Author Topic: Stuart Beam Engine in Diorama  (Read 16021 times)

Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #390 on: September 13, 2017, 08:17:52 PM »
The east wall is being laminated. It has a core of 1/4" hardboard and two outer skins of 1/8" hardboard, thus creating a recess all round the opening.

Hopefully I have anticipated its size properly when everything comes together later.
 


Offline J.L.

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A Nut Cutting Jig
« Reply #391 on: September 17, 2017, 02:44:33 PM »
Back to the links.

I have found that the model engineering #8-32 were very much out of scale for fastening the links. Theh were as thick as the link bosses.

A simple solution was to thread a piecce of 3/16" rod and make a cutting jig. The carriage was locked in place with the first nut cut, so that all subsequent nuts would be of the same thickness.


Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #392 on: September 17, 2017, 02:57:56 PM »
Because the supplied nuts were exactly the distance indicated by the drawings, they were threaded onto the ends of the link axles and used as a guide for the parting tool.


Offline J.L.

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Clearances
« Reply #393 on: September 17, 2017, 07:39:27 PM »
I am finding that the collar thicknesses indicated on the drawings are just not working for me at all.

I'll bet I'm not the first person to note this. It will be a lengthy, but interesting process to keep thinning the parts down so that they will  pass each other without jamming. The thickness of the nuts may also have to be thinned.

Good thing I didn't throw that nut cutting jig away.  ;)

I guess that's what they payed the fitters for with their files back in the day...  :D


Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #394 on: September 18, 2017, 03:32:09 PM »
The game begins with hooking up and getting everything aligned...

Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #395 on: September 19, 2017, 01:28:05 PM »
When a nut is threaded onto each end of a pivot axle, I'm finding it very important to have them bear up against a crisp shoulder to stop them and not let them bind the links on the axle.

So I'm undercutting the threads at the shoulder so that a nut will draw up and stop. It is then easier to measure exactly how to long to make the free movement on the axle with a whisker of clearance.

When the nuts are put on each end of the axle and snugged up,  they don't work loose  and let the links rotate freely on the fixed axle.

Basic stuff for most, but I'm enjoying learning this stuff as I go along.  ;)


Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #396 on: September 20, 2017, 11:52:31 AM »
Geometry was never a strong suit for me in high school. In searching out an explanation for Watt's parallel motion, I understood the first part of the Watt's 1784 motion here:

https://en.wikipedia.org/wiki/Parallel_motion

But apparently a much better system was developed in 1864. The moving diagram is excellent but the geometric explanation..

https://en.wikipedia.org/wiki/Peaucellier%E2%80%93Lipkin_linkage

Hopefully, I can get my linkage working today.




Offline tvoght

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Re: Stuart Beam Engine in Diorama
« Reply #397 on: September 20, 2017, 12:53:42 PM »
Geometry was never a strong suit for me in high school. In searching out an explanation for Watt's parallel motion, I understood the first part of the Watt's 1784 motion here:

https://en.wikipedia.org/wiki/Parallel_motion

But apparently a much better system was developed in 1864. The moving diagram is excellent but the geometric explanation..

https://en.wikipedia.org/wiki/Peaucellier%E2%80%93Lipkin_linkage

Hopefully, I can get my linkage working today.

John,
I've mentioned it here before, but this is a good time to mention again, a charming little book on such linkages from 1877:

How to Draw a Straight Line: A Lecture on Linkages
  by: A.B. Kempe

It is availabe free online from Project Gutenburg:

http://www.subdude-site.com/WebPages_Local/RefInfo/eDocs/Math_edocs/docs/OnLinkages_A-B-Kempe_1877_63pgs.pdf

I thought you or others might enjoy it.

--Tim

Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #398 on: September 20, 2017, 10:09:16 PM »
Thanks Tim.

Things need to be cleaned up a bit, but here are some shots of Watt's paralllel motion mechanical linkage.

I made a video of trying it manually by rotating the flywheel for YouTube, but alas something has gone wrong with my upload.


Online wagnmkr

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Re: Stuart Beam Engine in Diorama
« Reply #399 on: September 20, 2017, 10:41:35 PM »
It looks ... err ... parallel :lolb:

Good Job John. I wasn't looking forward to that part.

Tom
I was cut out to be rich ... but ... I was sown up all wrong!

Offline steam guy willy

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Re: Stuart Beam Engine in Diorama
« Reply #400 on: September 21, 2017, 12:10:21 AM »
Watt i find odd about his parallel motion is that nearly every engine i look at has the Radious reach rod in a different place !!!  Watts parallel motion ? Is that a two seater privy ?!!!!!

Online b.lindsey

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Re: Stuart Beam Engine in Diorama
« Reply #401 on: September 21, 2017, 12:18:00 AM »
It sure is looking good John. Will be even better with the diorama framing it!!

Bill

Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #402 on: September 21, 2017, 06:07:00 PM »
Hi Bill,

Thanks!

Here is a picture of those cross dowels I was mentioning to allow the walls to be quickly dismantled.

And also a sneak  peek at those walls in the rough.

I must get bak to the engine now and put it back together!

Cheers...John

Offline J.L.

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Re: Stuart Beam Engine in Diorama
« Reply #403 on: September 21, 2017, 08:59:40 PM »
Here is that test video I made of the linkage:



Offline crueby

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Re: Stuart Beam Engine in Diorama
« Reply #404 on: September 21, 2017, 09:25:24 PM »
Very nice and smooth working! 

 :popcorn: