The

"McVickerish" Engine

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Introduction:

On April 28, 1903, United States Patent Number 726,731 was issued to Walter J. McVicker of Rogers, Nebraska for an engine that operated on the Otto Cycle (four cycle) principle but had neither gears nor cams.  His idea was to use residual combustion gas pressure at the end of the power stroke to open the exhaust valve.

 

 

This was accomplished by locating a port in the cylinder that would open when the head of the piston passed it at the bottom of the stroke.  This port went, via a check valve, to a small cylinder which operated the exhaust valve.  The exhaust valve would stay open until the pressure in the small cylinder was vented to the atmosphere when the bottom of the skirt of the piston uncovered another port when the piston reached the top of the stroke.

 

 

Since the engine only had overpressure in the cylinder at the end of a power stroke, the valve would only operate after the engine had fired a fuel/air charge.

 

 

The engine was of the hit and miss governed type, the governor turning off the ignition at speed.  Because both the exhaust and intake valves stayed closed when the engine was not firing, the engine would simply compress and expand the gases within the cylinder.  If a fuel/air charge had been drawn into the cylinder before the governor turned off the ignition, the charge would simply be compressed and expanded over and over until the governor turned the ignition back on and allowed it to fire.

 

 

If there was no charge in the cylinder when the governor turned on the ignition, I assume the engine would quit running, unless a small amount of piston blowby caused the engine to draw a small amount of charge while the engine was not firing.  I assume that, once the engine fired the weak charge, there would be enough combustion pressure to operate the exhaust valve to clear the cylinder and allow a full charge to be drawn in.

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13 March 2010:

Description of The McVickerish Engine:

 

I plan to build a small version of the McVicker engine, taking license to incorporate some things I'd like to do.  (Since I am not actually "modeling" the McVicker engine but just using the principle of the patent, I call it "The McVickerish" engine.)

 

 

The bore will be 2-1/2 inches and the stroke will be 3 inches, giving a displacement of about 14.73 cubic inches.  I'm thinking of a compression ratio of around 5:1.

 

 

The McVickerish Engine will have a cantilevered crankshaft.  This will make the crankshaft much easier to assemble.  I'm thinking of using a caged needle bearing for the connecting rod big end.  This bearing will run on a hardened steel dowel pin.  The mains will be sealed ball bearings.  I'm doing the bearings like this so I don't have to concern myself with lubrication except for the cylinder (drip) oiler and the engine will be able to be run for long periods without stopping.

 

 

Cooling will initially be via a cooling tank.

 

The flywheel will be 10" in diameter.  Rod and main bearing journals will be 7/8" diameter and the base of The Mcvickerish Engine will be the same width as that of The Homebrew Hvid so, if if it works out, I will put it on The 2009 Algore Edition Green Hybrid Hoyt-Clagwell and convert The Homebrew Hvid back into it's Hvid configuration for showing.

 

 

I'm not sure when I'll start making chips on this project but it'll probably not be until early summer 2010 when it gets too hot to play outside.

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19 March 2010:

I've about finished the drawings and am getting ready to do a scrapyard run for some of the metals.  I had to purchase some of the metals (piston aluminum, sleeve steel, etc.) and the bearings.

 

 

While I was refining the drawings, I decided that I didn't need to go to the expense of a 5" diameter piece of steel bar for the crankshaft so I redesigned the crank using a scrap I had picked up on an earlier scrap run.  It just looked too good to leave there.

 

 

Another change is an enlarged water jacket.  Because the displacement is larger than the Homebrew Hvid/Regular engine, I figured it may need more cooling volume around the cylinder.  After I make the head, I'll see about drilling some water passages.

New drawing showing some of the changes.

I've also stretched the base horizontally (not shown here) so it will share the same mounting holes in the 2009 Algore Edition Green Hybrid Hoyt-Clagwell if it's reliable and makes enough power.

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20 March 2010:

 

Today, I started on the crankshaft.

   

Raw material.                                    One side saw cut.                    Both sides finished.

The raw material is 1-1/2" thick by 3" wide by 5" long.  The first thing I had to do was to flycut it to exact dimension (and get all the scale off) and square it up enough to lay it out.

 

 

My first plan was to saw cut the sides of the 1-1/2" thick blank with the bandsaw then use the mill to get it to dimension and add the fillet.  After leaning on the saw for about an hour (it seemed like it took that long) to get one side cut-off, I finished that side in the mill then used a carbide roughing mill to hog-off most of the material on the other side before finishing it with a regular end mill.

