# Farm Boy 651



## Rudy (Nov 2, 2017)

I have started to plan my next build, a Farm Boy hitn miss engine. Plans are purchased and the serial number is 651. Looks like a fun machine to build. Lot of machining.
I am wondering about how to source the material for the flywheels. They are some substantial chunks of iron. 1x6 blanks are needed. Cutting these out of a plate is an industrial sized task. I have tried to come up with an idea to use something easier to get, like a weight or even a car fly wheel. However, most such things have a large hole in the middle.
Would appreciate some inputs on this.


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## perko7 (Nov 2, 2017)

Perhaps look at blank flanges for pressure pipework?  They will have a ring of holes around the perimeter but just go up a couple of sizes until the bit in the middle is the size you want.  1 inch thick might be a challenge but in the larger sizes and for high pressure pipe it could be possible.


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## DavidLloyd2 (Nov 2, 2017)

Rudy said:


> I have started to plan my next build, a Farm Boy hitn miss engine. Plans are purchased and the serial number is 651. Looks like a fun machine to build. Lot of machining.
> I am wondering about how to source the material for the flywheels. They are some substantial chunks of iron. 1x6 blanks are needed. Cutting these out of a plate is an industrial sized task. I have tried to come up with an idea to use something easier to get, like a weight or even a car fly wheel. However, most such things have a large hole in the middle.
> Would appreciate some inputs on this.



Rudy
       You can use mild steel for the flywheels

I have lots of 20mm mild steel  so I will be using that for my flywheels and I will be making  the spokes a little bit bigger to add weight,

DavidLloyd


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## Rudy (Nov 3, 2017)

David, pity we are on the very opposite side of this globe.., otherwise I would be on your doorstep begging for some steel . However, hope you will make a thread of your build too. I could need someone to seek advice from.
20mm steel is of cause ok. Do you plan to make the flywheels heavier than original? Or just to compensate for the difference in the original 20,32mm to whatever you can get from a 200 steel plate after turning? The center is 24,64mm, but it should be no problem modifying that to less.
Like the idea of heavier flywheels if that would make the engine turn longer between ignitions.


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## kuhncw (Nov 3, 2017)

Rudy,

Gary Martin of Martin Model and Pattern  sells flywheel castings in a number of styles and sizes.  www.martinmodel.com 
Gary is near Portland, Oregon.  I see you are in Norway.  If shipping is not an issue, this might be a source of flywheels for your Farmboy.

Chuck


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## Brian Rupnow (Nov 4, 2017)

Just about anything will work for flywheels, as long as it's weight is comparable to steel, which weighs 0.283 pounds per cubic inch. Cast iron, mild steel, bronze, brass, or even a two part flywheel with the central portion turned from aluminum and the outer rim of heavier material (think heavy wall steel pipe or tubing) Loctited to the aluminum center.


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## Rudy (Nov 4, 2017)

Brian, cutting a piece from a steel tube and make a center of aluminium was a nice idea..
Getting castings from US over here is costly..
However, the task is about to be solved. A friend of mine shal cut some pieces for me.


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## TonyM (Nov 5, 2017)

If you did have a mind to buy castings there are some really good ones here  http://www.ateliermb.ch Free EU delivery on orders over 80Euro


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## Rudy (Nov 24, 2017)

While I'm waiting for the materials for the frame I started with the cylinder.
It started as a 75mm lump of leaded steel.

After a lot of cutting and turning I finally got a nice cylinder. I made a split wooden stick in the lathe for lapping.
Did the piston in the lathe well over final dimension. Then placed it in the mill and did the inside milling and drilling. Note the flat on the bar stock. It serves as reference when I lay the work down to drill the pin hole 90 degree to the slot inside of the piston. I trued the piston to the quill with a dial indicator for each operation.
I should have done the cylinder finished before I made the piston, but I had to take the piston work out of the lathe to make the lapping stick. However, when I put the piston back in the lathe I managed to get it in without any measurable run out (wouldn&#8217;t been very important). Then I did the final cut to dimension. Polished with Autosol fine polish compound.


