Yet Another Webster Begins

[CFLBob]

i used my table belt sander to cut (sand) the angle on my exhaust pipe

For some reason, that didn't occur to me, although I've done it to put tapers on other things, or to cut small corners on pieces.

As best I remember, I turned the part as per the plan (attached), set the part in my vise, protected by some wood (? I think?) at the proper angle, and milled it to the correct angle. I think. Apparently, if I didn't take pictures, I can't remember exactly how I did it!!

My first thought was to put it in a milling vise with one end held up the right number inches to get that angle (kinda like a sine plate). Then I started worrying about it being destroyed by the cutting forces. I have a fine tooth slitting saw blade for my Sherline and it seems that the forces aren't that bad, but it's a CNC mill so I've never turned the wheels by hand where I can feel it. I could drill a hole into a chunk of wood that needs to clamp the piece, but not too hard. Drill the hole, then split the wood in half and use screws to hold it together?

 

[awake]

The wood is a good idea. I would start with two pieces with a bit of shim in between (a layer or two of construction paper or something like that) - pop a couple of brads in, or something like that, to hold them together. Drill the hole right through the center where the shim is. Separate and remove the shim. Now you have a jig that will put a bit of pressure on the piece to hold it secure. Voila!

 

[awake]

Oh, missed the reference to screws - yes, you could screw it together before drilling. You could use the screws to reassemble and put pressure on the part to hold it ... or you could let the vise apply the pressure. Either should work fine, I would think.

 

[werowance]

i should also add that on mine, I made a 2 piece muffler. I had brass tubing like you get in a pack from a hobby shop which made up the larger portion of the muffler with the angle tip, then the base of the muffler I used a piece of brass and turned it, rounded over the base piece, drilled the hole through and soldered the 2 pieces together. but I sanded the angle on the tubing first before joining the pieces together.
circled in red you will see the solder line. but your idea sounds like a great way to do it as well. I was just trying to use up some scrap stock on mine

 

[CFLBob]

It's nice looking. Mine is a bronze rod that I got from Online Metals. It's sold as 3/8 but with a note that it's oversized, I think it's really 13/32. It's OK but I have to turn it down to be anything. Not knowing how much room I had between the muffler and what's behind it, I just made it like the prints.

I've ignored the oil cups until now. I'm wondering how people handled that; if you guys made all the little cups or just put a drop of oil in all those holes before starting it up. I'm sure it will be running for like a minute at a time.

 

[werowance]

i did ball bearings. I did do the oil cup for the cylinder but that's all.

 

[awake]

Like Werowance, I did ball bearings for the main bearings, and for the bearing on the cam gear. I used a bronze bearing on the rocker arm, with a small hole for oil - I just put a drop in there, and it seems to last forever. Likewise a bronze bearing at the little end, and I put in the hole in the cylinder and piston ... but so far I have just been lining it up an putting in a drop or two of oil from time to time.

 

[CFLBob]

I also got ball bearings for the main ones in the side plates. I need to look at the others. I remember the bronze bearings in the connecting rod, but that's about all.

Meanwhile, the wooden fixture worked as intended. Setting up for the cut.

I cut a bit high of the full cut, so I lowered the blade about half its thickness and cut again. Twice.

Finally,

Like you said, Andy, I took pictures to remind myself how to do it. If I ever need to cut close to a 30 degree angle on a piece of 3/8 stock, I have a fixture.

For the other 99% of cuts like that, I have a technique.

 

[werowance]

well, that's not what I had invisioned on the wood fixture but that really was a good idea. thanks for showing that.

on the crank to rod I changed that a bit from drawings and did a ball bearing there as well. but rod to piston is brass busing and I ran mine a lot with nothing more than a drip or 2 of oil in the hole where the cylinder oiler goes. but I did make sure the oil drops also hit the hole in the piston to run down on to the wrist pin area. but id say if you omitted that oiler for now and just drilled the hole for where it goes would be fine.

 

[CFLBob]

As usual, I keep working on stuff but not posting. I started trying to understand how this all goes together.

I ran into my first booboo. I drilled the mounting hole in the cylinder head in the wrong location. The tapped 10-32 hole in the bottom is supposed to be 0.688" from the inside edge of the relieved portion of the cylinder head and I put it 0.688 from the outside edge. When I put it together, it looked like this:

I'm sure there will be more. This is the area after I fixed it. The valves and intake/exhaust manifold wouldn't mount before. An extra hole on the bottom of part that nobody will ever see is the easiest kind of mistake to live with.

And a wider shot. Just because.

I started looking into a fuel tank and asked myself if I'm using an RC carburetor, why not an RC fuel tank? Webster says he uses a small one that holds like 1 oz of fuel. My first search only turned up model fuel tanks that hold quite a bit more, like even 8 ounces.

I keep asking myself "now where does this go?" or "what's this?"

