# Dieter Hartmann-Wirthwein patent engine by Gail in NM



## GailInNM (Mar 5, 2014)

A few years ago there was a flurry of interest about the Ducati Elenore V8 motorcycle. A V8/lnline 4 patent drawing was released by the inventor of the engine.  To my knowledge there were only two prototypes built. One a V8 of about 860 cc displacement and one an In-line 4 of 125 cc displacement.  Both were installed  in Ducati motorcycles and there are a few Youtube videos of them running.  I don't know of any models being built.

I have found very little information on the engines.  One page of the patent and the video model that I have attached to this post.  A few general specifications and a few photos of the engines external appearance.  Most everything else links back to these sources.  A couple of little discussions on HMEM a few years ago went nowhere. I would welcome any additional information on these engines as I am far from being a master at searching the internet.

What I am thinking of doing is building a 45 degree slant 4 in line demonstration engine with an open crankcase so the motion can be seen.  Design would be so everything could be mirrored and a second set of parts built that could convert it to a V8 if the inline 4 is successful. Only two parts should be troublesome.  The forked main connecting rod and the piston with two intersecting orthogonal wrist pins.  The wrist pins had me stumped for a while but I now think I have a way that will work.  Everything else is standard design stuff.

All comments are welcome. I have not detailed out any parts yet.  Just a few (bunch) of sketches.
Gail in NM








[ame]http://youtu.be/7E6KglXPmTs[/ame]


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## Generatorgus (Mar 6, 2014)

Very, very interesting engine.  Sorry I don't have anything to contribute,
but I'll be looking forward to seeing your progress.

GUS


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## GailInNM (Mar 6, 2014)

Thanks Gus.
A gentleman on another forum chased down the patent abstract and following that link I found the patent grant that has a fairly good description of what is going on along with a drawing of the piston.
http://www.google.com/patents/DE102008047719B4?cl=en
Gail in NM


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## GailInNM (Mar 7, 2014)

Here is a sketch of things.  I have started drawing things up a bit so I can build a dummy mock up of the action. l Everything is scaled for an engine with a 1/2 inch bore by 3/8 stroke.  This is quite a bit over square and new territory for me.  All the engines I have built in the past have had square ratios or been under square.  But it is a balancing act on this engine.  As the bore increases it gets harder to get the cylinders close together and have enough cooling fin area. I could make it liquid cooled but I really don't want to.   If I use a small bore and larger stroke the angularity problems with the linkages increase and I run out of room inside the piston for all the goodies. This seems like a good compromise.




First up on the mock up parts will be the forked connecting rod. I need it to check clearances and I think it will be the most difficult part to make.

I will make it out of 6061 aluminum but the actual engine connecting rod will be made of 7075 T6 for the additional strength in the thin sections. The work is not lost in making the mock up parts as if it is successful I can use the fixtures to make it to make the working parts. 

No shop time tomorrow so it will have to wait until the weekend.  I will post photos as I go.
Gail in NM


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## aonemarine (Mar 7, 2014)

If you build it, It will run


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## Path (Mar 8, 2014)

Where's the pop corn. Time to sit back watch the good stuff...


Pat H


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## Hopper (Mar 8, 2014)

Goodness, only Ducati could come up with something like that.
Yes, an open-view engine with all that going on inside will definitely create some interest.
Will you be building it with the traditional desmodromic valve gear as well?


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## GailInNM (Mar 9, 2014)

Thanks  for the support and interest.
Hopper:  I originally thought that Ducati was responsible for the development of this engine but the more I look into it it seems that Ducati had little if anything to do with it.  The confusion came from the fact that the inventor used many Ducati part to build his prototypes and the finished engines were installed in Ducati motorcycle frames.  But it appears that the patent was never assigned to Ducati as one would expect if that were supporting the development.

One article is specific in mentioning that the desmodromic valve gear was not used.  I plan to use conventional pushrod operated overhead valves.  The only odd thing is that I plan to locate the valve gear on the outside such that if a V8 were built it would leave the center between the vee open for visibility.

Gail in NM


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## GailInNM (Mar 9, 2014)

Before I get started making parts a few comments about machinery may be  in order.  I will be using an ancient 2-1/2 axis CNC Bridgeport and a  manual milling machine.  All the parts should be able to be made without  CNC, but a few of them will be much easier with CNC. If making them on a  manual mill I would probably leave some of the curved features square  and file them as necessary. Most turned parts will be made on an 11 inch  swing tool room lathe., but for ease I will probably use a small CNC  lathe for some of the valve parts.  I is certainly not necessary however  but is much quicker for me.

Gail in NM


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## crueby (Mar 9, 2014)

Looks like a fascinating engine. Any idea why they went with pairs of pistons moving together rather than single larger ones? Is there some advantage in wieght or space that way? The linkage is very clever - the open case model is a great idea - looking forward to your progress on it.


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## GailInNM (Mar 9, 2014)

Except for the different linkage arrangement  operation is identical to a conventional 4 cylinder inline 4 stroke engine. 
In  the diagrams below on the conventional 4 cylinder the two center throws  (Cylinder 2 and 3) are replaced with the forked main connecting rod on a  single crank pin. Same action.  Cylinders 1 and 4 are driven by the  bell cranks from Cyl 2 &3 instead of the outside throws of a crank  shaft. Again it is the same action.  So is is a conventional inline 4  with just a different way of driving the pistons to accomplish the same  thing. Although  two pistons, ie 1&4, are moving in phase with each other they are firing 360 degrees apart.











 smooth_4cylinder.jpg                                          (7.38 kB, 250x131 - viewed 8 times.)






 ducati-v8-drawing.jpg                                          (48.71 kB, 530x477 - viewed 9 times.)


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## GailInNM (Mar 9, 2014)

Before I get started making parts a few comments about machinery may be  in order.  I will be using an ancient 2-1/2 axis CNC Bridgeport and a  manual milling machine.  All the parts should be able to be made without  CNC, but a few of them will be much easier with CNC. If making them on a  manual mill I would probably leave some of the curved features square  and file them as necessary. Most turned parts will be made on an 11 inch  swing tool room lathe., but for ease I will probably use a small CNC  lathe for some of the valve parts.  I is certainly not necessary however  but is much quicker for me.

