Author Topic: Farm Boy #876 - Mike's Build  (Read 3696 times)

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #30 on: September 28, 2022, 09:23:09 PM »
That does look very secure!  How deep did you make the pin holes?  Seems like the pin hole might cut through the screws you were using to hold it together if the pin hole went very deep.

But I'm sure it's a very solid connection regardless.

Kim

Kim, I just checked on my CAD model.  From the center of the top hole to the top of the frame, it's .625" I drilled from the top .50" deep with a #41 drill and then used a .093" bit of brass rod that was .40" long.  Doing it that way prevented drilling into the shcs and leaving the brass rod a bit short left the top a bit shallow at the top so it would be easier to fill with Bondo flush later. 

I can't imagine those frame halves coming apart ever!  And there have been a number of Farm Boy engines built with no problems reported for this joint.

Glad you're following along!

Mike
MIke
Wichita, KS, USA

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #31 on: September 28, 2022, 09:26:13 PM »
A very fine result so far - so I can see why you are happy with the parts shown  :ThumbsUp:

If you haven't admitted up front that this isn't a Live Build - I would seriously wondered if we are witnessing someone faster than Chris and his Elves  ;D     :cheers:

Per

Per, I was indeed careful to disclaim that this wasn't a live build!   I'm certainly no speed demon.  However, I have already selected my next engine to build and I will make every attempt to document that one close to real time. 

Thanks very much for following along!

Mike
MIke
Wichita, KS, USA

Offline Bearcar1

  • Full Member
  • ****
  • Posts: 824
  • Chicagoland Area, USA
Re: Farm Boy #876 - Mike's Build
« Reply #32 on: September 29, 2022, 01:33:04 AM »
Nicely done!! Mike... I am still following along and enjoying the ride... Boy oh boy, that is alot of work,,,, Very well executed.... :ThumbsUp: :ThumbsUp:


BC1
Jim

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #33 on: September 29, 2022, 09:30:19 PM »
So with the major frame parts permanently assembled, it's now time to move on to the rest of the bits.   I decided that next would be the cylinder head.  It looks like a relatively simple part, but there are a fairly large number of operations to get this part completed.

First i turned the small feature that fits into the cylinder liner.  I had a short piece of 2" Al so it was just a matter of polishing up the OD a bit and using an insert tool to turn the feature.  It's .100" high and .998" OD.  I verified the fit in the cylinder liner.



And here's the head parted off with the back side cleaned up.  You can see it on the drawing for comparison.



Here's the part in the mill vise after most of the features on the bottom side were drilled.  I'm reaming 13/32" here for the 2 holes that will accept the valve cages.  I'm holding with a v-block against the fixed jaw and a small scrap of Al between the part and the movable jaw.  There are parallels under the part to keep it oriented flat.  Of course I centered the part under the spindle before doing any of the ops and placed the various features using the DRO. 



And here's the part with the bottom features completed.  The round recess was made with a 3/8" ball end mill plunging .285" deep.
 
You can see the drawing I made from the CAD modeling I did.  This isn't strictly necessary but I find that it's more convenient for me to put the added dimensions I like for the way I tend to work. 



At this point, I needed to create a fixture in order to complete the rest of the features.  I had some Al plate so I cut out a piece and squared it up to 3" x 3".  The size is pretty irrelevant but it needs to be square for reasons that will become clear later.  Here I drilled a center hole in the exact center of the piece and then drilled and tapped 4 6-32 hole that match the mounting holes for the head. 



Then I took that piece over to the lathe and centered in the 4J using the center hole drilled in the mill as the reference.  Here I'm drilling thru 7/16".  This will eventually become a port for an air fitting that I'll use for pressure testing the head.



Next was boring a 1" ID recess to accept the raised boss from the head. 



And here's the fixture and the head next to each other.



With the head bolted to the fixture, it's now possible to orient features front to back and around the  OD as required.  First I located, drilled and reamed for the rocker arm pivot mount location.  That's a 3/16" reamer that does NOT go all the way thru the head. 



I then made a small center hole at the location that will be the center of the angled hole for the spark plug.  This is just a reference and I'm pointing it out here.  This was done via the DRO.



Here's where the fixture really comes into play.  I've reoriented the fixture in the vise and angled it at 20 degrees using an angle block under the fixture.  Since the fixture is square the distance from the fixed jaw is always known for y and I just have to locate in x.  I'm just visually aligning the small center hole with the sharp tip of an edge finder. 



Here I'm plunging in with a 1/2" 2 flute end mill .350" deep.  JE Howell's drawing calls for a 7/16" counter-bore at this location but I enlarged it as I want to be able to use a thin wall 5/16" socket to install the spark plug and the 1/2" ID gives that clearance.



