Jitsie Sprockets Rip Off?

[guys]

How can a sprocket with less machining than ever before cost more than ever before,

http://www.trialsuk.co.uk/products/jitsie-recessed-enclosed-rear-sprocket

Utter nonsense.

That's how:

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

[shyted]

Go to talons web site and check out how many sprockets are cut at one time . Mass production has to be cost effective and , my view only here , even in Europe , they will be done to a price per 1000 etc . So to me ,lazer cut ,machine cut , pressed,it's all the same , once your tools are set you do a run.

It's not as though they're being made by a team of Elve's is it . The manufacture cost between the two types will be small in comparison by volume surely ? Not saying i know , just judging by how thing's go here.

It's the middle men who put the price up before it comes to us . Or is it just trend?

Edited April 21, 2014 by shyted

[eddie_lejeune]

That's how:

completly wrong, there is no way one of those is machined complete in 5 minutes when you take loading, unloading deburring etc

They could be machined complete on a turn mill centre.

[guys]

But the Jitsie sprocket isn't made that way is it.

Your question was:

"Jitsie Sprockets Rip Off?"

My answer: No I don't think so.

your second statement was::

"How can a sprocket with less machining than ever before cost more than ever before,

http://www.trialsuk....d-rear-sprocket

Utter nonsense."

My answer: The JITSIE sprocket isn't made with less machining

I'm sorry I wasn't clear enough.

Of course you can get sprockets made in a Chinese sweat shop or with a high speed top of the range machine, that are cheaper, but that wasn't your original question.

[eddie_lejeune]

My answer: The JITSIE sprocket isn't made with less machining

it is easier to machine the Jitsie sprocket than the standard with the the cut outs the whole way through.

[sawtooth]

A. Adding another machining operation to a component will obviously add more cost, the place I work at charges £40-£50 per hour for each CNC machine to be running.

B. I do know someone who has had 2 fingers sliced off when they got caught in the spaces on the rear sprocket. And I REALLY don't want that to happen to me so the extra cost on top of the cost of a normal sprocket is worth it's weight in Gold.

And to those saying that the solid sprocket has less machining, you're wrong. The old style sprocket would have had those shapes pressed out, water jetted or lasered, NOT machined. Machining would have been an expensive way of mass producing that part.

Edited November 16, 2014 by sawtooth