Gail in NM


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## GailInNM (Mar 9, 2014)

I started with the forked connecting rod because it is the part will be most likely to give interference problems. It is also going to be the most difficult to machine of all the parts.

Friday night, day before yesterday, I blanked out two parts.  By mid morning Saturday I had screwed them both up with stupid mistakes so I got to start over again. 

A blank was made, actually 2 so I could screw one up and still get one good one. It  was finished accurately to thickness and width and one end squared up to use for a reference.  The other end is just saw cut and will get machined off early in the machining.




The big end was machined on one side and the part flipped and the other side machined.




The big end hole wad drilled and reamed.  Then the small ends were drilled and reamed from both sides. 




A radius was put on both of the small ends.




And it looks like this so far with all the edge work done.




The contours were cut on one side holding the part on parallels in the vice.  Not much to grip on, but enough.




A pocket to hold the part was machined into a 3/16 thick set of plate softjaws in the vice.




The excess material was machined off the second side down to the contour that had been cut thus bringing the part to final thickness .




And as luck would have it I did not screw up either of the two blanks so I have two parts that agree with my drawing.  If they will work will be seen later on.




Gail in NM


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## GailInNM (Mar 15, 2014)

The fun is in progress.  Trying to stuff all the goodies into the pistons.  Slow going.
One  item that is necessary are some washers to keep things centered and  avoid collisions.  I made allowance for 0.007 thick washers and to allow  for machining tolerances and personal errors I made the washers out of  0.005 thick PTFE (Teflon) sheet.  The washers are 0.141 diameter with a  0.096 hole in them.There are 4 washers in each piston so at least 16 are  required. Double that to feed the swarf bunnies their share. And a few  extra.  I made about 100.  They could be machined from rod but for all  but a few the deburring the cutoff ring is a challenge. So I punched  them.

Many years ago I ran across an idea for a quick and dirty  way to punch thin materials and have been doing it that way ever since.   It will work on plastics and shim brass and alumninum up to about 0.025  thick. For plastic the die can be alumninum but for metals it needs to  be steel. Using a quill on a mill to drive the punch about a 1/4 inch is  the upper limit for most materials with out stressing the quill feed.  I  thought a how to might be useful.

For simple punching of a hole,  just clamp the material for the die in the mill vice.  Position the  table to a convenient location to drill a hole in the die and lock the  table.  It is best to drill the hole undersize a little bit and then  drill with the correct size drill for the hole that you want to punch.  That gives a cleaner edge.  Clean up the hole with a stone or abrasive  paper backed by a block.  Don't do anything that will take the edge off  the hole.  Now remove the drill and grind the end of the shank square  and sharp. Bench grinder is fine.  Put the drill back into the chuck  upside down and adjust the quill so the drill enters the drilled hole a  short distance.

Just put the material to be punched over the hole  and pull the handle. A little oil on the punch will make life easier if  punching metal as it will try to stick to the punch.

Here I  punched blanks out using the hole nearest the camera.  Then for the  center hole I put a little pocket for the blank to drop into and punched  the hole.  I left the washers on the punch and stripped them off after  all had been punched.  The die is a piece of scrap 1/4 x 3/4 alumninum  and the punch is the back end of a number 41 drill bit.

Gail in NM


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## GailInNM (Mar 15, 2014)

I have drawn the linkage up several times. I keep vacillating between what I can build and what I can assemble.  I finally have decided on a course of action.  All the alternatives should work once assembled. Then we get to see what goes bump in the night with the parts.

To satisfy both requirements I decided to put yokes in the pistons to carry the wrist pins and held in place with a screw into the yoke through the crown of the piston.  I have done this before on steam and Stirling engines but never on an IC engine although I have seen several examples of model aircraft engines from the 1940's that were built thlis way.

One additional advantage of this is the piston can be mounted on a stub mandrel with a screw for final finishing.  That way I don't have to make up a more complex expanding mandrel for lapping the piston. Also, since no wrist pins go through the piston wall I can make the piston wall thinner thus giving me more room for the goodies in the piston and since there is no hole to get in the way I have more freedom in positioning the oil distribution groove and the shallow ring grooves.

Gail in NM


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## GailInNM (Mar 15, 2014)

Getting started with the simpler yoke that is used in the outer cylinders.
A  piece of 0.281 brass rod was surfaced on two sides to form a "Double D"  shape with the sides 0.172 apart and finished to length.
Then the wrist pin hole was drilled and reamed 0.094 in the mill.




The  part was then moved to the lathe and a hole was drilled and counter  sunk so the part would sit flat on the inside of the piston crown.  It  was drilled into the wrist pin hole.











And finally tapped 2-56 to take the mounting screw.





Gail in NM


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## GailInNM (Mar 15, 2014)

The yokes for the inside cylinders are a bit more challenging. In  finished form they have two intersecting wrist pins of 0.094 diameter.   While the other yokes were made of brass these yokes are made of steel  as two stub wrist pins are machined as a part of the yoke. Steel is  needed both for strength and for a bearing surface for the small  connecting rods.

I started by blanking out the yoke on the lathe using 3/8 diameter 1144 steel.










Then  the bar was transferred to a spin index on the mill where the sides  were milled off and the pins rough turned using CNC.  As the pins will  be turned to finish size later the pins could be roughed out to 0.100  square on a manual mill and fitted into a 9/64 collet or an ER style  collet on the lathe for turning later.





While still on the mill, the hole for the other wrist pin is drilled and reamed 0.094.





Then  back to the lathe where the yoke is parted off long and then reversed  into a 0.218 collet and finished to length. The blank was turned long to  allow the end mill room for roughing out the stub wrist pins.










Finally  one of the stub wrist pins was pun into a 0.125 collet and the exposed  end finish turned and polished to 0.094 diameter. Then it was reversed  into a 0.094 collet holding onto the just finished pin and the other end  finish turned and polished. 





Gail in NM


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## GailInNM (Mar 15, 2014)

After the yokes I needed an easy part so I made the through wrist pins.   They are just 0.094 12L14 steel polished and cut to an accurate 0.375  length with the ends faced off square and burrs removed.
Gail in NM


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## GailInNM (Mar 15, 2014)

And for the last post for today a family photo of the above parts.  For my non USA friends that US penny is 19 mm diameter.
Now  I have to blank some material for the bell cranks and then do some  decision making about the cylinder head design to get the push rods by  it and an intake and exhaust port in place.  I need to do that before I  can finish the frame.  And while I am thinking I need to make the short  connecting rods.
Gail in NM


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## robcas631 (Mar 15, 2014)

Sounds interesting.


