerogative.   :)

The 3/32” wide keyway is the smallest one on the range of kits I produced but I duly bought a broach back in the day.

A tool like that will last a lifetime, if cared for, well maybe more! As I was also providing a machining service at the time the £30.00 cost soon disappeared.

The gib head key was just an 1/8” one carefully milled down from my stock of 200, I used to do them in pairs as the tapers then cancelled themselves out.

Your progress is excellent and your workmanship also. I can’t tell from the photograph but how deep is the
“ O “ ring groove in the “ hot pot “ ? I used to make mine with quarter depth in both “ hot pot “ and platform which gives an ideal thermal separation,  the “ O “ ring itself becoming the register for alignment.

Cheers Graham.

Offline Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #19 on: January 10, 2018, 05:00:54 PM »
Good evening Graham.
I spent all my pocket money on castings so I don't have any broaches  :(. I reckoned two grub screws 120° apart would suffice instead of an authentic look.
The groove is 0.15" deep so the O ring is about 0.050" above the surface of the cast iron displacer cylinder AKA 'Hot Pot' to be compressed and seal against the platform.
O Ring Groove by Andy, on Flickr

For alignment i'm relying on the three 1/4" Whitworth studs that secure the base to the platform, they almost touch the displacer cylinder flange so there is virtually no movement. It didn't occur to me to machine grooves in the hot pot and platform.
Will make the piston next.

Andy

Online Jo

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Re: Strictly.... “ Hot Air “
« Reply #20 on: January 10, 2018, 05:12:02 PM »
I spent all my pocket money on castings

:facepalm:

Tell your wife I said she needs to give you need more pocket money so you can buy more castings  :ThumbsUp: (or broaches  :naughty: )

Jo

In the meantime if you hear of any casting sets I am willing to consider buying them to keep them safe  :mischief:
« Last Edit: January 10, 2018, 05:19:23 PM by Jo »
Usus est optimum magister

Offline Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #21 on: January 10, 2018, 05:57:50 PM »
Yes Jo, if only all women saw things the same way as you !

if I become aware of any casting sets in need of saving I'll let you know  ;D

Andy




Offline Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #22 on: January 10, 2018, 06:06:17 PM »
This Tesco Tuna tin will be the displacer after the contents have been consumed.
I may need to bore out the displacer cylinder / hot pot further to achieve optimum clearance.

WP_20180103_16_09_43_Pro by Andy, on Flickr

Andy

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #23 on: January 10, 2018, 06:36:15 PM »
I spent all my pocket money on castings

Jo

In the meantime if you hear of any casting sets I am willing to consider buying them to keep them safe  :mischief:

Hi Jo, are you joking or being serious?

Cheers Graham.

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #24 on: January 10, 2018, 06:45:43 PM »
Hi Andy.

I’m not sure if the “ O “ ring modification was put in writing in the construction notes as I have mislaid them.

As you can imagine the “ O “ ring will perfectly register the two components whilst both acting as a seal and thermal barrier.

What weight is the Tuna can with contents? My supermarket no longer sells the 185 gram tin which is the correct depth. I’m using a tinned Crab meat here, sadly the contents, I’m told leave a lot to the imagination!

Cheers Graham.

Online Jo

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Re: Strictly.... “ Hot Air “
« Reply #25 on: January 10, 2018, 07:01:21 PM »
In the meantime if you hear of any casting sets I am willing to consider buying them to keep them safe  :mischief:

Hi Jo, are you joking or being serious?

Cheers Graham.

Graham how long have you been a member on this forum  :stickpoke: when have you not seen me looking to help out casting sets by providing them with a loving home  :noidea: my usual supplier has run out of desirable ones (that he is willing to sell me  :wallbang: )


I decided that I would take Alan's recommendation on my new year resolution about buying casting sets so I will be buying fewer not more :mischief:

Jo
Usus est optimum magister

Offline Chipmaster

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Re: Strictly.... “ Hot Air “
« Reply #26 on: January 10, 2018, 07:25:06 PM »
Hi Graham,
I'm using the photographs of your plans that I took in your kitchen and I haven't seen construction notes but I'm content that the three 1/4" Whit studs will do the job, they'll have to now !

Tesco Tuna Chunks in Spring Water 160g net weight, contents very good. Will the height of the tin be critical?

Andy

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #27 on: January 10, 2018, 08:07:21 PM »
Hi Jo.

How desirable does the Alyn Foundry half scale Robinson hot air engine sound?

Because....

I have 90% of one here, well might be 80%, I’m not sure yet. Alan tells me we haven’t got a flywheel.

As you know, thanks to Andy we got some cylinders cast, and they have machined up nicely. The next part is to see if they can manage the horrendously complicated platform casting. I have loads of the other parts left over.

Cheers Graham.

Offline Alyn Foundry

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Re: Strictly.... “ Hot Air “
« Reply #28 on: January 10, 2018, 08:11:38 PM »

Tesco Tuna Chunks in Spring Water 160g net weight, contents very good. Will the height of the tin be critical?

Andy

Hi Andy.

The working depth of the “ Tuna can regenerative displacer “ is 45mm. Anything less in depth might not work.

Cheers Graham.

Online Jo

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Re: Strictly.... “ Hot Air “
« Reply #29 on: January 10, 2018, 08:31:41 PM »
How desirable does the Alyn Foundry half scale Robinson hot air engine sound?

:naughty: I have been hoping to add a couple of Sterling's to the collection.. You will have to see how much of a set you can find...  ;)

Jo
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