Ford 300 Inline Six

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mayhugh1

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I wanted to wind down for the Thanksgiving holiday by machining some standalone parts that I could fully complete. The first of these was the alternator. My camera's SD card failed and took the alternator's construction photos along with it, and so I staged a photo showing its disassembled parts. The aluminum housing was bead blasted to simulate the surface finish on the full-size casting. The armature spins in a set of inner/outer ball bearings. Its cooling fins were Alodine'd to simulate a period cad-plated finish. The steel mounting brackets turned out to be the trickiest pieces to machine. I thought I had finished the head long ago, but one last drilled/tapped hole was needed for the upper bracket. Unfortunately, the alternator's output voltage and current turned out much too low to charge the battery, and so the alternator's only real function will be to tension the fan belt.

Another of these parts was the mechanical fuel pump that I also 'cad plated'. Since I normally run electric fuel pumps on my model engines, its sole function will be a block-off plate.

The last pieces machined before Thanksgiving were a spin-on oil filter and the dip stick and dip stick tube. The filter was Gun Kote'd white to match the Motorcraft filter that was stock on the engine. - Terry

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Sparkplug

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Hi. I've come late to this particular feast, I'm only a few weeks into my build, I have a basic question regarding the two helical gears for the distributor drive, is there a particular reason why they have to be a14 tooth gear? Surely if the gears are 1:1 ratio they could be larger, say 10 teeth as these are readily available.
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gbritnell

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Hi Sparkplug,
The gears have to be that size so they will pass through the cam bores.
 

Sparkplug

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Hi. George.
That wasn't what I was asking, it was the number of teeth, the o/d of the 10 tooth gear is 8mm. So making the bore 8mm rather than 5/16th should be fine and as the ratio is 1:1they should work okay, I was only making sure there wasn't some reason for 14 teeth that I was unaware of.
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Charles Lamont

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The involute tooth profile for gears with few teeth (less than 12, say) gets nasty, with a lot of undercut that weakens the teeth, and, I should think, would make the skew gears tricky to cut. This can sometimes be mitigated by measures such as addendum modification but I don't think that would be applicable in this case. A few more teeth, 14 for example, makes the tooth profile more sensible and makes for a smoother drive. On the other hand, bigger teeth (larger module or smaller DP) are stronger. In a fixed, limited space, the design choices will be a compromise. Do you hold something against 14-toothed gears?
 
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gbritnell

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The outside diameter of the gear is based on the diametral pitch of the gear. The D.P. is 72 so the calculated O.D. is .303. Are you asking if a 10 tooth MOD. gear would work? A 10 tooth, 72 D.P. gear won't work. The cam bore could be changed to M8 (.315) but I don't see how that relates to your gear question.
 

Sparkplug

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The involute tooth profile for gears with few teeth (less than 12, say) gets nasty, with a lot of undercut that weakens the teeth, and, I should think, would make the skew gears tricky to cut. This can sometimes be mitigated by measures such as addendum modification but I don't think that would be applicable in this case. A few more teeth, 14 for example, makes the tooth profile more sensible and makes for a smoother drive. On the other hand, bigger teeth (larger module of smaller DP) are stronger. In a fixed, limited space, the design choices will be a compromise. Do you hold something against 14-toothed gears?
I've nothing at all against 14 tooth gears, I'm sure the vast majority lead blameless lives, but as I've only got a very modestly equipped workshop producing them would be nigh on impossible. But I can source two 8mm diameter x 10 tooth 45 degree helical gears from Germany for 16 euros, so all I wanted to find out was the reason that 14 tooth gears were specified
 

mayhugh1

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The stock bore for the cam bearings is .312" which was probably selected so a standard reamer could be used. There's enough excess block material around it so you could increase that to .320" or so (and the cam bearings accordingly) so you could use the commercial gear set you found. So long as the tooth ratio is 1:1 I would think a 10 tooth gear set would work. - Terry
 
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Sparkplug

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The stock bore for the cam bearings is .312" which was probably selected so a standard reamer could be used. There's enough excess block material around it so you could increase that to .320" or so (and the cam bearings accordingly) so you could use the commercial gear set you found. So long as the tooth ratio is 1:1 any number of terth will work. - Terry
Thanks for the vote of confidence Terry, I can't see any reason why it won't work. I suspect few engineers don't have a cnc with a forth axis as I don't know of any other way, except for a dividing head driven by a gear train from the table feed to produce these gears, so have no other choice than to use commercially available gears.
 

mayhugh1

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Thanks for the vote of confidence Terry, I can't see any reason why it won't work. I suspect few engineers don't have a cnc with a forth axis as I don't know of any other way, except for a dividing head driven by a gear train from the table feed to produce these gears, so have no other choice than to use commercially available gears.
CNC isn't actually required. Here's how George did it using a Chuck Fellows fixture:


You can search this forum for Chuck's work. - Terry
 
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Sparkplug

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CNC isn't actually required. Here's how George did it using a Chuck Fellows fixture:


You can search this forum for Chuck's work. - Terry
Ingenious, I take my hat off to people who think out of the box. But, on balance the choice between the time and effort in making the fixture and with no real guarantee that my efforts would be successful versus a set of precision gears for 18 euros, although a tough one, I think I'll go with German gears. But thanks for posting the video, you truly do learn something new every day with this game!
 

gbritnell

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Do a search for helical gear cutting lathe attachment. It will come up under Chuck Fellows posting
 

Basil

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Very impressive! Nice to know I can make a helical gear when the need arises.👍
 

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