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## Rudy (Dec 4, 2017)

Made the con rod while waiting for frame material. This piece is actually both easy and difficult to make. Easy to get accurate in terms of function. Difficult to make look right. I found a setup that worked fine to me. Drilling holes to make radiuses and then support it with drill bits to align it for milling. I used screws not threaded all the way in order to get support between the rod and end cap, just like a real car engine. I had to make my own reamer to get the fit tight, moveable but no play.


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## Rudy (Dec 4, 2017)

Got the frame material! Some lump of aluminum! Nearly an hour in the band saw to cut it. Looking forward to many happy hours in the mill. This stuff machines like butter.


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## Rudy (Dec 17, 2017)

Some updates on the build. Lots of machining on those big aluminum lumps. Have to be really careful not to overshoot and destroy the whole thing. The DRO is really helpful in this case.


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## Rudy (Jan 8, 2018)

The engine frame material arrived. Nice lump... Good to have a band saw for this. Tock an hour to eat through.
There is a lot of right ways to setup the work on these parts. I tried several and found my ways. Since it is the first time I do such machining, I have to go slowly.
I got my selves a 16mm rough end mill. This one seems to do good work in this application. Lots of material to remove.


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## Rudy (Jan 8, 2018)

(Discovered I had posted some pics before).

The crank bearing caps was LockTited (603) on before drilling. This ensured a very good fit when the screws goes in. Had to heat it to separate. 
The two-piece frame is screwed together with several screws and LockTite 603 instead of fewer screws and pins in the split. Pretty sure it will hold.
Did the final finish with hand tools. It&#8217;s going to be painted and look like castings, so I will have to either roughen the surface or use shrink paint.


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## deeferdog (Jan 8, 2018)

Thanks for posting these pictures Rudy, I'm really enjoying following your build. Cheers, Peter


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## Rudy (Jan 8, 2018)

Glad you like it guys. I enjoy this project very much. I'm so eager to see this engine running. Being new to Model Engineering it is a very good feeling when you mastering new challenges. Guess it's like when athletes are winning something.
Anyways, what I can say so far, to someone considering this project, it is really a well designed engine. One will really get their machines work. There are many good ways to set up the work and make the parts. Many of the operations are not critical and can be done with just layout lines. However, keep in mind the critical measurements and dimensions. I have DRO (digital readout) on my milling machine and I can hardly imagine doing anything with some accuracy without. Highly recommended.
Next up is the crank. Brian Rupnow encouraged me to make it from silver steel rods, cold rolled steel webs and pinning, so I will do so. A bit reluctant to use silver solder and have a warped shaft.

Rudy


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## Rudy (Feb 4, 2018)

Made the crankshaft. I went for the pin and rod approach. The shaft is 10mm silver steel (drill rod) and I left it as is. The webs are cold rolled steel. I made them equally sized pieces and Locktited (603) them together and drilled them as one to ensure the two holes being parallel.
I actually could turn the ends in the four-jaw with light interrupted cuts holding just with the Loctite.


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## Rudy (Feb 4, 2018)

I managed to make the crank absolutely true. No measurable run out.
However, when it was time to fit it in the frame, I had a real fight. I struggled to get the frame line bored straight. First I tried to bore with just a 13mm drill since I have no reamer at this size. I can't believe how crocked a drill bit can make a hole. Discovered that after having made bearings with very close fit. The crank was locked solid when the bearing caps where tightened up.
Then I bored up the hole with the boring head. Made new slightly larger bushings, still no luck. Made another attempt, now with extremely slow feeding when boring. 10 minutes through each bearing (that was actually boring for real..). New bushings with absolutely no play, tightened up the bearing caps, bingo! I can't believe it! The crank falls around by its own weight. The fit is so close that if I loosen a bolt the crank locks up.
This was a major discovery for me. I'm working way beyond the native accuracy of the machines and really have to learn how to work around and understand really what's happening here. The issue was the long thin boring bar. It had to work out the spring force fully and equally through both holes.
Can't remember last time I had such fun!

