Farm Boy #876 - Mike's Build

[mikehinz]

I'll quickly document the build of one more part today since the last part was pretty straightforward. 

This is one of the smaller bits and I'm not sure the way I did it is/was the best way, but it worked.

This part is the exhaust valve rocker arm and I'm starting with a piece of .5" brass rectangular bar stock saw cut to just slightly more than the finished length of the part.



The first operation was to trim the stock to the OAL of the rocker arm using the mill. 



Then I blued up one side of the brass stock and drilled and reamed the 3 holes required, 2 were 3/32" and one was 1/8".  I also lightly scribed a couple of reference lines using the mill, mostly just for reference for subsequent operations.



Next I marked the end radii required using a 3/16" end mill by just barely scratching the surface using the end mill.  These are reference marks only, no functionality implied.



Here's the stock laid on the drawing.  You can see why I blued and marked up the stock.  I was then able to scribe the angled surfaces for reference and eventually I'll be able to create the rounded ends using these marks for reference.



Then back to the mill with the stock set on an angle block.  Here I'm starting to mill away the first angled surface using a 1/2" 4 flute end mill.



And the stock back on the drawing showing the progress so far. 



Back to the mill again.  I'm now milling the 1/8" slot in one of the ends of the rocker arm.  Pretty straightforward after finding the center line of the stock in y and finding the right edge of the stock for x positioning. 



And here I'm milling away the material on the sides of the stock to form the shape.  Fairly straight forward using the DRO referenced to the y center line. 



I didn't show the operation, but I sawed the part off the stock using a slitting saw.  I rounded the ends and center using the belt sander and polished it just a bit using a small Scotch Brite wheel. 

Here's the part as viewed from the side.



And as viewed from the top.



I think the part came out pretty well using the process I described above.  I'm sure that there are other ways to do this part, but this turned out to be fairly easy.

Enjoy!

Mike

[Admiral_dk]

Great description and result 

Per

[mikehinz]

Next parts up are two really fiddly bits, the push rod guide and rub plate, qty 2 required of each.  On the push rod guide, I thought long and hard about the order of operations as some of the sections through the part get really thin and I was afraid of breaking the part during machining.  Here's what I ended up doing.

I started with a small piece of rectangular brass stock, .5" x 1". 



Then after inserting the brass into the mill vise, I milled the stock to the required external dimensions and milled the material out of the middle of the part. 



I parted the piece off with a slitting saw and here's what I ended up with so far:



Then back into the mill vise and after locating the edges drilled the 2 required holes into the part.



Then without moving the part, I milled the two recesses into each side of the part as shown here.  End mill was a 1/8" 4 flute that I just barely stepped over to achieved the spec'd width.



And here's what the part looks like with the operations completed so far.



Back to the mill vise one more time with the part tilted using an angle block and then milling the side features.



And after that operation, you end up with this.



I didn't show milling the top of the part flat, but I indeed did so.  Then I repeated everything again and ended up with two parts.  For comparison the 2 completed push rod guides are shown near a 20p British coin.



The rub plates actually caused me a LOT of grief trying to get them done.  I had a strip of .025" brass of exactly the correct width so I thought I'd simply glue them to a bit of AL scrap and drill and mill them to length.  But after numerous attempts with different adhesives and technique, that approach utterly failed.  The milling operation broke the glue bond each and every time.  I don't know why as I've seen others use this same technique, apparently successfully, but alas it didn't work for me.   Suggestions on how to make something small stick to a fixture are most welcome!

So I took a much more direct approach.

I started with the same piece of .5" x 1" brass stock and milled the top of it to the required external dimensions and then drilled the 2 required holes.  This was of course easy as the stock was completely secure and stable.



Then I simply sliced off 2 pieces using a .030" slitting saw.  I find that I can perform quite accurate cuts with this setup.



And here are the two rub plates laid on the drawing with the 20p coin for comparison.



And that's those 2 parts done! 

I'm going to post one more part right after this as the next bit is integral to this assembly.

Enjoy!

Mike

[mikehinz]

I'll document how I did one more part of this assembly, the 'Primary Exhaust Valve Push Rod'.  I found this to be fairly straightforward and easy'ish most because it's slightly larger and easier to hold.

I started with a piece of tool steel I had on hand.  I'm not entirely sure what the alloy is, but I think it's A2.  It actually machines quite well.



After sawing it to rough length, I machined it to the finished length, thickness and width and then machined the reduced thickness on one end of it.