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## GailInNM (Mar 17, 2014)

I found a bust in my CAD drawings.  A stupid snap to the wrong place  that then propagated to several more detail drawings.  It will take a  couple of hours to clean them up.  I did get the cylinder heads detailed  out enough that l could order material for them, which I did a few  hours ago.  And, as they were not affected, I made the short connecting  rods.

In the first photo you can see a 1/16 diameter spot in the  middle each rod.  This is to identify them as being made of 6061  alumninum as the final ones will be made of 7075.  I only need 8 for the  mock up blut of course I made extras to feed the swarf bunnies.





Here  is the other side so you can see the three small tabs used to hold the  part in place for the final finishing operations. They are 0.007 wide  and 0.015 thick.  You can also see that I did not all the exit burrs  from reaming off the parts on the right end. They are gone now.  Just  have to clip the parts out with a pair of diagonal cutters and file off  the bits of the tabs that are left.
Gail in NM


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## GailInNM (Mar 19, 2014)

I have spend the last few days at the computer fleshing out some of  the parts and changing my mind on a bunch of them. Nothing like trying  to fit a few things together in CAD to make you wonder about your  sanity.  But I still have not found anything that would keep this from  being a successful runner.  Finally today I could not stand it any more  and had to get my hands a little dirty.  I made a dummy piston out of  12L14 (final pistons will be cast iron) to check for fits.  So far every  thing looks OK but there may be a bit of interference  in one area  between the rods.  I have plenty of meat there to relieve it if  necessary and knew it would be very close.  It will be a while before I  know for sure as I will have to build a frame with cylinder and bearing  mounts and a crankshaft up to be able to check it all.  They are all  drawn except for a few details that I need to decide on, none of which  affects functionality of the parts. 

Here it the test fit of parts in one of the center pistons.
Gail in NM


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## GailInNM (Mar 20, 2014)

I have been showing parts photos so I thought you might like to see the general direction I am going with all this.
This  is a working SKETCH so parts may appear to overlap as I did not clean  them up so one appears in front of another.  This is not a finished  drawing by any means.  It is just one for my own reference but ilf you  close one eye ans squint it might give you the idea.
Gail in NM


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## kf2qd (Mar 20, 2014)

I fail to see any benefit to this design. It is just adding complexity and many many more stress and wear points. Complexity rarely adds efficiency. Complexity rarely adds reliability...


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## GailInNM (Mar 22, 2014)

Just because we don't see any obvious advantage to a design does not mean we can't  have a lot of fun modeling them.  The inventor claimed there were economic and weight advantages from the simplified crankshaft and reduced number of main bearings. Of course neither of these will occur in a demo model such as I am building.

In product development brainstorming meetings we always encouraged any ideas to be presented, even if there was no obvious advantage to them.  Sometimes they would spark an idea that would have advantages.



The blanks for the dummy cylinders were turned and bored in  conventional manner out of 6061 alumninum.  No real care was taken on  the bore.  I just reamed to 1/2 inch diameter and smoothed the bore out  until the dummy pistons were an easy fit.  They had been turned a little  undersize for this purpose. 

After indicating the cylinder in  the mill, drilling the mounting holes in the mill was just a case of  center drilling and drilling by coordinates.





Then  locating the cylinder with two rods inserted in the mount holes the  sides were milled. Or so I intended.  After milling one side, the rods  were repositioned and milling started on the second side. 





I  did two things wrong and I knew better -- but....  I did not clamp the  cylinder tightly and I neither centered the cylinder in the vice or put a  spacer in the far end of the vice jaws to keep the vice jaw parallel.   As a result the milling cutter snatched the cylinder and the results  were ugly.





For  the purpose of a dummy cylinder I was able to rework it.  If it had  been a functional cylinder I would have had t make another one. Then I  finished milling the sides withe the part centered in the vice using a  stop to position the part.






And finally ended up with two usable dummy cylinders.





After  the mishap I spent the rest of the day cooling off by redrawing the  cylinder mount and crankcase parts.  New parts will be a little more  work to make but will make alignment of everything easier at assembly.
Gail in NM


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## GailInNM (Mar 24, 2014)

I got a  bit of a start on the crankcase. The crankcase is built up  of 7 parts.  The base plate, two end plates which carry the outer  bearings, two inner bearing holders, a back plate and the cylinder deck  plate.

The cylinder deck plate is the most complicated and I  started with it.  Photos tell most of the story.  ^he plate is 3/16  thick and just over 3 inches long.

Gail in NM


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## Path (Mar 24, 2014)

Gail in NM

Keep'em coming, great photos. Can't wait to see it running.
Thanks for the updates.


Pat H.


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## GailInNM (Mar 26, 2014)

Thanks Pat.

All of the crankcase plate work is finished.  Everything is 3/16 inch  thick plate except for the base which is 1/4 inch thick. The bearings  were test fitted bult won't be installed until later. The test fit up  just has a few screws to check for fits as it will all have to come  apart later.
Gail in NM


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## ddmckee54 (Mar 27, 2014)

Gail:

I'm assuming that the two flanged bearings shown in the photos are for the camshaft.  Is the cam going to be stiff enough that it won't flex with no support in the middle?  I realize that the loads on a model camshaft are fairly small, but then again so's the cam.

Just wondering,
Don


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## GailInNM (Mar 27, 2014)

Don,
I think that the cam will be stiff enough.  The root shaft diameter is a little bit larger than I would normally make it if I had additional bearing support. But, just in case, I have a center bearing support on the drawing that I can add in.  It is open on the top side so it can be slid into place with the engine assembled.  Since the deflection forces will mostly be downward and some front to back from friction on the tappets the open top will not affect anything. Since it would be a plain bearing I would make it a couple of thou oversize so it would not touch unless there was some deflection.

The cam, as drawn, is fairly gentle and combined with low speed operation should not put too much load on the cam.  Besides< I have to make it run before I worry much about such details.

