Introducing ... the "Steel Webster"

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stragenmitsuko

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The article makes a lot of sense , especially if you already understand ( more or less ) what's goin on .
The trick for the calculations seems to be think in degrees instead of divisions like I did .
Then it's just basic trigonometry .

Indeed there are not that much passes needed as one would inituitively think .
The gears will wear in quite nicely and remove the high spots themselves .
In fact , that is how the involute profile was "invented" . It comes naturally .
I don't know , maybe some grinding paste could be used running them in ?

One small remark re the article , the pages where you staircased the pictures are a bit difficult to read .
Wich text goes with what ? Maybe some outlines could improve that .


Patrick
Stragenmitsuko btw is just a relic from a time where everyone used a nickname . :)
 

Cogsy

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Cogsy, it may have been a post of yours some time back that talked about using only one pass, and I mentally marked it at the time as something I needed to consider. As always, theory is an excellent guide to experience, but ultimately, experience trumps theory!
I can't take the credit for the idea - here's the link to the page which describes the tool with the following pages covering the math, etc. to construct one (if you're interested to see how it compares with yours) LINK.
 

awake

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The article makes a lot of sense , especially if you already understand ( more or less ) what's goin on .
The trick for the calculations seems to be think in degrees instead of divisions like I did .
Then it's just basic trigonometry .
Thanks!

One small remark re the article , the pages where you staircased the pictures are a bit difficult to read .
Wich text goes with what ? Maybe some outlines could improve that .
Yep, I thought the same thing when I was re-reading this. Ultimately I plan to send it in to a magazine, with text and pictures separate, and they will do the layout. (It's a three-part series, and I need to finish part 3, so it hasn't been submitted yet.) I had done this version with pictures just so that I could get a sense of the overall length.
 

awake

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I can't take the credit for the idea - here's the link to the page which describes the tool with the following pages covering the math, etc. to construct one (if you're interested to see how it compares with yours) LINK.
Interesting. I actually wrote the article some years ago (haven't sent it in yet because I still need to finish the 3rd article in the 3-part series, and I just haven't had a chance to do it). I wonder if this site was already up before I wrote the article, or vice versa. In any case, there was no interaction between the site and the article, so it must be a case of great minds thinking alike ... I should say, great and modest minds. :)
 

Cogsy

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I first used the helicron site around 2013 from memory, 2014 at the very latest, so it's been around for a while.
 

awake

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Oi. I went back and looked at the dates on the files - apparently I finished writing this article in early April, 2014 ... but the actual making of the cutter and gears went back to February 2009. I guess I need to get on the stick and finish this set of articles!!
 

awake

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Part 13 of the build log, the ignition components:

ignition.png

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:

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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:

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Now it was simply a matter of setting the proper radius and rotating the RT to the proper angles to cut the curved slot, the curved bottom, the straight part of the right side, and the angled part of the right side:

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Continued below ...
 

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awake

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

I continued cutting around the periphery of the points mount, cutting the rounded top and down the left side:

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Then I positioned the cutter and began to cut out the middle hole:

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When that was finished, the part was complete:

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It fit perfectly on the bearing boss around which it rotates to set the timing:

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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:

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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

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Part 14 of the build log, the carburetor:

carburetor.png

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:

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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. Failing to do that meant scrapping yet another part and having to do the drilling again:

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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:

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Then I turned the round sections on each side:

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Making the needle control screw was easier than I had thought it might be, 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!) Here it is in the turning phase:

IMG_7909.JPG


Voila! A completed carburetor. 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.

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Next up is the gas tank ...
 

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awake

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Part 15 of the build log is the gas tank:

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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 and bored the inside to .875":

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There was also a bit of additional boring, called out in the first drawing (sheet 15) - 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:

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

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I also machined the threads for the screw-in end cap:

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Not shown - I then machined the bore and chamfers in this end cap, parted it off, and machine in the two holes in the outer face used to screw the end cap into place.

Part 15 continues below ...
 

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awake

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

Next I machined the inlet and outlet pieces, including machining a curve in the face so that it would fit snugly against the OD of the pipe:

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Not shown was machining of the fixed end cap - just a simple piece to fit into the non-threaded end of the pipe. But you can see the cap, along with all of the other pieces machined to this point, in the picture below:

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The next step was TIG-welding the fixed end cap in place. With a little clean up, that came out pretty well:

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By contrast, 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:

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I was hoping I would do better with the inlet pipe. I used my "third hand" to hold it in place on the pipe:

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I 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:

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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:

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So, how did it all work out 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:

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

Cogsy

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Interesting - I wasn't aware acrylic could stand up to gasoline. I machined a fairly complex part out of extruded acrylic rod a few months ago and polished it up so it was nice and optically clear, then hit it with a spray of isopropyl alcohol to remove any oil residue before I used it. Within the space of a few seconds it had turned into what looked like a piece of shattered safety glass in the shape of my part. As soon as I picked it up it fell into pieces. So now I'm very careful with what solvents I get near my acrylic!
 

awake

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According to this link, Cast vs Extruded Acrylic Tubing and Rod (which despite the title that shows up, should take you to a chart on chemical resistance), acrylic has good resistance at 68°F/20°C, but only fair at 122°F/50°C - so not the best ever, but good enough. With isopropyl alchohol, it drops to fair and not recommended, respectively.
 
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