Then there are 2 holes that need to be drilled and tapped 2-56.  I used a spiral point plug tap and rotated the tap by hand while held in the drill chuck with the mill kicked into neutral.  If this would have been a couple of blind holes, I'd have used a tap follower and a very small tap handle to rotate the tap as that gives a much better feel of what's going on. 



Then I stood the part on end and made sure it was vertical and then drilled 1/8" hole in the end as per the drawing.



And here's the completed part on the drawing.



This valve push rod requires a 'Push Rod Stop'.  I started with another small bit of tool steel and milled the external dimensions and the slot in the center as shown here.



Then I cut the part from the stock stub using the slitting saw.  I think I ran the spindle at about 500 rpm and slowly hand fed the saw through the work.  I used my mql system to blow the chips clear and to keep the cut lubricated. 



And here's the part on the drawing.


This is showing the fit of the stop to the push rod.



And finally, here's how the assembly goes together, although I forgot to put the stop in place for this pix. 



So that's it for another sub-assembly for this engine.  Onward and upward!

Enjoy!

Mike

[Charles Lamont]

Some fiddly work there.

[RReid]

Very nice, Mike. Still following along and enjoying!

[mikehinz]

Gents, thanks very much for watching this build!   

Now, on to a few more fiddly bits, plus a failure!!

None of the actual operations shown for this as it's so simple.  This is the 'Secondary Exhaust Valve Push Rod'.  It's just a piece of 1/8" drill rod, trimmed to length and threaded 5-40 on one end.  The only change I made was to make the thread longer as I want to incorporate a lock nut to prevent rotation of the clevis/rod interface.



Next is the push rod clevis.  I'm sure you can start with a piece of square rod, but I decided to start with a piece of round rod.  Here I've just turned the lower portion, which remains round, to the spec'd diameter and now drilling/tapping it 5-40.



Next I placed the part in a collet block and squared up the outer dimensions as per the drawing.



I didn't show the operation, but I did reorient the collet block and drilled the thru hole for the clevis pin.  I DO show the disaster though!  As i was making the last past to mill out the slot down the center, one side bent which of course destroyed the part and also the end mill.  A sad day!



And here's the aftermath with both bits clearly shown.



I really don't think I did anything terribly wrong as I was taking very light cuts at this point.  So I took a bit of a brute force approach and simply increased the thickness of the part by about .020" overall, so about .010" per side.  This gave the part a bit more strength so that I could withstand that last bit of milling without failure.

And here's the part, version deux nearing completion.  For this attempt I used a 1/8" 4 flute carbide end mill.  Everything went fine this time, with really no change in technique, other than slightly increasing the part thickness through that dimension.



And here's how the parts made so far look in combination. 



And here's a closeup pix of the clevis installed on the push rod with a nut for locking the assembly to prevent rotation.  I rounded the end of the clevis just marking it with a radius gauge and rounding it over on the belt grinder.



I'll quickly document the build for one more small part, the Governor Catch Lever Block.  I started with a small block of tool steel and milled the overall dimensions and here I've tilted the stock using an angle block, and am about to mill the angled edge on it.



Next i used a slitting saw to cut the part off the stub stock.



And lastly, mounting the part in the mill vise and drilling and tapping 2-56 for the mounting hole.



And here's the finished catch block with a 2-56 hex bolt installed. 



And that's it for today! 

Enjoy!

Mike.

[Admiral_dk]

Breaking the Part is bad enough - but killing the Tool too - now that is Very Annoying 

All the finished Parts looks very good - so at least you are moving in the right direction (even with one step back) 

Per

[mikehinz]

Breaking the Part is bad enough - but killing the Tool too - now that is Very Annoying 

All the finished Parts looks very good - so at least you are moving in the right direction (even with one step back) 

Per

Yes, breaking tools is annoying AND costly!

Mike

[Kim]

The parts look great, Mike!   

Sorry about the broken end mill.  That happens.  Guess it's a hazard of our hobby.  But always a real bummer!

Kim

[mikehinz]

After entirely too long a delay, I'm back and will try to post the rest of the build as quickly as I can.  I had a few issues around health, some long overdue travel, holidays, etc,  blah, blah, blah, but still no GOOD excuses!

In any case, on with the build.  Next up are the various bits that make up the governor assembly that's attached to the flywheel, along with a few related parts.

First up is the governor weight fulcrums.  First I modeled these and generated a new drawing as there seemed to be a few needed dimensions missing from JEH's original drawings.  Here I'm starting with a piece of brass that was just exactly to size in x and y.



