Introducing ... the "Steel Webster"

[Craig DeShong]

Reviewing this build Andy.  I make my own springs also.  The first few were pretty rough but once you “get the hang of it” you can turn out some pretty nice work.

[awake]

I probably made it sound a little easier at first than was actually the case. I think I said above that my first spring was a success. What I failed to mention was that there were two or three globs of wire that didn't actually qualify as springs along the way ...

But still, I was pleasantly surprised at how relatively easy it turned out to be. Having a lathe that goes down to 30 rpm probably helps!

[Craig DeShong]

I don't count the "globs" either, and a slow lathe certainly is a benefit.  My south bend gets down to 45; slow enough.

[awake]

I don't count the "globs" either, and a slow lathe certainly is a benefit.  My south bend gets down to 45; slow enough.

There are advantages to "old iron"!

[awake]

Part 12 of the build log, the gears (attachment 1 & 2).

In my design, the exhaust cam is part of the larger gear, and the smaller gear has a hub section on each side, to allow for spacing of the flywheel and a place for the set screw. Both gears begin with slightly oversize blanks (attachments 3 & 4), with the critical dimensions being the 13mm (.512") ID of the larger gear (sized for a slight press fit of a pair of F686 bearings on which this gear will ride) and the 10mm (.394") ID of the smaller gear (for a close sliding fit on the crank shaft).

Along with the blanks, I made arbors to run between centers, one for each blank (attachments 5 & 6). The blanks were loctited to the arbors, and once set, I machined the OD of each blank (attachments 7 & 8 ).

Continued below ...

[awake]

Continuation of part 12 of the build log, the gears:

Since the gear blanks are mounted on arbors, it is easy to transfer them over to the dividing head on the mill to cut the teeth. Initially I cut the gears using my module 1 "semi-hob" (attachment 1). This is a home-made cutter, but unlike a true hob, the teeth are just horizontal, rather than being a continuous helix. To get the best results with this sort of cutter requires making multiple passes per tooth, with each pass slightly rotated and offset. In other words, it can be tedious ... and even more tedious when someone (who will not be identified) messes up the math and winds up having to cut the smaller gear twice.

When I finished cutting the teeth on larger gear, I also switched over to an endmill and began cutting the cam in stages (attachment 2). After a bit of smoothing with a file and emery paper, I had a very nice cam gear with cam (attachment 3). All that remained was to remove each of the blanks from the arbors using my trusty heat gun (attachment 4).

Naturally, I immediately mounted them on the crankshaft and the pin in the frame on which the cam gear rides ... at which point I discovered that, when one designs for a 24 and 48 tooth gear set, and then winds up cutting a 20 and 40 tooth gear set, for some reason the gears do not mesh. (I failed to take a picture ... it was the most deflated feeling to see these beautiful gears sitting with a good quarter inch of air in between.)

So, I had to make new blanks, and cut both gears again ... and at that point I decided to break down and buy a couple of M1 gear cutters. They were inexpensive imports, but seemed to do an adequate job (attachment 5).

With the CORRECT gears cut, I still needed to put the key way in the smaller gear, which I did with my trusty 7" shaper (attachments 6 & 7). I also needed to drill and tap for the set screw that bears on the key. To position it correctly, I used a long key in the key way to "hang" it over the jaws of the vice (attachment 8 ), then tightened up the vice and removed the key. Then I drilled and and tapped the set screw.

This concludes the building of the gears; next up will be the ignition.

[awake]

Part 13 of the build log, the ignition components (attachments 1 & 2).

The only hard part of the ignition components is the points mount. The first step was to prepared a slightly oversized blank, including not only milling to thickness but also drilling the two .159" diameters holes that will later be tapped 10-32, along with a counter-sunk hole in the middle of the axis of rotation just large enough to take a drywall screw. I also drilled the .219" hole that accepts a protrusion from the points, and a start and stop hole for the curved slot.

With the blank prepared, it is time to cut all the curves in this piece. The curved top and the curved slot allow the mount to be adjusted easily while still staying securely attached to the frame. The key to making these curves in a non-CNC shop is, of course, a rotary table. After centering the rotary table under the spindle and setting the DRO accordingly, I fastened a piece of scrap plywood to the table with four bolt. Then I used the DRO to determine the placement for drilling screw holes to match the center hole and the .159" holes that I had prepared in the blank (attachment 3). I then fastened the blank to the plywood with a drywall screw in the center and two pan-head screws that just fit in the .159" holes, thus both securing the blank for cutting and locating it correctly on the RT (attachment 4).

Now it was simply a matter of setting the proper radius and rotating the RT to the proper angles to cut t the curved slot (attachment 5), the curved bottom (attachment 6), the straight part of the right side (attachment 7), and the angled part of the right side (attachment 8 ).

Continued below ...

[awake]

Continuing part 13 of the build log, the ignition components:

I continued cutting around the periphery of the points mount, cutting the rounded top (attachment 1) and down the left side (not shown). Then I positioned the cutter and began to cut out the middle hole (attachments 2). When that was finished, the part was complete (attachment 3), and it fit perfectly on the bearing boss around which it rotates to set the timing (attachments 4 & 5).

