Author Topic: Stephenson's Rocket  (Read 28574 times)

Offline sid pileski

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Re: Stephenson's Rocket
« Reply #120 on: June 02, 2020, 01:54:22 AM »
Brian- are you going to quarter the drive axle, I assume?

I notice in the model they are not.

Sid

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #121 on: June 02, 2020, 02:32:48 PM »
the drive axle will be one piece.

Offline crueby

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Re: Stephenson's Rocket
« Reply #122 on: June 02, 2020, 02:36:33 PM »
The crank pins should be 90 degrees offset from each other though, otherwise it wont self start.

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #123 on: June 02, 2020, 07:31:55 PM »
I know that Chris, but thank you for the information. Always helps to have a second pair of eyes on a design.---Brian

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #124 on: June 03, 2020, 01:20:26 AM »
I spent far too much of today getting the cylinder assemblies  to extend and retract when connected to the cross-head guides. In all honesty, I don't think I would recommend this style of cross head guide system. With the offset between the cylinder rod and the two cross-head guide rods, there is simply too much binding. I ended up having to o-ring one piston. My intent here was to use no o-rings, just a couple of oil retention grooves in the pistons. The best cross-head guide system I have seen is the one used on the Cretors Popcorn engine, where there is no offset involved. By the end of the day I had both cylinders extending and retracting while attached to the cross-head guides, but it was a hard fought battle.

Offline Jasonb

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Re: Stephenson's Rocket
« Reply #125 on: June 03, 2020, 07:41:43 AM »
Usually the cross head is a lot longer so less likely to twist and lock up, take a look at the photo George posted on page 2 or 3 and you will see that it is about 3 times longer than yours.

It's quite common to have the guide off to one side, often in the form of a flat guide channel rather than a rod like you have, this sort of thing



But you can see that the guide part is a lot longer than the offset


Offline crueby

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Re: Stephenson's Rocket
« Reply #126 on: June 03, 2020, 01:37:42 PM »
I found some pictures of the original Rockets crosshead in the Glithero book,. It had square cross section bars, each turned 45 degrees, with the crosshead bolting over in two pieces. Its crosshead was short, and showed severe wear from the twisting and rocking forces. As an early engine, they had not yet learned to make the crosshead longer to handle being offset.

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #127 on: June 03, 2020, 06:42:24 PM »
Both cylinder assemblies mounted to cross bar of test fixture. I can't do any more now until I go and buy some material.

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #128 on: June 04, 2020, 01:35:07 AM »
Went across town to see my metal supplier and picked up a 1" thick offcut for $5.00 this afternoon. Brought it home and added it to the flat bar which supports the cylinders. I wear a mask my wife made from black cloth material, and every time I see myself in the mirror I think of the Lone Ranger. ---or some other masked desperado. Damn, I hate this covid stuff.

Offline crueby

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Re: Stephenson's Rocket
« Reply #129 on: June 04, 2020, 01:59:52 AM »
The stand looks good, kemosabe!

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #130 on: June 05, 2020, 09:20:43 PM »
The engine test stand is almost complete. About 95% of this stuff is "Pre-engineered" in my 3D cad work.--The other 5% is "make it up as I go along", then go back and update the model and drawings to reflect what I have really done. I have to make up a baseplate to add to the bottom of this stand, and then I'm about ready to begin all of the small pieces which are required to get power to that front "axle". You will notice that the front axle support has a weird shape. It is actually the drive axle support which goes on the train body itself, I just haven't cut the arc yet where it bolts to the underside of the boiler.

Offline steam guy willy

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Re: Stephenson's Rocket
« Reply #131 on: June 06, 2020, 04:11:38 PM »
The stand looks good, kemosabe!

Hi Chris, Yea Kemosabe !!Takes me back 50 years to the 9" black and white  TV set !! ;D

Hi Brian. I also draw out stuff to make., but when I get in the WKSP what actually comes out depends on the tools and materials  the part emerges and then the drawing is modified !!  :popcorn: :popcorn: :popcorn:

Offline Brian Rupnow

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Re: Stephenson's Rocket
« Reply #132 on: June 06, 2020, 07:20:13 PM »
The hole that my front axle sets in was drilled and then reamed to 3/8". When I put the axle in the hole, it was a terribly sloppy fit. I couldn't figure out why my reamer had cut oversize---it never did before. A closer examination this morning showed that I've been METRICED---the 3/8" reamer I had used was a 10 mm reamer, which is 0.394". Don't know what fool put the  metric reamer into the 3/8" reamer stand!!! Then I went to make the eccentrics which attach to the axle, and totally buggered them up. At that point I shut things down and took my good wife out for lunch, then had a walk and an ice cream cone. Now I will take another run at those eccentrics.---

Offline crueby

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Re: Stephenson's Rocket
« Reply #133 on: June 06, 2020, 08:11:14 PM »
Uhoh, sounds like Jo sent over a shop elf to rearrange your tools. Bait a trap with some tea...

Offline Art K

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Re: Stephenson's Rocket
« Reply #134 on: June 07, 2020, 05:06:07 AM »
 
Quote
Uhoh, sounds like Jo sent over a shop elf to rearrange your tools. Bait a trap with some tea...
:lolb: :ROFL:
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

 

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