Thanks for the comment.  It's too easy to overlook details that others may catch.
Gail in NM


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## GailInNM (Mar 28, 2014)

With the  bearing mounts inside the crankcase ready I thought I would make up the  crankshaft.  I will still eed to make some other internals before it has  anything to do but it will give me something to diddle while I am  thinking on the next parts.

I tarted with a 3-1/2 inch long, or  so, length of 3/4 inch diameter 1144 stress proof steel.  Turned it down  to 0.687 diameter and then turned 2-3/8 of one end down to a finished  0.250 diameter to good fit for the main ball bearing races.
Then I whittled down the remainder to leave a 1/8 inch wide crank web and a roughed out crank pin.
















Now  to turn the crank pin.  I could do it in a 4 jaw chuck but I normally  make up a turning fixture. It takes about the same time as setting up  the 4 jaw so there is no real time advantage either way. I will cover  the fixture next time.
Gail in NM


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## GailInNM (Mar 28, 2014)

The crankpin turning fixture started life as a length of 1-1/8  diameter 12L14 steel.  Nothing scacred about the 1-1/8 except I bought a  bunch of bar ends that size and about 5 inches long from a screw  machine shop. 

I turned down about 3/4 of an inch to 1.000  diameter and then cleaned up another 3/16 inch so it was smooth and  concentric with the 1 inch diameter.  Off to the mill where I centered  it in a vee block with an indicator.  Drilled and reamed two 1/4 inch  holes with 0.1875 offset for the throw dimension.  I did two  holes  because it makes it easy to set the fixture up for slitting with just  two rods in the holes resting on the vice jaws.  Then pull the rods and  cut the slot.

Before cutting the slot I milled a pocket for the  crankshaft about 1/16 inch deep.  This aligns the crankshaft and  provides insurance that the crankshaft will not turn in the fixture.  
Gail in NM


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## GailInNM (Mar 28, 2014)

The fixture with the crankshaft was held in a one inch diameter collet  in the lathe.  First the crank pin was roughed out with a carbide insert  turning tool and then finished with a high speed steel turning tool  that had close to a zero radius on the tip.  Not great for stress on the  crank pin to crank disk interface but for all this engine will get run  it will be OK.




After  polishing the crank pin the connecting rod was test fitted and after  oiling it was run in for a few minutes.  Easy to do now with the crank  pin on center.




Notice  the step on the end of the crank pin.  This is to engage the other half  of the crankshaft and drive it.  Since it is not necessary for basic  operation of the engine I will not build the second half of the  crankshaft at this time.
Gail in NM


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## AussieJimG (Mar 28, 2014)

Thank you Gail for the information about the crankshaft turning fixture. I have been thinking about this for a while and you have given me some new ideas.

And the thread is quite absorbing. I look forward to a dose of Gail each morning - it's much more interesting than the newspaper.

Jim


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## GailInNM (Mar 28, 2014)

Glad it has given you some ideas Jim.  That's what forums are all about.

Here is the latest development. Everything clears so far.  Now to make some bell cranks and mounts for them.
Gail in NM

 [ame]http://youtu.be/eoC6cqL97Ho[/ame]


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## GailInNM (Mar 30, 2014)

The bellcrank and associated parts that get stuffed into the pistons are  completed.  I still need to make the bellcrank pivot mount and an outer  arm support for the pivot.  Once these are done I can fit both  cylinders and pistons to one side and see if I need to "adjust" any  dimensions.  There should be 0.005 inch clearance but machining  tolerances can eat that up quickly with this many parts.
Gail in NM


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## petertha (Mar 30, 2014)

That engine has some funky kinematics. Very interesting indeed. 

 Can you elaborate on your pins with the e-clip ends: material type?, hardened after? grooving tool used? 
 Is the end result Aluminum-On-Steel with most of these links? (ie no bushings).


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## GailInNM (Mar 30, 2014)

Petertha,
All the small pins used in this engine are 12L12 steel.  The mating parts that they run in are made of 7075-T6 Alumninum. The 7075 is harder than the 12L14 and they run well with each other.  2024-T4 also works well. Many commercial model engines used 2024 connecting rods directly on a hardened steel crank pin ant that is much more severe duty than these pins will ever see as they are  only in a rocking motion and not making full rotations.  

The main connecting rod is also 7075 and it is running directly on a crankpin of 1144 steel.  All the steel pins are lightly polished but not hardened.  I typically finish polishing with 1200 grit abrasive paper using a metal backing to keep things flat. It is not really necessary to use bushings on a small demonstration engine like this. I do have the room on this engine to put a bronze bushing o the main connecting rod big end but did not think it would be worth the bother. One of my "Tiny" Hit-n-Miss engines has over 1000 hours with a 2024 conrod on 1144. It is a little bit loose now but well within acceptable tolerances. 

For grooving I use a Nikcole carbide insert grooving tool 0.5 mm wide (0.019 inch). The e-clips are E-6 clips with the groove diameter 0f 0.052 inch. The width could be narrower as the recommended width is 0.012 inch but I am too lazy to grind a special tool for them.  Other people like to use the Warner HSS insert tool with a 0.015 wide blade and it also works well.

Gail in NM


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## GailInNM (Mar 31, 2014)

The penny in the photo lin the previous post has to be the worst looking penny I had in my pocket.  I did  not notice it until I posted the photo.  Made me feel guilty about using  it so I took all the pennies in my pocket and dropped them in the  ultrasonic cleaner and then reserved the best looking one for future  photos.   With all the crud on the parts I need to start running them  through the cleaner before photos.  I will clean all of them before  final assembly.

All that has been productive has been to make the  pivot pins for the bellcrank. One photo of the pins and one showing  where it gets installed.










With  the pivot pins in hand I assembled all the conrod linkages and found I  did have a bit of a rub between two parts. I could turn the engine over  but there was a binding spot.  It was where I thought I might have one  but it was not because of tolerance build up.  I had changed one part a  bit and did not plug the new numbers into all the drawings that used it.  Good news is that there is an easy fix and it is under way.  Since  things are apart I am also making another small change the while not  really necessary will make assembly easier. Another hour or two and I  can start assembling all over again. More photos then -- with a clean  penny.
Gail in NM


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## GailInNM (Apr 1, 2014)

It's been apart and back together several times now and is finally working smoothly.  
	

