Author Topic: "Robby" Roberts Straight Line Mechanism engine finished  (Read 5141 times)

Offline tvoght

  • Full Member
  • ****
  • Posts: 1001
  • Indiana
"Robby" Roberts Straight Line Mechanism engine finished
« on: April 30, 2016, 05:23:39 PM »
While the build log for Robby, my Roberts Straight-Line Mechanism engine, is in a somewhat unfinished state,, the engine is essentially finished. I showed it at NAMES last weekend.

Here are some shots of the engine.







And video:

<a href="https://www.youtube.com/watch?v=x3nB2itmFlo" target="_blank">http://www.youtube.com/watch?v=x3nB2itmFlo</a>

I'm painfully aware of every little (and big) flaw in the engine , but I'm overall pretty happy. I hope you like it.

Thanks for watching,

--Tim

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #1 on: April 30, 2016, 06:07:09 PM »
Very neat Tim!  That motion is interesting, different than the usual steam engine.
Thanks for sharing the video.  Not as good as seeing it in person at NAMES of course, but since most of us couldn't see it there, the video is great!
Kim

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 6133
  • Switzerland
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #2 on: April 30, 2016, 07:50:59 PM »
Very nice  :praise2:  :praise2:

it's an interesting varient of the Watt parallel linkage for the piston rod guide.
Best regards

Roger

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6811
  • West Chester, PA, USA
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #3 on: April 30, 2016, 07:59:10 PM »
Very interesting. I hadn't seen anything like that before.

Thanks for posting.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline philjoe5

  • Full Member
  • ****
  • Posts: 1012
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #4 on: April 30, 2016, 09:02:52 PM »
Tim,
Thanks for sharing your work.  As I said to Art K on his recent visit, this is a unusual mechanism which appeals to me.  Should you ever decide to make plans available for it count me in.  You did a great job finishing this engine. :ThumbsUp:  I apologize if I missed it somewhere but how did you accomplish that neat lettering?

Cheers,
Phil
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13860
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #5 on: May 01, 2016, 12:47:21 AM »
That is beautiful Tim. If there are any flaws the are well hidden. The finish looks lovely and it runs very smoothly. Nicely done!!!

Bill

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 4693
  • Boise, Idaho USA
    • Photo Bucket
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #6 on: May 01, 2016, 12:57:46 AM »
Very nice Tim!

I'm glad that I got it see it in person; it runs as nice as it looks! Also enjoyed being able to visit with you again.

Dave

Offline Don1966

  • Full Member
  • *****
  • Posts: 6817
  • Columbia, MS
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #7 on: May 01, 2016, 02:48:55 AM »
Gorgeous engine Tim and runs a treat, well done bud...... :praise2:


Don

Offline fumopuc

  • Full Member
  • *****
  • Posts: 3231
  • Munich, Germany, EU
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #8 on: May 01, 2016, 07:46:44 AM »
Hi Tim, it is fun to watch the motion. Nice engine very well made.
Kind Regards
Achim

Offline tvoght

  • Full Member
  • ****
  • Posts: 1001
  • Indiana
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #9 on: May 03, 2016, 09:51:57 PM »
Thanks to everybody who commented.

Phil, the lettering on the steam chest cover was engraved using the CNC mill. I used open source software called f-engrave to generate the g-code.

Tim

Offline vcutajar

  • Full Member
  • *****
  • Posts: 2555
  • Marsascala, MALTA
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #10 on: May 04, 2016, 05:05:07 AM »
Congratulations.  Very, very nice Tim.

Vince

Offline gbritnell

  • Full Member
  • ****
  • Posts: 2460
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #11 on: May 04, 2016, 12:19:31 PM »
Hi Tim,
Great looking and running engine. I'm sorry I didn't get to see it running at NAMES but I hardly had time to look at anything.
gbritnell
Talent unshared is talent wasted.

Offline tvoght

  • Full Member
  • ****
  • Posts: 1001
  • Indiana
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #12 on: June 26, 2016, 05:42:27 PM »
Well, it seems I forgot to thank Vince and George for comments. Thanks guys.

I never wanted to take the time to produce a full set of drawings for "Robby",
but I was inspired to learn 3D CAD when I discovered OnShape. I think it was
someone on this forum who suggested it.

(OnShape is a 3D CAD program which operates "in the cloud" and doesn't require
any software on the user side except a modern web browser).

I've now managed to create a 3D model of the engine in 45 parts, not including
fasteners. Unfortunately, that still leaves undone the task of creating 2D
PDF drawings, which would be (I think) the preferred method for distribution
on the forum.

The creation of undimensioned 2D drawings in DXF would be trivial, but the task
of dimensioning them is largely manual and doing it well and properly requires
time and skills I don't really have.

I have made the 3D model public on the OnShape site, and anyone can access it
there.

Here is a link to the OnShape document. I'm pretty sure you don't need an
OnShape account just to view it.

https://cad.onshape.com/documents/576dae70e4b0cc2e7f468d75/w/b5ce5fc2ab3e5ffbb7388406/e/eaa5728c2260a854c8039794

OnShape users are free to make a copy, and do as they wish with it, including
modifying it for their own uses.

If you don't wish to use OnShape, but don't mind signing up, you could sign up
(free), grab a copy of my public document, and export it in a 3D format that's
usable in your own 3D CAD program.  It appears supported export formats are
Parasolid, ACIS, STEP, IGES, Solidworks, STL, and Rhino.

Hope this is interesting or helpful to someone,

--Tim

Offline Hugh Currin

  • Full Member
  • ****
  • Posts: 720
  • Box Elder, SD, USA
    • www.currin.us
Re: "Robby" Roberts Straight Line Mechanism engine finished
« Reply #13 on: June 27, 2016, 12:13:20 AM »
Tim:

First, nice design and build. I hadn't been following the build log carefully, but will have to go back. A quick glance shows a lot of good information on tips and set-ups. Thanks. I do hope you finish up the build log.

Also thanks for the f-engrave link. I see this will run under Linux so I'll give it a try. I used to have an engraving scheme, two or three programs if I remember, but the process has been lost to my bad memory. I'll dig into this when I again need to do some engraving. The program, and the results, look nice.

As for plans, I'm not sure what's needed. If good 2D DXF drawings where provided the dimensions are there for the taking. No tolerances are available but those aren't common on model engine drawings anyway. The critical dimensions are usually apparent and with an instruction sheet describing real critical ones, like press fits etc., it would be workable. 2D DXF also allows shapes to be pulled out to a CAM program. I'm not as familiar with 3D and especially OnShape. The same may be true if accuracy were maintained through export to say IGES. In my program, VariCAD, it's harder to pull out 2D drawings which might be needed.

In a way it's leaving the 2D creation (from 3D) and/or dimensioning (of 2D) up to the builder. Many times I'll draw in 2D and print out without dimensions, then pencil in dimensions before I go to the shop. So while dimensioned drawings are nice an un-dimenioned set of DXF drawings would be workable, and a lot easier for the designer. I haven't seen a discussion of this anywhere.

Thanks.

Hugh
Hugh

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal