Yet Another Webster Begins

[CFLBob]

Just a weekly update. My two side panels are cut out and ready for the holes to be drilled and tapped along the edges.

Grabbed a picture while the mill was cutting out the two pieces, the last of five passes. As you can see, I took the small piece, rotated it 90 degrees counterclockwise and moved into the space above the bigger piece. This allowed a better fit of the two sides onto one piece of 5/16" plate that I have. I cut the two out with a 1/2" EM, after drilling the holes and finishing them (three get tapped and three get reamed to final size).

This got me thinking about using ball bearings in those three reamed holes instead of trickling oil from a cup mounted above the bearings. I did that on my flame eater and I thought it worked out well. That .250" hole is the size of the shaft for the two bearings I used last time, and they only needed a .375" hole. There's tons of room to put ball bearings in all three holes.

Does anyone have feedback on that idea?

 

[Brian Rupnow]

Bob--I try to use sealed ball bearings in all of my engines. Most of the engines I build are open crankcase. The only recommendation I would make is that the plate in which the bearing sets should be at least 0.050" thicker than the bearing itself. I have tried using oilite bronze bushings and 660 bronze bushings. I have found that even with the greatest of care, my crankshafts are never 100% straight and true. The result of a "not perfectly true" crankshaft is that the bronze bearings very quickly wear out and become "sloppy", and then the engine rattles. There is enough "give" in a ball bearing that even if the crankshaft isn't 100% perfect, the inner race can "wobble" a bit while the outer race remains fixed in position. This makes for a quieter, smoother engine.--Brian

 

[CFLBob]

Thanks, Brian.

The only recommendation I would make is that the plate in which the bearing sets should be at least 0.050" thicker than the bearing itself.

In this case, it's easy. The plate is 5/16, .3125, thick. The bearings for the .500 diameter shafts require 0.750 holes and are 0.1562 front to back. Almost half the thickness of the plate.

I found my old record from when I bought the ball bearings for the Duclos Flame Eater and found I have two spares. Those were for a .250" diameter shaft, exactly what I need now, and were .375 OD. I needed two, bought four, and now I just need one.

 

[CFLBob]

A couple of updates. The first goes with a topic on Werowance Builds a Webster, where we've talked about a poor finish from Irwin countersinks. I think most of us are reading both of these threads, but I'll put it here first.

When I did the two countersinks on the end of the long side plate, I used the exact same countersink as I used on the sample picture I posted before. I did this on my G0704 mill with the countersink held in 1/4" collet instead of on my drill press in its Jacobs chuck.

The exact same countersink on my drill press did this:

I suspect it's because the drill press has wobble and unwanted movement.

My main reason for posting this is to update the side pieces themselves:

Where the 1/4" hole used to be is the ball bearing set I had. I've ordered the ball bearings for the half inch reamed holes, but I need to buy a drill bit and reamer. Those ball bearings require a 3/4" hole.

 

[werowance]

i actually did 4 more countersincs in the valve block using the drill press this time and mine came out nice. what I did is ran the drill press at full speed and kept an even steady preasure on it. and that seemed to work better on mine. I also tried in the mill with collet chuck and everything clamped or in the vice and had bad results on that. I think it has to do with the speed and feed rate. but just my guess. more testing and practice for me to be sure.

 

[werowance]

this hole, where the cam and gear shaft goes, it looks like a pressed in ball bearing? or is it just where swarf spun around and is making an optical illusion on the finish?

 

[CFLBob]

It is a pressed in bearing. The bearing measured .3733 and I have a .374 reamer, so I drilled to the next size down (in 1/64ths) and reamed to the .374. Then I used that woodworking bench vise that the piece is sitting on as a press by putting a piece of eighth inch aluminum over the bearing to get aluminum pushing stainless into aluminum all nice and square.

Interesting we seemed to have opposite results with the drill press and mill.

My drill press kinda sucks. It's one of these Grizzly imports
https://www.grizzly.com/products/Grizzly-5-Speed-Floor-Radial-Drill-Press/G7946
and it seems to have too much slop for metal working. I guess it's OK for wood, but it seems to move around and flex too much when you put pressure on the handle.

 

[werowance]

ok, so I don't understand why a pressed in bearing there? the gear/cam spins on the shaft that goes there right? I thought only bearings in the top holes where the crank shaft goes. a ball bearing setup would free up some friction there but not sure how you will mount the gear and cam on it like that. would have thought a bearing pressed into the gear would be required or something.

 

[CFLBob]

Maybe I'm using that term incorrectly. I just pressed it in so that it doesn't fall out on me and I don't need LocTite.

If my numbers are right, at room temp the hole in the plate is .0005 to .0007 bigger than the bearing so it needs to be precisely aligned when it's pressed in, but it's not a special fit.

 

[werowance]

I guess I mean why is there a bearing in that place. the plans show a .250 post pressed in there for the gear to spin on.

 

[CFLBob]

That's a few posts up, #41.