	
	
		
		

		
		
	


	




First  I slimmed down the small connecting rod and that got rid of the bind.  For additional security I also took off a little of the main rod.










But  I could still get a tick when turning it over in the lathe and taking  out the slop in the linkages by pushing things around with a stick. I  could have just relieved the spot with a needle file but I put a little  45 degree bevel on the spot with a drill/mill cutter that I have.  Then  for what I hope is the final assembly I played with it for a while.






The  end of the pivot pin will get captured by an outboard support at final  assembly and keep the bellcrank in place as well as supporting the pivot  pin.

Back to the lathe for some more testing and every thing  seems good.  The video shows the engine upside down so the free con  section will hang down by gravity and not get caught in the rest of the  linkage.

[ame]http://youtu.be/hZyoh8yHMEA[/ame]
Gail in NM


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## Generatorgus (Apr 2, 2014)

Gail, 
Wow, that's really neat, and the fine machining on the small parts.
What else can I say except, that's a nicer penny.

GUS


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## GailInNM (Apr 4, 2014)

Thanks Gus,

I finished up the parts for the other two cylinders and assembled  the linkages on the second side.  Every thing still works smoothly.  Now  with all the unknown areas addressed I can move on to making real  parts. Most everything now is standard engine stuff.  Of course it still  takes time to make them.

To start with this phase I started on  the cylinders.  The cylinders are class 40 cast iron.  Started them off  by drilling the bore undersize and then turning the spigot that goes  into the top deck.






Then  the fun part of machining the fins.  Not hard but very repetitive. All  the grooves were cut with a standard P-4 cutoff blade.  The fins and the  spaces between the fins are both 0.040 inch wide with the top and  bottom fin wider for extra strength.











I  made an extra cylinder because I messed up the fin spacing on one of  them.  It is close enough to be usable but would not look quite right  with the cylinders so close to each other when installed.





Next  up is to bore the cylinders to a 0.4988/.4900 target dimension. As a  finishing step the cylinders will be lapped to a 0.5000 target  dimension. But, before lapping all the external work will be done. This  is because there will be a small amount of distortion when the outside  features are machined and the lapping will take that out.
Gail in NM


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## GailInNM (Apr 5, 2014)

The cylinders are bored using a carbide boring bar.  First all the  cylinders were bored to 0.496 so I would have a uniform amount to of  material to remove for the final boring operation and could do the final  boring operation on all the cylinders with out having to change the  cross slide setting.  After the preliminary boring it was time to fix  dinner in the oven so I put all the cylinders in the oven with the beans  at 350 degrees F.  When the beans were done I increased the temperature  to 450 degrees while I ate dinner and then turned the oven off after  dinner and called it a night.  This is to reduce residual stresses in  the cast iron. It is not really necessary and I some times do it and  sometimes don't.  Probably does not make much difference if the iron is  of a good grade but it gave me a good reason to call it a night in the  shop.

The cylinders were then final bored today.  All of them  were done without changing the cross slide setting between them.  Next  up will be the external machining of the flats on 3 sides and drilling  the mounting holes. Then on to lapping.
Gail in NM


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## Philjoe5 (Apr 5, 2014)

Looking very good Gail.  Thanks for the update

Cheers,
Phil


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## GailInNM (Apr 5, 2014)

Thanks Phil.

The cylinders as they are bored now are about 0.001 +/- 0.0001 from the  finished size.  I will detail the finishing operations next week after I  finish the external features.  The cylinders will have a lapped finish  and the pistons will also be lapped, but separately.  No rings will be  used so a much finer finish is used than would be used with rings. The  pistons will typically be lapped to 0.0002 under the cylinders for a  running fit. I have been using this technique on the last dozen or so  engines.  This engine is a little bit different in that it has a 1/2  bore where the others have had a 3/8 inch bore.  On my larger engines of  previous years I left the bore with more texture to seat the rings.  
Gail in NM


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## GailInNM (Apr 6, 2014)

The external work on the cylinders is complete.
Started by indicating  the cylinder in the mill vice with a vee block to hold it and a  parallel underneath it to give the drill a place to go. This parallel  placed so the drill bit will not hit it.




The  cylinder is placed with the locating spigot up as the holes on that end  have to match the tapped holes in the cylinder mounting plate.  This  makes sure that the holes at that end are located correctly. Cast iron  bar stock is slightly softer towards the center and long drilled holes  that are not on center line tend to drift towards the center.  To reduce  this I started the holes with a extra long end mill that would reach  almost halfway through.




Then  followed with a sharp drill bit to finish the holes to the other side.   The milled hole was the same size  the drill so it formed a good drill  guide.




The  sides were milled off on three sides. Rods were run through the two of  the drilled holes at a time and rested on the vice jaws to index the  cylinder.




And  finally the hole for the cylinder lubrication was drilled using a 1/16  end mill.  An end mill was used as it raises less burr on the exit side  of the hole so it is easier to remove with the lap.




Gail in NM


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## GailInNM (Apr 6, 2014)

I had to stack the  parts up to see what it is looking like so here are a couple of photos.   The cylinder mounting plate has to come off so I can drill the mounts  for the cylinder oilers. Still have to draw up the oilers but they are  just going to oil cups. 
Gail in NM


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## GailInNM (Apr 10, 2014)

To finish up the cylinders the bore needs to be finished to size and be  parallel and smooth. I had left about 0.001 inch for these operations  when I bored them.  I started with a Flex-Hone to knock off the tops of   the ridges left by boring. This took out about half of my finishing  allowance and left some cross hatch pattern in the bore.  Some of this  pattern will remain after lapping and is good for oil retaining.  As  this engine will not have a continuous oil supply while running this is  important. I used a 280 grit Flex-Hone and only one full length pass in  and out at about 500 RPM with lots of light oil. Of course the lathe bed  was covered with paper towels during this operation.






Then the cylinders were cleaned very well to remove any abrasive that might be left over.