Below you can see the setup I used to get the line boring 90 degrees to the cylinder. I also made good use of my new center finder. This is actually a very easy and reasonable accurate way to find the center.


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## Rudy (Feb 9, 2018)

Made my first ever gear today! Can&#8217;t remember I had such fun since I got the line bore right. It was not difficult at all. I have to rush in and say, this is not a precision gear. But for a slow turning hit'n miss engine? I recon it will work.
I made the tool to my best ability by copying another gear profile from my model RC car that has the same pitch. I grinded the cutting tool under a magnifying glass. It will of cause never be very accurate this way, but as long as it works, I'm happy. (Haven't tested it yet, but it simply has to work somehow).
As long as the number of degrees between the teeth is whole numbers of degrees, the simple rotating table works. In this case it is 5 and 10 degrees between the teeth, so the dials on the rotating table is more than enough accurate. And it was easy to keep track of the number for the next tooth.
Again, not a precision gear, but I had such a fun time doing it. That's what matters to me. Hope it will work. If not, I will put more effort into grinding the cutting tool.


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## rlukens (Feb 9, 2018)

Rudy said:


> (that was actually boring for real


I see what you did there...


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## Brian Rupnow (Feb 9, 2018)

Rudy--Congratulations on your first gear. That is a big step upwards in your engine building path.---Brian


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## Rudy (Feb 11, 2018)

Made the head. Not any difficulties. The valve guides/seats are more critical. Turning the pocket and guide hole in one operation to ensure accuracy. The fit to the holes in the head is 0,03mm oversize if I managed to measure right. Pressed them in with the wise having a sleeve over the guide to press against the thicker part.
The valves are probably the hardest part to make in the head assembly. Like TinkerJohn on JouTube says, 50/50 chance to get them right. I believe making them in two pieces is harder to get straight compared to turning them from one piece. However, it was too attempting to do the two-piece version. It is an easy way if it gets straight. I actually Locktited the valve heads and stem together. Adding to the believe that it will hold I made some dimples at the end. My impression is that Locktite 603 is very strong until it let go with a snap. With no hard knocks and no very high temperatures, Im willing to take the chance. If someone having experience here, Im grateful for feedback.
The reason I didnt silver solder them is that I guess I would have to make a running fit to get some solder inn between. I made a tight fit to have no play and hopefully maintain the parallelism with the valve stem. I have good experience with Locktite and tight fit.
At least they look nice and when testing in the head, there is actually no leaks when Im blowing in the ports. That before the valves are lapped.

Rudy


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## Brian Rupnow (Feb 11, 2018)

I don't think that the Loctite will hold up on your exhaust valve assembly. I have made many one piece valves and it is not terribly difficult. the hardest part of any valve is getting it to seal properly in the valve seat to enable good compression in the engine. I struggled with this HUGELY until I found a plan for the George Britnell valve seat cutter. Since I made one of them, I haven't had any real problems.---Brian Rupnow


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## Rudy (Feb 12, 2018)

Thanks again for the feedback Brian. I started with two-piece because it was so easy. A piece of rod and a little disc. The plan was to silver solder, but I hesitated. If the valve head gets loose, I probably will damage the crank and more, so I will make one-pieces. I have done hundred car valve jobs, so I have an idea of how things work.
My goal is to make the seats and valves right and having them tight without the need for lapping.
To achieve that I figure a straight valve is the key to success. If I have a straight valve I can always lap down the seat if it&#8217;s not straight. Or I can make it straight with a good reamer. However, I can&#8217;t straighten a hard valve by lapping, because the soft material in the seat will give before the valve. The valve will probably never seat properly if not straight. Right?!
In this Farm Boy engine, the valve guide and seat is the same part that is turned in one operation. This makes it easier to get them in line to each other. 