I kind of like ball bearings and asked for feedback. Brian Rupnow said he likes them and tends to use them everywhere. I'm putting ball bearings in both reamed half inch holes, too.

 

[werowance]

ah ok, now how are you going to keep the gear and its shaft fastened to that bearing? E-Clips or something? I agree the more rollers you can put in the better I think. I managed to get them on one side of my connecting rod.

 

[Brian Rupnow]

Bob--You may have screwed that up. As Werowance says, that hole in the sideplate is for a pressed in shaft that the gear spins on. The shaft is cantilevered---that is to say, there is no outboard support for the other end of the pressed in pin. If you want to use a bearing there, the bearing has to be pressed into the gear. You can not cantilever a shaft supported by a bearing in the sideplate. If you have already bored that hole out to take a bearing, you will have to make a stepped pin and press it into place.---Brian

 

[CFLBob]

I was about to tell werowance that I hadn't gotten that far and now I'm even more sure I haven't figured it out, yet. I'll take the bearing out and leave myself notes on the drawings.

 

[CFLBob]

Bob--You may have screwed that up. As Werowance says, that hole in the sideplate is for a pressed in shaft that the gear spins on. The shaft is cantilevered---that is to say, there is no outboard support for the other end of the pressed in pin. If you want to use a bearing there, the bearing has to be pressed into the gear. You can not cantilever a shaft supported by a bearing in the sideplate. If you have already bored that hole out to take a bearing, you will have to make a stepped pin and press it into place.---Brian

It was easy to push the 1/4" ID, 3/8 OD bearings out of the hole, but the hole is 3/8 so the original approach is out the window.

I don't understand how these things go together. I ordered bearings for those 0.500 reamed holes, and since they require a 3/4" mounting hole, I bought a 3/4" chucking reamer and a 47/64 drill bit (1/64 under 3/4). Both are unnecessary and just go in the tool box. What I should have bought were bearings that accept the 0.313 crankshaft and fit in the 1/2" reamed hole. I see them referenced on the last page of the plans - four of them. He calls out four flanged bearings, so I assume one on each side of the two pieces.
CRANKSHAFT BALL BEARINGS: 5/16" I.D. X 1/2" O.D X 5/32" THK., FLANGED
SOURCE: W.M. BERG: P/N B2-21 -OR- STOCK DRIVE PRODUCTS: P/N A 7Y55-FS5031
(4) REQD.

It looks like I'm supposed to take the exhaust cam (bottom right on sheet 8) and press fit that into the large gear on top left, sheet 9. That assembly then goes on the camshaft, made of 1/4" drill rod (sheet 8, bottom, 2nd from right), which goes into the 1/4" hole where my small ball bearings were. I don't understand what you mean by a stepped pin and what I'm pressing that into.

 

[Brian Rupnow]

Bob--You have a detail of the cam shaft, which is given a diameter of 0.250". There is a hole in the one sideplate which is also given as being 0.250" diameter. This is not shown as being a press fit on the plans, so I am making the assumption that the cam shaft is held into the sideplate by applying Loctite to it before putting it in place. If you had already bored that .250" diameter hole out to something bigger to suit a bearing (which I thought you had), then your camshaft would have two diameters on it. One diameter to fit the hole which I thought you had made larger, and one to fit the cam gear which rides on the cam shaft . That is what you call a stepped pin.

 

[CFLBob]

How could the cam shaft be held in the side plate with LocTite? It wouldn't rotate. I'm assuming the shaft rotates with the gear on it. Does the gear rotate on the shaft?

The exhaust cam (which gets the quarter inch shaft) goes onto the big gear - the drawing says to LocTite and press that cam onto the cam gear. The cam shaft has an .063 hole drilled across it, .094 from one end. I don't see where the instructions say what goes in that hole or why it's there.

 

[stevehuckss396]

From the Webster Drawings.

When making the CAM SHAFT, shoot for a press fit into the engine frame and a free rotating fit with the
CAM GEAR. Alternatively, you could use a set screw though the bottom of the SIDE FRAME to retain
the CAM SHAFT in it's bore.

Last weekend I helped someone get a Webster running. The camshaft was removed so we could reshape the lobe. It was installed using the set screw through the bottom of the frame method and the gear and cam lobe spun on the shaft.

 

[stevehuckss396]

More info from the drawings.

Press the bearing(s) and CAM SHAFT into the SIDE FRAME, slide on one CAM GEAR WASHER,
the CAM GEAR ASSY (with the CAM pointing towards the frame) followed by another
washer, and secure with a cotter pin. Be sure that the gear spins freely on the shaft - adjust
as necessary

 

[CFLBob]

Thanks, Steve.

I can make a little stepped pin/camshaft like Brian suggested, but the important part here is the CAM SHAFT is motionless, and the CAM GEAR, with the EXHAUST CAM mounted on it spin on the shaft. A cotter pin keeps it from sliding out of place.