Author Topic: Planis Farm Boy Engine  (Read 6543 times)

Offline Plani

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Planis Farm Boy Engine
« on: April 25, 2020, 08:26:34 PM »
Hi everyone

Since I always enjoy watching buildlogs, I want to start one of my adaption of the Farm Boy engine.

Some time back i got my hands on a set of drawings of the famous Farm Boy engine from Jerry Howell. I liked the design of the engine a lot and also the fact that it can be made from bar stock.
Since I'm all metric I had to redraw the plans. While playing around on the CAD I figured, I might as well make the engine a little bit bigger than original and so I settled for a scale of 32mm to the Inch. This means the engine will be about 30% bigger than original.



The engine specs are:
 - Bore: 32mm
 - Stroke 44mm
 - Compression ratio 4:1
 - Displacement 35cc
 - Flywheel diam 192mm

Because I've never made a one piece crankshaft before, I decided to start with that one, so in case it is not turning out right I can still abort the project...

To start with I got some normalized S355 bar which will hopefully not distort too much while being machined




The round bar was machined square and then the shape of the crank was roughed out




Then turning the crank pin




Roughing the outer parts of the shaft




Since I've done some wrong thinking :facepalm:, the crankshaft hat to be shortened and center drilled  again



To then finishing the shafts




That's what it looked like so far. I left some material to take a skim cut on the crank webs too.




Moment of truth  :thinking: I think I can live with a runout of about 0.02mm  :)




So I went on with cutting the keyways




And cutting the key accordingly




Done:




Plani









Offline yogi

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Re: Planis Farm Boy Engine
« Reply #1 on: April 25, 2020, 09:27:59 PM »
Looking good!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
I'm looking forward to see this one coming together.  :popcorn:

Offline Roger B

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Re: Planis Farm Boy Engine
« Reply #2 on: April 26, 2020, 09:01:21 AM »
That's a good start  :praise2: You may find that the runout changes over time as the stresses in the metal release. Generally it can be trued up again.
Best regards

Roger

Offline Brian Rupnow

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Re: Planis Farm Boy Engine
« Reply #3 on: April 26, 2020, 03:11:29 PM »
Nice cad work and very nice job on the crankshaft.---Brian

Offline awake

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Re: Planis Farm Boy Engine
« Reply #4 on: April 26, 2020, 08:08:26 PM »
Great work! Looking forward to seeing more.
Andy

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #5 on: April 27, 2020, 05:42:51 AM »

Thank you guys for the kind comments  :cheers:

Roger, I sure hope it will not distort more. But we will see, time will tell....

Plani

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #6 on: May 03, 2020, 08:59:45 PM »
Hi everyone

Next I started with the flywheels. There have been two blanks of steel of pretty much the perfect size lying underneath the shelf in the shop for ages. As it seems, these have finally come to their destination.  :)


Ready to go




Turning the outer shapes






I decided to mill the reliefs in the wheels instead of turning them. Here are the two Flywheels ready for the mill




 :Mad: :censored: :censored: :censored: :cussing: :cussing: The crappy endmill I used for this didn't quite cut it. It got dull an therefore pulled out of the collet. This is the inner side of the governor side Flywheel. That's going to leave a mark. I guess....
But since I'm planning to paint this engine, I think I'll be able to fix that.




I purchased some decent carbide endmills (what I should have done from the beginning) and these made live much easier.




Relief milled of the non governor side flywheel




There was some material left at the bottom of the reliefs to be cleaned up on the lathe.






Next step was to mill the spokes.




Then a radius cutter was used to mill the radii on each side of the spokes.




Milling the slots for the spoke lugs on which the pulley will be fixed.




Milling the relief to balance the weight of the piston using a ball nose endmill.






The flywheels so far. There is still the bore to do and on the rims there is also some material left for a final cut in the same set up as the bore will be done.




Thank you for following along an stay tuned for more
Plani

Offline kuhncw

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Re: Planis Farm Boy Engine
« Reply #7 on: May 03, 2020, 09:44:31 PM »
Very nice work on the flywheels.

Chuck

Offline Dave Otto

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Re: Planis Farm Boy Engine
« Reply #8 on: May 05, 2020, 12:56:57 AM »
The flywheels are beautiful!
Very nice work.