Then I drilled thru and tapped 1/4"-32 for the spark plug.  I did touch this with a center drill before drilling thru, but this operation was easy since the drill intersects the surface square after the milling op.



Next I reoriented the fixture in the mill vise again and found the center of the head in x.  Y is known as that reference remains the rear fixed vise jaw.  I'm using a 1/2" diameter edge finder as that can easily find the edges on large OD objects.



Here I'm gauging the depth of the hole so that it just intersects the 3/16" hole.  I did end up tapping this 4-40 rather than the 5-40 that the drawing calls for.  I did this as I typically have 4-40 set screws but don't typically have 5-40 set screws on hand. 



And here's the cylinder head assembled with the spark plug.  There are more operations to be done on the head, but they can't be done until the valve guides are completed.



And that's it for now!  More to come as there's lots of little parts that are attached to the cylinder head.

Enjoy!

Mike


« Last Edit: September 29, 2022, 09:37:53 PM by mikehinz »
MIke
Wichita, KS, USA

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #34 on: September 30, 2022, 11:52:10 PM »
And here's the last bit of work necessary to finish the cylinder head, at least with the permanently installed bits. This is of course, the valve guides or valve cages as HE Howell refers to them.

I decided to use plain 360 brass for the guides vs the phosphor bronze as the drawing specifies.  I based this choice on the 2 previous I/C engines that I've built and successfully ran and also on the wise words of Brian Rupnow who almost always uses brass  guides for his engines.  Here I've put some 1/2" brass stock in a collet and turned the major diameters and the pix shows reaming .125" thru after drilling thru.



Then after parting off to length I plunged in with a 5/16" ball end mill to create the recess with bottom rounded as per the drawing.  I just held the end mill in the tail stock chuck.  It seemed to work OK, although there was a bit of chatter as I was finishing up the plunge.



Then I turned the part around and turned the taper using the compound.  I think this was a 4 degree angle.



And here are the finished valve guides on the drawing.



Since these guides need to be pressed into the head, I made a simple tool for the pressing operation.  This way the pressing operation can be done without damage to the guides.   This little tool is just made from Al round bar.



And here's the pressing operation.  I used my old Dake press and I coated the guides with Loctite 620 prior to pressing them into place.  The guides were what I would call a 'light press fit' and my thinking was that this fit plus the Loctite should form a good seal.



And here's the head with the valve guides installed as viewed from the top side.



And from the bottom side.  You can see the chatter marks at the bottom of the guides.  I made the judgement call that a bit of chatter at that location would not matter at all. 



After letting the assembly cure overnight, I then placed the head back onto the fixture I'd previously made and then drilled thru with a letter "I" drill and here I'm tapping 5/16"-24. 



Then I reoriented the fixture and drilled and reamed for the intake passage.  This involved milling a small flat to get a starting point, center drilling, then drilling thru 1/4" into the valve guide and then enlarging the hole to .375" to .440" deep.  The pix shows reaming .375" to create a good fit for the pipe from the carburetor. 



And here's the now completed cylinder head from 3 views. 

First looking at the intake port.  Note that I put a small chamfer on the head just to make assembly a bit easier plus I hate sharp edges!



Viewing from the exhaust port side.



And lastly from the bottom.



And that's it for the cylinder head!  Although there are a lot of steps, it wasn't actually terribly difficult once I figured out the simple fixture.  That really made positioning easy!

Enjoy!

Mike

MIke
Wichita, KS, USA

Online Admiral_dk

  • Full Member
  • *****
  • Posts: 2995
  • S°ften - Denmark
Re: Farm Boy #876 - Mike's Build
« Reply #35 on: October 01, 2022, 11:05:27 AM »
That is a fine looking Head Mike  :ThumbsUp:

I'm sure you are right abouth the chatter marks @ the very slow speed this Engine is supposed to run.
Plus they might actually help the Air/Fuel to mix even better on the Carburator side ....

Per

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #36 on: October 06, 2022, 01:19:39 AM »
Next up is the crankshaft.  Howell's plans call for the crank to be carved from solid stock, but I chose to do a built up crankshaft as I've done it that way a couple of times previously and both of those came out good.  So here we go!

Here are the raw materials.  Some 3/8" drill rod, I think W1 and some bits of 3/8" steel whose identity is a bit of a mystery but it acts and looks like and acts like O1 or A2.

