Author Topic: Roberts straight line linkage  (Read 951 times)

Offline SwarfnStuff

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Roberts straight line linkage
« on: December 08, 2016, 01:39:30 AM »
Hi All,
  Stumbled across this on YouTube and, thinking it rather unusual and a possible future project (maybe) I wondered if anyone has seen or made one. https://www.youtube.com/watch?v=x3nB2itmFlo
Fascinating, but I don't seem able to find plans either. Not that that means much, searching for specific plans is somewhat problematic for me and the original poster does not refer to there being any.
Worth a look at the link anyway and I would appreciate your views.
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Offline Ironhorse57

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Re: Roberts straight line linkage
« Reply #1 on: December 08, 2016, 01:55:30 PM »
I haven't seen this set up before - looks interesting but I don't see any advantage in using it over a conventional crosshead & guide

Dave

Offline chipenter

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Jeff

Offline John Stevenson

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Re: Roberts straight line linkage
« Reply #3 on: December 08, 2016, 05:12:32 PM »
Actually got for more moving parts and links to wear out plus not as much bearing surface as a crosshead, so even more wear .
John Stevenson

Offline SwarfnStuff

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Re: Roberts straight line linkage
« Reply #4 on: December 09, 2016, 12:38:21 AM »
Thank you for your responses. All appreciated.
  Dave, possibly no advantage whatsoever. Just as I said fascinating, and, as a model could be interesting.
  Jeff, thank you for the link. It contained useful info and well worth the read.
   John S, I agree, but still fascinating.
  Perhaps it's my curiously twisted brain but quirky = interesting and, let's face it if I ever build it into an engine model it is just for that reason, interest. As for wear, models typically run for minutes at a time and therefore unlikely to wear out in my remaining years.
 I assume many of these linkages were invented to circumvent patents on existing crosshead or parallel linkage designs. Or, perhaps were the precursor.
   Anyway, following Jeff's web link. Since Robertson lived (1789 - 1864). His design seems to be somewhere between his birth and 1852 when his firm collapsed.
       My Guess, from the dates in Wikepedia somewhere between Watts' Linkage 1784, and Chebyshev's 1878
    All interesting but not essential to messing about in the shed.
Thanks again.
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Offline S. Heslop

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Re: Roberts straight line linkage
« Reply #5 on: February 23, 2017, 08:02:14 PM »
I think the advantage would be that rotary joints are much easier to make accurately than linear slides. I imagine crossheads and guides would've taken some effort and machinery to make in the days before flat bar stock, where as for this you can just cast the beams and only worry about the ends.

Offline SwarfnStuff

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Re: Roberts straight line linkage
« Reply #6 on: February 25, 2017, 12:02:59 AM »
It just so happens that one of the chaps in my local model engineering club is actually building one of these.
   All my fault for sending him the info.  :lol: 
So far he is happy with his progress, so here's waiting.

   Hopefully I will be able to get some pics or even better video to post in due course.
   
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)