 

[werowance]

well, does the hole actually make it to line up with the oil hole in the piston to hit wrist pin at any point during the rotation? even just enough to see part of the hole? if so id say it will be ok since the engine doesnt run for long periods of time. the oil cup though will have to have a little more clearance to clear the fins on the shank where the trheads are..

also does the piston ring groves run over this hole? if it does then might be a problem. but if you rotate the assembly without the rings on it and the ring grove shows through the hole then i might be conserned about it catching

 

[CFLBob]

I think you're thinking of the hole in the cylinder toward the left of the fins? It's not that one. It's the tapped hole on the bottom. In this picture, I made it 0.688 from the right side, not as shown.

 

[werowance]

doh, sorry, i understand now. yeah your right no body will see it on the bottom. plug an lock tight it if your worried about it being seen but otherwise it shouldnt be any problem. one thing on that particular area, mine vibrates loose. the 2 side screws and the 1 bottom screw all gets loose after a bit of running. so just a heads up if yours starts moving, its probably not because of the extra hole, i think its just because of the design. or in my case maybe the person who built it......

 

[minh-thanh]

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Your engine is a lot nicer than my first 4 stroke

 

[CFLBob]

Your engine is a lot nicer than my first 4 stroke

Thanks. It will get a lot prettier when it runs! I was going to say if it runs, but I'll be positive.

 

[CFLBob]

One of the things I needed to do was make up a little piece that's not part of Webster's plans to fit the counterweight that I copied from Brian Rupnow and adapt that to drive the connecting rod.

There's another piece I need to make because of a mistake I made around post #44 where I misinterpreted things and instead of making a 1/4" hole to hold the camshaft, I drilled it out for ball bearings. I'll make a brass adapter to fit in that hole and drill a quarter inch hole axially.

 

[CFLBob]

I have a question for those who have put a Webster together.

Back when I was working on the side frame, when I went to make the hole for the camshaft, I made the mistake of making it to fit a ball bearing set that I had 3/8 OD, 1/4 ID instead of just plain 1/4 (reamed) like the drawing says. I hadn't understood that the shaft is stationary in that hole and the cam rotates on it.

Today I made a little bushing to fill the hole and present a reamed 1/4" hole for the camshaft.

This is the oversized hole the bushing and the camshaft. As you can see, I left lip on the bushing that will stand proud of the side frame either on this side or the inside. I left it 1/32 thick. It looks like that should be OK on the outside because the conn. rod, the counterweight and the all that is far from the side plate. Is there any reason to either put that shoulder on the inside, or get rid of it completely?

And while I'm here, I have a shoulder like that on my ball bearings for the crankshaft. Are those good on the outside, where they are? You can see the one above the camshaft hole.

 

[scottyp]

I had a little mishap when I drilled same hole. Long story, but the hole ended up being at an angle and off of the correct location. I was able to make a tight press fit plug (without a lip) and re drill it correctly and it has been OK. As long as you have the clearance for the lip, I’d hide it on the inside. Either will be fine. Just make sure your bushing is a tight fit, some locktite will help ensure that it doesn’t come out. The lip is really only helping in one direction and there isn’t a ton of force on the shaft so it may not be super important. You could also recess it a bit if you had an end mill with the same diameter as the flange. But really not a big problem, nobody will care when the thing comes to life.

I’d run the flanges of your bearings on the inside of the frame since all of the crankshaft spacers are between the frame sides and the is what locks in everything. And there is not a spacer between the ignition cam and the frame and I wouldn’t want to have the one little set screw be what holds everything in the right place.

 

[CFLBob]

View attachment 119868

I had a little mishap when I drilled same hole. Long story, but the hole ended up being at an angle and off of the correct location. I was able to make a tight press fit plug (without a lip) and re drill it correctly and it has been OK. As long as you have the clearance for the lip, I’d hide it on the inside. Either will be fine. Just make sure your bushing is a tight fit, some locktite will help ensure that it doesn’t come out. The lip is really only helping in one direction and there isn’t a ton of force on the shaft so it may not be super important. You could also recess it a bit if you had an end mill with the same diameter as the flange. But really not a big problem, nobody will care when the thing comes to life.

I’d run the flanges of your bearings on the inside of the frame since all of the crankshaft spacers are between the frame sides and the is what locks in everything. And there is not a spacer between the ignition cam and the frame and I wouldn’t want to have the one little set screw be what holds everything in the right place.

Thanks, Scotty. That's helpful.

The thing I'm spending the most time on is trying to visualize how that area between the two frames goes together. Would you have a picture of that? Did you have your own build thread here?

 

[scottyp]

https://www.homemodelenginemachinist.com/threads/scottys-webster.32160/
Not a super detailed build thread but there are pics. My frame rails were a little thinner than the plan so I made my bushings and spacers to fit.