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[Rob Spence]

I don't see how this could be done.  I could see it with a flanged pulley without teeth but not for a timing belt pulley. 

To be clear.  I agree, timing belt pulleys should and usually do have two flanges, and I think they should.  I am only saying that the mold is a bit simpler if you cheat and make it with one flange.  Not a good design.

Looking at the pics of the fader gear, in normal use, gravity might help a little to keep the belt near the flange but what struck me was that with only the one flange, it was then possible to install the belt without slack adjusters. With two flanges, some force would be needed (or belt stretching) to install it.


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[Frank DeWitt]

Looking at the pics of the fader gear, in normal use, gravity might help a little to keep the belt near the flange but what struck me was that with only the one flange, it was then possible to install the belt without slack adjusters. With two flanges, some force would be needed (or belt stretching) to install it.
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Often the non driving pulley has no flanges, and that appears to be the case here.  The belt would be placed over the flanged pulley first, and then over the pulley at the other end

[Per Sovik]

Anyway you guys, the design is of course not flangeless, it is simply a two part design with a single flange pulley sitting on top of a washer that performs the function of the second flange. This is not an uncommon design. The forces working on the pulley (or the variation in product consistency or raw material consistency) was obviously underestimated to some extent, thus there has been some instances of the pulley slipping off the axle. The pulley has been secured with a spot of glue/locktite for a long time now, and applying it to every pulley is as far as I know part of the procedure when a board is in for repair.
Set screws, as JR comments, comes with their own set of issues, they are extra work, and not least they come loose and become more of a problem than a solution unless the set screw is properly secured, which of course is more work again.

Torque/current/resistance-sensing is of course part of a lot of chips and circuitry for driving small motors. On a mixer you would want to use that both for protection and for touch sensing (for going to automation recording when you don't have capacitive touch sensing for instance). I have no idea what the motor driving circuit looks like, and if there are chips with torque sensing, and if the necessary pins on these chips are connected and available for future firmware updates.

While some of you are too prejudiced to see clearly, I doubt if the Behringer designers are raving idiots, and a lot of testing has gone into these faders. There have been a number of loose pulleys ( out of more than a million), but it doesn't seem to be a dramatic failure and the fix is relatively quick and easy if one is willing to risk voiding the warranty.
(Being able to use the equipment to me is more important than preserving warranty, I bought it to use it, not to drool over the warranty)

[John Roberts {JR}]

How many sound guys does it take to design a pulley?  :-)

JR

[Frank DeWitt]

Anyway you guys, the design is of course not flangeless, it is simply a two part design with a single flange pulley sitting on top of a washer that performs the function of the second flange.

Thank you for the information.  I could not see a lower flange and the text said "13. As you can see the belt has slipped under the gear" So I assumed based on what I saw and read that there was no flange on the under side of the pulley.  I am glad to hear that I was wrong.

[Frank DeWitt]

Unrelated but interesting  Here is a video of a fader for the Midas Pro 1  http://www.youtube.com/watch?v=oqCplmX3Rkw  That mixer uses a drive pulley with one flange.

[Per Sovik]

Thank you for the information.  I could not see a lower flange and the text said "13. As you can see the belt has slipped under the gear" So I assumed based on what I saw and read that there was no flange on the under side of the pulley.  I am glad to hear that I was wrong.

There is no flange as such, the washer, from what I can faintly remember from a picture or video I saw a long time ago, simply fills the gap, and the gap opens up and allows the belt to potentially drop off when the pulley travels too far up the axle.

[Bob Leonard]

Correct, a washer is not as flange. If the sprocket had an upper and lower flange the belt would ride with the sprocket up or down eliminating ANY possibility of the belt coming off due to up and down movement on the shaft. That's not to say there might be another reason for belt failure.

Set screws are a method commonly used, as is Loctite or other adhesives. Either method might cost almost a nickel per fader to implement.

