Film-Tech Forum ARCHIVE: Sidewinder -- double MUT

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Sidewinder -- double MUT (Page 3)

This topic comprises 3 pages: 1 2 3

Author

Topic: Sidewinder -- double MUT

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-20-2007 04:54 PM

On a standard drive open loop type VFD system the frequency can be well on spec. but the motor is still going to drift around no matter what you do. Wouldn't matter much on a demand type system though. Then the only alternative is the more expensive closed loop stuff.

Mark

| IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

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

posted 07-20-2007 05:25 PM

I tried one of those AC-Tech drives with a Bodine inverter rated motor...under load it was on the money...rock stable based on the strobe.

I've found that many cheap VFDs aren't so accurate even with the same motor.

| IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-20-2007 07:05 PM

I agree that some are inherently more stable than others. But in truth I met an engineer at Baldor that was in town that told me that all of the VFD's out there come from less than a half dozen manufacturers... most are custom or rebadged for other companies. I have a similar highly accurate VFD system on my VV projector except even a little higher end and it was quite expensive 15 years ago, I chose it because its very compact. Both Bodine and hall effect drive... it still drifts a bit too. Temperature and load variances will all affect any open loop system and there's no compensation for it available. Just ask the manufacturer... Been there done that myself of just about all of them! Ya can't get around the law of physics ya know is the typical answer. Closed loop drives start at about 2 grand too... makes the general use of them a bit pricy.

Mark

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 07-20-2007 07:19 PM

quote: Michael Moore
that's a perfect little project to get as a kit and put together. I think that will work great for what you propose.

hehe thanks! but gonna meke all electronic by me, and mechanical parts by mine colegue. So I get used to development and if this doesn't work well at first time, or something blowes up the's normal for me [Big Grin]

quote:
Its going to take a really big Q-1 or multiple in parallel to hold up under driving large reels. Also be sure to match the multiple Q-1's so each shares the current equally!!

There's no problem with this.....because MOSFET are cheap and one can take about 20A like nothing!

quote: Mark Gulbrandsen
Also with this setup there is a dangerous prospect of the drvice shorting and the large real all of a sudden going full tilt

How did You mean "shorting" Mark?

quote:
lso the PWM chip used in the drawing in the above link is interesting as one can also add an error amplifier to it. In other words you could regulate the pay out/take up speed by counting perfs with an opto pair and comparing them to a refrence frequency. The tourque of the motor would adjust relative to the refrence to keep that payout/take up speed linear regardless of the diameter of film thats wound on the reel.

Good idea indeed Mark....but question is that needed in this system? More components and completive, more potential problems to get in work!

| IP: Logged

Jeremy Jorgenson
Phenomenal Film Handler

Posts: 1002
From: Chicago, IL, USA
Registered: Feb 2005

posted 07-20-2007 10:27 PM

quote: Michael Moore
by the way when I use the quote button how do I give credit for the original poster?

It should automatically give credit to the original poster, unless multiple people have written the same thing quoted in that thread. This is assuming you don't change anything that they wrote (even a space).

If it is a quote from some place other than the thread, after the first "QUOTE" in brackets, put = and then the name (or whatever) that you want credited.

| IP: Logged

Michael Moore
Expert Film Handler

Posts: 188
From: Dover, DE / USA
Registered: Jun 2006

posted 07-22-2007 07:33 AM

quote: Jeremy Jorgenson
"It should automatically give credit to the original poster, unless multiple people have written the same thing quoted in that thread."

ok I had to do this to test it, however I got it work with the = inside the firts guote[]

thank you for the help on thie off topic thread
Mike

| IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-22-2007 10:53 AM

quote:
Good idea indeed Mark....but question is that needed in this system? More components and completive, more potential problems to get in work!

Well, the Double MUT is an extremely reliable piece of equipment... thousands are still in use. In fact the Sundance Film Festival almost completely relies on the Double MUT transports for the majority of the 35mm thats run there every year. I just don't see that re-inventing the "steam engine" is a better idea... Double MUT is a prooven design that works and never fails... at least never fails until the motors wear out. There are few parts that have to be made.

Mark

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 07-22-2007 12:26 PM

mark said "at least never fails until the motors wear out"
or the light bulbs burn out [Big Grin]

| IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 07-22-2007 12:40 PM

quote: Gordon McLeod
mark said "at least never fails until the motors wear out"
or the light bulbs burn out

I replaced the light bulbs in our rental unit with Thermometrics thermisistors of similar characteristics to the bulbs.... sort of like in the degaussing circuit of a color tv except in the Eprad its used a ballast resistor. I asuppose one could also use a resistor but thermisistors have more of a characteristic like light bulbs. This is even a brighter idea than the original 200 watt bulbs... and the lamp lighting up was annoying under some conditions of use. I don't think the thermisistors existed back when it was originally designed for Cinerama so the bulbs went in.

Mark

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 10-08-2007 04:35 AM

I think I want to built double mut with mehanical friction, because this way is simpler and if something gone wrong is easyl so fix, and DC motor are quite expensive.

I want to make whole friction new and connected it to motor via belt drive with cca 200rpm on friction.

Other motor gonna be for rewinding connected directly to other rell.

I want to ask if someone has experiance with friction which can drive film up to 5000 meters??? Or may bee some drowning...also on every rell I want to ad dancing arm so that can compensate bad film or bad rells.

Can someone share opinions with me?

| IP: Logged

Marin Zorica
Jedi Master Film Handler

Posts: 671
From: Biograd na Moru, Croatia
Registered: May 2003

posted 06-20-2008 09:45 AM

To get this post to life a bit again [Smile]

I did over with this project, results you can see on pictures, this one is second prototype made for this Prevost P-86X portable machine, first is normaly for use with standard projector.

Check on rollers, they are from 35mm copier machines :-)

| IP: Logged

Tim Reed
Better Projection Pays

Posts: 5246
From: Northampton, PA
Registered: Sep 1999

posted 06-20-2008 09:17 PM

Wow. Good work! [thumbsup]

| IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1 2 3

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.