Why  do I show a photo of cleaning with a brush?  Only to emphasize the  importance of cleaning after every abrasive operation.  Here I used a  test tube brush with dish washing detergent and then rinsed off  afterwards.  If a plug gauge is ever used this is very important as the  hard plug gauge will embed any loose abrasive in the bore for ever.
Gail in NM


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## GailInNM (Apr 10, 2014)

It should be noted that Flex_Hones do nothing other than improve the  surface finish of a bore.  They will not correct any out of round or  parallel conditions.  I use them just to reduce the time required to lap  a bore. Lapping can be done with out using them but it takes longer to  get the same results.

For the final lapping I use an adjustable  Acro lap.  They are inexpensive enough to hardly make it worth while to  make my own in small sizes such as this.l  I use diamond lapping  compound.  In this case I only used a single grit.  It is  8 to 12  micron or approximately 1500 mesh.  If I had not preconditioned the bore  with the Flex-Hone I would have roughed out the bore with 20 to 36  micron first then changed laps and finished with the 8-12 micron. 

On  a new lap I would have first charged the lap with compound by rolling  the lap on a hardened surface with compound on it.  Here I am using a  well used lap so I just added a little fresh compound to the lap along  with a liberal amount of light oil. In the second following photo you  can see a drop of oil just forming on the bottom of the lap.  It does  not take much compound.  I am using a 5 gram syringe that I have been  using for at least 15 years and it is still over 1/2 full.  If you are  going to buy diamond compound shop around carefully.  Medium load 5 gram  syringe prices vary from about US$6 to US$25. The amount of compound I  put on the lap is enough for all four cylinders.











The  lap is adjusted so there is a comfortable pressure using a  thumb-forefinger grasp on the part.  The part is slid along the lap from  one end to the other.  There will be a slight bulge in the lap from the  adjustment and you can feel as this enters the bore and exits.  Goal is  for there to be a uniform cutting pressure along the entire bore.  I  did all 4 cylinders at one setting and then expanded the lap and  repeated, again with all 4 cylinders.  This was so the cylinders all  came out to the same size.  My target was 0.5000 but I ended up with 2  measuring 0.5002 and 2 measuring 0.5003 inch.  Since the pistons will be  lapped to about 0.0002 undersize of the bore they will be close enough  that they can be interchanged if they get mixed up. Of course this is  not necessary but it's just the way I like to do things.

While  lapping I made about 20 passes along the lap at each setting.  500 RPM  and keep adding oil as necessary for a smooth feel. 

Final photo  is staged after cleaning the lap and my hands.  I don't like to handle  the camera with filthy hands.  Next up are the pistons.
Gail in NM


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## petertha (Apr 10, 2014)

Great description & pictures!
I've always wondered on those commercial barrel laps - as you tighten the end fitting, does it bulge/enlarge the middle portion of the lap body (exaggerated blue line) and you pass the cylinder 'over the hill' to finished size so to speak?


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## petertha (Apr 10, 2014)

I'm also curious about this end block. Never seen that before, looks lie a good robust setup. But how is it attached to the assembly?


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## GailInNM (Apr 11, 2014)

Petertha:  The short answer to your question about the lap is "yes" for the through hole barrel laps.  The blind hole laps expand on the end.  This bulge is thought to be a disadvantage by some but it is actually very useful. With a little practice you can easily feel less than 0.0001 difference in the bore diameter as the part is traversed from one end to the other and it is really easy to get a good feel for where the bulge is. If the part "feels" the same over the entire distance then the bore is parallel. If it has a tight spot it is easy to dwell or lap that area a little extra but this is rarely necessary as the lap will naturally cut more in the tight areas.

Where this bulge really comes in handy is in building small compression ignition engines.  It is accepted practice to slightly taper the cylinder bore of these engines so the piston fits really tight at the top of the stroke to make a good seal and looser at the bottom half of the stroke for easy running with low friction.  On compression ignition engines the compression ratios typically are in the 18:1 range and a tight fit on the piston is necessary as max compression is approached. 

To put this slight taper in the cylinder is first lapped parallel to a very high finish.  I generally use 6 micron diamond compound on 3/8 inch bore and smaller. Then the bottom part of the cylinder is further lapped to relieve that area by 0.0001 or 0.0002 inch.  These are my numbers and other builders may use different amounts of clearance than I do.  This tapering is done using the feel of the lap caused by the bulge.

Of course this is not necessary on low  compression spark ignition engines such as this build which has a target compression ratio of a little over 5:1.
Gail in NM


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## GailInNM (Apr 11, 2014)

Petertha:  I assume you are asking about the vice stop in the photo.  It is just a piece of 3/8 mild steel that has been ground flat and has a slot for mounting.  I am using a Chick 4 inch vice which has the body ground accurately to 4 inches wide by the manufacturer.  There are 8 holes in each side of the body that are threaded  1/4-20. The slot is off center so I can rotate the stop out of the way if I need to have stock hang out the side or the stop can be slid up and down if needed.  The top is milled down to 1/4 wide to accept clamp on spacer bars that I have made up in increments from 1/4 inch long to 3-3/4 inches to position parts in different places in the vice jaws.  The stop is just held in place by a single 1/4-20 socket head cap screw.

Gail in NM


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## Generatorgus (Apr 14, 2014)

Gail, thanks for detailing the finishing operations on the cylinder bore. You covered all of the gray areas that I've wondered about.
GUS


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## GailInNM (Apr 14, 2014)

Glad to have you following along Gus.

Before starting to machine the pistons I turned down a 1 foot as  purchased length of 5/8 nominal class 40 grey iron to a uniform diameter  so it would fit a collet. Grey or cast iron comes oversize so it will  finish up to the nominal size.  In this case the stick was about 0.690  diameter so  I turned it to 0.672 (43/64) to fit a collet. I do this  when I purchase my iron so it is ready to use when I am ready to make  something out of it so this was already done and not pictured.

I  also made the mandrel to hold the pistons. It serves not only to hold  the pistons for finishing to final size but also as a plug gage to use  while boring the upper part of the piston next to the crown.  For this I  made the diameter 0.388 as the loose wrist pins are 0.094 diameter by  0.375 long.  0.388 is the minimum dimension such a pin will fit into if  the pin has square ends.