Rudy


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## Rudy (Feb 13, 2018)

Tried to make one-piece valves. Ended up turning a couple of tapers. Reverted to the study and did some research. Came across your valve tutorial Brian . I&#8217;m going to try it. However, I also going to try another method I&#8217;m thinking of. I&#8217;ll let you know..

Rudy


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## Rudy (Mar 14, 2018)

I have great progress in this build and I will come back and post many pictures, but I&#8217;m stuck now and need some help. The governor catch lever shall have a hole for a speed adjustment screw. I don&#8217;t understand how this screw shall be made or how it works. The plans are not very clear on this. At least I don&#8217;t get it. Is it an adjustable spring pushing the lever out? If so, why not just a grub screw with a spring in front? 
Grateful if someone could help me out here.

Rudy


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## Engine maker (Mar 14, 2018)

Yes you probably could just tap it and use a screw against the spring, but if you back the adjustment screw out you may loose the spring. This way the spring is captured and can only come out one way but is blocked by the limit of the arm's movement. Also if you use the threaded barrel you have more room for a longer spring which gives you more adjustment.

By the way, a good spring to use in this place is the spring from under the flint in a BIC disposable cigarette lighter. I built Serial #003, the first one other than the prototype and it still runs great. It now will coast + 70 revolutions between firings and on a good day I can get it to do + 100.


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## Rudy (Mar 14, 2018)

Think I got it Engine maker. The screw body in the plans is going to be pressed into the widest part of the hole and stay attached (plans doesn&#8217;t tell). Preferably with some LockTite. Then I have a clean hole for the spring with no threads for the spring to catch up on. And the spring, as I understand, shall press the arm out from the latch. There is no spring in the plans, so I wondered.
So you have built one your selves! Just had a glance at it. Looks like a real show piece. This is as far as I can tell, a very well-constructed engine. A pleasure to make. Lots of machining. Easy to correct if you go wrong (compared to a casting kit). This is my second build and I&#8217;m so eager to have it running. I do everything as accurate as I can, so I expect it to run well.
What is the secret to make it turn 100 times between hits?
Rudy


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## Rudy (Mar 14, 2018)

Think I got it right. Maybe the spring I have here is a bit small. One other detail.. the screw for the catch block is drawn in the plans at a 4 degree angle to the block. That will easily brake the small screw if it is tightened. Fixed that.

Rudy


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## Johno1958 (Mar 14, 2018)

Rudy that's one hell of a good looking engine your making. Great work.
Cheers 
John


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## Engine maker (Mar 14, 2018)

You can also solder the speed screw adjustment body in the arm. It takes just a touch.

  Yes, It's a great engine to build. It will coast 30- 40 revolutions as the norm. I made 1 or 2 minor changes that I'm keeping secret ( how else will I keep my status as a "Miracle worker")? But I'll give you a hint, you have to go on a MAJOR drag reduction effort. I also found out that mine runs much better on Coleman (camp stove fuel) than on alcohol or acetone.  
Can't wait till you let us know it's done. You'll enjoy it!


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## Rudy (Mar 15, 2018)

Engine Maker, I want to earn my selves a nick name to! I will pick you up on that 100+ revs! When I succeed, I want some fancy name. My first build, the Stuart 10V, runs on 0.4psi with no running in, so I&#8217;m feeling I can manage it with even more practice. My &#8220;thing&#8221; is accuracy.
I noticed Jerry Howel wrote something about Naphtha as fuel. Have a bottle I will try. I also got the plans for the Propane demand valve. Like the Propane idea because of the very clean exhaust and no soot.

