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mayhugh1

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I've enjoyed working on the magneto, and despite my efforts to stretch out its construction, it's sadly coming to an end. Like the water pump, it's one of the few sub-assemblies that I'll be able to check off as fully tested before the engine is completed.

One of the photos shows its internals just before being installed inside the body. The thickness of the spacer behind the gear on the input shaft was trial/error trimmed to set the pinion depth for smooth operation and nearly zero rotor backlash. The end of the magneto's 3/16" input shaft was machined with the male half of an Oldham coupler. It meshes with the female half machined into the end of the 1/4" shaft sticking out from the drive block.

The white Delrin rotor has a relatively thick brass tip electrode and a .003" running gap between it and the tower electrodes. A flat phosphor bronze spring provides positive electrical contact between it and the high voltage button in the magneto's cover. An 0-80 flat head screw holds the pieces in place inside a close fitting slot in the rotor. The rotor is a snug fit on its shaft with a 2-56 grub screw adding insurance against slippage. A witness mark engraved on the top flange of the magneto's body will be used during final timing adjustments to locate the rotor directly under the #1 tower electrode.

Ron's last post resonated with me. Although I don't plan running above the full-size engine's 6k rpm rating, I'm having second thoughts about the current lack of timing control especially during starting. Even with a modest 10 deg fixed advance, I get occasional attention-grabbing kickbacks when starting my Knucklehead. Not having been through Ron's original development work, I'm not yet as comfortable as he is with the engine's starting system whose teething pains included the nose of a crankshaft that I don't want to machine more than once.

Ron mentioned that his engine's timing is controlled with a board purchased from David Bowes. David designed and sold a PIC-based controller for his EVIC-111 engine published in the final issues of Strictly IC magazine during 2001-2002. As expected, after contacting him, I learned these boards are no longer available although his website is still here:

http://rbowes1.11net.com/dbowes/index.htm

Hardening the controller electronics against ignition EMI was probably no easy feat, and I'm impressed Ron's board is still working after all these years. Although it would be an interesting challenge to design an electronic advance, my last minute decision was to simply add a manual control to the magneto.

This change involved scrapping the already completed end plate and replacing it with one that can manually rotate the Hall sensor 20 (distributor) degrees. This will allow retarding the timing during starting but provide up to 40 degrees (crankshaft) advance while running. The photos show the new advance-able end plate that will now house the Hall device. Since this rather complex part required some involved fixturing, I made several spares while still set up.

I wasn't confident in the friction between the Delrin body and the new advance plate being able to maintain its setting under vibration, and so I added a fixed metal back-up plate between the two. The plate was machined while sandwiched between a couple pieces of sacrificial aluminum, and so there was no effort involved in adding a couple extra pieces to the stack for experiments. The photo shows the piece of .005" thick stainless shim rolled into a beveled washer that I finally used. Although the advance arm can later be controlled by the throttle positioner, an obtrusive non-original linkage would be required.

I didn't do myself any favors with the tiny space that I left for soldering the connections to the sensor. If I were doing it over, I'd make this portion of the arm a little longer. After coming up with a soldering fixture, I installed sensors and cables in all the plates I made and backfilled them with JB-Weld.

The Oldham coupler between the magneto and the gear tower's right angle drive block is concealed by a faux aluminum housing that contains a pair of trigger magnets. Three setscrews lock this housing to the drive block's shaft in order to fix the ignition timing to the engine's camshaft. Preliminary testing showed the magnets triggering the sensor as expected, and so the next step will be to come up with the ignition module so the entire system can be finally tested with actual spark plugs. - Terry


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petertha

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I've had to marry quite a few awkward wiring harnesses together for RC work.

For things that need to be soldered, my go to method is a small plate of something heat resistant like glass & if necessary 'shim' supports from arborite scrap. And Kapton tape. You can usually get everything pre-positioned & aligned so your only remaining task is applying heat & solder to the joint. The Kapton wont burn or let go under the heat.

For joints that see any kind of vibration or hard bends or torturous routing that might strain solder joints, I've become fond of these pure silver crimp tubes. They sell a special plier & its foolishly easy to make crisp strong joints. The resistance is as good or better than solder.
https://www.amazon.ca/Beadalon-Variety-Silver-Plated-600-Piece/dp/B001FD3BAM/ref=sr_1_1?keywords=beadalon+silver+crimp+tubes&qid=1583118989&sr=8-1

Sometimes you just cant get teeny sections of heat shrink tubing into tightly constrained wiring bundles so I like this stuff. Paint it on the exposed conductors with a detail brush & it makes a nice insulation layer.
https://www.amazon.ca/Permatex-85120-Liquid-Electrical-Tape/dp/B003ERU04W/ref=sr_1_5?keywords=liquid+electrical+tape&qid=1583119638&sr=8-5
 

tornitore45

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Is there a reason why you twisted the red and black wires?
Is to match the already defined connections sequence at the end not shown?
What is the white piece under the Hall device?
 