Drilled the holes using xy coordinates after finding the block edges.



I scribed the overall shape of the fulcrums on the stock just to avoid getting confused and also used the mill to locate the 2 points that define the length of the inner horizontal flat.  You can see here that I've already been to the mill and milled away part of the material of the raw stock.



Milling out the 'center' material. 



Then setting the stock at the required angle(s) using an angle block and a couple of parallels then milling out the remaining material.



Next I used a slitting saw to cut off two pieces plus a spare.  With the slitting saw and a bit of care in the setup I can get the thickness required to within .001" or so. 



Here are the parted off fulcrum levers and the leftover stock, just prior to filing and sanding them.  You can see that the slitting saw leaves quite a good finish.



And here are the qty 2 finished fulcrums after a bit of work with a file and some sanding.



I'll stop this post here just to avoid a single post getting too long, but will start the next part in a following post here shortly.

Enjoy!

Mike

[mikehinz]

As promised, here's the next part in this long-overdue saga, the Governor Weight Fulcrum Hub.  JEH's drawing was entirely clear and complete on this part so I used his drawing as is with no need to model it again.

I had some brass round stock, but it was a bit oversize and I couldn't fit it into a 5c collet which I needed to be able to do for subsequent operations.  So I chucked it up my 3J and turned one end of it down so it could change over to my collet setup.



Then into a collet to finish the OD turning.



And here's what I have ready to go to the mill.



Stock was secured in a 5c collet block and was centered under the spindle using a DTI.  Here I've drilled and am countersinking the qty 2 holes for the 2-56 flathead screws that will be used to mount the assy to the flywheel.



Milling the 2x slots required just positioning the spindle offset using the DRO.  Since it was a pretty deep slot, I used a 2 flute cutter, high rpm and also used my MQL setup to clear the chips out and keep it lightly lubricated.



And here's the fulcrum hub with the fulcrum arms fitted into place.



Next I did exactly as JEH calls out on the drawing.  I moved over to my welding table and used my oxy/acetylene torch with a small tip to apply heat to the assembly.   Note that I inserted some small pieces of drill rod to keep the fulcrum arms aligned during the silver brazing operation.  For the brazing materials I used Harris Safety-Silv56 with the white Harris flux.  That combo seems to work well for me. 



Here's the part after brazing and prior to the lathe operations and general cleanup.



Back to the lathe with the part installed in a collet.  Here I've drilled out the center and am using a boring bar to take the ID to .602" as per the drawing.



Parting the hub off using a HSS parting blade extended perhaps a bit too far, but necessary to clear the fulcrums arms.  Brass parts pretty easy so I wasn't scared with this setup.



And here's the hub showing how it will fit on the flywheel.  I still had a bit of cleanup and polishing work to do it the hub, but wanted to make sure it all went together correctly.



And that's it for this fairly involved part.  On to the next one!

Enjoy!

Mike

[Dalboy]

Been watching with interest as I have still to get these buts done on mine as I am still working on the frames.

[mikehinz]

And finally one more post today, the Governor Catch Lever. 

As for the fulcrums I started with a piece of rectangular brass stock that was milled to the length required.  I did model this part in CAD to add a few dimensions that were helpful to me during the machining operations.



Since this is a fairly complex part with multiple setups being required I blued it and scribed the outline of the part on it.  Then when mounted in the mill vise, I drilled the 2 holes called out on the drawing and also drilled an 1/8" hole that defines the corner radius and it certainly aids when milling away the rest of the material.



Here I'm milling away the material that can be removed with the part in this orientation. 



Next I using a 4 degree angle block to orient the stock to mill the front surface as per the drawing.



Then I used a 9 degree angle block to orient for milling the 'sloped' surface on the top of the lever.  I had to used a longer end mill to reach the surface to be milled as I've left the majority of the stock in place to aid orientation.



Reorienting the part yet again to drill the 2x holes through the 'Z' side of the material. 



And after all that, the actual part is sawed off from the stock to yield the actual part.



And here's the finished part from several different views.

View 1



View 2



View 3



Last view showing the stock the part was sawn from and a Coin with the Queen for size comparison.



And that's it for today's posting.  I'll make every attempt to finish posting this build tomorrow.

Enjoy!

Mike

[mikehinz]

Been watching with interest as I have still to get these buts done on mine as I am still working on the frames.

Dalboy, thanks for taking a look!  I THINK I'll get the posting on this build finished tomorrow. 

Mike