Model Engine Maker

Help! => Specific Engine Help => Topic started by: vcutajar on July 31, 2014, 06:50:46 AM

Title: Corliss Flywheel
Post by: vcutajar on July 31, 2014, 06:50:46 AM
Hi guys, hope everything is well.

I have a question about my MEM Corliss flywheel.  I need to drill a hole for the grub screw to hold it to the crankshaft and as the flywheel is a one piece construction I can only drill for the grub screw at an angle which is going to be fun.

Instead of one grub screw I was thinking of putting in two grub screws.  One on each side of the hub and offset by 90 degrees.  Do you think that this is overkill and one grub screw should be enough?

Vince
Title: Re: Corliss Flywheel
Post by: Jo on July 31, 2014, 07:24:53 AM
Have you thought of using a key ?

Jo
Title: Re: Corliss Flywheel
Post by: pgp001 on July 31, 2014, 08:47:58 AM
I agree with Jo.
When did you ever see a full size engine with a flywheel secured by a grub screw  :ThumbsDown:

OK for vee belt pulleys etc but not in keeping with a steam engine model, it makes me cringe when I see cross head screws etc on models.

Having said all that, you might be surprised to learn that the flywheel on Agnes is actually "located in position" using no less than eight grub screws which bear down onto the four flat keys.
These are buried in the middle of the flywheel hub and can only be accessed down the holes where the spokes fit, so will never be seen again once it is all assembled.

Phil
Title: Re: Corliss Flywheel
Post by: vcutajar on July 31, 2014, 09:24:56 AM
Thanks Jo and Phil.

If I use grub screws they will eventually be hidden.  If I use a key, wouldn't the flywheel still be able to move sideways?

Vince
Title: Re: Corliss Flywheel
Post by: pgp001 on July 31, 2014, 01:11:37 PM
Vince

This type of key is used for holding the flywheel on many old engine crankshafts, the taper locks the two together very efficiently, and would look a lot better than modern grub screws.
http://www.technifast.co.uk/documents/Page34GibHeadKeys.pdf

http://www.oldmarineengine.com/discus/messages/5/2215.gif

Google "Gib Key"

Phil
Title: Re: Corliss Flywheel
Post by: Ian S C on July 31, 2014, 02:54:47 PM
When I rebuilt a Stuart Turner S9, I used a gib head key as the sole means of attaching the flywheel to the crankshaft.
On my hot air/Stirling Engines I fit the flywheels, and pulleys with two set screws at 90*, and these are usually brass screws so that they don't damage the shaft, they are done this way as the pulleys are changed often, and the flywheel is taken off when the motor is transported.  They are not scale motors, but motors in there selves, ranging from 3/8" bore, to 2 1/4" bore, and flywheels from 2" dia, to 6" dia, the heaviest around 900gm.  A bit OT I suppose, but that's me and flywheels.   Ian S C
Title: Re: Corliss Flywheel
Post by: arnoldb on July 31, 2014, 04:52:16 PM
I used two M3 grub screws on my Corliss flywheel.  The holes aren't particularly noticeable.  As the flywheel is relatively large and heavy I went for two instead of just one for added security.  I made them either side of the flywheel hub, but in-line, so that tightening them up wouldn't slightly "twist" the flywheel and make it run with a wobble...

Kind regards, Arnold
Title: Re: Corliss Flywheel
Post by: vcutajar on August 01, 2014, 04:53:38 AM
Thanks guys.

Vince