 

When I get my materials order which includes the 7/8" dowel pin for the rod and a hunk of 7/8" shafting for the shaft, I'll put the blank back into the mill and bore for a press fit of the crankpin and shaft.  I've got a ten ton hydraulic press on order and, when it gets here, I'll press in the crankpin and make a fixture to go in the mill vise so I can hang on to the crank cheek and rotate it around the crankpin, using a mill to round the rod end of the crankshaft.

 

 

After the rod end is finished, I can then press the shaft into the cheek and either use the same fixture to round the end opposite of the rod pin or put the whole sheebang in the lathe and turn it.  If all else fails, I've been known to saw-cut something like that and grind and file a finished surface on it.

 

 

When the engine and flywheel are finished enough to turn it with the rod and piston in the bore, I'll motor it to see how bad it shakes (if at all).  If it does shake, I think I have a way to use a couple of position sensors and my oscilloscope to see which way it shakes and either add or trim weight off the rod to get a semblance of balance. 

 

 

I've ordered a 2" thick piece of 10" diameter gray cast iron bar to make the flywheel out of.  I can machine most of it in the lathe (I think).  If not, I can always do it the same way I did the flywheels for The Homebrew Engine.  This flywheel will not have spokes and I may machine it  narrow between the hub and the rim (if I feel like going to the trouble).

 

 

The valves will be 1" diameter so I'm thinking of mooching-up to the local lawn mower repair shop to see if I can dismantle some junk small engines for these parts.

 

 

Details of the valve actuating cylinder, check valve, etc. haven't been worked out but I have the cylinder sized and positioned as it will most likely end-up.

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21 March 2010:

Well ..... yesterday, I worked on the crankshaft.  I got in a hurry and ended-up getting the crankshaft bore in the cheek too big for a press fit.  Anyway, I've figured out a fix.  Since there's a thick spacer between the crank cheek (about 0.400") and the adjacent main bearing, I've decided that the spacer can also be an "aw-shoot" removal tool.  

The "AW-Shoot" Removal Tool Drawing.

 

What I plan to do is to put the cheek back into the mill and bore the crankshaft to 1.000", then make the spacer with an integral  bushing that will reduce the bore to 7/8" (-) so the shaft will press in.  I think I can get away with a light press fit of the bushing into the cheek and a tight press fit of the shaft into the bushing.  The force on the bushing from the shaft should tighten the bushing in the cheek.

 

Today, I bored the flywheel blank.  AGAIN, I took just a little too much out and it's just a tad too loose to suit me.  Of course, I could "do it the easy way" and use Loktite but I may just make another "AW-Shoot" removal tool.  If I do a steel bushing for the flywheel, I will make the wall thickness about 1/4" so there'll be enough meat in it for the gib key.

Boring the flywheel hub.

I've made a device to rotate large parts on the mill bed for machining.  I then put the flywheel on the rotating head and got the 10" O.D. cleaned-up.  Talk about slow!!  It took over two hours to clean the O.D.  About 0.075" was removed.  I started with a carbide roughing mill that was too dull to work without chattering then graduated to a carbide rotary file which did the job, although it was SLOW.

Getting to know the flywheel!

In order to keep the rotary file from overheating, I used just a little soluble oil coolant.  That made the dust turn into mud and stick to the wheel.

 

I think my setup for turning the flywheels on The Homebrew Engine was better and faster but this wheel is a bit too big for me to do that.

 

Since the blank was saw cut at the warehouse, I have to face it perpendicular to the bore and rim.  

Facing the wheel.

This little job took the rest of the day.  I used a TiN end mill that was about done-in and finished killing it.  Since it wanted to chatter, I rigged-up an anti-chatter brake using the piece of angle, clamps, 1X2 board and a piece of leather.  It worked okay but, again, this is too big a job to do with my machinery.

 

The tool was quickly getting too dull to use and I only got about 1.5" of the first side done.  What I plan to do is clamp the wheel on the mill table through the center hole with a couple of 1/8" spacers against the true surface.  Then, I can flycut about half of a side, rotate the wheel and do the other half side.  To finish, I will clamp the edges of the wheel, remove the center clamping bolt and finish off the area around the hub.  Oh, yes - the wheel will be straight sided.  I have no way of doing anything fancy.

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22 March 2010:

Today was somewhat better but I'm getting the idea that I should be making smaller engines!  My machinery is just too light-duty to be able to do it and not doze off while working.

