March 23, 201412 yr I was riding gear right foot, back brake left foot today - no problem. It's when I change back to standard I have problems. Edited March 23, 201412 yr by b40rt
April 16, 201412 yr Back to the sprocket. Making the sprocket stronger just means you break the hub instead of bending the sprocket ?
April 19, 201412 yr The fact still remains that stamping a hole is a lot faster and cheaper than milling a recess How many sprockets available for trials bikes have you seen stamped out on a press, Talon as used standard by some manufacturers are fully machined & knowing how they're made they won't take long to turn a full sheet of alloy into multiple sprockets
April 19, 201412 yr Alright then, machining a recess takes longer than machining the same shape right through. It won't take long, but will take longer which is my point, I thought that was obvious by now...
April 20, 201412 yr Author Alright then, machining a recess takes longer than machining the same shape right through. It won't take long, but will take longer which is my point, I thought that was obvious by now... It wont take longer, it will be quicker to machine a recess than right through or were you being sarcastic?
April 20, 201412 yr I can see in this picture that it takes one pas to go around the recess to make a hole and about 3 to make a recess. And if you take in to account that in most sprockets that I have seen, the holes are made either by lazer, water jet or stamping, I think it takes more work to make a recess. As I am always prepared to learn more about my trade, I would like to know how you come to your conclusions. I hope the didn't offend anyone, lost my patience for a moment
April 20, 201412 yr Author I can see in this picture that it takes one pas to go around the recess to make a hole and about 3 to make a recess. And if you take in to account that in most sprockets that I have seen, the holes are made either by lazer, water jet or stamping, I think it takes more work to make a recess. No
April 20, 201412 yr Author If you are machining one of those triangular shaped pockets through the sprocket it will take longer to do it than it will to machine to a depth. Looking at the machining pattern inside each of the recesses they are using a small cutter and taking small cuts at a high speed and feed, to go right through would take a different approach where you would need to leave a membrane that would need snapped out and then deburred.
April 20, 201412 yr Author Also as far as punching sprockets out goes, I would like to see that in action. They would surely need some sort of second opertion on them to machine the tapers
April 20, 201412 yr Why would you machine holes when it's possible to laser them? And none of the sprockets i have, have a tapered edge or are even deburred at the holes, a laser cutter leaves a scharp edge but it's not so sharp that it would cut your skin easely, (although it would be better when they did have a chamfer for safety reasons) But nuff said, if you think it's cheaper so be it.
April 20, 201412 yr Why not just drill the mounting holes and cut the teeth and the little chamfer thingies at the teeth and call it good? Solid piece, no recesses, no big holes at the recess spots. Just a flat sprocket, and then put a sticker on it with a kick ass design. When making the sprocket the entire piece of alluminum is purchased, whether it is turned into little shavings or not. Less time machining = cheaper Stickers = cheap(ish) in bulk.
April 20, 201412 yr Author Why would you machine holes when it's possible to laser them? And none of the sprockets i have, have a tapered edge or are even deburred at the holes, a laser cutter leaves a scharp edge but it's not so sharp that it would cut your skin easely, (although it would be better when they did have a chamfer for safety reasons) But nuff said, if you think it's cheaper so be it. Im talking about the chamfer around the teeth, sorry I didnt explain that correctly.
April 21, 201412 yr I find these sprockets interesting with the cleaning grooves not on every tooth like most do have From my experience on cnc machining I can give you a quick run down of how they are done. Assuming the maker has multiple machines which a decent production shop will then a sheet will be cut into basic pieces, either squares or strips then transferred to the first machine which will drill the holes, machine the recesses for the bolts & cut the centre out, the recessed pattern can also be done at the same time which appears to have been done with a chamfer cutter, cleaning grooves done at the same time . Machining time with a modern high speed machine would be in the region of 1 minute Next the part machined blanks are transferred to the next machine on a sub-plate which locates & holds the parts by the bolt holes & machined centre, from here the taper at the tip of the teeth is machined & then the outside & teeth profile done in 1 pass, using a strip rather than separate blanks will cut done on tool changes which speeds up machining time Final machine change will have each sprocket mounted on a sub plate using the bolt recesses as location to finish off the chamfering of the back, clamps will need moving between doing the centre & bolt holes as 1 operation with the teeth chamfer as a second operation Total machining time would be around 5 minutes with each sprocket being exactly the same which cannot be said the same as far as a pressing goes, lasers & waterjet cutters normally have a sharp start & finish point which is undesirable for accurate fit on hubs & will produce a tight spot in the chain run. The best part of using the cnc's for teeth etc is that by changing which program is used is number of teeth changes instantly, centres etc are the same story with each variation of centre & bolt position being saved as a program with the manufacturers name being it's title
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