The  mandrel was also turned down to a loose fit in the cylinder for the  length of the cylinder so when finishing the piston I could make trial  fits in the cylinder pushing the piston the full length of the  cylinder.  To hold the piston in place the end of the mandrel was tapped  2-56 so a screw through the crown of the piston could secure it.  The  piston will have this hole in it as this screw secures the yoke that  mounts in the piston.
Gail in N


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## GailInNM (Apr 14, 2014)

To start machining the pistons I first turned down the iron stock for a  length long enough to get 5 piston, the 4 needed plus one spare.  I  roughed it with a center so I could take reasonable depth cuts and then  finished it to size with out the center so it would be sure to be  turning parallel. I do this when working to close tolerances as any  defect in the center hole or tail stock misalignment will not affect  things.

As the largest bore of the cylinders was 0.5003 the Iron  was turned to 0.5005 to leave about 0.0004 finish allowance to, that is  0.0002 to get it to size and 0.0002 for clearance in the cylinder. A  little bit more will have to come off for the smaller cylinder bores.






Then 5 blanks were cut off about will about 0.020 left for finishing the ends.





Gail in NM


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## GailInNM (Apr 14, 2014)

The ends of each blank were faced off to bring the blank to finished length.

Using  a sharp pointed 60 degree threading tool, two labyrinth grooves were  cut 0.005 deep near what will be the crown of the piston.  These act as  pseudo rings by trapping a small amount of oil in them and also help  distribute some oil to the upper part of the cylinder.





The  piston is reversed and a 0.040 groove is cut 0.010 deep near the lower  end of what will be the piston skirt.  This groove lines up with the  hole from the oil cup on each cylinder when the piston is at BDC and  then distributes oil up the cylinder wall.






All  the grooves were lightly deburred with 400 grit abrasive paper as they  are done to remove any burrs raised by the vee tool or grooving tool.

Gail in


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## GailInNM (Apr 14, 2014)

Before starting to bore out the pistons I had to modify a boring bar.  I  has bars that were small enough diameter that would not reach the  bottom of the bore and ones long engough that were too big in diameter.   The bar needed to be small enough in diameter that it could be used to  make the bottom of the bore flat so the yoke would have a good surface  to bolt up to otherwise it would try to work loose.

With my  modified boring bar I bored out the piston to 0.388 diameter and used  the mandrel as a plug gage to test the size.  Then I relieved to skirt  to 0.438 diameter for clearance for the connecting rods.






Reversing the piston, the crown was center drilled and drilled for the screw that mounts the yoke.




Gail in NM


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## GailInNM (Apr 14, 2014)

The last machining operation on the pistons is to put the countersink in  the hole in the crown. There will still be the finishing to size but  that will be an abrasive procedure so no chips will be generated and the  pistons will still look the same.

The only hard part is getting  the countersink depth right so the head is flush or slightly below the  surface.  Here is what works for me.

I position the tail stock so  the counter sink will hold a metal strip in place and zero the tail  stock quill dial. I use a machinist 6 inch rule for the metal strip.  Then, after removing the rule, I countersink the hole some easy to  remember amount that still leaves the countersink undersize. I knew that  0.100 was a safe number in this case. Then the piston was removed and a  screw inserted in the hole and I measured how much it stuck up.  0.009  inch was the magic number. The piston was put back in the lathe and the  tail stock was zeroed again using the rule. Then the tail stock was  advanced 0.110 to give an extra 0.001 to be sure the screw did not  protrude.  

For the rest of the pistons all I had to do was zero  the tail stock with the rule and then advance the tail stock 0.110 to  cut the finished countersink on each one.










To  finish up, I rubbed the crown against some 400 grit abrasive paper to  remove any burr thrown up by the counter sink and then did a finger  twist of the counter sink inside each piston to deburr the hole.
Gail in NM


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## GailInNM (Apr 16, 2014)

Fitting up the pistons is one of the easiest operations on the build.  But until someone has done it a few times it's a bit of a challenge to  get the right fit.  That's because it's a feel type of thing and how do  you tell some with words how it should feel like.  Easy enough if you  are showing them in person on a machine.

First off I engraved the  bottom of the cylinders lightly with the numbers 1 to 4.  These will be  the position they go in on the engine later and will also let me keep  track of what pistons belong to what cylinder.  Then I sorted the  cylinders for bore size.  When fitting the pistons I start with the  largest bore first so if I make a piston too small I can use it in the  next size down cylinder.  When I get to the last cylinder then thats one  reason why I made a spare piston.

A piston is mounted on the  mandrel with a screw holding it in place.  Using a strip of flat metal  to back it, I started with 400 grit abrasive paper and a few drops of  oil.  With the lathe running at about 800 RPM I press the abrasive paper  against the piston using both hands and apply about a 1/2 pound of  pressure.  I oscillate the paper back and forth along the length of the  piston while keeping the paper with it's backing strip flat against the  piston OD. After about 15 or 20 seconds I clean the piston and try it in  the cylinder.  I repeat this as necessary until the piston starts to  enter the bore.  Then I switched to 600 grit paper and repeat until the  piston will fully enter the bore with firm pressure.  Switch to 800 or  1000 grit paper and repeat until the piston can be slid length of the  cylinder with about 3 or 4 ounces of pressure. I repeated with 1500 grit  paper until it was fairly easy to slid the piston the length of the  cylinder with about 1 ounce of pressure. Before each trial fit into the  cylinder the piston was cleaned using mineral spirits and a paper towel  so no abrasive residue could be transferred to the cylinder.  Finally  with some light oil on the piston I ran the lathe at about 300 RPM and  slid the cylinder back and forth along the piston for about 30 seconds  to make sure that it felt even the whole distance and to knock off any  high micro spots.  When rotating the piston fill slid much easier than  when not rotating. After cleaning one more time the piston is removed  from the mandrel and the crown is engrave with the number of the  cylinder it is mated to.

Now repeat for the other pistons.  Sorry  for this to be so wordy but there really is not much to see in photos.   It took much longer to write this than to do all four pistons. The  first photo is staged and there is no oil on the piston.  The metal  strip supporting the paper is about 1 inch wide.  In the second photo  it's a little hard to see but the two cylinders in the foreground are  number on the mounting flange and the two pistons in the background are  numbered on the crown.
Gail in NM


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## GailInNM (Apr 21, 2014)

With all the cast iron machining done the first order of business was to  clean up the lathe and mill.  I had kept them reasonably clean as I  went along but it still took a hour or so the do the job right. Cast  Iron is nice to machine but a pain to clean up.

