Water Cooled Webster

[Swifty]

What a bummer Bob, I don't think that brazing rods have the same capillary action as silver solder. This ability is needed to flow into small gaps.

Paul.

 

[bmac2]

Hi Paul.
The crank was probably ok but for the amount of time and material it takes, making a new crank won out. Did another buildup and this time just silver soldered it and trimmed it up on the band saw. It still needs to be cleaned up but I’m happier with it.

The more I played with the crank the more I understand why most of the You-Tube videos I’ve seen of a Webster running it’s clamped to the bench. If this thing ever runs that’s a decent hunk of mass being thrown around. I was leafing through the Nov.2012 Model Engineer and saw that the crankshaft used in the Nemett Bobcat and Jaguar engine have a bolt on counter weight. I can do that. After reading a couple of articles off the web I calculate that I’d need to add about 40 grams to the webs. If my math is right this works out to give or take ¼ slice of 1 ½ cold rolled.

Like the drawing? I do use CAD for most everything I make except my lunch but sometimes all you really need is a pencil.

 

[Brian Rupnow]

Bob--Go over and look at the counterbalances added to my crankshaft in the Nemett Jaguar--Canadian style. This was not my original design, but it certainly does work well, and doesn't interfere with how you make the crankshaft.-Whoops--Just re-read your last post and I see that you have it already.--Brian

 

[bmac2]

Hi Brian. Hey thanks for the e-mail
Ah. Page 14. I saw the screw holes in the drawing for the crank on page 10 but must missed the picture on 14. In the Nemett Bobcat article is the same thing a bolt on half disk with a notch to fit the webs.

 

[bmac2]

I started the counter weight by putting a small recess in the face of the weights then parted it off ¼” thick

 

[bmac2]

The way I use to setup a thin piece of stock for facing is to get it snug in the chuck but sitting proud of the jaws. then with the tail stock Jacobs chuck opened all the way use it to press the disk into the chuck. Then faced the back.

 

[bmac2]

I have to cut this disk in half and the “Center Square” in the front is more of an “About the Middle Square” so on a 1 ½ inch disk I used a ¾ parallel to mark it out. Thought of a couple of ways I could cut this and in the end decided to just screw it down to a piece of scrap and cut it in the band saw.

 

[bmac2]

It went Pac-Man on me when it broke but didn’t grab the blade.

 

[bmac2]

I then milled out the ½ inch notch (actually .498 ) for a good press fit on the webs then spotted and drilled them #50 tap size.

 

[bmac2]

Setup the crank in the vise and used the counter weights as a jig to start the holes in the webs. Drilled and tapped the webs 2x56 then opened up the holes in the counter weights to clearance size and countersunk then for the screw heads. It may not be perfectly balanced but it’s a heck of a lot closer than it was. The disks where relatively simple to make so it would be easy enough to add or remove a little weight later if I want to. Worst case I could just take them off and be back to stock. I don’t think I’ll take them off . . . I like the look.

Basic crank = http://youtu.be/t7JqF8euBK4

With counter weights = http://youtu.be/HNWK42qVMkU

 

[ShopShoe]

That's another way to make a crank I wouldn't have dreamed up. Thanks for posting that.

--ShopShoe

 

[bmac2]

Hi Shopshoe
With all the Nemett Jaguar builds going on I can’t believe I missed it but it sure makes counter balancing easy. Your Avatar looks a lot like the shoes I have in my shop. Hell on floors but great on ice.

 

[bmac2]

I can’t really do anything more if I don’t get this thing bolted down to the base plate. I’ve been putting it off because I couldn’t decide exactly what I wanted. In the end I decided to just go a piece of ½ in aluminum 3/16 larger than the engine. It’s a bolt on part so if I change my mind I’ll make something else and use this as a drilling jig.

 

[bmac2]

I messed up when I laid out the two front holes. I’d forgotten about the two 2x56 screws that I used to hold the block to the sides before brazing so I just moved them down ¼ inch. Hey, if it’s a screw-up on the bottom, and no one will ever see it . . . I can live with that.

 

[bmac2]

Now that things can’t move around I can get on to the bearings caps. Milled the blanks to size and clamped them in place, then drilled and tapped 4-40.

 

[bmac2]

It took a while to get this setup in the mill and I’m still not sure it’s 100%. I could be here for weeks. With it packed up I drilled and reamed the holes for the bearings ½ in.

 

[bmac2]

With a length of ½ inch rod in the bearing holes and the engine sitting on the Chinese Tombstone I checked it with a height gauge. It is out a bit but I think I can correct it by putting a small shim under the left hand bearing. This is why I buy feeler gages when I see them cheap.

 

[bmac2]

Well the alignment’s good but I did have to put a small shim under the one bearing.

 

[bmac2]

I couldn’t resist putting in the sparkplug.

 

[bmac2]

AAaaah Crap!
Now it looks like Snoopy :rant: