Nemett Jaguar--Canadian Style

[Brian Rupnow]

Okay--There is a lot going on here, some you can see, some you can't. The original cam bearings called for were 4mm i.d. x 12mm o.d. x 4mm thick. I had a pair of new bearings left over from my Atkinson build that were 5 i.d. x 16 o.d. x 5 thick. I bored out the outer case to accept them and monkeyed with the cam spacers at each end to have an extension that slid into the bore of the bearings to make up the difference between the 4mm shaft and the 5 mm bearing bore. The green cam shaft cap had to grow from 12mm dia. to 16nn dia., and now it sets in flush with the outer side of the main housing to prevent fouling the main bearing support (that will show up better in the next post.) The cam shaft is extended out through the gear case and that yellow thing on the right hand end of the cam is the ignition cam. I have to put a hole in that case for the shaft to pass through, and an oil seal. I wanted to make the camshaft something in imperial, but there is no close conversion to get a 4mm shaft into imperial. 1/8" is too small and 3/16" shaft  (4.762mm) would have been too large to allow a proper spacer inside my 5mm bearings, so I left the shaft at 4mm dia.

[Brian Rupnow]

More interesting stuff happening here. The original plans had two different sizes of crankshaft bearings, a 12mm on one side and a 10mm on the other side, plus an additional bearing at the outboard end of the bolt on bearing support to help support the weight of a propeller.  I had a pair of 10mm bearings, so have eliminated the third bearing and went with a 10mm brg on each side of the crankshaft.The light blue bolt on bearing support has become much shorter and tucks in tight to the side of the main crankcase so that the new flywheel basically fits right over top of it. It had to grow in diameter to suit my 10mm bearings which have a larger outer diameter then the original bearings which were called for, so actually overlaps the cam shaft cap---That is why the cam shaft cap now sets in flush with the outside of the main crankcase. The cast iron liner has been eliminated. The cylinder is now cast iron instead of aluminum and has now been given a 7/8" bore, with an extension piece which extends below and above the original cylinder bottom and top faces to end where the cast liner originally ended. The gudgeon pin and cylinder cross bore have changed to 3/16" diameter. The piston is now 7/8" diameter and the crown area has been thickened up. The ring grooves, rings, and cylinder grooves have all changed to 1.5 mm because that is the width of parting off tool that I have. The flywheel is much larger in diameter than the original, and the support feet have been extended to give adequate backing so that the flywheel doesn't hit the table. The bolts which secure these bolt on angles to the sides of the crankcase have been moved down considerably in the crank case sides. The cylinder head, valves, and rocker arms are basically unchanged.

[Brian Rupnow]

The timing gear cover has underwent a shape change and is squared off at the top to match the squarish profile of the main crankcase. It has also been widened in critical areas to act as a base for my standard Chrysler ignition points. I now have to change the gears from metric mod style to 24DP to match the cutters that I have and hope that I can fit them into the "existing" gear cover.

[Jasonb]

Brian I can't see anything that will stop the crank and its trwo bearings from moving backwards as you have it. In the old design the front and middle bearing were trapped onto the crankshaft by the tapered collet when the flywheel/propdriver was tightened and they could not move within the nose.

Also why could you not use 5/32 for the cam as its only about 0.001" difference from 4mm? you can get 5/32" drill rod and bearings

[Brian Rupnow]

The crank can't move to the left, as a shoulder on the crank bears against the inner race of the left side bearing and the outer race of the left side bearing sets tight against the light blue bearing support, which bolts to the engine case. As far as moving to the right, I may drop a spacer ring in between the bolt on gearcase plate and the outer race of the right hand side bearing. Thanks---I hadn't seen that.

[Brian Rupnow]

Jason--that cyan blue spacer ring I added should keep the crank from moving endwise.

[cfellows]

Looking purty, Brian!

Chuck

[Brian Rupnow]

So-----Here we are, 99% finished, complete with Chuck Fellows style carburetor. Since my gear cutters are 24 dp. which cut larger gears than the .08 mod that this engine was originally designed with, the gear cover grew proportionally. I like it. It does have its own very distinct identity now, and as such, will be renamed the "Canadian Cub". I will be starting to make detail drawings sometime this week. I don't think I will post any drawings now, except for the general arrangement, because I have found that there are always changes as I go through the build, and I don't want to have to be constantly revising posted drawings. The drawings will all be done in inch decimal measurements, and the purchased components are a bit of a mish-mash,because the bearings I have used are all metric, while the sparkplug will probably have imperial threads. (Its becoming increasingly more difficult to get inch measurement bearings anyways). So----I assume that since the drawings will only be of use to model engineers in Canada and USA because of the inch measurements, who wants a copy of the finished drawing package once I have worked through the engine build and updated the drawing package to be correct? Let me know now please.

[Brian Rupnow]

[PStechPaul]

Nice compact little engine, Brian. Good styling. Looking forward to its fabrication, start-up, and run. 

[Brian Rupnow]

Jeez---I've been detailing my brains out. I'm up to 27 drawings now, and I have a question. I want to build the flywheel in the attached drawing, but the high price of brass is killing me. I do have enough polished 1/4" brass plate which some kind soul off the forum gave me 2 years ago, to cut 3 circles 1/4" thick. I also have enough left over 2" diameter cast iron "butts" to make the smaller diameter. I'm wondering--If I laminate all of the plates and the chunk of cast iron, using a circle of 6 hidden #8 bolts (with the bolt heads counterbored on the side which faces the engine)--would the 3 pieces of polished brass plate blend well enough when turned on the lathe together that the laminations wouldn't be obvious?

[Brian Rupnow]

This morning I'm up to 37 drawings, and I haven't done the general arrangement yet, but all of the part details are finished. In typical Canadian fashion, this design is 95% imperial "inch" measurements, and about 5% metric. That 5% is because the metric bearings demand metric bores and metric shafts. Some of the things that were done originally in metric just don't convert worth a damn. The nearest "reasonable" imperial dimension is so weird that you can't buy a reamer that size, so I stuck with metric in a couple of places. One of the drawings is a sub assembly of parts found on other drawings, so that means there are 36 "unique" part details. Many of these parts are "two required" so I believe there are something like a total of 99 parts, but that includes 4 bearings, a couple of nuts and bolts, and all of the carburetor parts. Definitely not an engine you would build over a weekend. If I'm not very careful, I may find myself starting to cut metal this week.--Thats okay. We are having a wet cold, totally sucky summer, following a long cold wet sucky spring, following the winter from hell.---I may never go outside again anyways!!!

[SHOPGUY]

Brian,
You could always make a rim out of steel which would cover any separations between the laminations.  The plates would have to be very flat to avoid the laminations being visible.
Your design looks really good. Thanks for including us on another interesting journey into model engine design and construction.
It's always an education to follow your work.
Ernie J

[cfellows]

Actually, I don't see anything wrong with letting the laminations show.  I would probably put a circle of recessed socket head cap screws around the rim from the outside as an additional decorative affect, kind of a steam-punk affect.  Plain flywheels get kind of boring after a while... 

Chuck

[Jasonb]

Or you could add a Vee or half round groove on the two joints, it would look like its meant to take a belt but would hide the joint