Film-Tech Forum ARCHIVE: How to: variable speed on sh-1000

This is topic How to: variable speed on sh-1000 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Louis Bornwasser (Member # 3063) on 04-10-2006, 07:25 PM:

Have need to provide "silent/variable speed" on gearbox style simplex sound heads. Kit available? Louis

Posted by Steve Guttag (Member # 268) on 04-10-2006, 08:40 PM:

I don't know of anyone that makes a "kit" persay but it can be done with either a DC motor or a 3-phase motor with a decent inverter we've done it both ways. The DC approach is cheaper faster but less accurate and controllable (ramp ups and downs).

You will generally have to adapt a motor to the soundhead with spacers too. For the 3-phase approach, we also generally go to 1800RPM gear sets so 24fps is absoulte rather than approximate though that is not entirely necessary...just nice.

Posted by Alan Gilbertson (Member # 242) on 04-10-2006, 09:43 PM:

We did this for years on SH-1000's for special show over the summer. We just put a AC variac on the projector motor that was running the fastest and all ran fine. The variac we used was the same one in a Potts or Strong platter or make-up table.

Posted by Bill Enos (Member # 440) on 04-10-2006, 09:48 PM:

Attach a motor mounting plate that extends outward to the underside of the existing motor mount. Mount a second motor along side the present motor, remove the hand wheel/knob from the main motor and install v belt pulleys on both motors. Use an accurate tachometer to determine the actual speed of the new motor and calculate the pulley diameters necessary to achieve the input shaft speed you need. Put a belt in place, tension it properly and go! Operate only the auxilliary motor. Cheap and quick. I've seen it work.
Reducing the voltage on an ac motor to regulate speed is not a satisfactory method and will eventually damage the motor.

Posted by Mark Gulbrandsen (Member # 72) on 04-10-2006, 10:49 PM:

Louis,

Rather than using a hand crank I highly reccomend that you go the inverter route. Look at Baldor in particuluar. They make a double ended(Shafts at both ends) 3 phase inverter intended motor that can be had for just over 100 bucks and a 120 volt AC input inverter that puts out the required 220 volt 3 phase to drive the motor which is also reasonably priced. Being 120 volt allows it to work practically anyplace. We have over 30 of these systems in operation driving directly to the input shaft through custom couplings on DP-70's for many hours day in, day out. After 12 hours operating the motors are barely warm.

The only down side of them is don't believe the RPM readout on the display. Its innaccurate and can't possibly display the absolute correct speed due to it being a non servo type system. Servo type drives are VERY expensive starting at 2K plus! Use a digital tachometer and measure sprocket rpm!!

This inverter also allows a jog feature(among many other features). We have adapted the jog feature into the DP-70 as a function to put the projector in the thread position at show shutdown. Works great and not a failure of any motors or invertors in over three years. Also it is speed accurate enough to do interlock if each units RPM is carefully adjusted under load.

P.S. You won't need a flywheel on the motor any more. This motor has variable run up and run down settings and being a three phase motor that operates on 2.5 khz switching it is smooth as silk.

Mark

Posted by Louis Bornwasser (Member # 3063) on 04-11-2006, 08:32 AM:

Thanks, guys.

Mark: do you have the numbers of the motor/inverter? Louis

Posted by Scott Norwood (Member # 30) on 04-11-2006, 09:03 AM:

The installations that I've seen all use a "TB Woods Micro-Inverter" that accomplishes the same thing (variable speed, programmable run-up time, etc.). They work fine, though the interface is a bit clunky for adjusting the speed during a show.

Posted by Gordon McLeod (Member # 33) on 04-11-2006, 09:52 AM:

The invertor I use is the Baldor 15J serries on the cinemecanicas and have yet to have a failure

Posted by Richard Fowler (Member # 893) on 04-11-2006, 10:04 AM:

I did this 20 years ago for the Miami Public Library on their SH1000 to allow for silent prints and 20 frame per second Deforest Phonofilm prints for archive meetings. I installed a motor mounting plate usually used to mount a sylsen, installed a 1/5 H.P. D.C. motor, timing gears on the motor shafts, jockey roller to allow quick removal of belt for regular motor operation. Mounted a machined fitting to clamp on the soundhead drive gear shaft to mount a tachometer...and a control box with speed control and digital readout [Cool]

Today maybe an invertor set up.....but driving the original motor/flywheel kit with the D.C. motor was smooth and easy [Wink]

Using an invertor on the Cinemeccanica motors is O.K. and I much prefer this to the Glavezzi "Slow start" unit, which in todays market, cost more than most of the invertors I use.

Posted by Steve Guttag (Member # 268) on 04-11-2006, 04:05 PM:

We use the TB Woods products but normally make a user control panel of some sort. Generally this can make things quite easy to use. Also we generally try to have the controller read out in FPS. The better controllres/motors will actually run at the frequency that they state...the cheaper ones, while work more often than not, are a bit sloppy on their frequency.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 04-14-2006, 11:58 AM:

Louis,

If you are still in need of the numbers of the Baldor parts or a motor and inverter from our stock of them give me a call on Monday morning. Have been on the road the last two weeks and taxes getting my done today [Eek!]

!

Mark
801-355-1250 Office