 

I mounted up the crank cheek in my handy-dandy home-made rotating head and milled off the corners of the counterweight end, swapped journals then milled the crankpin end round.  When I get the mill vise back on the mill, I'll have to stick the cheek back in the mill and trim off the ends to have a nice overall finish.  What I know now is that the piece of steel I used as a blank was probably cut with a water jet and that made the kerf wider at the bottom of the cut than at the top.  I didn't check the dimensions of both sides of the piece and measured-off from the "big" side.  That's why I have to trim the part.  NOW, I know!  (if I can just remember!!)

Trimming the crank cheek ends with my version of a power rotary table.

 

 

Crank cheek and partially faced flywheel awaiting the next step.

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23 March 2010:

Proceeding smartly, today the flywheel was faced.

Facing the flywheel.

It took a while, roaming around the surface of the wheel with the flycutter, blending as much as I could.  I had to loosen the center bolt and rotate the wheel 180 degrees to finish it.  The wheel was sitting on the bed with 0.125" spacers on the previous partial facing.

 

I may (If I think I can roust up the energy) wet sand the surface to finish blending the tool marks.  We'll see.

 

While leaning on the mill, I decided that, since the flywheel is going to be flat sided (as seen above), I'd kill two birds with one stone.  

Making the flywheel hub.

The first bird is the fact that I overbored the flywheel (0.876" for a 0.874" shaft) and the hub would correct this sloppy fit.

 

The second bird is to have a hub for the wheel.  I also think it will be a bit easier to broach the wheel for the gib key.  The hub is a piece of 1.5" bar stock that I turned to 1.450" with about a 0.0005 taper in it with the small diameter at the right hand end of the hub in the photo above.  I also turned the first 0.100" of the hub 0.001" smaller than the rest of it so I could gauge the fit when boring the flywheel.  The turned diameter is about 0.020" longer than the thickness of the flywheel.  The larger diameter will stick out on the outside 0.500" to make it look more like a real flywheel.  

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27 March 2010:

The flywheel hub is in the wheel. 

Semi-finished flywheel with hub.  Crankshaft is in the hub.

I made the hub about 0.001" larger than the hole in the flywheel and then heated the wheel to about 200 degrees.  I thought it would be an easy push fit but I had a big hammer and a steel backing plate handy.  I'm glad I had the hammer and plate.  It was TIGHT and I had to beat the tar out of the hub to get it seated against the shoulder.  It only took a little dressing of the I.D. of the hub for the crankshaft to be an Oh-So-Close fit.  Now, I've got to mill the gib key slot in the shaft and broach the hub.  Can't do that 'til my press and broach set get here later in April.

 

I made the bushing for the crank cheek and bored the cheek for it.  I made this a press fit and could just get the bushing in the cheek using my big bench vise.  Then, I put it back in the mill and dressed off the face you see so the bushing almost disappeared.

Crank cheek finished with rod pin in about 1/4".

I started the crankpin into the cheek but with all I could do with the vise, I could only get it about 20% of the way in (1/4").  I'll have to wait for the press to finish pressing it in.

 

The fit of the crankshaft into the cheek is going to be another press job.  It's also about 0.001" tight.

Semi-pressed crankshaft with roller rod bearing.

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2 April 2010:

Today, I worked on the connecting rod.

Raw materials for the rod

I picked some pieces of scrap for the ends and bought a 12" joint of 1/2" steel pipe for the rod itself.  Note that I'm using a roller bearing for the big end.

Turning the zinc and goobers off of the pipe.

Since I'm going to weld the ends of the rod to the rod itself, I had to remove the zinc from the pipe.  It's not supposed to be good to breathe the fumes from the zinc.  Anyway, it will look better when it's turned.

Little end blanked-out and laid-out.

While I was whittiling out the little end block, I found out that I'd made a complication that I'll have to design around.  Note the 0.5" radiuses on the rod-sides of the ends.  This will be a hard shape to make so I may just put a small radius there when I radius the outside end of the big end, which I can do with a fixture in the mill that allows me to pivot the rod around the bearing bore in the mill.

Big end semi blanked.

I saved one of the "built-in" radiuses on the big end that just happened to be around 0.5" radius.  I will try to saw, grind and file the other radius.  If it looks bad, I'll back-up and try something else.  I still have the thickness to do on the big end.  The ends will be bored for a light press fit of the rod before alignment and welding ...... THEN probably re-alignment.

