Author Topic: Double acting Double cylinder Oscillator  (Read 9519 times)

Offline 10KPete

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Re: Double acting Double cylinder Oscillator
« Reply #195 on: June 15, 2018, 03:29:43 AM »
The 'ghost' model you posted there is exactly correct, Brian. Just like that...

Pete
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Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline sbwhart

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Re: Double acting Double cylinder Oscillator
« Reply #196 on: June 15, 2018, 05:56:26 AM »
Very smooth runner and nice and slow Brian very nice engine indeed. Are the port caves running together both ally. I have some drawings of a reversing valves for engines that Iíve made if you want i can mail them

Stew

Stew--Not sure what you mean by "port caves". The frame is aluminum and has port passsages drilled in it. The rocking cylinders are cast iron and have the mating ports drilled in them, in typical wobbler fashion.---Brian

It was a predictive text error Brian it should read Port Faces, but you've answered the ? thank you, I think I have your email address so drawings will be sent that way.

Stew
A little bit of clearance never got in the way

Offline Jasonb

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Re: Double acting Double cylinder Oscillator
« Reply #197 on: June 15, 2018, 07:11:53 AM »
Simple piston valve would seal a lot better than your lever design Brian, take a look at Peter's (Gas Mantles) post a few days ago about how an engine reversed.

Muncaster also shows a simple reversing valve for his wobblers.

Offline NickG

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Re: Double acting Double cylinder Oscillator
« Reply #198 on: June 15, 2018, 07:30:53 AM »
It took me a while to figure out too, but came to same conclusion Brian, model looks correct.


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Offline Ramon

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Re: Double acting Double cylinder Oscillator
« Reply #199 on: June 15, 2018, 07:58:14 AM »
'Morning Brian,

I'm sure you have it as mine is as far as I can remember. The two connections either side are not in line vertically, the two outlets are.

It will act as a throttle but only over a very small radial movement - it soon allows a full flow of air through so perhaps a secondary valve on the inlet side might be in order for a more varied throttle control.

Glad to be of help - Tug
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Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #200 on: June 15, 2018, 04:11:24 PM »
Thanks to Raymon in the United Kingdom for sharing his rotary reversing valve design with me. I will probably build this. It only consists of two pieces plus the center pivot and handle.
« Last Edit: June 15, 2018, 04:33:53 PM by Brian Rupnow »

Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #201 on: June 15, 2018, 10:42:16 PM »
I had hoped to start on this reversing valve today, but life got in my way. Had to take good wife out to buy a new patio umbrella, which turned into a patio umbrella and two wicker patio chairs. Then had to wash the rear deck before we could put the new chairs on it, then had to dismantle the old patio umbrella-----anyways, you get the idea. I did stop at my metal suppliers and check out a piece of 660 bronze to make the reversing valve out of, but decided that for $42 (which was the asking price) I could use a piece of aluminum I already have for the dark blue part and some brass that I already have for the round reddish colored part. That dark blue piece is 3/4" thick, and has more holes and passages in it than Mamoth Cave. My original plan was to have that round reddish colored piece 3/8" thick, however since I have 1/4" brass plate I may end up soldering two pieces of 1/4" plate together and make it 1/2" thick. I'll figure that part out when I get to it.

Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #202 on: June 16, 2018, 10:55:50 PM »
Work is progressing on the reversing mechanism. The first plate with all of the passages in it is finished, all except for the area at the top where the blue layout dye is. That will be filed to match the contour of the rotary plate which I hope to make tomorrow.  A search of my brass drawer yielded a piece of brass 1/2" thick so at least I'm not going to have to laminate two pieces of 1/4" brass together like I originally thought.

Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #203 on: June 17, 2018, 02:20:38 AM »
Ramon--I'm going to tell you how I think your valve goes together. If I get it all right, then great. If I haven't got it right please speak up. The steel pivot shaft fits into the brass block from the far side, with the red o-ring under it's head. Probably the o-ring and the head set in a counterbore on the back side of the brass block. The o-ring isn't there to seal as much as it is to create a bit of pre-load between the face of the brass block and the face of the disc with the slots milled into it's face. This disc with the slots has a partial bore to fit the smaller "step" in the center of the pivot shaft. It also has a thread to match the thread on the end of the pivot shaft. The pivot shaft is restrained from turning (slot in far end for screwdriver maybe) and the disc with slots is tightened onto the thread until a fairly good pre-load is arrived at (from the crush resistance of the o-ring setting under the head). Enough thread on pivot shaft sticks out past outside of disc with slots to allow a hex nut to be threaded on, which acts as a lock nut to prevent the disc from unscrewing as it is swung back and forth to reverse the engine. I see that you have relieved the area on the brass block that is not part of the "mating face" and that you have a ring of material on the "disc with slots" that fits down around the mating face on the brass block. I think that is more cosmetic than a sealing lip, but I'm not sure. The o-ring will also seal any pressure trying to sneak back around the pivot shaft and escape out the back side.--Is this about right?---Brian

Offline Ramon

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Re: Double acting Double cylinder Oscillator
« Reply #204 on: June 17, 2018, 06:20:17 AM »
Morning Brian, Yes you have that dead right  :ThumbsUp:

As you say the lip on the disc is not important and can be done away with - the rest of it is as you describe.

I'm off early for a day at a model show so will look in tonight to see how you got on. Apart from the odd look on here I've had little to say for some time - pleased to say that hopefully the causes are at an end and I'll be back in the workshop this week  :)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #205 on: June 17, 2018, 02:47:15 PM »
Thanks Raymon--You are a great guy for sharing this knowledge.---Brian

Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #206 on: June 17, 2018, 04:42:10 PM »
This morning I finished the reversing disc. In the "set up" picture you can quite easily see that the slot on one side was cut with a 4 flute endmill that was duller than a hoe. The other side was cut with a new 2 flute carbide endmill. And of course, the all finished shot. Now I have to go and take two grandchildren to a live play of "Cinderella" at our community theater. I liked the Grimm's fairytale version where the ugly stepsisters cut off their toes with the axe to try and get the slipper on.--Might not set well with todays audience though, I suppose.


Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #207 on: June 18, 2018, 08:41:28 PM »
Today I successfully completed my first reversing valve. These valves are not difficult to build, but the set-up is a bit fussy so that the valve doesn't have any major air leaks. A gentleman in the United Kingdom was kind enough to send me a picture of a disassembled reversing valve that he had built, and that served as the basis for my design. Thank you, Raymon. The video shows me operating the reversing valve, and I must say, I am very pleased with it.
« Last Edit: June 18, 2018, 09:05:29 PM by Brian Rupnow »

Offline NickG

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Re: Double acting Double cylinder Oscillator
« Reply #208 on: June 18, 2018, 09:18:38 PM »
That is working great Brian, I think these can be operated by solenoids for boats etc. I have a question though, do you think there is a leak somewhere? Itís sounds a bit hissy compared to your previous video where I could hear a much more distinct exhaust beat.


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Offline Brian Rupnow

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Re: Double acting Double cylinder Oscillator
« Reply #209 on: June 18, 2018, 09:51:08 PM »
Yes, it's a bit hissy. The "hissy" is happening between the mating faces of the rotary disc and the reversing valve. They should have been lapped better.