John Deere Engine

Hi Chuck

I want to get my two cents worth in here. I personally and on behalf of our other members would like to thank you VERY MUCH for sharing and assisting our other members to duplicate YOUR John Deere engine after your hard work of designing and experiencing the pain of modifying and correcting the problems you encountered on the way to the conclusion of the building of this, a mighty fine engine. This is truly an unselfish deed on your part and shows your love of the hobby and towards your "fellow" (if I may use this term Chuck) man. I say this knowing that I myself will never gain enough experience to build this particular project. However I am gaining a wealth of knowledge and learning just seeing and following how these operations are carried out. You can be sure I will be watchfull for more of your projects. - Yours Truly - Billmc

Thanks, Bill. Knowing that others are looking and learning is gratifying.

I also know how much I appreciate seeing and learning from what others are doing. The imagination and talent of people, particularly in model engineering, never ceases to amaze me!

Chuck

Definitely green!

Charlie, really, really :bow: Nice!

Defiantly green.

Glad to see you got the painting done.

Looks like your ready to start another build.

What will it be......

-MB

http://www.youtube.com/v/_0Ea4kzZwYM&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

Charlie,

Very nice indeed :bow: :bow: :bow:

Best Regards
Bob

Charlie, super nice to see your John Deere running! :bow:

I can only imagine how good you must feel watching it run. 8)

Its also very exciting for me, since I'm building the same motor. ;D

Its running very smooth on your bench without any mounting or base. Amazing, its obviously a well balanced motor.

In the fist half of the video it seems you have it running at a slow to moderate pace. Can you tell me what the air pressure was? A slow runner is good and always my goal.

-MB

I had the air regulator set to 50 psi, but the pressure at the engine was something less. 20 psi is about the least pressure it will run on. There are enough air leaks in the engine to be sure the working pressure is less than shown on the gauge.

Charlie

radfordc said:

I had the air regulator set to 50 psi, but the pressure at the engine was something less. 20 psi is about the least pressure it will run on. There are enough air leaks in the engine to be sure the working pressure is less than shown on the gauge.

Charlie

Click to expand...

I have a suggestion for sealing up an engine that your probably already aware of.

I usually put a thin coat of RTV silicone gasket compound on mating parts during final assembly. Its great stuff. It holds on well to seal things up and peels off easily if-and-when things need to come apart.

I bought a tube at Harbor Freight for about $2. Its available in a red and black color.

Thought I would mention this sealing method in case it could benefit someone.

Here's what to look for: http://proseal.supergluecorp.com/80726.html

I guess I'll be using the red! :big:

-MB

The hardest part of the engine to seal up are the valve assemblies. The o-ring does a decent job if the groove is cut right. The groove needs to be a couple of thousandths shallower and about .006" wider than the thickness of the o-ring. It also helps to use oil or a thin grease around the o-ring.

I unpacked my JD engine tonight and checked a few things out. Using a pressure regulator, it does take about 50 psi to run it slowly. I verified that the slave valve springs were as I described earlier. I also checked the valve timing and dwell. The rocker arm makes contact with the valve stem right at top dead center. The valves are open for the full stroke and close right at bottom dead center.

I also ran the engine using a simple ball valve to regulate the air flow. The pressure was 110 PSI from the compressor. The exhaust note using a ball valve at full pressure is somewhat louder and sharper. It's also possible to get the engine to run slower with the ball valve than with the pressure regulator. My theory is that the pressure is higher when the inlet valve first opens then quickly drops as the air flow is restricted. The higher initial pressure overcomes the slave valve spring more readily and the drop in pressure lets the engine run slower. Anybody have any other ideas about this?

I do have a new video of it running that I will upload later.

Chuck

I kept having trouble getting one valve to seal and I always found the o-ring had been cut. I finally realized that the hole drilled for the ball valve that intersects the hole for the poppet valve was the culprit. The sharp edge was shaving off part of the o-ring.

Charlie

Let me start by apologizing for all the toes I'm about to step on.

I worked with O-rings (and quad rings) for about 15 years. This gave me first hand knowledge and experience using these little critters. They are used in a variety of applications to produce inexpensive and effective seals. There development and existence is largely based on a need to control production costs. There usage spans from a small shaft seals all the way to there use on space shuttles.