Rudy


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## Rudy (Apr 24, 2018)

Some progress in the build. Got to try my new Soba 8&#8221; rotary table. After having two crap tables this one is way better. A bit large, but you can still use it with small parts. Very rugged. Made the cutting tool for the gear just free hand on the grinder. Of cause not very correct profile at all, but I believe it will work. Also remade the valves from one piece after the Brian recipe. Made the rocker arm a bit more ornamental than the plans called for. Thought it was wort some extra just for the looks. After all, it&#8217;s the main part of the &#8220;jewels&#8221;.
Another feature I added was offset bearing split on the connecting rod big end. I liked the idea of having the con rod support the bearings, not just the bolts. The second last pic shows the split in offset to the bolt grove. The last pic shows the setup to get the two groves for the bolts in parallel. 
Summer is coming and lots of other activities waiting. The progress will be slower now. I have never been looking forward to the winter like after having taken up this hobby..

Rudy


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## LorenOtto (Apr 29, 2018)

I am enjoying your posts very much.  Keep up the good work.


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## Rudy (Aug 31, 2018)

I’m back in the shop after having most of the summer holydays with all kinds of other activities, behind. Had the fly wheel blanks ready and started to dig into them. Figured the best way was to screw them on to the surface plate. The chuck isn’t big enough, so it had to be this way. Faced of the plate to ensure it will run true. I had recently bought an 8” rotary table that came in very handy despite being a bit large for my mill. Don’t regret that now.

Rudy


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## natalefr (Aug 31, 2018)

WOW !


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## minh-thanh (Aug 31, 2018)

I think it will be very beautiful when finished,!!


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## terryp (Aug 31, 2018)

Hello Rudy, Working my way toward a hit & miss so watching your thread with interest. Looking at the date stamps on your photos makes me slap my forehead in amazement. it would take me forever to do what you have accomplished in a month or so. You make it looks so easy.... truly an inspiration for us amateurs! Of recent interest is your flywheel. I was trying to figure out a tapered spoke flywheel but yours looks great. I do have a six inch rotary table so that will be the tool of choice for the setup. Thanks! Terry from Texas


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## Johno1958 (Aug 31, 2018)

Hi Rudy , good looking flywheel. Roughly how long did it take to machine?
Glad your back at it .
Cheers
John


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## Rudy (Sep 3, 2018)

Terry, I started this build last winter, spent a lot of hours at it. However, the summer calls for other activities. Feels good to be back in the shop though. I will pick up the pace towards the winter.
John, it took a while to make the first flywheel. The material is some kind og hard cast Iron. I did not manage to mill sideways, so I did many small increments of plunge cuts before going sideways to make a smoother surface. Made up a sketch with all the degrees to all the holes, used my DRO and tested all hole positions before I did drill the holes and started to mill out the spokes. Guess a week on each, all in all.

I really love building this engine. A lot of machine time. Started to think about the color scheme.

Rudy


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## BIGTREV (Oct 18, 2018)

Seriously impressive work


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## Bob44 (Oct 18, 2018)




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## Bob44 (Oct 18, 2018)

Made these for my Farm Boy about 3-4 years ago. I bought 1.5"x6" solid cast disks from Speedy Metals and cut them out on my mill using the measurements in the Howell plans. It took a while but they seem to do the job.


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## Rudy (Oct 19, 2018)

I had an issue with the flywheels getting them to run straight. I did everything possible to make the crank straight and the hole in the flywheel in line with the wheel. Despite all the effort the flywheels ran visibly wobbly. The problem came down to the collets. I had drilled and reamed the center hole. Might be my reamers, but when accuracy has been critical, I have never managed to get a drilled and reamed hole perfectly straight. I had to bore it with a boring bar. Just as I did with the holes in the flywheel. So the second attempt became a lot better. Sidewise runout is now 0,05 - 0,1mm. If I tweak the collets I believe I can cancel it out to neglectable. At least I can sleep again now.
Other than that I have done some trail assembly and started to fine tune the parts. I´m particularly happy with the crank and bearings. No play and the shaft spins freely forever when the flywheels are mounted. This was also a drilling/boring exercise. Drilled and reamed holes in the block did not work. Despite perfect fit on the bearings the shaft locked up when the bearing straps was tightened. Had to line bore the block with a boring bar and taking out all the spring in the bar. Took about 10 minutes for each pass on each bearing. Same with the bronze bearings, turned and bored. It paid off.

