Theatre Design & Technology - Spring 2023 - 11

Answers to selected operational questions:
Q The base frame segments are not fitting into the central hub. Q What if the final outer ring wedge is not going in properly?
BASE FRAME
What do I do?
Due to the pie shape of the base frame pieces, they cannot slide into
the central hub. The inner portion of the segments must be lifted and
pushed down into the central hub grooves. If still not fitting with the
rest of the segments already in, slightly lift on all segments so they're
halfway into the central hub and with a group of people, push them
all down at the same time. Using your feet or a soft mallet, hit the
outside ends of the 8' boards on the segments to push the segments
tighter. DO NOT KICK THE CASTER BOARDS. These are fragile and
can easily break if kicked hard enough.
Q How do I align the segments properly if the bolts do not fit
This needs to be done after the segments are already inside the
central hub. Once the central hub has all the base frame segments
aligned, use a drill, and focus only on one seam between two segments
at a time. Drill the bolts through one hole and someone else
can gently mallet the ends of the 8' board until the holes align and the
bolt threads through both boards. This can be repeated in a clockwise
or counterclockwise direction for the rest of the segments.
tent around the circumference of the gap, how do I fix it?
through the 8' boards on the sides of the base frame segments?
Q What do I do if the center disk starts to vibrate or is rotating at a
reduced speed than specified?
Stop the system. This most likely means that the chain is slipping in
its groove. If this happens you should stop the stage and add more
tension to the desired chain loop. For the inner disk, this can be done
by adding tension to the under-stage tensioner. For the outer ring
this is done with the AC tensioner.
Q The gap between the outer ring and the inner disk is inconsis- Q What do I do if the outer ring starts to vibrate or is rotating at a
OUTER RING SUPPORT AND GAP MATERIALS
reduced speed than specified?
Utilize the opposing access panels to adjust the physical outer ring
supports. If the ring consistently becomes off center, ensure that
the bolts that adhere the metal plate to the plywood are sufficiently
tightened.
Q After long term operation, the outer ring has shifted significantly.
How should this be fixed?
The chain that drives the outer ring is under a significant amount of
tension. It is likely that this force has pulled the outer ring off center.
Adjust the two outer ring supports directly opposite to the motor
driving the outer ring to ensure that the system can remain properly
positioned.
Q How can I reduce the noise produced by the outer ring wheel
support?
Each wheel has an access nipple that can be used to grease the
bearings that allow for rotation. Applying more grease through this
nipple will help reduce noise.
ing straight up?
Stop the system. Check that the outer ring supports are in place
properly and check that the chain has enough tension.
Q What if the chain is coming out of the groove?
Stop the system. If the chain is not running level, it can work itself
out of the groove. Check that the tensioner is at the same height
as the groove and that the motor drive gear is at the same height as
the tensioner.
MOTORS AND ELECTRICAL
Q What do I do if Spikemark displays position faults for the motor
movement?
Using Spikemark, manually jog the motor and ensure that the encoder
counts are increasing when jogging forward and decreasing
when jogged in reverse. If the encoder is not the problem, look at
the motor tuning parameters and change proportional gain. Increase
by a value of one to correct the positioning error. Be aware of lurching
to ensure that you are not specifying a greater acceleration than
possible.
Q What if the alignment rods for the central hub top are not stay- Q How can I troubleshoot the encoder if it is not working properly?
STAGE TOP
Connect an oscilloscope or a multimeter to the encoder plug
Add tape around the lower end of alignment rod until a firmer fit is
achieved into the steel swivel.
Q What if the stage top pieces are not going together?
Ensure there is no debris between the wedge and its connecting
point. Then, ensure the wedge is properly aligned with the connecting
wedge.
Q What if the final inner disk wedge is not going in properly?
To help make this process easier, unbolt the surrounding
wedges from the central hub only. This will allow for more lifting
range on the surrounding wedges, allowing more clearance to insert
the final wedge.
SPRING 2023 | THEATRE DESIGN & TECHNOLOGY | 11
pins; supply power to the appropriate pins. Refer to the encoder pinout.
Rotate the shaft of the encoder to check that correct power is
being supplied and pulse outputs are being displayed properly.
Q What if the AC Motor is not running smoothly and making noises?
Go
through the Auto-tuning process in Spikemark or look on
the AC Stagehand Pro Manual. Please ensure that the Mitsubishi
A700 Variable Frequency Drive is set to the correct voltage,
frequency, and current ratings that match the motor nameplate
ratings.
Ensure the gap between the inner disk and the outer ring
is as uniform as possible, if necessary, apply spacers between
the inner disk and outer wedge closer to the location of the final
wedge. This will provide a slightly larger clearance to insert the
final wedge into place.
TRANSMISSION
Q What do I do if the AC or DC motor starts to make excessive
noise?
Stop the system. Depending on where the noise is coming from, you
can add a piece of vibration insulation material. If the chain is making
excess noise, check for misalignment with all components and
check that the chain is running level.

Theatre Design & Technology - Spring 2023

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