Author Topic: Potty Grasshopper steams into life  (Read 2822 times)

Offline Gas_mantle

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Potty Grasshopper steams into life
« on: September 08, 2017, 06:50:04 PM »
Hi,

I finally finished my Grasshopper engine so here are a few photos of the end result along with a short video of it running on steam.

For those unfamiliar with the engine it's a double acting half beam 'Grasshopper' engine made from a design by Stewart Hart who kindly supplied me with the plans. It's a bar stock engine that uses the same cylinder and valve chest as Stewarts other 'Potty' series engines.

It is predominantly steel construction with an aluminium cylinder / valve chest and a brass piston with graphite corded piston rings. I decided to scale up Stewarts original by 50% so it is approx. 1" bore x 13/4" stroke, the flywheel is 10" diameter. It weighs a rather hefty 30lbs.











Here it can be seen running on steam, with a strong wind outside and my gas tank getting low my little boiler was struggling to cope but you at least get the idea :-)

<a href="https://www.youtube.com/watch?v=W3tvB7WwxJA" target="_blank">http://www.youtube.com/watch?v=W3tvB7WwxJA</a>

Lastly I'd like to thank those of you who offered your support and advice on my build log of this engine.

A special thanks also to Stew Hart for designing the engine and supplying me with the plans and to forum member PGP001 who helped me out in machining the flywheel that was too large to fit in my lathe.

Cheers  :)
Peter



« Last Edit: September 08, 2017, 06:59:00 PM by Gas_mantle »

Offline Ye-Ole Steam Dude

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Re: Potty Grasshopper steams into life
« Reply #1 on: September 08, 2017, 07:12:44 PM »

Hi Peter, left you a  :ThumbsUp: on Youtube. Great looking engine.

Thomas
Thomas

Offline b.lindsey

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Re: Potty Grasshopper steams into life
« Reply #2 on: September 08, 2017, 07:15:50 PM »
Gorgeous Peter, and even more impressive under steam power!!

Bill

Online Jasonb

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Re: Potty Grasshopper steams into life
« Reply #3 on: September 09, 2017, 08:39:59 AM »
That's a nice slow steady runner, you must be doing something right :)

Was that with your new boiler or are you still waiting?

Offline Gas_mantle

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Re: Potty Grasshopper steams into life
« Reply #4 on: September 09, 2017, 10:16:25 AM »
Thanks guys, I really enjoyed making it and learnt a lot on the way. I've made a start on the V twin as featured in the Uk 'Model Engineer' magazine but looking also for something else to build at the same time.

It's running in the video on my little 3" dia vertical boiler but the gas was getting a tad low so it's struggling to maintain pressure hence the short video. It does actually run a lot better and can maintain something like 150 rpm and will also run as low as about 40 rpm. I expect to have my new 5" boiler in about 6 weeks and will make a better video of it running properly on coal once I have it  :)

It's not a very good photo but here is the boiler and temporary plumbing I used for testing.



Peter.


Offline pgp001

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Re: Potty Grasshopper steams into life
« Reply #5 on: September 09, 2017, 11:24:29 AM »
Spot on Peter, you should be very proud of that.

Phil

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Re: Potty Grasshopper steams into life
« Reply #6 on: September 09, 2017, 11:31:30 AM »
Nicely done Peter!

Question?    The brown stuff ...what did you finish it with?...and how well does it hold up to steam/hot condensate ?


Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Gas_mantle

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Re: Potty Grasshopper steams into life
« Reply #7 on: September 09, 2017, 11:39:55 AM »
Thanks guys  :)

The wood is Sapele and I just varnished it with yacht varnish that can be bought in any hardware store.  It stands up to steam very well - I just wipe it down with a cloth and there doesn't seem to be any damage.

I did initially think of adding a brick pattern using a stencil and a compound (as on dolls houses) but I want to run this on steam now and again so varnished wood seemed a better option.

Peter.

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Re: Potty Grasshopper steams into life
« Reply #8 on: September 09, 2017, 12:03:39 PM »
Thanks guys  :)

The wood is Sapele and I just varnished it with yacht varnish that can be bought in any hardware store.  It stands up to steam very well - I just wipe it down with a cloth and there doesn't seem to be any damage.

I did initially think of adding a brick pattern using a stencil and a compound (as on dolls houses) but I want to run this on steam now and again so varnished wood seemed a better option.

Peter.

NO NO   I really like the wood!   I just wondered about the finish!    The cockpit floor boards in my launch are from a wood called "Massa anduba" ( spelling?)  anyway   it's about as hard as woodpecker lips and is a deep caramel color...a good bit darker than the sapele...though I would have swore that was mahogany.     Anyway...M A  holds up well to sand and crap ect with just a good varnish, but it's hard to work

 :ThumbsUp:
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline crueby

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Re: Potty Grasshopper steams into life
« Reply #9 on: September 10, 2017, 01:56:04 AM »
Woodpecker lips???   :ROFL:

Another interesting wood to use for a Mahogany look is Spanish Cedar - after varnishing it looks a lot like Mahogany. I used it on the deck of a small sailboat to get the look but not the wieght of Mahogany. I've used Sepele  for several projects, makes very sturdy and stable furniture, looks terrific, and is available is very wide knot free boards. Made a fantastic base for your model!

Offline sbwhart

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Re: Potty Grasshopper steams into life
« Reply #10 on: September 10, 2017, 07:39:46 AM »
Hi Peter

 I'm  little late to see this. A great result I think this is the first time one has been in steam thanks for showing

Stew
A little bit of clearance never got in the way

 

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