Rudy


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## Rudy (Nov 19, 2018)

Done some progress lately. The "carburetor" and drip oiler is done. The 90 degree bend took a bit to make. Lots of manual grinding and filing. The final buffing is the easy part.
The oiler looks difficult to make, but it wasn´t. The glas is from a test tube. I struggled with cutting it in the first place. It´s very hard glass. The ordinary tube cutter doesn´t make a scratch. Tried the method filing a scratch and warm with a micro torch, but that did´t work at all for me. However, a diamond cutting wheel in the Dremel and spinning the glass in the lathe, the job was done in seconds.
Rudy





.


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## Rudy (Nov 20, 2018)

Here is a "problem".. (if only all problems was that nice to work with..). The oil from the drip oiler is fed to the cylinder through some drilled passages in the block and through the hole in the cylinder sleeve. However, there is some play between the block and sleeve for the oil to escape in between. I didn´t want to make a tight press fit between the sleeve and block that probably could minimize the problem. I´m trying to find a way to seal the gap. A thin gasket will be pushed out so I´m thinking of making a O-ring seal. The problem is the angled pocket and rounded surface. I plan to make an bigger hole, put in an insert with the right profile, with room for an O-ring.

Rudy


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## Rudy (Nov 20, 2018)

Help needed!
I´m having an issue getting compression. The valves are sealing well, but the piston ring is not. I have used a smaller O-ring than the plans say so I have the posibility to make a larger groove in the piston for a larger o-ring.
The plans gives dimesnsions on the groove, but not the ring!
Anybody that knows?

Rudy


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## johnstij (Nov 20, 2018)

Hi Rudy.
On sheet 5 showing the piston drawing the note says " make the groove .105" wide and .110" deep for 094" section by 1" diam O ring"
Ian


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## Rudy (Nov 20, 2018)

Thanks! How could I miss that... lets blame my metric eyes 

While we are at it. How important is it to harden the wrist pin? I have made it from dril rod and not bored it out.

Rudy


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## johnstij (Nov 20, 2018)

I did not harden mine but I think the idea of drilling it out is to lighten it a  bit.
 I build mine a couple of years ago. Here is a short video of it running:-


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## Rudy (Nov 20, 2018)

Thanks John. I had already found that video. Runs very well!
I´m soon to be starting my own. Very exited, it´s my first IC engine and my second build.
Rudy


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## Pierkemo (Nov 20, 2018)

Knap gemaakt Hanss, fijne modelbouwer!!
Toi, toi!


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## Rudy (Nov 22, 2018)

Made the O-ring seal between the cylinder sleeve and block, or water hopper as the plans say. Think it will work. As I mentioned I have a small play in the sleeve to block fit. Some of the oil from the drip oiler would be leaking away from the hole in the sleeve and out under the sleeve. Maybe the gap would be filled with oil and stayed there. Anyway, I made a fix for it.
Bored the hole in the block with a 5mm endmill. Made a bushing with the same profile as the diameter of the sleeve outside (+1.5mm). Inserted a tube to make a support for the O-ring. Lock-Tite to hold the parts in place.

Rudy
















Here is the finished O-ring seals. I´m using a flexible piece of something to press down the O-ring when I push the cylinder sleeve in place. Works fine.


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## Rudy (Nov 27, 2018)

Painted the engine block. Started to assemble the finished parts. This is really a big moment, seeing the final stage of the long build. Posting some random pics of the parts so far.
Have yet to make a nice base, tank and ignition.

