BrokenBiker
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I will check when I'm home but I think my duplicates are 73 and below
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BrokenBiker
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Just had a look, no 127t spare sorry
BrokenBiker
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One thing I wanted ask...In the gear train the 120 tooth idler gear has its own sort of hub thats its bolted to with a bearing that rides on the stud but the 100/50 gears don't fit on that hub and from the chartn
it looks like I'd need them to compound the gears for certain pitches.
The gears themselves have a 3/4 bore but the stud on the idler is 3/8 straight shaft...is there a part I'm missing to key those gears together and let them run on the 3/8 stud, or am I going to have to make something? I've got decent steel and some brass here so could make a sleeve for a keyed bushing to run on so they run freely if needed
BrokenBiker
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Ah fair enough
Yes, If they're compound gears you will need a 3/4" drive going through them.
BrokenBiker
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Assumed so...chart shows a 120 for most pitches which is the standard gear on the hub, but for a few metric pitches shows 100 - 50 for the same position. I'll whip up a steel sleeve with correct spacing that will tighten down to the shaft and then a brass bushing with a keyway to run on the sleeve and key the gears together
Agroshield
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When you use a compound gear, the gears before it and the gears after it are on different planes when you look at it sideways (they are stacked). So on one gear you need provision to move it fore and aft. Hence you might also need to make a thick washer/spacer to achieve this stacking if there is not one already there.
BrokenBiker
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I have much smaller gears than the ones required so can use those as spacers.
Just so I know I'm reading this right, for the 2.0mm pitch for instance, the 50 is driven by Gear A (60 tooth) the 100 is keyed to the 50 on the same shaft, then the 100 drives gear D (127 tooth)
Pete.
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On that chart above where the 120 appears on it's own in the box it is just an idler. The tooth count is unimportant.
Where the box has 50/100 it's a compound which will provide 1:2 ratio in the gear train.
Here's a handy rule to remember:
If a gear meshes with one other gear, it affects the overall ratio. If it meshes with 2 other gears it does not.
Where the box has 50/100 it's a compound which will provide 1:2 ratio in the gear train.
Here's a handy rule to remember:
If a gear meshes with one other gear, it affects the overall ratio. If it meshes with 2 other gears it does not.
BrokenBiker
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Cheers for that. The 120 idler is used the majority of the time and is mounted to a hub with 4 screws...the 100 and 50 i have aren't plain 3/4 bore with a 1/8 keyway...I will make a sleeve and bushing so it all sits right and runs smoothly
Pete.
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Yep and you set the gearbox for 12tpi.
Whenever I set up a geartrain for screw cutting I make a pass with a magic marker drawing the threads first and then check the pitch with a pitch gauge. It's saved me so many muck-ups
BrokenBiker
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I always check with the pitch gauge first. Just good to know I'm reading it right regarding correct gear set up.