First, i cut one piece of the drill rod to the overall length that I needed.  I actually made it a bit longer than Howell specified on the right side.  I need to sneak in a delrin disk for the ignition trigger magnet on that side of the engine and need a little more clearance.  Additionally I made a few other minor dimension changes as I wanted to leave the throws .375 vs .382" on Howell's drawings.  I did model the crank, engine frame, and bushings to make sure everything fit with proper clearance.  Here I'm drilling center holes on each end of the main shaft of the crank.  This is partially for appearance and for turning between centers should that prove necessary. 



Here are the 2 pieces of drill rod cut to length along with the 2 pieces of flat stock Loctited together and clamped together to cure.



Here the holes for the throw and the main shaft were drilled and reamed exactly .6875" c/c.  Note that i did this operation with the 2 pieces Loctited together and held in the mill vise using some Al between the stock and the floating jaw.



Then I rounded over each end using the rotary table with a pin to establish the center or rotation.  I did this op this was as this is way easier with a built up style crank.



The throws finished and laid on the drawing.



Then I milled a 1/8" slot on each end of the crank's main shaft.  I'm going this different than Howell as my intention is to use a key and set screw arrangement vs the hub clamp. One thing that I figured out is that when milling keyways, the specified depth is taken from the point that the cutter creates a full-width flat, NOT when the cutter touches the top of the rounded surface.  There are calculations that give the depth required from the touch point, but it's just easier to mill away a bit until you have a perfect flat.  That's easily determined by scraping your fingernail across the area.  I used a 2 flute HSS end mill turning about as fast as the Bridgeport can go plus I used my MQL system to keep the slot clean and lubricated. 



And here I'm checking the fit within the frame and bushing prior to permanently securing all the pieces.



Next i applied Loctite 638 to all the joints and carefully positioned the pieces and to make sure the spacing between the throws was correct I clamped a small bit of Al milled to width, between the throws.  And I assembled it on a surface plate to keep everything as well aligned as possible.  I then let us cure overnight prior to the next work on it.



To further secure the joints, I drilled thru in 4 places and drove in some small finish nails liberally coated with Loctite 638.  I carefully selected the nails so they were each a very light interference fit that took just a bit of tapping to get into place.



After that i clipped off the excess length of the nails and fully flattened them using my belt sander.  Here I'm milling out the section of the main shaft that has to be removed to turn it into an actual crankshaft.  Believe me, I checked about 10 times that i was milling away the correct bit before commencing!



And here's the completed crankshaft!! 



And that's it!  I find this method of making a crankshaft entirely satisfactory.  I think the Loctite plus pinning the joints is adequately strong for anything that this engine might experience.

Enjoy!

Mike

MIke
Wichita, KS, USA

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5893
  • Portland, Oregon, USA
Re: Farm Boy #876 - Mike's Build
« Reply #37 on: October 06, 2022, 04:57:54 AM »
Great crankshaft!  Nice set of pictures showing the steps you took to make it too!  :popcorn: :popcorn:

Kim

Offline A7er

  • Full Member
  • ****
  • Posts: 197
Re: Farm Boy #876 - Mike's Build
« Reply #38 on: October 06, 2022, 05:44:14 PM »
You made that look very easy! I am starting to believe that even I could do it.
Lee

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #39 on: October 07, 2022, 05:00:54 PM »
Lee, Kim and everyone, thanks very much for watching this build and for the nice comments!  They are definitely appreciated! 

So next up is the connecting rod, a part that has plagued me in the past.  Let's see how this one goes.  I thought a LOT about how I'd approach this and what my OoO (Order of Operations or Order of Oops) would be.  I started by making a 3D model of the conrod in Fusion 360 and generating a drawing that added a few coordinates and features that I thought would be helpful. 

I started by cutting and milling to dimension a piece of 3/8" thick Al.  I didn't show the operation but I stood the stock upright in the milling vise and drilled and tapped qty 2 6-32 holes with clearance at the top as per the drawing.  Next i made a couple of bits of brass rod threaded 6-32, again as per the drawing.  Then I used a slitting saw to cut off a piece at one of the stock .400" thick AFTER the holes were drilled and tapped.  Next i fastened the two pieces back together using the brass studs I made plus a couple of small nuts.  Here I've placed the stock back in the mill and found the center of it then I zero'd up at the right end and drilled center holes at the big end and small end locations.  Here I'm reaming thru the small end and you can see the center drill mark at the big end.  Doing things this way should assure that the distance between the hole centers is as accurate as possible.



Next I moved back down to the big end location, drilled thru 1/2" and then used my boring head to enlarge the hole to .5625" as per the drawing.  You can see why Howell specifies brass for the temporary fasteners.  You end up cutting through a portion of them.  Also you can see a center hole at the end of the cap, the purpose of which will become clear shortly. 