Rudy


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## Johno1958 (Nov 27, 2018)

Rudy you've got to be chuffed. That is "sweet as".
Sorry Rudy in Australian slang that means absolutely beautiful and you have to be happy about it.
Cheers
John


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## Rudy (Nov 28, 2018)

Thanks John. Yes, I´m happy about it. Also this engine is something I will recommend. The construction is very good. Making engines from bar stock is also a good thing, especially for beginners. I have done several of the parts two-three times. Don´t be put down of the small price for the plans. This is nothing compared to the man hours we spend making an engine. 
Rudy


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## Rudy (Mar 20, 2019)

Have been busy pleasing the wife refurbishing the living room. However, my Farm Boy did it's first puffs. Didn't get hold on any fuel, so I just placed a butane torch in front of the mixer and let it sip some gas into it. Works just perfect! Not to recommend though. There will be some unburned gas in the room.
I soon run into problems with the ignition. The micro controller on the pcb died. Also the hall sensor. Maybe the car coil is to heavy for it? Run it on 7,2V. Made a new electronic ignition of my own construction, same problem. I will deal with it when the house is done and come back with a write up.

The initial run was OK, but after that the compression disappeared. Use an "ordinary" O-ring. Polished the cylinder to a better finish and put in a new O-ring. Seems to be much better now and it ran better, until the ignition quit..

I have plans for a propane demand valve. Think I will go that route. Propane burns so clean and leaves no smell from the exhaust.
Made a ignition circuit similar to the PIC TIM, but with analog circuits (NE555). It makes a series of (approx 6) sparks as long as the hall sensor is engaged. When the rpm increases, the number of sparks decreases. If I get it right I will put up a diagram of it.
Now I try to get hold on a suitable ignition coil.

Rudy


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## DavidLloyd2 (Mar 20, 2019)

Rudy - That is absolutely beautiful,

Thanks for that video
                             DavidLloyd


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## a41capt (Mar 20, 2019)

What a beauty! Excellent running machine and the finish is amazing. Thanks so much for sharing.

John W
Camp Verde, AZ


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## Rudy (Mar 20, 2019)

Glade you like it. After all, not many around the house understanding what we are doing and the effort we have to put into this hobby.
I like this build. Think I have watched every FarmBoys out there.
There is stil some work. I'll make a stand for it, and a tank (Even if I run it on propane). I will also make new gears. The ones I have are making a bit noise. I made them with a gear cutter grind by eyeballing. I have bought proper gear cutters now.  
There are two things I will point out for those wanting to build one (newbies like me). The first is make sure the block is line bored straight. I did't manage to achieve that with drill bit and reamer. Holes didn't line up, at least not with the accuracy I wanted. Had to use a boring head.
The other is the collets on the flywheels. If not machined and bored absolutely true, the flywheel will wobble.
I have described this earlier in this thread.
Rudy


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## a41capt (Mar 20, 2019)

Thanks for the great reply Rudy! I’m going to build an IC engine sometime this year, and your Farm Boy is just the inspiration I needed to get my butt in gear.

Thanks again
John W


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## bruedney (Jul 30, 2019)

Hi Rudy

Nice engine. Thanks for the build thread

I am currently modelling up #770 and am having difficulties reconciling the dimensions on the Exhaust Valve Rocker Arm Bracket. I see from your drawings on post #33 that you may have had the same difficulties.

Could you please shed some light on the dimensions you used?

Cheers
Bruce

EDIT: Got it sorted - 0.660" should be 0.690" and 0.440" should be 0.430"


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## Rudy (Jul 30, 2019)

Hi Bruce,
Glad you sorted it out. Can't remember if I had any problems. Anyway, if you want some measurements or other advice, I'm more than happy to help.
At the moment I'm trying out the propane demand valve from Howel. It works, but doesn't hold back much pressure from the gas bottle. Need an additional pressure regulator before the demand valve. Anyway, propane seems to be very forgiving to get going. Just a torch laying in front of the intake and leak some gas works fine (but of cause lets unburned gas into the room).

Rudy


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