Author Topic: Piston material  (Read 1153 times)

Offline Dan the man

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Piston material
« on: March 20, 2021, 09:55:23 AM »
Hi folks I'm just wondering what you guys think is the best material for a lapped piston, cast iron?and why

Regards

Dan

Offline derekwarner

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Re: Piston material
« Reply #1 on: March 20, 2021, 10:58:23 AM »
Hullo Dan.....there is usually an optimal type of answer to such a question, but only after you divulge   :facepalm: a few important points

1. steam?........
2. internal combustion?
3. compressed air?
4. cylinder material?
5. scale?

Or just a few lines  :happyreader: on the planned type & size of engine build 

Derek
« Last Edit: March 20, 2021, 11:02:48 AM by derekwarner »
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
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Offline Dan the man

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Re: Piston material
« Reply #2 on: March 20, 2021, 06:28:51 PM »
Hi Derek I thought I had replied to your question but I think I failed to send it somehow!
It would be an internal combustion engine of about 1cc

Dan

Offline derekwarner

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Re: Piston material
« Reply #3 on: March 20, 2021, 10:26:27 PM »
OK Dan.... :slap: an alloy [aluminium based] cylinder?.........or an alloy cylinder head with a steel liner? ....Derek
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline Dan the man

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Re: Piston material
« Reply #4 on: March 20, 2021, 10:54:04 PM »
The latter Derek!

Offline Ramon

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Re: Piston material
« Reply #5 on: March 20, 2021, 11:15:36 PM »
Hi Dan, just seen your latest request!

Outside of a high speed specialist 'racing' engine then definitely cast iron in steel is the best set up for a home build ic engine or replacement parts for a commercial one.

Best running combination is Meehanite (continuous cast bar) piston and a En1a leaded steel liner.  Cast in cast will also work as well but will initially wear slightly until bedded in losing a slight amount of piston seal.  Steel piston in cast is not so good due to differing expansion rates.

I've written quite bit on here about making diesel engines covering the making of piston and liners - a quick search should find them.

Tug

« Last Edit: March 20, 2021, 11:18:50 PM by Ramon »
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Offline Dan the man

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Re: Piston material
« Reply #6 on: March 21, 2021, 07:25:30 AM »
Thanks Tug,your a mine of information!this will be a practice run for maybe something more ambitious, its a little OS 10 glowplug that seemed to loose compression very early in its career, I think it wasn't run in properly or at all!
If I put a drop of oil directly into the cylinder it fires but won't run on ,and turning it over by hand it seems to have very little compression!

Cheers

Dan

Offline Ramon

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Re: Piston material
« Reply #7 on: March 21, 2021, 08:21:22 AM »
Hi Dan,

You'll probably find that the liner in that is soft steel anyway so I would certainly re lap the bore before you make and lap the piston to fit - its not a good idea to use diamond lapping paste unless you can clean the parts in an ultra sonic cleaner. The diamond embeds itself into the surfaces and ordinary solvent cleaning will not remove it. Best to use carborundum or aluminium oxide powder.

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Dan the man

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Re: Piston material
« Reply #8 on: March 21, 2021, 08:34:44 AM »
Thanks Tug,yes I am planning to lap the sleeve first based on that same logic!

Cheers

Dan

Offline Dan the man

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Re: Piston material
« Reply #9 on: April 06, 2021, 08:02:48 PM »
Hi Tug ,thought I should let you know that thanks to your advice a piece of an old lawnmower crankshaft has now been turned down and polished into the little OS glowplug engine and is now running!
I'm dead chuffed!
I think a diesel scratch build will have to be next!

Thanks again for the advice

Danny

Offline Ramon

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Re: Piston material
« Reply #10 on: April 06, 2021, 11:16:16 PM »
That's good news Dan - always great when you resurrect one of these little engines back to running order but - perhaps not quite as much as seeing one you've made yourself break into it's first run  ;) ;)

So, 'Good Luck' with your intention, do you have anthing specific in mind? Only comment I'd make is not to go too small as fits have to be exceptional to get a result 1.5 to 2.5 is ideal but if you fancy a 5cc I do have the odd drawing should you fancy it.

Do keep us posted on progress

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Dan the man

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Re: Piston material
« Reply #11 on: April 07, 2021, 07:14:13 AM »
Hi Tug,5cc sounds just about right, I would be delighted to have access to your drawings if you wouldn't mind!
I will keep folks up to speed on progress, although I I know it will be slow!

Cheers

Danny

Offline Ramon

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Re: Piston material
« Reply #12 on: April 08, 2021, 09:29:07 AM »
Be glad to help Dan - PM sent

Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Ramon

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Re: Piston material
« Reply #13 on: April 08, 2021, 04:07:50 PM »
Drawings sent Dan, hope it suits your intentions.

FWIW I did do a post on it (though not a full build log) on ME https://www.model-engineer.co.uk/forums/postings.asp?th=37520 which may be of interest/use. I'm amazed to find that was eleven years or so ago!

Good luck with it if you go ahead - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Dan the man

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Re: Piston material
« Reply #14 on: April 10, 2021, 08:47:42 AM »
Thanks Tug,the drawings look great, I hope I can do them justice.

Regards

Danny