And no Per, I am not prejudiced or due I consider the Behringer engineers to be raving idiots. I'm sure they thought a good press fit would suffice, but unfortunately that is not the case. The problem, which is much more common than you care to believe, requires a future redesign or recommended fix from Behringer, then it will be problem solved and time to move on. 

[John Roberts {JR}]

Correct, a washer is not as flange. If the sprocket had an upper and lower flange the belt would ride with the sprocket up or down eliminating ANY possibility of the belt coming off due to up and down movement on the shaft.

Second guessing this from a far distance, if a two flanged pulley rides up the motor shaft, the belt will interfere with the bottom flange on the pulley, and if it binds that could throw the belt. The lack of a bottom flange "might" reduce alignment related belt friction, while it will still interfere with the top flange of the lower pulley.

That's not to say there might be another reason for belt failure.

Belts are like tires on a car, they are expected to wear out given enough time and use. There is a reason "all" moving faders have less than lifetime warranties.

Set screws are a method commonly used, as is Loctite or other adhesives. Either method might cost almost a nickel per fader to implement.

I would not expect there to be anything close to cost parity. A set screw first requires a drilled hole, then tapping that hole, then inserting the screw, then finally tightening in place (not to mention set screws and plastic pulleys don't really mix (IMO).

A press fit, with adhesive for insurance strikes me as a practical, and cost effective approach. It's hard to imagine anything requiring a human touch for only $0.05, while application of adhesives can be more easily automated.

And no Per, I am not prejudiced or due I consider the Behringer engineers to be raving idiots. I'm sure they thought a good press fit would suffice, but unfortunately that is not the case. The problem, which is much more common than you care to believe, requires a future redesign or recommended fix from Behringer, then it will be problem solved and time to move on.

I am prejudiced by personal experience and Behringer's past behavior. I try not to allow that to interfere with current engineering discussions.

JR

PS: Trying to discredit Bob's observations as being prejudiced reminds me of the current political climate in the US.    Bob has his own personal life experience set, while IMO model shop work is a long way from factory floor high volume production. I've been involved in my share of both. I even worked in a real machine shop as a kid (summer jobs). 

[Bill Schnake]

And no Per, I am not prejudiced or due I consider the Behringer engineers to be raving idiots.

Bob, I have finally had it and decided to say what's on my mind...You saying that you're not prejudiced against Behringer and the X32 in particular is like me saying I love to eat cooked strained spinach...it simply isn't true.  I guarantee you that I don't like to eat cooked strained spinach and that you can't stand the fact that Behringer has a hit on it's hands.  So my free advice is why don't you get off the 'let's bash Behringer bandwagon' until you have used an X32 live for say 6 months.  I hated Behringer until they came out with the X32.  I didn't even want to look at buying one until one of the people that works for me finally convinced me to give them a chance.  It took him 6 months.  Bang for the buck the X32 is better than anything that I have personally worked period.  I own several other digital mixers and have access through Mason Sound, to even more, and I can tell you from my personal experience I use the X32 over the M7CL, LS9 and SC48 more times then not.  If I have a National that requires the M7CL, SC48 or CL5 then I will bring them out.  Otherwise I use the X32, because it's smaller, does what I need it to do and the iPad App is amazing.

You can write all of this off as me being a 'Newbie' around here.  You should know however, I've been doing this since 1977 when I started with a Peavey MC12 non powered mixer and a Peavey CS400.  So why don't you do everyone a favor and lay-off until you have actually used the X32 for 6 months or so and know what you are talking about when it comes to that particular piece of equipment.  You don't seem me complaining about equipment that I haven't used...that could be a good lesson for you to take home from a 'Newbie'.

Sorry about getting off topic about the faders...there have not been nearly as many problems with them as Bob would like to have you believe.  Could the design be improved...sure...could the design of a Mercedes  SLS-Class Coupe be improved...sure it can.  Am I comparing Behringer to Mercedes...not a chance.  I would rather mix on the Behringer and drive the Mercedes...they were designed for two different functions.

Oh, and I still hate cooked, strained spinach.

Bill

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