Lauson LA build

[Hugh Currin]

Craig:

Thanks for posting details on this method of making rings. I've used the "Trimble" method for this, which includes heat treating the rings. But I've not before heard of this method. It seems simpler and should work well.

Thanks.

Hugh

[Brian Rupnow]

Craig--I have been a total failure at making cast iron rings that seal. I haven't tried the method you have outlined, so if I ever set out to make another i.c. engine I will hunt down this post and try your method. Thank you for the good "how to" post.---Brian

[Roger B]

Still following along with interest        I have always soldered the halves of my split bearings together before machining. Do you have problems with the two halves moving?

[Craig DeShong]

Carl, Cletus, Dave, Hugh, Brian, Roger; thanks for your responses.  Roger; the 4-jaw chuck holds the pieces firmly.  I usually allow as much material in the chuck as outside.  I’ve never had a problem with the material shifting in the chuck.  I did have a problem with the drilling operation spreading the pieces but after I started using a C-clamp to hold them together this hasn’t been a problem.  Once you start turning the two pieces it’s difficult to see the line where they meet.  I do take great care to make sure the two mating surfaces are smooth and flat before joining them together.

I didn’t devise this technique.  Years ago, and error required me to bore one of my locomotive cylinders over size, resulting in the purchased piston ring being too small.  Trying to salvage the casting and this bad situation, I came across this technique in a book describing the construction of model steam locomotive rings.  I’ve found it works as well with the IC engines I’ve built.

With this interest I might need to fill in a few additional details; firstly, how to appropriately sizing the cylinder that forms the ring blanks so that you have enough “meat” to turn the ID and OD of the rings round.  I’ll do this by example of this engine.

I figure the OD as follows: my bore is 1.125.  1.125 * pi (3.14)= 3.533, the circumference of the engine bore and outside circumference of the compressed ring.  Add the ring gap, in this case .125= 3.658, now divide by pi 3.658/3.14= 1.161.  This is the diameter of the ring blank with the ring gap still in place.  This is the minimum diameter for the outside diameter of the ring blank but you need to add a few thousandths of an inch so that you have material available to get the ring blank (once the gap material is removed and the ring is compressed) back to round.  Around .030 inch ought to do, so the final OD of the cylinder used to form the ring blanks is 1.161 + .030= 1.191

The ID is calculated in much the same way.  The diameter of my ring grove is 0.967.  You need a little spacing between the ring and the grove; I used 0.020 so this gave an inside ring diameter of 0.987 with a circumference of 0.987 * pi (3.14)= 3.099.  Once again add in the ring gap 3.099 + 0.125= 3.224, and divide by pi (3.14)= 1.027.  This is the maximum diameter for the inside of the ring blank.  Again you need additional material to get the ring round so this time, reduce the inside diameter by around 0.030 thousandths.  This gives an inside diameter of 1.027 – 0.030= 0.997.

To summarize, the hollow cylinder used to form the ring blanks should have an inside diameter of around 0.997 and an outside diameter of around 1.191.  This should provide enough material to allow formation of round surfaces on both the inside and outside of the ring.  Of course, with different diameter pistons, different sized ring groves, and different ring gaps; all these number will change but I hope you can get the principal from this example.
 
I will also encourage you, when you form the outside diameter of the ring, to turn the ring OD to within a thousandth or two of the final diameter, and then finish with a fine file and emery paper.  The smoother you can get the outside surface of the ring, the less time that will be required for the ring to wear in and seat.  In reality, you need to turn the ring OD slightly undersized so that the ring gap doesn’t entirely close when installed.  Remember that for each thousandth lost in diameter, the circumference is reduced by pi.
 
After I install the rings and check for binding and am satisfied that everything is ok, I usually chuck the crankshaft in my lathe, support the engine base on the ways, and spin the engine for as much as ½ hour at around 200 rpm.  While I’m doing this I load the cylinder with oil (for these vertical engines I just keep the top of the piston covered).  This helps to “run in” the rings and helps with initial compression.

With these rings, my engines have little compression when they are first started.  For the first few runs I need to load the cylinder with oil to help with the compression, so they smoke like crazy.  After they’ve run for a while and the rings finally seat, the compression improves dramatically.

[Craig DeShong]

... I’m sure you’ve shown, but, how will this one be started?... Cletus

Looks like I omitted answering this question, sorry Cletus.  I have a 12 Volt model airplane starter I use to crank my other Lauson models.  I'll probably use it for this one, using a sewing machine belt to a pulley on the PTO side of the crankshaft.  I'm HOPING that I can use the kick-start mechanism once it's run a bit and has some compression.

[Craig DeShong]

Work has continued this week, though I haven’t taken too many “in process” pictures.  I’ve fabricated the crankcase breather and the governor cap as seen in the picture below.  A little filler before paint and I’m thinking everything will blend quite well.
 


Today I started working on the head.  Here I’m using my rotary milling head to cut the half-circle on the PTO side of the engine.
 


Here I’m starting on the cooling fins.  I’m cutting these to nearly a ½ inch depth, so numerous passes will be required.   Fortunately my mill has a x-axis power feed, but I still need to keep flooding the end mill with fluid, lest the aluminum shavings bind to it and it shatters. 
 
 

Earlier in the week I was working on some of the internals of the governor.  This is a lever that fits inside the governor cap (a photo further on).  It converts the linear motion of the governor spindle to rotary motion so it can be carried outside the governor cap where an attached lever, though a pushrod, can move the carburetor throttle. 
 


Another picture of the same part, but complete and being cut off the base stock.
 


Here is a picture of the above lever, fitted to the governor cap and with the governor spindle installed as it would be on the engine.
 