Then, before removing the part from the vise, I milled some of the thickness away at the 'top' of the conrod, so that that feature ends up 3/8" x 3/8".  Wot you ask, is this for??  Standby!!



And here's the part back in the mill vise, repositioned with some Al packing material on each side of the conrod.  I started by locating on the big end hole and here I'm using a 2 flute mill to create 4 holes that will form the radii for transition between the rod body and the ends.  Doing is this way helps subsequent operations. 



Here's the conrod laid on the drawing I generated where you start to see why those holes were formed. 



Over to the lathe with the work being held in a square collet on the mysterious feature formed earlier and being supported by a live center using the small center hole at the end of the cap.  To gain access to this area, I used a left hand tool and had to place it at a bit of an angle to avoid interference with the center.  I keep telling myself to purchase an extended nose live center, but I've just not done so yet.  The sole purpose of this exercise is to round the edges of the big end of the conrod.  I don't think that this was strictly necessary but that's what the drawing called for, so i did it.



Here's the part, back on the drawing after bluing it up and scribing a couple of reference lines on it.  I did this mostly to keep myself sane and out of trouble for the subsequent operations.



Next the part was placed on my rotary table back over at the mill.  I made an alignment pin for the small end and centered it under the mill spindle.  Here I'm using a DTI to assure that the part is aligned with y.  There was no other good way to establish alignment in y that I could think of. 



Howell doesn't specify the angle of the sides of the rod on his drawing, but from my model and drawing, it's 1.66 degrees.  So here I've rotated the table by 1.66 degrees and just for being double sure, I used the pointy end of an edge finger and traversed the mill table in y to make sure that I was close with my rotation.  Belt and braces as they say!



I'm not showing all the various moves and repositioning of the part on the RT, but you can see the end result.  The holding feature was removed from the small end and the rod body now has the properly angled sides as the drawing calls for.



The rod body needs to be thinned to .250" from .375" and this requires the RT to create the round feature at the small end as this pix shows.  I flipped the rod over to do both sides, but I don't show that as it's exactly the same as the first side. 



The conrod on my small mini-pallet about to be secured to it.  I secured the small end with a bushing sized to just slip thru the small end and fastened with a 10-32 shcs and a washer.  You can see the width milled down on both sides near the small end.



After aligning the rod to make sure the cut was straight at the big end, I commenced milling the rod body on the first side, being careful to match the depth of the cut around the small end.



Doing the same operation on the 2nd side, but this time with some AL packing material under the rod body for support.



And here's the rod body in what I'm declaring to be the finished state. I don't personally like the recesses on the sides of the conrod as Howell specifies, so I simply left that feature off. 



So that's it for the conrod body but there's much more work to complete the assembly  but I'll save that for another post as this one is getting quite long.

Enjoy!

Mike

MIke
Wichita, KS, USA

Offline RReid

  • Full Member
  • ****
  • Posts: 973
  • Northern California
Re: Farm Boy #876 - Mike's Build
« Reply #40 on: October 07, 2022, 08:20:04 PM »
Conrods often take a lot of work, don't they? But the end result looks so cool! Great job, Mike. :cheers:
Regards,
Ron

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #41 on: October 08, 2022, 01:42:25 AM »
Ron, conrods are indeed a lot of work and the work is not finished yet!  In this post I'll show how I made the big end bushing. 

First I took a piece of SAE 660 bearing bronze and mounted in the mill vise and cut in half using a slitting saw.  i previously turned it round to .75" just to clean it up a bit. 



Then I took the two halves and smeared a liberal coat of this tinning flux.  This is the type that is for lead-free plumbers solder and it does have some finely powered solder in it that helps solder flow into the joint when heated.



I bound the two halves together with some 20ga annealed wire and then heated the assembly with a plumbers propane torch and applied some Harris Stay-Brite solder, which I think is 4% silver content.  The solder flowed easily into the joint once I got the halves up to temperature.



Then it was back over to the mill to turn the OD just enough to get it round and so that it would fit in the next size down collet.  Here I've done one end of it and I've flipped it around and changed the collet to do the remaining end.



Back to the lathe holding the part with the excess material and turning the recess in the center.  I also started the cut to indicate where the 2nd shoulder will be in order to check the dimensions.  I used a 2mm carbide parting tool for all this work.  That SAE 660 cuts like butter!



And here's the part on the drawing with the first stage of lathe work done.  At this point, there's no hole through the middle.