Dave

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #9 on: May 06, 2020, 04:49:52 PM »
Thank you for the kind comments Chuck and Dave  :cheers:

Is it only me or does some one else also know this behavior: On a project first the most demanding Part (i.e. crankshaft) is made, then the "interesting" ones like flywheels and then it boils slowly down to the fiddly bits which need be done...
So to counteract this at least a little, I decided to make the spoke lugs next.


Milling the contour from some steel bar stock:




The hole for the bolt drilled




Milling the thickness, all of the lugs in one shot :)




Test fit




Thank you for following along.
Plani

Offline Admiral_dk

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Re: Planis Farm Boy Engine
« Reply #10 on: May 06, 2020, 09:23:06 PM »
Quote
Is it only me or does some one else also know this behavior: On a project first the most demanding Part (i.e. crankshaft) is made, then the "interesting" ones like flywheels and then it boils slowly down to the fiddly bits which need be done...

No - I believe that this is a very common thing among many of us  :-[

Nice parts so far  :ThumbsUp:

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #11 on: June 07, 2020, 07:43:08 PM »
Hi everyone

Next part to make was the conrod.

I started with the bearing cap of the big end




The bearing cap was then bolted in place on the stock for the conrod in order to mill the outer contour




Milling the recess on the first side




And then the seat for the bearing and the relief




First side done




Set up for the second side. In the scrap aluminum underneath were two bosses milled to locate the con rod.




Milling the contour




Contour done




And the final setup to mill the lubrication access in the small end




Finished part




Thank you for following along.
Plani

Offline b.lindsey

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Re: Planis Farm Boy Engine
« Reply #12 on: June 07, 2020, 09:45:15 PM »
Very nice progress Plani. I am just seeing this thread. The parts are all very nicely finished as well. Looking forward to your continued progress on this great engine.

Bill

Offline yogi

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Re: Planis Farm Boy Engine
« Reply #13 on: June 07, 2020, 10:09:10 PM »
Looking good!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Offline scc

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Re: Planis Farm Boy Engine
« Reply #14 on: June 08, 2020, 11:24:15 AM »
Cracking job Plani  :ThumbsUp: I see no coolant so do you use a gentle airstream to keep swarf away from cutters? That must help towards your beautiful surface finish.          Terry

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #15 on: June 08, 2020, 09:33:59 PM »
Thank you gentlemen for the kind comments!

Terry, actually I'm doing both. To mill aluminum I'm using a little bit of coolant mixed into the airstream mainly to provide some lubrication. Milling steel with the carbide cutter is done dry. For carbide it's better to use either a lot of coolant (really flood it) or none, because if there's only little coolant the thermal stress on the cutting edge is increased and the cutter won't last as long.
The air helps to keep the swarf away from the surface. This is also vital to mill steel with high feedrates because otherwise the cutter tends to gall up and break. With the aluminum it helps the finish if there ar no chips mangled between the cutter and the finished surface.

Plani

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #16 on: April 29, 2022, 08:52:57 PM »
Oh dear, how time flies by..... :old:

Nevertheless, some Progress was made but I didn't get around to keep the buildlog up to date. I'll try to catch up, since some Pictures were taken along the way.

Next up the Flywheels needed some finishing work. Therefore the split collets used to clamp the flywheels to the crankshaft where prepared by turning them whit some stock left on the outer diameter and the bore reamed.

Drilling and tapping the holes for the bolts




The flywheels where then set up in the lathe in order to turn the conical bore for the collet and the rim in the same setup






To ensure a proper fit of the collets, a mandrel was devised and the conical outer diameter was turned with the compound slide of the lathe still set at the same angle as for the bore in the flywheels, running the lathe backwards




Collet finished turning




Cutting the slits in the collets




In order to align the keyway to the spokes, a custom guide for the broach was made




Broach in action




Flywheels finished  :D



Plani




Offline propforward

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Re: Planis Farm Boy Engine
« Reply #17 on: April 29, 2022, 11:44:24 PM »
Excellent. Nice parts, and thanks for sharing your description of the process.
Stuart

Forging ahead regardless.

Online crueby

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Re: Planis Farm Boy Engine
« Reply #18 on: April 30, 2022, 12:51:59 AM »
Those flywheels look terrific!

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #19 on: May 08, 2022, 07:39:10 PM »
Thank you gentlemen for the kind comments!

Next I wanted to start with the parts for the engine frame. I was able to purchase a decent chunk of aluminum to make these parts from.