Here I give you a photo of the governor spindle.
 


This is a photo of the flyweights inside the governor cylinder at the rear of the engine.  When the engine is assembles, this is covered by the governor cap.  If you look very closely you might see the arms attached to the flyweights that push the governor spindle out into the governor cap.
 
 
This photo is the same as above, but with the governor spindle removed from the governor cap and installed against the flyweights.  From these photos you can probably get an idea how this governor works.
 


Now for my dilemma.  If you look three photos back at the photo of the governor spindle (above the quarter) you will notice that it is one solid piece.  On the full size, the left disk (the one that bears against the governor flyweights) is a ball bearing so that, as the flyweights are spinning, they revolve against the bearing and the governor spindle does no rotate.  On the model, with this as one piece, I’m going to have a lot of wear in this area; the portions of the flyweight that bear against the spindle are quite small and will be moving relatively fast .  During the design, I didn’t think this would be an issue but now that the parts are made I’m having second thoughts.

I’ve re-designed rthe end of the governor spool as a rotating end but, man, the parts are SMALL!  Any other ideas out there? 

[Brian Rupnow]

Craig--If the parts are riding in an oil bath, make the two parts that bear against each other from o1 steel and harden them. I had always been taught never to let similar metals rub against each other for fear of galling, but when I worked for Volkswagen of Canada it was common practice to do that on many of the automated machines I designed. It worked, and worked very well. This may not be an option if the parts are already made.---Brian

[Craig DeShong]

That is an excellent idea Brian.  I wonder if kasenit would suffice, the parts are 1018 cold roll.

[Brian Rupnow]

Yes it can be hardened--maybe. Read all about it here.
http://www.steelforge.com/aisi-1018/

[Craig DeShong]

Progress continued with fabrication of the cylinder head.  The detail on this piece, for the most part, will be covered by sheet metal; but if you’re making a model you might as well model even the stuff you can’t really see.  I also started on the oil pump, more on that later.




The “real” progress these last few days however has been on the governor spindle.  I took Brian’s suggestion and hardened the ‘levers’ on the governor weights.  I don’t believe this is the definitive solution but it can’t hurt.   
I finally settled on a solution that is, pretty much, a scale version of the ball bearing end to the full size governor spindle.  These parts are pretty small and I’m amazed that with my limited talents, I was able to successfully fabricate things this small.  The photo below show the complete assembly.  The green arrow points to the “levers” on the governor weights that bear against the governor spindle.  The red arrow points to the bearing end of the governor spindle.



These next three photos are exploded, and then assembled 3-D cad drawings of the revised governor spindle. 
The governor spindle has been revised so that it captures 1/16 in. diameter ball bearings in a bearing race (the orange part).  Running on the ball bearings is a rotor (brown part) and a cap (green part) fitted over the rotor, capturing the rotor with a thin lip.  The cap fits onto the orange part with a press fit.  This results is a rotor that turns freely on the ball bearings and is the contact surface for the governor weight levers.





With the governor spindle assembled with the governor weight assembly; the weights spin freely while the spindle remains stationary, hurrah. 

[Brian Rupnow]

Great stuff Craig. I really enjoy seeing your project come together. There is a lot of quality work there.---Brian

[Dave Otto]

Nice progress Craig, I like what you came up with on the governor bearing.

Dave

[b.lindsey]

Coming along well Craig!! That cylinder head looks fantastic.

Bill

[Craig DeShong]

Many thanks to Brian, Dave, and Bill for your encouragement and kind responses.  Also, thanks to the others who are silently following along.

My 3-D CAD program is marvelous; I wouldn’t want to do without it. With all the positives though there are a few drawbacks.  One of the annoying “features” is that it is perfectly willing to break the laws of physics and allow two objects to occupy the same space at the same time.  This can be a blessing at times, but also a curse.

When I went to install my newly fabricated oil pump and dipper trough in this engine, much to my chagrin, I found that in the real world two physical objects CAN NOT occupy then same space at the same time.  A quick reference back to the CAD assembly clearly showed the dipper pan I had designed entering the side of the block and disappearing on BOTH sides.  Had I been observant, I’d have seen this and revised the dipper trough BEFORE I fabricated it.  Not a terrible big deal, but a few hours wasted due to carelessness that didn’t need to be.  With the revised dipper trough here you see a photo of the oil pump and dipper trough installed in the oil sump.



With the revised dipper trough the oil pump fit nicely into the engine.  The clearances were tight and I did need to shave a bit of the block away at a few places to get the clearance and free space I needed but this wasn’t a huge surprise and the interference was minimal.  I WAS happy to see the oil pump plunger make positive contact on the eccentric on the cam shaft and effectively drive the oil pump.  Here you see a video, looking into the block as I rotate the camshaft and drive the oil pump.
<a href="https://www.youtube.com/watch?v=M3nssNXVxG4" target="_blank">http://www.youtube.com/watch?v=M3nssNXVxG4</a>


At this stage I’m pretty happy.  I’ve verified that the connecting rod will skim across the surface of the oil in the dipper trough, splashing a bit of oil around to lubricate the engine internals; and everything moves freely as it should without anything hitting and with no binding.  You expect all this of course, but it’s nice to see that you didn’t make some dumb arithmetic error or omission that results in unforeseen problems.

[zeeprogrammer]

What 3D Cad are you using?
I've not done any such analysis (I have very simple models) but under my 'Viewing and Analysis', I have a selection for 'Interferences.
My program is Cubify Design. I bought it for $99 back in 2014.

Hm. I just tried it. Not sure it's very good. Had two interferences, move the model, then had one. Shown as 'volume' but did highlight the area.