I think that is what's done to create what's called a lower Turn motor. I believe the armature space is always filled with wire. - Terry
Ford 300 Inline Six
- Thread starter mayhugh1
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Yeah, I agree my paltry 4:1 rear ratio is a big part of my problem. I can't get the motor close enough to the ring gear for a smaller pinion and higher ratio. An additional gearbox is really needed but I'll want it inside the bell housing which makes the design difficult. Also, by the time I add a couple more gear meshes, a one-way driving clutch becomes a necessity, and then I have something else to stuff into the bell housing. - Terry
How about putting the starter in the transmission through a 1 way bearing, as in ,shrink your drill starter
inside the soon to be cnc'd transmission?
inside the soon to be cnc'd transmission?
Hmm ... I wonder if the motor and planetary out of a cheap cordless drill (e.g., Harbor Freight or equivalent) would be small enough but powerful enough for the purpose?
It's a relay to handle the motor current.
Arild
Member
Yes, correct, thicker wire result in less turn tu fill up the space. I've done this on R/C car-motor, and it make a huge change in torque!
Bentwings
Well-Known Member
also race cars use a drawn or spun round bell housing to protect against clutch explosions so possibly you could simulate this out of bar stock aluminum technically those aren’t race legal but would look great on your motor. If you are creative you could make a starter pocket just like the full size cnc would be crazy cool otherwise I’d probably weld or bolt the thing in . We used to rewind slot car motors like noted there were a few real scale smoky melt downs. Otherwise read up on stepper motor conversions. I have at least half a dozen I’ll drive with generated power from my new steamer when it’s operational stepper can have a lot of torque for their size you may need a driver to use an un modified one . I’m really new to them so I have to side step here as I’m on unstable ground LOL. Motor is great
My final candidate for a 390 ring gear starter was a Nichibo MD5-2445. This 12 volt motor was selected from Jameco's published inventory of 66 motors with comprehensive specs. Although its speed/torque data wasn't encouraging, I was curious to see how it performance would stack up against the 7.5 volt RC aftermarket motors recently tested. It was worth trying since the smaller Ford might be happy with a lower cranking rpm and not require the entire 50 watts in my original starter requirements. Unfortunately, testing showed it was considerably less powerful.
Although they fell short of my requirements, the RC aftermarket motors did appear to deliver more power than specified for same size generic motors. I'd hoped to get additional short term performance from them using 12 volts but ended up damaging their commutators after only a few minutes at moderate loads.
With only a 4:1 ring gear reducer, cranking loads will drag the operating point of a 390 motor into territory where internal dissipation literally kills it. Additional gear reduction is needed so the required torque is available with the motor running at a more efficient operating point. This doesn't mean though that it won't have to deliver the required 50 watts of mechanical power, and this doesn't seem feasible for a 390 brushed motor. If the RC motors had been able to handle 12 volts, additional off-board gear reduction might have gotten them near the ballpark.
I considered hiding a 550 gear motor inside a faux transmission housing as suggested by Propclock, but it also wound up well outside the scaled envelope of the engine. (A quarter scale engine would be much easier to work with.) I finally gave up and decided to drill-start the engine after all.
So, a bell housing for a faux starter was machined. I started with George's design but modified it to enclose the entire flywheel. Construction began with squaring up a 6061 workpiece. The bell housing's interior was machined first and included drilling and temporary tapping the housing's mounting bolt holes. The interior was temporarily packed with clay for vibration control and then mounted to a fixture plate. With full access to the workpiece's outside surface, the bell housing's exterior could be machined. A final operation machined the clutch fork opening in the side of the housing. Total machining time was about 6 hours. Finally, the entire bell housing was bead blasted to simulate the surface of an aluminum casting. A machined cover plate and faux starter motor will wrap up this portion of the build. - Terry
Although they fell short of my requirements, the RC aftermarket motors did appear to deliver more power than specified for same size generic motors. I'd hoped to get additional short term performance from them using 12 volts but ended up damaging their commutators after only a few minutes at moderate loads.
With only a 4:1 ring gear reducer, cranking loads will drag the operating point of a 390 motor into territory where internal dissipation literally kills it. Additional gear reduction is needed so the required torque is available with the motor running at a more efficient operating point. This doesn't mean though that it won't have to deliver the required 50 watts of mechanical power, and this doesn't seem feasible for a 390 brushed motor. If the RC motors had been able to handle 12 volts, additional off-board gear reduction might have gotten them near the ballpark.
I considered hiding a 550 gear motor inside a faux transmission housing as suggested by Propclock, but it also wound up well outside the scaled envelope of the engine. (A quarter scale engine would be much easier to work with.) I finally gave up and decided to drill-start the engine after all.
So, a bell housing for a faux starter was machined. I started with George's design but modified it to enclose the entire flywheel. Construction began with squaring up a 6061 workpiece. The bell housing's interior was machined first and included drilling and temporary tapping the housing's mounting bolt holes. The interior was temporarily packed with clay for vibration control and then mounted to a fixture plate. With full access to the workpiece's outside surface, the bell housing's exterior could be machined. A final operation machined the clutch fork opening in the side of the housing. Total machining time was about 6 hours. Finally, the entire bell housing was bead blasted to simulate the surface of an aluminum casting. A machined cover plate and faux starter motor will wrap up this portion of the build. - Terry
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Beautiful ! I need a bead blaster. How do you mask the flat machined parts as in the webs?
Always inspiring.
Always inspiring.
Thanks. They weren't masked - just sanded after bead blasting. - Terry
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Thanks that makes sense.
Beautiful as always Terry. How did you index the part when you flipped it over from the inside machining to the outside machining? Did you simply touch off the the edges of the squared off workpiece?
Greg
Greg
Thanks. The holes in the fixture plate were drilled using the same code that drilled the mounting holes in the bell housing during its internal machining. The center hole through the housing was done at the same time. Once the part was flipped and mounted to the plate, the center through hole was used to reference the part for the outside machining. - Terry
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I saw George's engine again at CF; it's a lot smaller than I had thought when following this build.
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I have been following this build from the beginning since I do love the old 300 Fords. As it happens I have a complete 300 EFI motor and drive train sitting next to me. The typical ring gear count would be 164 tooth with a 9 tooth starter pinion giving a ratio of 18.2 to 1.
When I first started this project and before doing any math, I was assuming I'd have a 20:1 ring gear reduction available to me. It wasn't until I started designing actual parts that I realized that with a 2" diameter flywheel, the pinion would have to be some .1" in diameter to get that much reduction. By the time all the other real world issues were accounted for I was left with a paltry 4:1, and I knew I was in trouble. - Terry
I don't suppose your flywheel is thick enough to fit a planetary gear inside it, arranged to drive the ring gear at 4 or 5 times the flywheel speed, with a roller clutch in the sun wheel, so that the whole lot runs at crank speed when not driven by the starter?
Peter,
It is hard to realize how small this engine really is. Look back at the last batch of pictures Terry put up. In one he has a one/two/three block clamped to the work piece for vibration dampening. The one/two/three block looks huge next to the bell housing. I can't imagine getting anything inside of it but a flywheel.
It is hard to realize how small this engine really is. Look back at the last batch of pictures Terry put up. In one he has a one/two/three block clamped to the work piece for vibration dampening. The one/two/three block looks huge next to the bell housing. I can't imagine getting anything inside of it but a flywheel.
That's pretty clever. I need to think about it. The current flywheel isn't thick enough, but a new one could be made thick enough. - Terry