They can be-and-are used effectively in model engineering applications. And I do not discourage their use. Most sealing areas on the small motors built by members of this forum do not require a seal of any type. And when an area does require sealing an RTV silicone gasket compound is another proper and effective solution. When I built "Chucks Single" I sealed the valve body to the cylinder head using the RTV compound. I could have used two O-rings on opposite ends of the valve body to seal it effectivly.

The precision grooves, surface finishes and diameters required for proper O-ring seals could be somewhat tedious for beginners like me using manual machines. And will add a complication to the machining of certain parts. Consider the effort required to machine two grooves for sealing the cylinder head/block on a twin cylinder motor vs spreading a thin layer of gasket compound, or cutting a paper gasket.

I hope this post reaches at least a few beginners and helps them to understand that there are many ways to archive a goal. And that making changes to engines designed by others to suite their skill level or desire is worth considering, and something I feel worth encouraging.

-MB

Hey MB,

I agree that in many modeling applications, an o-ring is probably overkill. However, in this particular application, I could think of no other way to get an effective seal.

The problem isn't in keeping the air from escaping around the valve assembly flange. Rather, it's to keep the air from leaking from the air inlet chamber to the port which leads to the cylinder and exhaust. There is only a small length of the bottom of the valve assembly between these two openings and an o-ring seemed like the only practical solution.

cfellows said:

Hey MB,

I agree that in many modeling applications, an o-ring is probably overkill. However, in this particular application, I could think of no other way to get an effective seal.

The problem isn't in keeping the air from escaping around the valve assembly flange. Rather, it's to keep the air from leaking from the air inlet chamber to the port which leads to the cylinder and exhaust. There is only a small length of the bottom of the valve assembly between these two openings and an o-ring seemed like the only practical solution.

Click to expand...

Hi Chuck. I don't consider O-rings to be over-kill, they are simply one of the standard industrial approaches to creating a cost effective seal in production environments. I understand where the sealing areas are on the "Deere" head. If a very thin layer is used it would minimize its creep up the valve body creating a clean up around the flange. In theory the contact area of the RTV need not be greater than the contact area of the O-ring. As a mater of fact RTV is specified as an additional precaution under certain conditions by certain manufacturers, and added as an assembly top coat on O-rings. The reason being that a specific surface finish is required for an O-ring to seal. With RTV the surface finish is not a factor.

I don't disagree with your use of O-rings on your build.

I could use a Quad Ring coated with RTV! Now thats over-kill! ;D

-MB

When I finally ruined my 6th o-ring I got fed up and decided to try something else. I turned a piece of delrin plastic to .375 OD and drilled and reamed to .250 ID. I parted off a piece of this tube .063 wide. I then sliced through this plastic ring at an angle. I slipped the ring into the o-ring groove and with alot of effort got it installed in the head. It sealed as well or better than the o-ring. I just hope I don't need to remove the valve body again.

Charlie

An oldie but a goodie & one of my favorite Fellows designs.

I am looking at creating a complete detailed drawing set of this engine & would like any input from anyone here who has built this engine or anyone who can add any constructive input to help me out.

Back in 2008 or 2009, "Radfordc" & some other members here contributed some drawings, pics, & info that have allowed me to complete a detailed 3D model of this engine & would like to complete the detail drawings of it so I can share them here.

I have contacted Chuck about doing these drawings after we created the drawings of the Maudslay engine, & he has given me his authorization to complete & share these drawings.

I look forward to your input & am excited about the project,

John

Looking forward to drawings on this engine. I have booked marked this thread to come back when drawings are available. Hope I can make one.
Grasshopper

Sadly Mr Fellows has passed away
http://www.modelenginemaker.com/index.php/topic,8916.msg196945/topicseen.html#new

RIP Chuck. I made the Cirrus V-8 Compressed Air Engine that Chuck designed. When I made a modification, Chuck steered me in the right direction. I will forever be in his debt. I dedicate my building to him.
Grasshopper

Sad news indeed. He will be greatly missed. RIP Chuck.