Water Cooled Webster

[bmac2]

A quick bolt up and now it’s got some compression and the intake valve does jump when I turn the crank.

 

[Brian Rupnow]

bmac--I never had much luck with copper gasketing either. I use a treated paper gasket material about .025 thick. The water cooled engines never get hot enough to burn it away.

 

[bmac2]

I can't put it off any longer I have to start on the flywheels. I just don’t like making flywheels. Its’ probably that anything I’ve made other than a small solid ones always wobble.
I could go with the hockey puck flywheel shown in the plans but I did promise this thing a pretty dress so I want spokes.

 

[bmac2]

This is going to be a built up flywheel because . . . . . I want to, and if I mess up part of it I won’t have to start from scratch.
It’ll have the outer rim, spoke insert, a ring to hold it all tougher, and a two part screw tougher hub.

 

[Brian Rupnow]

Use brass or steel for the outer rim. Aluminum isn`t heavy enough.---Brian

 

[bmac2]

Hi Brian
I plan on only using aluminum for the spokes for ease of machining and its’ what I have. I’ve got steel for the rest of it. It will be lighter than the stock Webster but then again there will be 2 of them.

 

[bmac2]

Change of plan.:idea:
Doing a little more research on built up flywheels I found a pretty good posting by Cedge here at http://www.homemodelenginemachinist....p?topic=3169.0 describing a Philip Duclos article on manually machining curved spoke flywheels with just a milling machine and a rotary table. Unfortunately it’s from 2008 and the pictures are gone.

One of my go to sites on the web when I need to make a tool or just want to look around is Dean Williams http://www.deansphotographica.com/machining/projects/projects.html. If you have a Taig or one of the other small machines out there you must check out this site.

I remembered he'd made curved spokes on one of his engines. Lucky for me “Building the Tripod Steam Plant” was near the top of the page so I didn’t even have to search. Read the article a couple of times and though Deans flywheels are only 1” and mine are going to be just shy of 4”, I decided with a jig this was doable. One advantage I have is where Dean says "got out some of my old drafting tools" I use my CAD. This might take a while. My couple weeks of “do nothing” vacation is over. Work really interrupts my “Machining and Hiding in the Basement” time.

 

[bmac2]

It looks like I used a Spirograph but this is what I came up with for the milling/drilling template. This is either going to be great, or be like my first set of piston rings. As long as I don’t break anything and there’s no blood, it’s all good.
Caution this might get a little verbose.

 

[Brian Rupnow]

Do you realize that your "Webster" engine is morphing into a "hit and miss" engine. This is a picture of my "Odds and Ends" hit and miss engine designed by Philip Duclos. Same style, same carburetor/exhaust arrangement, same long rocker arm arrangement. All you would need are the flywheel mounted weights and mechanism for the governor.----Brian

 

[bmac2]

Hi Brian

If you where to put your Odds and Ends in a room with your Kerzel Hit and Miss, add soft music and a bottle of wine (Coleman fuel?) for the night it would come pretty close. Rof}

I did said wanted to try things I’d seen on other engine.

 

[bmac2]

I picked up the X, Y coordinates for the reference holes off the CAD drawing using the origin as X-0, Y-0 and transferred them to a spreadsheet. Made the template from some more or less 1/8” plate I had around. Started by mounting the rotary table using a slug I made up that is a very close slide fit into the center hole of the table.

 

[bmac2]

I have a ¼” centre hole in my work plate so I made up a drop in plug that gave me a 3/32” pivot pin. Drilled a 3/32 hole in the centre of the plate and mounted it to the work plate.

The size, shape and positioning of the plate doesn’t matter as long as it’s bigger than the spokes because everything is referenced from the center point.

I then drilled the 26 reference holes using the X, Y coordinates. This is one of those times when I have to tell myself that even when it “doesn’t look right” to trust the numbers. This plate has two purposes in life, as a drilling guide for the 1/8” and ¼” clearance holes, and the 3/32 holes that act as centre points for the inner and outer radius of the curved spokes, and inner rim.

 

[bmac2]

I had to blue it up and scratched some lines just to reassure myself of which holes did what.
(Love that sentence; I can just see my old English teacher having a fit)

Sort of reminds of a field trip to the planetarium. Constellation Fuge Rotæ ?

 

[bmac2]

I got the 2 blanks for the spokes cut from a peace of 3 ½” aluminum and trued them up in the lathe drilling a 3/32 centre hole. The plan was for these to 3/8” but I messed up one of my cuts on the band saw so 5/16” it is.

 

[bmac2]

Aligned the blank to the drill jig using a 3/32’ drill bit and drilled the holes using the plate as a drilling jig. Then opened the clearance holes to 1/8” and ¼”.

 

[bmac2]

Mounted the blank to the top of the jig using two 3/32” bits to ensure things are lined up and it’s ready to make some chips

 

[bmac2]

With a 1/8” end mill I started with what will be the outside radius of the spoke by putting the pin in the bottom (what I’ve been thinking of as) “radius hole” and set the X offset to 1.1875. From here it’s just a matter of running the milling cutter between the two 1/8” holes that mark the beginning and end of the arc then moving to the next hole in the plate.

 

[bmac2]

Mounted the plate to the top “radius hole”, set the X offset to .5646 and did the inner radius of the spokes.

 

[bmac2]

For the last bit I put the centre hole on the pin, set the X offset to 1.5” and did the inside of the rim.

 

[bmac2]

Well that was easy, on to my second set of spokes. I realised while making the first set of spokes that drilling the 3/32” holes in the blank cut in to the spokes just a bit. I’ll have to fill them with some JB Weld before I clean them up. For the second one I shortened the 3/32 centre pin to just under 1/8” and only drilled the centre hole, the 1/8” and the ¼” holes in the blank.