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Author Topic: Seeking advice: motor/control replacement on Century projectors Joe Beres Jedi Master Film Handler Posts: 606 From: Minneapolis, MN, USA Registered: Nov 2000 posted 11-10-2010 10:22 AM                     I think this is my first post in 5 years or so. I've been out of the booth during that time, but am back in, and happy to have a good reason to be around here again. Anyway... We have a pair of Century projectors with some homegrown motor controls on them that allow us to run at slower speeds for silent films. One of them has basically crapped out, and the nature of the electronics and bizarre install has us looking to replace the motors and controls rather than try to repair this Macguyver looking mess. The trick is that we need to maintain our ability to run variable speed (I'd like to have the capability to run 16(though we don't really have the right shutter for this) - 25 fps) and still keep costs down. The current plan on the table is to put in 3-phase, frequency drive motors and frequency drive controls. However, the motors that our tech has found, and used in a previous install emit a fairly loud, high-pitch whirring sound, and we're concerned that this may be audible in the house. These will work, but I wanted to see if anyone had any alternative ideas, or perhaps knew of some quieter frequency driven motors that could mount to the projectors. Thanks in advance for your ideas and advice.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-10-2010 10:45 AM                     The whine is normally a function of the inverter frequency...typically around 4KHz for torque...unfortunately, it also is right around the sensitive part of human hearing. Some inverter models have the ability to change frequency based on the torque needed. Thus, you will hear the 4KHz when it starts or ramps down but once it is at speed it might be at a safer, less noisy 16KHz. For the Motor, Century and Leeson have drop-in replacements. For the interverter, we have used TB Woods and Lenze. The TB Woods micro-drive was one that had that floating frequency...unfortunately, it was discontinued some years ago (damn you RoHS!!!). I don't recall if our Lenze ones we have used more recently has the floating frequency but I think so. Steve  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-10-2010 03:34 PM                     On most inverter drives you can manually set the frequency..I have had good results using 8kHz to reduce the annoying whine. One caveat: If you put inverters on your projectors, be sure that your "A" chain is wired and grounded properly..use quality wire and observe good grounding practices or you could end up with the inverter whine in your audio!! Make sure the motor and projector are grounded properly too.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-10-2010 04:37 PM                     The last Lenze ones we used were the SMVector. They default to 6KHz and can be set as high as 10KHz but will automatically drop to 4KHz if the load hits 120% (when it needs torque to start up).  |  IP: Logged Joe Beres Jedi Master Film Handler Posts: 606 From: Minneapolis, MN, USA Registered: Nov 2000 posted 11-30-2010 04:57 PM                     Things are progressing a bit. Here is the inverter our techs have proposeed: Fuji 3XA39 And the motor: Dayton 6XH88 Does anyone have any opinions on what they're thinking of? Any thoughts on the issues that might arise with this set-up? Thanks.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-30-2010 05:54 PM                     A Dayton Motor? Oh please... those are junk from China! Ok, China also makes some good stuff but Grangers isn't selling it. Tell your tech to look beyond the great wall of WW Grainger. There is much better stuff out there and Graingers is typically high priced. Unless you are doing something simple where speed drift is irrelevant you need an invertor capable of utilizing a feedback loop from the motor to the invertor so the invertor can track the RPM and speed remains constant. As your projector warms up the load changes and the speed will drift come hell or high water. I've installed many types of invertors including the Lenz and some people may claim this one or that one is rock steady without feedback but just try interlocking two of them together for a long feature. Then you'll find out how much they drift... Little in the short term... lots in the long term. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-30-2010 06:07 PM                     I'm not a big fan of second guessing the folks you are using to do the job. Did they give you the reasons they wanted to use this stuff? That motor has a rated speed of 1725...are your pulleys set up for that? It has a top speed of 1800 RPM...are you ever thinking of going over 25fps? Note, the shaft is 1/2"...the Century uses a 5/8" so having the correct pulleys are on you. There may be other dimensional issues. I'm encouraged that the motor is inverter rated but I do find it odd that it would have a 1725 speed rating at 60Hz. It may have a "slip" factor to it...which can be adjusted in many inverters...if it does slip, you will need to test it under load (including with a reel holding back tension) to keep it accurate. A motor that will not have this issue is this Bodine Motor Note that it is the size you are needing with a wide speed range (if you want to handle faster than 25fps). It is an 1800 RPM motor (at 60Hz) so you may need a new pulley set if you are not set up as a synchronous system yet. Regardless, if the motor mount does not match your particular Century motor mount, you might need Strong's motor adapter plate. It has a bunch of holes that can be used to mount most anything to a Century (PE-1308). You can also use the Leeson motor sold by Strong. I also recommend keeping the flywheel (another reason to slightly over-spec the inverter) as it remains the inching knob and it stabilizes things. On the inverter front...I have not looked at the one you are going with other than the quick picture...it seems pretty basic though and not forthcoming with information. If you check out the SMVector series (Lenze)you will see they have a display...which most find handy (regardless of brand or model). The display can often be set to read out in say FRAMES PER SECOND! With a better inverter set up, you can have fixed speeds...like 24fps and also have a "variable" setting so that you can dial in the specific speed (or change it on the fly) for the specific film. I also recommend over-specing the inverter for a conventional projector. The load difference on a projector when it is starting up versus running is pretty dramatic. I've been burned by 1/2HP inverters not being able to ramp up in time on a typical American projector set up...so consider a 3/4 or 1HP inverter...don't go too overboard...you just need one to get you over the hump of start up...after that, it will be loafing. The 1/2HP WILL work but you MAY have slow down the ramp up time to not over-current. This may mean a slower ramp up than you are used to or will like. Mark...actually...the motor they listed IS MADE IN THE USA!!! Shocker. As for drift...done many an interlock...for long features...no problems Anyone out there with Kinoton "D" or "E" series projector ever have a drifting problem on an interlock? I've done strobe testing and can see what if any drift. Not all inverters or motors are created equal, that is for sure. If you set up your inverter properly, loading should NOT be an issue...particularly when up to speed. I freely admit that a feedback system is superior for accuracy but for about 99% of the projection needs, doesn't not buy anything over a proper non-feedback system. -Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-30-2010 09:09 PM                     quote: Steve Guttag Mark...actually...the motor they listed IS MADE IN THE USA!!! Shocker. Hopefully they are finally learning...! The Kinoton D or E series would be the equivilent of having a crystal controled motor! Completely different thing than a closed loop servo motor. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-30-2010 09:11 PM                     Nah...probably an accident...note the "subject to change" disclaimer on the Country of Origin!  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-01-2010 12:41 AM                     I have had good luck with the Baldor and the Gavazzi  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-01-2010 08:58 AM                     Think of the possible consiquences of that and another reaosn you don't buy fomr ole W.W., he could also be getting a motor made in The Congo or Iran...  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 12-01-2010 10:53 AM                        Too bad; once good supplier. Louis  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 12-01-2010 01:38 PM                     I'm not ready to poo-poo Grainger across the board...but they have suffered the asianization like many others. Graingers has always had their convenience factor too. If you need something, they probably have it and there is probably a retail store close enough. -Steve  |  IP: Logged

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