 

Tomorrow, I hope to finish the rod.

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3 April 2010:

Well, it's taking longer than I figured it would.  The rod's almost done.

Ready to weld.

After cutting down the thickness of the big end and boring the holes in them to pilot the rod, it was clamped together and aligned for welding.

Welded!  Ugly!

I thought I'd be smart and make a sleeve to keep the rod from getting spattered.  It was hardly worth the effort.  I started on the big end using the stick welder.  Because the rod is relatively thin and the end is thick, I blew through the rod.

 

Changing over to the MIG welder, I had better luck, getting the blown hole filled and laying-in some metal.  Before you comment, I'll say right up front, I ain't your real excellent welder.  I get the stuff stuck together and it stays stuck, it just doesn't look like much.  Bless whoever invented the die grinder.

After die grinding.

It's looking more like a rod now, although the free-form profiling leaves something to be desired.  Before I press in the bearings tomorrow, I'll lay into it with a quarter round file and see if I can "slick" it up a little more.

In the mill, ready to bore for the bearings. 

This step went relatively well.  The nice thing about drilling it in the mill is that before clamping it down, it can be precisely aligned.  Then, after finding the location of the bore in one end, the horizontal readout can be zeroed and, when the other end is done, that bore can be positioned the exact distance it needs to be from the center of the first bore.  

 

Each bore was done in four steps.  First, it was center drilled to make sure that the second drill, 1/4" wouldn't wander.  After the 1/4" hole was made, it was re-drilled 3/4" then the boring attachment was used to open up the diameter for a press fit of the bearings.

Semi-finished.

Here is the rod with both bores done and the grease hole (big end) and oil hole (not seen, small end) are done.  The wrist pin oil hole is nothing special, just a 1/8" diameter with a countersink at the outside to catch oil.  On this rod, the 1/8" pipe plug will be used to grease the roller bearing.  Since a roller bearing doesn't need but just a little grease occasionally, I'll just remove the plug, stuff some grease in there and screw the plug back down, forcing grease into the bearing.  If that doesn't work well, I can always just add a Zerk fitting.

 

All that remains is to radius the ends of the rod.  This step isn't necessary but will remove some weight from this part and help the balance of the engine.  The next time I get into the shop, I'll make a fixture to do the radiusing.

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7 April 2010:

Today, I made a tool to radius the ends of the rod.

 

Setting up the radiusing tool in the mill.

It consists of a block of steel with a 3/4" shaft pressed into it.  Bushings are made with a shoulder and the diameter of the item to be radiused on the outside and a 3/4" bore.  There is a 3/8" stud, used with a big washer, that holds the workpiece down and applies a little drag.

 

Cutting the radius.

To cut a radius, first center the pin on the tool with the quill of the mill.  Now traverse the table to where the piece to be radiused  is just touching the milling cutter at it's "tallest" point.  Now, traversing the table in 0.010" increments and holding the workpiece tightly, slowly rotate it to take off some of the corner.  Do this a  number of times and you have a nice smooth radius centered on the bore of the workpiece.  I have to caution that, when you get close to the final radius, the tool will try to grab and suck the workpiece into it so be careful!

 

Here's the rod with the big end radiused.

After I do the small end of the rod, I still have some filing to do to slick it up.  Then, after the pin bushing and rod bearing are pressed in, it can be set aside.

 

I'll use the same base but will make another stepped bushing to fit the 1.000" bore of the wrist pin end.

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8 April 2010:

The little end of the rod is radiused.

Almost finished rod.

I still haven't filed the contours slick on the rod but it will probably get done in the next week or so.  Tomorrow, a friend and I are going "scrapyarding" for raw material for the frame of the engine.  I've also made up a floppy disk of the CAD file and will see if a local Panama City machine shop that does water jet cutting can handle my CAD file and blank out the 1/2" hot rolled steel plate frame parts.  This is just a bit more than my machinery can easily handle although I did do some swapping and now have a Makita abrasive chop saw but I haven't even taken it out of the box yet.

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9 April 2010:

Well, today ended up being very interesting!  First, I met a friend and we wandered around a local scrap yard.  I found some brass that I could use plus a 2 foot by 2 foot hunk of 1/2 inch hot rolled steel.  Actually, it was a piece of a larger piece that I got one of the guys there to burn off my piece.