Over to the mill with the part in a collet block.  Here I'm getting the part aligned at the solder joint in order to mill a couple of recesses in the sides of the part.  Aligned visually is more than close enough for the subsequent operations.



I didn't have a 3/16" ball end mill to create the grooves on each side.  That's what the drawing calls for.  Instead I used a 3/16" end mill and walked it in on each side to create the recess.  This method work perfectly fine plus I could do both sides without repositioning the collet block. I had previously found the centerline of the part and had zero'd x at the end of the part all by using an edge finder.



Then back to the lathe.  Here i drilled thru the center and then reamed to .375"  This isn't the end of the story for this bore as it won't actually be round when the part is separated into halves.



I didn't show the parting operation but here's the results after parting off.  You can see that the solder flowed and bonded each surface completely.  You can also see the temporary studs used to hold the conrod together for boring the big end hole, just for reference.  The 2 halves actually came apart when I started the parting operation as there's so little surface area left at the solder joint. 



I spent a bit of time deburring the halves and sanding the joint area clean using some 400 grit sandpaper laid on a small surface plate.  Here I've installed the 2 halves together in the conrod big end and centered the mill spindle over the big end hole.  Since the hole in the bushing is not round and is a bit undersize, I used a 3/8" end mill to clean up the ID as shown.  I figured this would cut true vs a drill.



Finally I reamed thru the hole .376" using a .001" oversize reamer. 



And just to prove it all worked, here's the conrod with the split bushing installed assembled on the crankshaft.  And if even rotates!!!



Making these split bearings is always a butt-clenching exercise for me and I'm not completely happy with the process I used.  One of the issues is, is that the OD isn't truly round when you do it this way, but it is close and it did fit within the conrod big end without difficulty. 

If anyone has any suggestions on a better way to do these split bushings, I'd really appreciate a description of a better method.

Anyway, another part done!

Enjoy!

Mike


MIke
Wichita, KS, USA

Offline mikehinz

  • Full Member
  • ****
  • Posts: 335
Re: Farm Boy #876 - Mike's Build
« Reply #42 on: October 08, 2022, 09:51:37 PM »
So at long last, the conrod is finished!  Here's how it all happened.

First, there is a 1/16" oil port to be drilled thru the big end into the big end bearing.  Here's the setup using a 30/60 angle block, centering on the y axis using an edge finder and visually aligning the drill location in x.  I placed the hole just in front of where the screw hole for one of the conrod caps breaks through.



Next I made the wrist pin.  First I cut off and then trimmed to length a piece of 1/4" drill rod and lightly polished the OD to bring it just under .250".  Here I'm drilling thru the center of the pin with an 1/8" drill.  I did first center drill the end.



Then over to the mill to make the 2 flats specified on the drawing.  These are to provide a landing spot for the set screws that secure the wrist pin in the piston.  Simple setup.  Just placed the pin on 2 parallels and tightened the vise.  Location was determined by determining the center line in y and also barely touching off the top of the work with the cutter. 



And here's the finished wrist pin.



I didn't take any pix of the operations to make the wrist pin bushing.  It was simply turning  a piece of SAE 660 rod stock to 5/16" OD and drilling/reaming a .250" hole thru the center.  Here's the finished bushing laid on the drawing.



Then I slathered the bushing's OD with some Loctite 638 and pressed it into the small end of the conrod.  Note that the bushing is slightly wider than the conrod body so I spaced the conrod body off the press anvil with a feeler gauge by the required amount.  I didn't take any pix of the pressing operation as it's not at all interesting or exciting!  But here's the assembled pieces.



There's one more operation required in order to create an oil access port for the conrod small end.  Here's the mill vise setup.  Note that I inserted some Al packing on each side of the conrod since the ends are thicker than the middle and the ends are different thicknesses.



Then a small slot needs to be milled across the top of the small end.  Location was determined by finding the center line in y and locating x from the small end top.



Then without changing the setup, I drilled thru the conrod body and bushing using a 1/16" drill. 



And finally here the now completely completed conrod!!  There are indeed a lot of operations to make a conrod and I think that this one came out at least OK.

Enjoy!

Mike



MIke
Wichita, KS, USA

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5607
  • Switzerland
Re: Farm Boy #876 - Mike's Build
« Reply #43 on: October 09, 2022, 04:40:18 PM »
Looks good  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline Bearcar1

  • Full Member
  • ****
  • Posts: 824
  • Chicagoland Area, USA
Re: Farm Boy #876 - Mike's Build
« Reply #44 on: October 10, 2022, 05:34:17 AM »
I am enjoying watching your progress Mike.  :ThumbsUp: :popcorn:


BC1
Jim