RonC9876

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Terry: I love your advance set up. I designed a mechanical advance for my Sealion using fly weights working against a garter spring . It causes the magnet disc to rotate in the advance direction as the rpm increases much in the same way as the advance used to work on older model cars. It works very well, but it advances very quickly and gives the advance very suddenly. The electronic module advances the timing in several steps and does it smoothly. Great job on your design as usual.
 

mayhugh1

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Is there a reason why you twisted the red and black wires?
Is to match the already defined connections sequence at the end not shown?
What is the white piece under the Hall device?
Mauro,
I had to twist two of the wires to keep the color coding consistent with my other projects: red=Vcc, black=gnd, and white=signal. I can usually buy a 32 AWG version of the cable that more easily handles the twist, but the local Hobbytown didn't have any in stock and I couldn't find any on Amazon. The white piece is a sliver of Teflon used to protect the wood soldering fixture. It wasn't part of the final assembly. I wasn't entirely happy with the final parts, but they passed my 'tug' tests still working with no shorts to the housing, and so we'll see. - Terry
 
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Ghosty

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mayhugh1

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petertha

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30 & 32 AWG here in various flavors. He is my go-to crack dealer for good quality plugs, pins, crimp tool...).
http://www.hansenhobbies.com/products/connectors/wire/servo_ec/
Check his write-ups on RC wires, they are not all created equal.

Strangely no AWG specified but I can attest to good resistance in long lengths. Its very thin & supple. We only really get fussy with the fine stuff when gram counting is the issue.
https://www.hyperflight.co.uk/products.asp?code=ULW-TWISTED-CABLE&name=ultra-light-servo-twisted-extension-cable-3-7-g-m
 

mayhugh1

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30 & 32 AWG here in various flavors. He is my go-to crack dealer for good quality plugs, pins, crimp tool...).
http://www.hansenhobbies.com/products/connectors/wire/servo_ec/
Check his write-ups on RC wires, they are not all created equal.

Strangely no AWG specified but I can attest to good resistance in long lengths. Its very thin & supple. We only really get fussy with the fine stuff when gram counting is the issue.
https://www.hyperflight.co.uk/products.asp?code=ULW-TWISTED-CABLE&name=ultra-light-servo-twisted-extension-cable-3-7-g-m
Thanks for the tip.
I ordered some from Hansenhobbies.
Terry
 

gbritnell

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Hi Terry,
The engine is coming along great! Like you I had been using 32 gauge Futaba wire for my Hall hookups but the supply seemed to dry up. I then ordered 32 ga. wire (individual lengths) white, black and red wire from Mcmaster-Carr. I twist my wires together so it actually made it easier to do. I will order some from Hansen and see how it works.
As far as ignition timing I have been pretty lucky. My 302 is set at 30-35 degrees and it starts without kickback and will go from idle (about 1200 rpm) to full rev very nicely. I can bring the idle down by retarding the ignition and adjusting the carb but I think it's more a case of the scale flywheel not having enough inertia.
My V-twin has ungodly compression but has never kicked back. The timing on that is about 20 degrees BTDC. I have no way of changing the timing while the engine is running so I don't know if the overall operating characteristics would be better or worse.
My inline 4 cylinder engine has linkage hooked from the carb to the distributor and the initial timing is about 10-15 degrees. At full song the timing goes to about 30 degrees.
My Holt is set to 15 degrees and the points are on a moveable base so I can adjust the timing while running. Curiously on the Holt timing doesn't make much difference other than change the sound the engine makes. That engine isn't meant to be a fast revver so it's not important.
I have seen Ron's engine run many times and it's very impressive (loud also) I can't wait to see how yours does.
gbritnell
 

petertha

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Just curious what makes 32 AWG wire more desirable in this application?
 

ddmckee54

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Just a thought, but 30 AWG grey flat cables are readily available up to 40 conductors. Strip off as many conductors as you need and mark the conductor on one side with an indelible marker. As long as you consistently number the conductors starting with the marked conductor, you can build your own custom flat cables in almost any width.

Sure the colored cables look pretty, but you can rob grey flat cables out of most defunct PC's.

Don
 

mayhugh1

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Just curious what makes 32 AWG wire more desirable in this application?
The smaller diameter wire is more in scale with the rest of the engine, and it can be potted for strain relief in smaller cavities in smaller parts. -Terry
 

mayhugh1

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As with most of the other engines I've built, an electric fuel pump will eventually supply gasoline to the carburetors. In this case, the pump will probably be hidden in a faux fuel cell on the floor of the engine stand. Since an electric starter isn't being used, I'll be able to get away with a 6V battery and no dc/dc converters.

The enclosure for the 'Engine Control Module' was machined from a block of gray PVC. Although there's no wasted space inside, it came out much larger than I would have liked. Rather than trying to hide it, I dressed up its exterior and will leave it in plain sight on the display stand. It was bead blasted to remove its shiny exterior surface in order to make it look like a pot metal casting.

A Magnum CDI from S/S Machine provides the high voltage for the ignition. A simple board of my own design located between it and the Hall sensor provides a trigger indicator that doesn't require the CDI to be powered up. It provides a convenient timing indicator during setup and troubleshooting that doesn't require hassling with the high voltage. The module receives the battery voltage and Hall trigger signal and outputs the spark plug voltages to the magneto and a manually controlled dc voltage to the fuel pump. I also added provision for the possibility of an electric radiator fan. After verifying the various controller functions, the next step will be to cobble up a fixture to run the magneto at speed so the ignition's performance can be tested with spark plug loads. - Terry

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dsage

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Nice work. Everything hiding in plain view. I like it.
 

awake

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That looks so good - hard to believe it is milled plastic rather than cast aluminum!
 
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