Another B.T.R. Build.......

You will be happy with that adjustment trust me. I sure like that blueprint for a frame. On my last two builds I just winged it but it turned out ok. I may use your design for the next one if you don't mind...ccc
 
culvercityclassic said:
You will be happy with that adjustment trust me. I sure like that blueprint for a frame. On my last two builds I just winged it but it turned out ok. I may use your design for the next one if you don't mind...ccc
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Go for it, don't forget I'm using ~27" tires so you might want to scale it differently if you use something else.
 
I've got a question for anyone with experience with comet (or the like) cvt's, I'd like to mount the driven clutch through the bottom bracket area where the pedals would normally be but I'd also like to mount the pedal shaft there. What I'd like to know is if there is enough material in the clutch to ream out the center and press pulleys in (where the keyed shaft would normally be) or maybe I can mis match a 3/4" driver clutch that will fit my engine with a different driven clutch that will have a larger bore? Any suggestions wold greatly be appreciated, I might post the question in the hub,gear section too.
 
I think that could easily be done with a oversize bore driven pulley. You might consider something like a hollow 1" thickwall steel tube shaft in the BB to carry a 1" bore pully and output sprocket.
then use bronze bushings internaly to save diameter room, and a smaller shaft inside the hollow one to carry the pedal crank and sprocket.
 
Awesome Wayne I have never had a comet so that is good to know. But how about a belt they have to be a sertin length to work just right don't they?.............Curt
 
curtisfox said:
Awesome Wayne I have never had a comet so that is good to know. But how about a belt they have to be a sertin length to work just right don't they?.............Curt
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Yes they need to be the correct length to work properly and they come in many lengths for the various size pulleys. Shouldn't be a prob figuring it out as the have diagrams for them online.
 
Thanks for the ideas, so it looks like I'd weld the driven unit to the outer shaft if I did this the same way as Goldy did on the merkel? The driven pulley is just steel right? If this is the case than I don't even need to go with an oversized driven pulley as I can just go to 3/4" with a 1/2" pedal shaft inside...


1 1 each 89955K59 4130 Alloy Steel Aircraft-Grade Round Tube .750" OD, .065" Wall Thickness, 6' Length

2 1 each 6061K431 Hardened Precision Steel Shaft 1/2" Diameter, 14" Length

3 2 each 2938T14 SAE 863 Bronze Flanged-Sleeve Bearing for 1/2" Shaft Dia, 5/8" OD X 1" L X 7/8" Flange OD
 
JohnThomas Sorrels said:
Thanks for the ideas, so it looks like I'd weld the driven unit to the outer shaft if I did this the same way as Goldy did on the merkel? The driven pulley is just steel right? If this is the case than I don't even need to go with an oversized driven pulley as I can just go to 3/4" with a 1/2" pedal shaft inside...


1 1 each 89955K59 4130 Alloy Steel Aircraft-Grade Round Tube .750" OD, .065" Wall Thickness, 6' Length

2 1 each 6061K431 Hardened Precision Steel Shaft 1/2" Diameter, 14" Length

3 2 each 2938T14 SAE 863 Bronze Flanged-Sleeve Bearing for 1/2" Shaft Dia, 5/8" OD X 1" L X 7/8" Flange OD
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Yes, the driven pulley is steel.......sounds like that will work just fine. If ya don't mind me asking John, where did you find the hardened precision steel shaft? I'm thinkin' that metal supplier in Kearny Mesa?

Thanks,
scotto-
 
That all is from Mcmaster-Carr, they're great for little things, Industrial Metals is maybe the place you are referring to? They have pretty good prices and a wide range of exotics and precuts but if you are looking for steel, aluminum, etc. I've found Competitive Metals in El Cajon has the best prices around lately.
 
Thanks John, yeah Industial Metal was the place I was thinkin'.....and thanks for the tip on El Cajon. Do you know off the top of your head if Mcmaster-Carr has the precision hardened shaft with the keyway already cut?

dnut
 
What I need is "hardened" and in the sense of hard and brittle kind of hardened. The 5/8" keyed shaft I'm using now lasts only 20 hours and that's keeping set screws tight as well as possible on the pillow blocks and the sprockets. Is this shaft truly "hardened" to your knowledge?
 
Try searching for Drill blank shaft, it is flame harding tool steel You quench in oil after machining the keyway slot or threading if needed...gets pretty hard after quench/file just skids on it!....I used it to make a back shaft on an old lathe works better than ever....Tigmaster....
 
Fully Keyed Drive Shafts

Steel Shafts—Made of 1045 steel, these shafts are stronger than stainless steel and aluminum shafts but are less corrosion resistant. Rockwell hardness is B95.

Fully Keyed Precision Drive Shafts with Certification

Shafts are 1045 steel. Hardness is Rockwell C14-C28. Straightness tolerance is 0.003" per foot. Ends are beveled.
 
Finally ordering some tubing, 1" and 3/4" .120 wall Dom, I layed out the frame on the floor to help with making the bends, will hopefully see some real progress in the coming weeks...

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Got the metal, before I start on the frame I wanted to get the fork squared away since it's the most complicated part. This way I can still tweak head tube angle and geometry if the fork ends up a little different than on paper.

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