 

Yesterday, previous to going there, I copied the CAD file and then modified the copy, showing only the parts that needed to be cut.  I also removed all but the largest holes.  All the parts were moved around to waste as little metal as possible, leaving a minimum distance between parts of 0.100" which I thought would take care of the kerf without making the parts too small.  

 

Then, it was on to the machine shop.  After showing the shop folks my file, they said that it would be a piece of cake to cut the parts from my steel with their water jet machine using the file I supplied.  I didn't think they would use my "nested" file but was surprised when they said it would work fine.  

 

As I recall, the technician said that the waterjet would cut with an 0.043" wide kerf and he was right.

 

Parts, reassembled in the raw plate.                                      Parts out of the plate.                

Sorry about the photos but I had all the stuff on my concrete shop floor and they just about disappeared there.  When the parts were cut out, I was amazed to see that the little web of material left between the pieces when the pieces were cut apart was, indeed, around 0.006" wide!

 

These photos try to show the finish of the cut using the water jet cutter.

The finish will leave little cleaning necessary.  I haven't measured the parts but the shop says they should be just about dead-on at the top surface and only about 0.002" under at the bottom of the cuts.  Even though I had to spend some bucks to get the job done, it is going to be well worth it because of the amount of labor I would have had to put into doing it "the old-fashioned way" with chop saw, bandsaw and a lot of milling.  Since I've already done it "the old fashioned way" on my previous two engines, I figured expense more than paid for the boredom of shaping them. 

 

While we were there, the guys at the shop showed a spur gear water cut out of what looked like 2 inch thick steel.  It was an emergency repair for a big machine somewhere.  The gear had to be backordered with a long lead time and the customer needed it immediately.  The finish on the waterjet cut gear looked very close that of a machine cut gear and was installed on the machine with no second operations and worked fine.  The machine that used the gear was down for less than a day! 

 

I've decided that I can afford to use this method in my future engines and may have the timing gears and flywheels made that way.  As a matter of fact, I think I would seriously consider having a timing gear or a set made for an antique engine rather than have one cast and machined.

 

Oh, yes - the crankshaft is now pressed together.

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11 April 2010:

I didn't spend much time in the shop today but did have time to lay the parts together with a magnet and check the fit.  It looks like everything is within 0.002" undersize due to the spreading of the kerf.  It only took a little filing of a high spot where the jet started to make the bearings go about half way into the bores so I will be running the boring bar through them after the frame is assembled if I can get it into the mill.  

 

       

 

I WILL check to see if it will fit BEFORE I weld it together.  If it doesn't fit, I can bolt the main bearing assembly to the side plate and bore it before putting the whole works together.

 

Gee willikers, gang!  That waterjet thing is a lot easier than doin' it the other way!

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13 April 2010:

The rod is done and ready for the final wrist (gudgeon) pin bushing fitting.  It's very tight and I will have to use fine sandpaper to get it until it is just snug.

Rod and crankshaft.

I learned something else today.  When pressing in the caged roller bearing, the cage will shrink a little, going from a kind of sloppy fit to a "preloaded" fit.

 

The black washer things you see are the home-made rubberized fabric dust seals.  There will also be an 0.020" brass thrust washer on either side of the rod big end.  The seals go inside the rod with the thrusts outside of the big end.

 

To keep the rod from trying to wander off of the crankpin, I'm going to grind a small flat on the crankpin and make a sleeve that can be attached via a setscrew.

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14 April 2010:

I changed the design of the sleeve so I wouldn't have to grind on the crankpin.  What I did was make a slotted collar with a 10-32 bolt to clamp it on the crankpin.

Connecting Rod Ready For Assembly To Crankshaft.

The thrust washers are shown.  The pinch collar was made of one of the "holes" that were water jet cut for the main bearing bores.  (NEVER throw anything away!!)

 

The Assembled Rod And Crankshaft.

To get the final fit of the wrist bearing, I got the fit close (VERY tight!) then pressed the pin all the way through the bushing.  This gave me a pattern of contact that I could sandpaper away until the pin was a workable tight fit in the little end of the rod.  Then, I chucked the pin in the lathe and, using the slowest speed (this speed has an overload clutch) and a lot of oil, ran the bearing until it is now a snug fit.  With wear, it will become a slip fit.

 

After I got all of this assembled I remembered that I have to mill the slot for the gib key in the other end of the crankshaft.  Oh' well, it'll look nice all clamped-up in the mill and I can cover the big end with a shop towel to keep the shavings off. 

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