Then it was over  to the mill to center drill, drill and tap the oil cup holes 3-56.  I  know it's not a common thread, but I like it.  Not too much to be said  about that and really not worthy of a photo, but I did one anyway.  Next  up the oil cups.
Gail in NM


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## GailInNM (Apr 21, 2014)

With the oil cup mounting holes in place I cleaned up the cylinder  mounting plate to remove the remaining machining marks. Then it was on  to the oil cups.

I normally keep the 3-56 lock nuts in stock as I  use a few of them from time to time.  I needed 4 but only had 3 on hand  so a mini production run of 2 dozen was made.  Started by drilling a  tap size hole in the end of some 1/8 inch hex stock. I drilled deep  enough that I could make 6 nuts. Then cut off the six nuts to 0.055  thick and repeated until I had 24 nut blanks.




A  collet stop was turned to 0.120 diameter and drilled 0.102 diameter for  a depth of about 3/8 inch to clear a 3-56 tap. The stop was installed  in the 1/8 inch hex collet I had just used to make the blanks. The stop  was adjusted so one of the nut blanks would just fit flush in the  collet.




The  tap was mounted in a tap handle and was supported by a spring loaded  center in the tailstock.  The Collet was adjusted so the nut blank just  fit in the collet with out closing the collet.  I just wanted to keep  the nut square and prevent it from turning.  The collet was NOT closed  as that would distort the nut.  Then each nut was tapped.




After a quick rub on a piece of 400 grit abrasive paper to remove the burr raised by the tap the result was 2 dozen jam nuts.
Gail in NM


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## GailInNM (Apr 21, 2014)

Next up was the nipple to connect the oil cup reservoir to the cylinder  mounting plate.  It is just a 3/8 length of 1/8 diameter brass that is  threaded 3-56 on one end and the other end left as 1/8 diameter to  solder into the reservoir at a right angle. It is drilled full length  with a 1/16 diameter hole for oil passage.  No attempt was made to  restrict the oil flow.  The oil will be added to two of the cups when  the pistons are at BDC and the oil will flow into the oil groove on the  piston. Then the crankshaft will be rotated 180 degrees and the other  two cups filled. With cast iron pistons and cylinders this will supply  enough lubrication for about an hour of running time after the engine is  broken it. More oil will be needed during the first couple of hours of  running while the pistons seat in the cylinders.

As I have a  small CNC lathe I made the nipples on it.  I single pointed the  threads.  The could lbe made easily on a manual lathe and a die could be  used to cut the threads.  No in process photos were taken.  The  finished nipples look like this with old Honest Abe for a size  reference. Honest Abe is 19 mm diameter for my international friends  benefit. A few extra were made to feed the swarf bunnies.
Gail in NM


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## GailInNM (Apr 21, 2014)

The reservoir is a short length of 3/16 brass drilled about 1/2 way to  0.156 for the reservoir it's self and then drilled 3/32 diameter with a  blind hole to just short of the length.  A short length of 3/16 brass  was turned down to fit the 0.156 hole and then the rest of it was turned  down a little  bit to be smaller than the lbody diameter of the  reservoir.  This was to insert into the reservoir to keep from crushing  it when clamping when putting the side hole in. The first photo shows  the plug and two finished cups. 






The  side hole was put in by clamping the part in the mill vice with the  part resting on a parallel and the plug inserted. A 3/32 end mill was  used to drill a connecting hole to the center of the part and then the  hole was opened up to 1/8 inch about 0.050 deep for the nipple to insert  into.
Gail in NM


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## GailInNM (Apr 21, 2014)

With all the parts made, I made a holding fixture to support them  while soldering.  It is just a length of 1/4 inch diameter aluminum rod  turned down for about an inch to an easy fit in the cup.  A little taper  was filed on the end to make it easy to fit into the cup. The rod was  split on the band saw and the cut deburred. The cut part was then spread  a little bit with a screwdriver so it would grip the inside of the cup.  It does not take much as all it is doing is hold things while  soldering. Besides the rod will probably open up some when it is split.   The reason for making it an easy fit in the cup is to minimize the heat  transfer from the cup to the fixture while soldering.  Here it is  clamped in a small vice ready to use.
Gail in NM


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## GailInNM (Apr 21, 2014)

Solder preforms were made to do the actual soldering. l also used some electrical non corrosive solder flux paste.

The preforms were made by by winding some 0.020 diameter (0.5mm) electronic solder around an 1/8 inch rod. 




I  put this spring shaped coil on an index card with the card on a hard  flat surface and inserted a hobby knife with a #11 blade in the coil and  cut the coils apart by pressing down and drawing the knife out.  The  card protects the edge of the blade and lets the blade cut all the way  through the solder.  Then I cut a small segment out of each coil with  the knife. When cutting the coils apart the blade will expand each coil a  bit so the cutout lets the coil close up to be a snug fit around the  nipple. Besides a full ring of solder is more than needed to make a good  joint.




A  small amount of flux is put on the end of the nipple.  There is usually  some in the lid of my flux container so I just scrape a little of that  onto the nipple.  Only a small amount is needed.  If I can see that I  have some on the part that is enough.  If I can see it easily then that  is too much. The flux makes the nipple end sticky enough that a solder  ring will stick to it when the nipple is pressed down into it.  I  inserted the nipple into the cup and a little twisting motion  distributes some flux around inside the cup recess.  The solder ring was  pressed down to conform to the joint.  I find it is easier to do all  this with the parts held in my finger before putting them on the  fixture.  The assembly was then slid onto the fixture.




A  small torch was used to heat the bottom of the cup until the solder  flowed.  If heated from the bottom the nipple is not over heated.  Soon  as the solder flows into the joint remove  the heat and let cool.
Gail in NM


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## GailInNM (Apr 21, 2014)

Old Abe showing off a finished cup assembly and two cups installed.
Gail in NM


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## AussieJimG (Apr 22, 2014)

The little bits of detail in your posts add somuch to the enjoyment. Thank you Gail.

Jim


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## Philjoe5 (Apr 24, 2014)

What Jim said, Gail.  The devil is in the details and you've got 'em by the tail

Cheers,
Phil


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