Hello again msaad10,

Kurre Spezialmaschinenbau GmbH is a very good wire and cable special machine company in Germany and I have known them for many years. www.kurre.net/spezial/en/index.htm

Select "Products" and then "Measurement units". In particular, take a look at model LMR-60-Z

This just might be the right machine for you but you will have to decide that. All I am giving you is something to look at and to review. It will of course need to be outfitted with a high precision count signal generator so that you get a very large number of pulses in one meter of cable length. Kurre should easily be able to work this all out with you.

Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Hello msaad10, again:

I have read a few minutes ago the latest issue of the journal Wiretech. A laser measurement manufacturer guarantees an accuracy of <0,05%.

Is this realistic or is this a marketing joke? The answer is: It depends of the point of view.

The laser measurement manufacturer says:
"The difference between the emitted wavelength (visible, invisible) and the received wavelength is an indication of the production speed. The integral between a time period is the length of the measured product."

This difference is of course better than 0,05% (It´s laser technology, perfect waves). But what exactly happens with the cable or the measured product.

Take a closer look to the picture of this topic:

www.wirenet.org/forum/viewmessages.cfm?Forum=8&Topic=716

It´s not a realistic cable but you can see rapidly where the problems are when you want to measure a product exactly (-> better than 0,05%). That's why you have payed a lot of money.

The length of the product depends on:
-the tension during the measurement procedure;
-a constant tension during the measurement procedure;
-the flexibility of the product;
-the wave-form;
-start and stop procedure (Without a Bragg-cell its not possible to count backward);
- etc. ...

In conclusion: If you want to measure a cable exactly, than you are trying to catch a phantom ...

msaad10 you didn't answer this important question of Mr. Stewart-Hay:

1) "Is the laser a non-contact cable length measuring device that somehow controls the embossing head to mark the cable at a specific point? How does this actually work?"

If the laser length measuring system works with the printer to your satisfaction and not with the embossing system then the problem is the embossing system. (If it is the same product you are measuring) If you buy now a new system and the problem doesn't disappear then please answer this question.

Best regards

Juan Carlos González Villar

Kabel.Consult.Ing
This email address is being protected from spambots. You need JavaScript enabled to view it.
www.kabelconsulting.de

By the way:

The acurracy of my pulleys are +- 0,00000%

The diameter of the pulley is exactly 318,3098862 mm

That means if it rotates 1x, the measured longitudal length is:

L = D x pi
L = 318,3098862 x 3,141592654
L = 1000,0000000 mm

I hope that you catch now the marketing joke when a laser measurement manufacturer sayed +-0,05%. It´s not the accuracy of your product, it´s the accuracy of the length measurement system.

Best regards

Juan Carlos González Villar

Kabel.Consult.Ing
This email address is being protected from spambots. You need JavaScript enabled to view it.
www.kabelconsulting.de

Dear Sir;

Thanks for your kind reply.

Actually regarding the answer to the question, yes the laser is a non contact device measuring by laser reflection beam & thus signal fluctuations cause the error in accuracy due to light vibration.

Regarding the suggested wheels, are these supposed to work on hot or cold cables(embossing or indenting) since the hot as many factors other than geometrical due to heat transfer & its effect on metal?

Regards

ms

It´s not recommendable to put a wheel or a caterpuller on a hot cable to measure the length, it´s not good for product, measuring instrument and specially for the result of measurement. It´s also not recommendable to put a laser on this zone.

When I studied physics there was a saying (in german: wer misst misst mist), translated in englisch: who measures measures garbage. That means that you have to live with an inaccuracy. The problem here is that if you want to get a perfect result you have to know everything about the process (product is running from a pay-off to a take-up, what happens between both -> process, mechanical, electrical, hardware, software) and you have to put know-how and technology inside.

When I wrote my diploma thesis the customers of the cable industry coult live with an accuracy of +-0,5%.
An accuracy of +-0,2 it´s also possible with low cost technology. 20 years ago the laser measurement companies try to pushed their products into market with the "<0,05%-marketing strategy". I have read this afternoon some wire and cable journals (ca. 5 jears old) with the advertisements of the above mentioned laser system. My conclusion is: a perfect marketing.

If you come to wire in Düsseldorf do not hesitate to contact me about this subject.

Best regards

Juan Carlos González Villar

Kabel.Consult.Ing
This email address is being protected from spambots. You need JavaScript enabled to view it.
www.kabelconsulting.de

Do you really think that your pulley diameter is accuate to 1/10 millionths? But then I assume you are being humorous to make a point. 318.32 mm would limit you to only 1/100ths of a mm accuracy regardless of the value of pi.

On the other hand I assume you are measuring the pitch diameter or root diameter of the pulley of which use would over time decrease the diameter and thus throwing off the accuracy of the meter.

Any time you have nonn-contact measurement using light waves, your greatest accuracy will only occur if every inch of cable was exactly identical and in the real world that nevers happens!