Gardner from barstock.

[TonyM]

I am far enough along with the Gardner to start the build log. I have a lot done but there is still a long way to go before it is a running engine. I have used a bit of licence with some parts as I only have the lathe to work with. I have the option of using one or two flywheels. I will make the decision when it is running. I intend to use propane with a demand valve. The engine I had was gas and was originally connected to the old coal gas mains.
I have scaled it based on 8 1/2''-9'' flywheel size. The largest I could get on the lathe. The model runs out at about 1/3 scale.

I started with the base. out of Aluminium plate. Bolted together with JB weld between every joint. It was also used to make all the corner fillets.

 

[TonyM]

The next step was the logo for the base. I had intended to buy a plate to insert but after being let down by the supplier decided to make my own. I soldered brass letters onto a tinplate backing. These were slightly bigger than I wanted but not too bad. They were then set into the sides of the base with JB Weld after gouging out a recess.

 

[TonyM]

The cylinder and liner were next. The liner has a blind bore. Water Jacket is part recess in the jacket and part undercut on the liner. The bore is 34mm.

 

[TonyM]

The crank is five piece using loctite and taper pins.

 

[TonyM]

So Far.

 

[PSP]

So Far.

Really impressed, especially with the base fabrication.

 

[TonyM]

Really impressed, especially with the base fabrication.

Thanks. I had thought about casting but ruled that out on cost and safety grounds. I could't justify buying all the kit for a one off. I was inspired to do the fabrication by seeing some of the work done by JasonB

 

[Jasonb]

You won't want to go back to castings now! Looks very good.

Did you consider the Alyn Foundry casting set or was it too big for your machines?

 

[timo_gross]

Thanks. I had thought about casting but ruled that out on cost and safety grounds. I could't justify buying all the kit for a one off. I was inspired to do the fabrication by seeing some of the work done by JasonB

Casting is interesting, but it gets really involved. Safety gear, a lot of practice, materials, other equipment. I am not casting anything yet (possibly never will start any), it is not something that can be done as a one off. (my opinion )

 

[TonyM]

You won't want to go back to castings now! Looks very good.

Did you consider the Alyn Foundry casting set or was it too big for your machines?

Thanks Jason I did consider the casting set but it was a bit out of proportion. The piston size was similar but the stroke and the overall length of the base was a bit shorter. I was a bit apprehensive about the built up base but I think it worked out OK in the end. The biggest problem I faced is the valve block so I have taken a bit of licence with that. I think it still looks OK.

 

[Alyn Foundry]

Some nice fabrication work there Tony. Our kit was based upon a 1911 size 0 engine so yes the proportions are going to be totally wrong in every respect. It took a lot of initial head scratching to design the bed suitable for casting. It has 8 loose pieces in total. You mentioned the flywheel for your model will be roughly 9” in diameter? Well that’s exactly the same as ours, here’s a photo of the latest batch from the foundry. If we can help you with this project please contact the boys via email.
[email protected]
https://www.facebook.com/groups/ALYNFOUNDRYMODELS/
Cheers Graham.

 

[TonyM]

Thanks Graham I may well do that. I am struggling a bit with the geometry of the trigger assembly. I have made some parts but whether it will work correctly remains to be proven only when the engine runs. I think this is where problems of scale rear their ugly heads. Inertia and friction don't scale very well. So it would be great to get advice from someone who has done it and made it work.

 

[TonyM]

When I made the timing gear shaft I turned the location end 0.5mm eccentric so that when fitting, it allows me to adjust the backlash of the gears before locking it into place.The eccentrics were fairly straightforward. The various holes in the gear are so that I could adjust the timing by half a tooth if required. Although easier to machine, I found the valve timing using eccentrics quite complex compared to ''normal'' cams. I found setting the inlet first and then setting the exhaust to match worked well.

 

[TonyM]

The exhaust valve block was fabricated from brass parts silver soldered.

 

[Alyn Foundry]

Good morning Tony. All the Gardner engines had an eccentric half time gear adjustment. The pin extended through the bed casting and was locked by a nut on the inside where the crank runs. At scale I thought this might be problematic so opted for a stub and used the bottom main bearing hole, extended and threaded to use a grub screw. We found the easy way to time the two valves was to fix, permanently, the exhaust valve eccentric boss and then fiddle around with the inlet side.
I wouldn’t worry too much about the governor, even at scale it works perfectly. The spring is the critical component, a left hand spiral with ends cranked to anchor it between the fixed arm and the adjustable nuts. I used the centre strand from the Bowden cables fitted to bicycle brake/gears as the basis for this.
The slowest speed recorded by a customer was 180 RPM, not bad for a model….
Cheers Graham

 

[TonyM]

Good morning Tony. All the Gardner engines had an eccentric half time gear adjustment. The pin extended through the bed casting and was locked by a nut on the inside where the crank runs. At scale I thought this might be problematic so opted for a stub and used the bottom main bearing hole, extended and threaded to use a grub screw.
Cheers Graham

That's a neat solution. There must be a bit of difference in mine at that end because on mine, the screw for the bearing cap is not in line with the pin.(Although it could have been if I had designed it that way.) For mine I drilled the sideplate 4mm and then opened the hole to 8mm leaving a 3 mm step on the crank side. I drilled and tapped the shaft M4 with a bolt through from the crank side. post 13. Just enough clearance for the head of an M4 bolt. Not enough to add a washer unfortunately.

 

[TonyM]

Exhaust valve set up and timed. The flange that can be seen on the front of the head is false. The two bolts secure the liner to the water jacket. They also assist in assembly allowing trapped air between the jacket and the liner to escape.

 

[TonyM]

The main inlet valve, gas valve, and end caps. The spark plug goes in the main inlet valve cap.

 

[TonyM]

Inlet valve attached and timing set.

I have been playing around with the timing to try to optimise. The short video shows what I have got so far. I would appreciate any advice if anyone thinks this can be improved or if it is wrong. Now is the best time for me to get it right.

 

[GreenTwin]

Tony-

That is a really nice looking engine.

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