The only other pictures I took as I made the rest of the components were a couple as I made the combination ignition cam / starter hub (attachments 6 & 7). Not shown are the making of the small retainer (which helps to hold the points mount against the frame while allowing it to rotate to adjust the timing), nor the drilling & tapping of the hole to mount the retainer and the hole to mount the screw that clamps the points in the selected timing position - nothing complicated about any of these.

Next up is the carburetor!

[awake]

Part 14 of the build log, the carburetor (attachments 1 & 2).

As shown on the plans, this is a slightly modified version of Chuck Fellows' carburetor. When I went looking for his carb on the internet, I found that he had put out several variations, some using a .125" throat and some a .156" throat. Not knowing which to choose, I decided to hit a joyous fortuneteller (aka, strike a happy medium) and designed this with a .140" throat.

The hardest part of the build, by far, was making the needle assembly. It would have made it a bit easier to use a length of 8-32 screw, and probably a lot easier if I had used brass ... but this is the Steel Webster, so I made it out of a piece of steel hex stock. Three times. Or was it four? Let's just say it took more than one try! Particularly difficult was drilling those itty-bitty holes, but I got it done in the end (attachment 3). Unfortunately, after I finally succeeded in successfully drilling it, I then discovered that one must support a long thin stem when trying to single-point the 8-32 threads (attachment 4). Failing to do that meant scrapping yet another part and having to do the drilling again.

Fortunately, the rest of the carb was pretty easy and straightforward. I prepared a rectangular blank for the body and center drilled each end to locate the throat; then I mounted it between centers (attachment 5) and turned the round sections on each side (attachment 6). Making the needle control screw was easier than I had thought it might be (attachment 7), except that I had my welder settings wrong when I welded the needle in place. (Yes, even there I went with welding. Someday I will attempt silver brazing!)

Voila! A completed carburetor (attachment . The plans showed a 10-24 SHCS for the throttle, but I wound up threading 10-32 instead, and I'm glad I did - no, I can't "blip" the engine with this throttle, but I can control its speed very easily and smoothly. I also went ahead and turned a thumbscrew with 10-32 threads, and added a spring to both the throttle and the needle adjustment to hold them where they are set.

Next up is the gas tank ...

[awake]

Part 15 of the build log is the gas tank (attachments 1-4). Let me say from the beginning: don't do it this way. I thought it was a simple and elegant design, but in fact, it was a royal pain. Perhaps a clue should have been that it took 2 sheets just to draw it up. It didn't turn out very well ... but it does work, so I suppose it was not all bad.

The tank began with a scrap piece of steel pipe; I turned the outside to 1" OD (attachment 5) and bored the inside to .875" (attachment 6). There was also a bit of additional boring, called out in the first drawing (attachments 1 & 3) - a section bored to .886" to create a lip to hold a flange, a threading relief, and the outermost .157" length bored to .897". This last part is then threaded to .926" x 32 tpi (attachment 7).

Part 15 continues below ...

[awake]

Part 15 of the build log, the gas tank, continued:

I mentioned in the previous post the lip that would support a flange - this flange is depicted on the second drawing (sheet 16) attached to the previous post. It was intended to be a press fit into the .886 section that was bored in the pipe, and it has a face groove to hold a viton o-ring - the same size o-ring that I used for the cylinder "ring," since I got a pack of 10 (attachments 1 & 2).

I also machined the threads for the screw-in end cap (attachment 3). I then machined the bore and chamfers in this end cap, parted it off, and machined in the two holes in the outer face used to screw the end cap into place (no pictures of any of this).

Next I machined the inlet and outlet pieces, including machining a curve in the face (attachment 4) so that it would fit snugly against the OD of the pipe (attachment 5).

Not shown was machining of the fixed end cap - just a simple piece to fit into the non-threaded end of the pipe. Attachment 6 shows all of these parts ready for assembly.

Part 15 wraps up below ...

[awake]

Part 15 of the build log, the gas tank, concludes with this post:

The next step was welding the fixed end cap in place. With a little clean up, that came out pretty well (attachment 1). Tig-welding the outlet pipe in place was ... well, it was successful. It doesn't leak. I was able to thread it for the outlet pipe. It also looks like crap (attachment 2).

I was hoping I would do better with the inlet pipe. I used my "third hand" to hold it in place on the pipe (attachment 3), fired up the TIG welder again, and ... once again, it doesn't leak. Need I say more?? Clearly I need more practice on TIG welding small parts (attachment 4).

I failed to take pictures of machining the outlet pipe, or of the thin circle of acrylic that serves as the window - no particular problems with either of those. I did get a picture of part of the machining of the inlet cap - again, no problems there (attachment 5).

So, how did it all work in the end? Well, first off, the press fit of the flange didn't achieve a seal, so I had to back-fill it with some sealant. Then I had to do it over when I realized that the first sealant I used was not rated for exposure to gas (and proved it by swelling up and detaching).

But, in the end, despite the sloppy welding and other challenges, it came out half-way decent, and achieved my goal of allowing me to see the level of fuel in the tank (attachments 6-7).

This build log is just about done - just the gas tank mount and a few odds and ends left!