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Topic: Masking Motors Recommendations

Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 02-03-2010 06:07 PM

My only experience is with ADC and they have worked fine for over 25yrs -- solid and never even had the limit micros wear shift or fail.

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Kyle Butler
Film Handler

Posts: 47
From: Belton, TX
Registered: Jan 2010

posted 02-03-2010 08:51 PM

All of ours are ADC's and the problems have been few to none.
( 5 years in operation )

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 02-03-2010 10:59 PM

quote: Steve Guttag
The logistop does have its own quirk. It accurately records where you set your stops but it has no anticipator so it does not stop until it hits your stop point. The problem is that there is a finite coast down time so it misses. Try hitting the same stop button over an over again and you will see it moves a little this way, then a little that way...always just barely overshooting.

What they need to do is figure their coast down time and build that into its "logic" so that it costs down to the right point and if you are within a certain range, not hunt around.

I have not encountered this "coast down" in ANY of the Logi-stops in the rooms I have installed/serviced. Sounds like there may be inertia issues with the mechanical rigging. All the ones I have dealt with index to the exact same stops repeatably, at UC Irvine I have not had to reset the stops in over 12 years.

Hitting the same button over and over will cause the masking to "bump" a tiny amount each time, and that will throw off the positioning, but to reset that simply go full open or full close and I have found it to return to exactly the original programmed position.

However, there is one major thing with Logi-stops that is very important..when setting the stops, the FIRST stop you set MUST be set from the forward direction of the motor, so that it is assigned a "positive" number on the encoder. If you don't do this the unit WILL lose positional accuracy. It is explained in the manual for the motors.

EDIT: On page 18 of the manual, there is mention of the use of the open and close buttons while in "SET" mode to assign a numeric COAST value..the purpose of and range allowed is not explained in the manual. But if need be, a call to ADC's tech support will answer that in detail, I have found their support to be excellent.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 02-04-2010 08:41 AM

Tony says:

quote: Tony Bandiera Jr
I have not encountered this "coast down" in ANY of the Logi-stops in the rooms I have installed/serviced.

And then Tony says:

quote: Tony Bandiera Jr
Hitting the same button over and over will cause the masking to "bump" a tiny amount each time, and that will throw off the positioning, but to reset that simply go full open or full close and I have found it to return to exactly the original programmed position.

Well yeah...that IS the coast down. The motor stops at the set point but the motor does indeed coast and overshoot every time. It isn't by a lot.

If you open you logistop next time...set a stop, look at the number. Then open/close or do what ever...see if it stops right at that number or a number a bit near. Remember you need to set a new stop to a new number.

Steve

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