Author Topic: Woody - but not quite a Forest  (Read 1375 times)

Offline Jasonb

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Woody - but not quite a Forest
« on: June 09, 2019, 02:23:39 PM »
I have always liked the look of the Forest engine reproductions that Wayne Grennings produced and thought that I might have a go at a smaller one myself. Chances of getting the non compression carrier flame ignition to work at the smaller sizes even if I could make up a suitable cocktail of gasses was slim but I thought it may work as a flame licker using the proven mechanicals of my Chuky and Alyn Foundries Chuk as a basis.



Graham from Alyn had said that it would not be easy and he was right, I could not get it to run due to a few factors. Firstly the Evan's beam linkage of the crankshaft adds more drag, you can't easily get a clean flame with the shutter rods etc directly above and the biggest problem was with the can being so close to the shutter it tended to push it off the port face.

I had always had it in the back of my mind that if I could not get it to run as a flame licker it may be possible to convert to an air/steam engine with poppet valves much like the Jowitt engine I made a while ago. Even this was going to be difficult due to the lack of room so a couple of weeks ago I decided that a spool valve may work and made up the various part which resulted in a running engine.













It will run even slower than this but starts to get a bit jerkey as it is only single acting, at this speed it will run for at least 20mins on my small compressor without the tank needing to refill so not too noisy to run. It was an interesting project with a few more first crossed off the list such as first spool vale, first Evans bean and first spiral cooling fins.


Another successful project for the Red Devil and Green Dragon combination

J
I won't do a full build thread but will in coming posts describe the major bits
« Last Edit: June 09, 2019, 02:27:13 PM by Jasonb »

Offline b.lindsey

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Re: Woody - but not quite a Forest
« Reply #1 on: June 09, 2019, 02:40:53 PM »
Fine looking engine Jason with some unique characteristics as well like the spiral fins!!  Well done.

Bill

Offline Brian Rupnow

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Re: Woody - but not quite a Forest
« Reply #2 on: June 09, 2019, 03:22:51 PM »
Jason--That is just beautiful. Amazing machining and paint job. You are a credit to all model engine machinists.---Brian

Offline Dave Otto

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Re: Woody - but not quite a Forest
« Reply #3 on: June 09, 2019, 03:59:44 PM »
What a cutie!
Beautiful work Jason.

Dave

Online Twizseven

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Re: Woody - but not quite a Forest
« Reply #4 on: June 10, 2019, 12:53:42 PM »
Jason,

Lovely work as usual.  What I want to know is how do you find time to go to work, let alone do any family/home related stuff.  Do you work 24hrs a day?

Colin

Offline Chipmaster

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Re: Woody - but not quite a Forest
« Reply #5 on: June 10, 2019, 07:12:37 PM »
Very nice complete with a superb finish.

Andy

Offline Jasonb

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Re: Woody - but not quite a Forest
« Reply #6 on: June 10, 2019, 07:51:46 PM »
Thanks for all the comments, on with the build.

The base plate was bandsawn from some 16mm 6082 plate and the two long edges flycut to size. Then with the plate held horizontally in the vice the two ends were squared up.



Then a full 12mm height x 1mm deep pass all around formed the rebate, I used a 2-flute aluminium specific cutter which gave a nice finish.



Then using a set of co-ordinates taken from my Alibre drawing the convex part of the ogee moulding was cut in 0.5mm vertical increments around the four straight edges





Luckily I had a ball nose cutter which meant that the concave part of the moulding was a lot quicker to cut.



While still in the vice the various holes were drilled and tapped, the smaller blind holes with a spiral flute tap and the M8x1 through hole with a spiral flute which just pushed the long spirals of swarf out the bottom of the hole and no need to keep backing off the tap to break the chips.



The base was then transferred to the rotary table to round and mould the corners, I decided to do every other cut on these.



It was then just a case of blending the stepped cuts into a nice flowing shape with files followed by some Emery cloth.



The two lugs for the Evans beam to pivot on were worked onto either end of a small length of brass.



Then sawn off and rounded over, again on the rotary table.


Offline Zephyrin

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Re: Woody - but not quite a Forest
« Reply #7 on: June 11, 2019, 08:25:19 PM »
Wow, beautiful model !
The original gas engine had a rotary valve in the cylinder head, as your engine uses air, such valve could be used.
I'm anxiously waiting for the spiral fins machining...

Offline Jasonb

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Re: Woody - but not quite a Forest
« Reply #8 on: June 11, 2019, 08:41:51 PM »
Thanks for that do you know what date it is from?

The one I based my model on was the 1883 slide valve 1/15HP engine, if I were making it again from scratch the exhaust would come out of the valve block rather than the one I made to suit the flame licker engine. The air does come out of a hole in the top of the valve block so most of the way there.

Details of the one I based it on here https://sites.google.com/site/grenningmodelscom/1883-forest-slide-valve-engine-reproduction

Offline 10KPete

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Re: Woody - but not quite a Forest
« Reply #9 on: June 11, 2019, 11:04:11 PM »
Jason,
Your pics have not been showing up lately. All I see is a box from PhotoBucket saying "Oops, your image was linked incorrectly. Please visit your account for the correct link".
Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline crueby

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Re: Woody - but not quite a Forest
« Reply #10 on: June 11, 2019, 11:26:52 PM »
All pics have been showing fine for me...  :shrug:

Offline b.lindsey

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Re: Woody - but not quite a Forest
« Reply #11 on: June 12, 2019, 01:01:20 AM »
Working for me too.

Bill

Offline Jasonb

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Re: Woody - but not quite a Forest
« Reply #12 on: June 12, 2019, 07:16:02 AM »
All look OK for me too both here and on another forum where I posted the same. PB was a bit slow the other day so maybe not showing if you only looked then.

Offline Zephyrin

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Re: Woody - but not quite a Forest
« Reply #13 on: June 12, 2019, 02:17:31 PM »
I took these pictures in an expo on Fernand Forest a few years ago near Paris, in Suresnes, where Forest was born.  it was figures of a patent of 1882 for a gas engine.
I have not yet succeed to obtain a copy of the patent.
Note that the cylinder head also has spiral fins !
I have some more details :

Offline Jasonb

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Re: Woody - but not quite a Forest
« Reply #14 on: June 12, 2019, 03:36:49 PM »

Note that the cylinder head also has spiral fins !

And tapered ones at that :o, looks like the whole head is tapered to match the internal taper which is what gives the "fit" or the rotating valve in the head much like you find on drain cocks.