Some work on the saw was needed




And some cutoffs were made on the mill




Raw parts for the water hopper, ant the two part engine frame prepared




Stay tuned, there's some machining ahead  ;) ;D ;D
Plani

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #20 on: May 11, 2022, 07:42:55 PM »
Hi everyone

Since there is quite some material on the bottom of the engine frame, I decided to place there an additional plate with four screws for each half of the frame in order to fix the parts of the frame.
This requires an additional pocket to be milled in the bottom of the frame, like so:




I started then with milling the front half of the frame.
Squaring up the stock.




Milling the front radius




Milling the pocket and reliefs for the fixing plate.




Pocket done and holes drilled and tapped.




Threads where the water hopper will be fixed and hole for the lubrication.




Then a pocket was milled where the cylinder will be fitted. The pocket is a bit deeper than the wall of the frame will be.




Next the radius on the upper side of the frame was milled.




Milling the top radius.




Holes for the bolts to connect the frame parts drilled and countersunk.




Milling the connecting part of the frame.




And then there is only a pretty deep pocket left to be done.




finishing cut with a ball nose endmill to create the radii in all corners.




Done  ;D  The thread for the oiler on top is missing, since I haven't decided on the size of the oiler yet.




Thank you for following along
Plani


Offline Roger B

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Re: Planis Farm Boy Engine
« Reply #21 on: May 11, 2022, 08:21:04 PM »
Looking good  :praise2:  :wine1:

What is the boring tool you are using to turn the taper in the flywheel? I am used to the boring bar being held in the tool post.
« Last Edit: May 12, 2022, 11:45:33 AM by Roger B »
Best regards

Roger

Offline Admiral_dk

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Re: Planis Farm Boy Engine
« Reply #22 on: May 12, 2022, 11:24:00 AM »
Very nice work converting stock to chips .... The parts looks fantastic  :praise2:

Per

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #23 on: May 12, 2022, 08:47:32 PM »

Thank you Roger and Per  :cheers:

Roger, to turn the taper I used a normal HSS boring bar. The only thing is, since the boring bar is rather small compared to the tool holder I used a clamping device to hold it and this device was then fixed in the tool holder.



Plani

Offline propforward

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Re: Planis Farm Boy Engine
« Reply #24 on: May 12, 2022, 09:07:25 PM »
This is great - lovely precision work that you are doing.
Stuart

Forging ahead regardless.

Offline Bearcar1

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Re: Planis Farm Boy Engine
« Reply #25 on: May 13, 2022, 10:35:31 PM »
Terrific piece of work! I appreciate your simple, no-nonsense approach in achieving the end results.  :cheers:


BC1
Jim

Offline Roger B

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Re: Planis Farm Boy Engine
« Reply #26 on: May 14, 2022, 07:32:28 AM »
Thank you  :) All is clear with a view from the other side.
Best regards

Roger

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #27 on: May 25, 2022, 09:41:27 PM »
Thank you gentlemen for the kind comments!  :cheers:

Next i made the fixing plate




as well as some bearing caps. The caps were then cut off the stock and milled flat on the bottom side




thank you for following along
Plani

Offline Plani

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Re: Planis Farm Boy Engine
« Reply #28 on: May 27, 2022, 10:50:06 AM »
Hi everyone

The next substantial part for the engine is the rear part of the frame.
I started by squaring up the stock.




Then the step on the rear end of the engine was milled square at first, leaving some stock in the corner to mill the radius.




Milling the radius using a ball nose endmill.




Then the part was tilted over to mill the angled face, trying to hit the tangent of the radius  ;D




In the same set up the cutout for the big end is milled.




The cut out is a little deeper than the wall thickness will be.




Roughing out the pillow block. The pocket for the fixing plate in the bottom was milled before.




Finishing the pillow block with an end mill with a radius.




Same thing on the other side.




Some more stock is left for the camshaft.




2nd side finished the radius on top was milled using a radius cutter.




Starting the deep pocket on the inside.




The pocket ist milled vertical first, also leaving some stock for the corner radii.




For the finishing cuts the head of the mill was tilted over to reach all the way in the corner.




Taking light cuts, I got away without chatter.




Test fit  ;D




Then the upper halves of the bearing blocks were installed and the bores for the bearings milled.






Family shot.




Thank you for following along.
Plani


Online Kim

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Re: Planis Farm Boy Engine
« Reply #29 on: May 27, 2022, 05:05:48 PM »
Wow!  That's some really nice work to reduce that block down to a part.  Amazing work!
Are you using CNC for this? 
Kim

 

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