The Sacrificial Belt Lamb

[KBK]

Just and idea I came up with, while talking about tuning Ducati cam belts on another forum. Let's see what comes of it here.

Quote:

Sorry. Then they likely use the sensor in the point of most flexure in order to utilize the greatest amount of flex in the 'string' (belt) for as much frequency accuracy as possible.

One can create a similar device with an extremely small amount of very light aluminum tape (hardware shop, or, old open reel metal tape for direction sensors)..and place a rigidly mounted tape head along side the belt,and then measure/record the frequency.

A handy electronics guy could have such a system up and running in a single afternoon, by butchering an old cassette deck and running the signal into a PC sound card for analysis.

The smart thing to do is to change the size/mass of the small piece of aluminum tape by a factor of exactly two, to check on any frequency change of the belt due to the added mass. If the change is negligible, then the numbers recorded stand a chance of being accurate.

If change is noted, then compensation must be intelligently applied. Weigh the belt, consider the tension, consider the mass of the suspended plucked section...and then compare the mass levels of the added tape piece - and then consider again.

I'm saying this all due to the fact that my mind is attuned to the idea of checking the belts on TURNTABLES. A far more delicate situation, with regards to measurement complexity.

Nice bike! But my mind went straight to the turntable belt.

Nice idea of the bike, though, I'm sure it works 100% fine.

I'll bet that Ducati does it the optical way with special hardware, strictly due to liability/warranty and consistency considerations. Not because they want their mechanics/shops to invest in ridiculously expensive hardware, it's just that reliable and consistent measurements need be taken, even in the hands of someone who could be termed a 'numbnuts'. Bulletproof and reliable application, is the byword.
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You'll have to sacrifice maybe a few belts, to get this right. Those sacrificed belts will be your 'operational belts' after they are properly utilized, maybe. You never know.

How about putting a THIN strip of conductive paint (flexible) on one side of the belt..and then placing a STEREO tape head OVER the edge of the belt, with the center of the head exactly centered on the belt?

Then the differential signal generated between the channels can be utilized to check for belt flutter.

I know the belt will be changed dramatically in function and effect by the paint, unless the paint is intelligently applied.

However, I cannot see how some great things cannot come out of this.

One can 'listen' to the amplified signal on a headphone set-up and gain all kinds of insight into generated and transferred noise, and it's sources.

You are DIY guys.

You all have dead cassette decks hanging around or can get one in near minutes.

You could be playing with this by the end of the day.

Issues will arise in the implementation of the system but they can be overcome with intelligence applied to the situation. For example....a secondary systems check can be done by rigidly mounting the head to the plinth, and then the differential of noise on the belt/plinth can be obtained as signal.

The whole story here, so about checking THE BELT, when it is 'in situ', or 'on the fly, in operation'. Which I'm not aware of having much chance of doing. This will allow for that, to some degree, without resorting to fancy laser systems, and all the issues involving them, as an expense and implementation. This does it with junk lying around the house - today. Now.

I violated the rule of 'checking first'..but I THINK this is a newer idea, at the least. We'll see after I post it.

[KBK]

The same trick can be used to check for generated arm noise.

Put the small bit of conductive paint on a given spot on the arm.

Put the head nearby, in the correct spot.

Drop the needle.

Listen with headphones cranked.....

Find the noise and kill it.

Listen for correctness and effectiveness.

build the best damn arm - ever.

As matter of fact, it can be used on just about every damn spot on the turntable.

[EC8010]

Tape heads are magnetic; moving conductive paint nearby will do nothing.

What were the Ducati boys trying to do, determine optimum cam belt tension? Timing would be best done with an optical sensor like the spoked wheel in a mouse fitted to each camshaft.

[KBK]

Not quite. I have lots of ways to make the paint retain a signal. or orientation. Perhaps I'd have to offer the paint. I've got access to a lot of different magnetically sensitive pigments, and most of them are already in the Tri-Art artists paints I'll talk to the paint engineer,and then he'll pick one... Imparting signal upon them is the easy part. Iron oxides are brutally common in the coatings/pigment industry.

And yes, if you are wondering, I covered my *** after the fact, ie, right now, I just made it up! But at least it works! Motional particles of coating will produce a signal- the question is, is it enough?

Yep, they are trying to produce a specific tension of belt on the Ducati.

As for the turntable - the in situ belt vibrational info is a treasure trove that sits unrealized. I'd venture that this is where considerable about of the remaining issues reside. More than enough to take a stab at doing.

[KBK]

In all seriousness, please folks, try and find some problems with the idea. pick it apart. Then I can try and find the solution. Then the measurement system could become useful.

For example: Split plinth. Stereo head. Dab of magnetically sensitive material on either part. measure difference between two by placement of the heads re placement of one part of the stereo head, one channel, over each dab. cue to the differential --listen to the output. The difference will be the part that is NOT transmitting.

See what I mean?

Use the same to check bearing assembly vs arm proper......

Both in near total non-interference considerations, which is critical.