Sammy Intl. Airlines

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How we solved the NexDome New Shutter Problem.

Like a lot of people, we had been unable to get the newest NexDome shutter to properly operate. The instructions were sparse at best and the inquiry we made to the manufacturer was not helpful. Due to the looseness in the chain we initially thought that the chain was skipping. After much fiddling around we determined the problem appeared to be that the stepper motor used did not have enough torque and was skipping steps. Once we committed to attacking that issue, we found a 5:1 dual axis reducer from Stepper Online and ordered it. After installation the shutter now operates flawlessly. Our shutter now takes less than 4 minutes for a full open to full close with speed settings at minimum. Following are some phots and explanations of what we did. Any measurements given are what worked for us and are for reference only. They may be a good starting point. Parts used will be listed at the bottom of the page.

1. This is with the Gearbox mounted.
The shafts were moved back 44mm and are up 57mm for us. Your's may vary. We changed the chain drive gears from the stock 11 tooth to a 25 tooth gear.
2. Here we used nutserts to mount the unit to the plate.
It would be better to just drill the holes for M6 bolts and bolt from the bottom with nuts on the top. There really isn't enough room to get an allen wrench in on the top.
3. This is a side view of the mounting.
This is the stock drive gear which was changed out to a 25 tooth gear. Between the square motor mount and the gearbox is a round bearing housing that sticks below and is butted up to the mounting plate. The gears are 2.8" or 71mm out from the outer side of Teflon block.
4. The cover on the floor shows where we marked it for the motor to exit out the bottom.
The top will also need to be cut as the gearbox extends above it. We 3d printed a cover to go over it.The manual switch will also have to be raised as it now touches the drive shafts. We also paralled a remote switch to a more convenient location.
5. This is the almost finished installation.
Obviously the gear box cover is upside down but will be corrected. We changed out the power connector to prevent the remote possibility of the power connector being switched with the limit switch connector. The close limit connector on the left was broken so we changed it out. The white cable to the right of the power cable is the remote / open close switch paralled with the chasis mounted one. We also had to change that switch out as it was intermittant.

6. This is what we did to correct the floppy limit stop brackets.

Single point mounts on these types of brackets just don't work. No matter how hard you tighten them they work loose. We 3d printed these and mounted them with 6-32 screws. Unfortunately the motor does not stop immediately when the switch is tripped so it does flex the flipper on both ends.

Some further info and parts list.

Here are the parts that we used in this operation. We bought off Amazon, shopping around you can probably find them cheaper and we are not an Amazon affiliate.

1 each Stepperonline MMRV30 5:1 dual axis Gear Speed Reducer. $50.00 when we bought it 2/24//2024 Gearbox at Amazon

2 each Stepperonline single output shaft for MMRV30 Gear Speed Reducer. $13.00 each, $26.00 2/24/2024 Output shaft at Amazon

1 each Stepperonline Shaft Sleeve Adaptor, 11mm to 8mm for MMVR30 Gearbox. $9.99 on 2/24/2024 Sleeve adaptor at Amazon

2 each uxcell 25 tooth roller sprocket B Type, 25 chain, 1/4"Pitch, 8mm bore. $11.59 each, $23.18 2/24/2024 25 tooth gear at Amazon

3 feet B Type, 25 chain, 1/4"Pitch, 8mm bore. $9.27 each 2/24/2024 #25 roller chain at Amazon

#25 Roller Chain master link (5 Pack) $5.99 2/24/2024 #25 roller chain master link at Amazon

The output shafts will have to be center drilled to accept the gear axles. They are 8mm which is close enough to 21/64" that worked for us. We used a lathe to drill the holes approximately 12.5mm or 1/2' inch deep but a drill press will work. We then drilled and tapped 2 each #18 or .1695 (since these are SAE screws I didn't convert to metric. It's approximately an M5 screw so 4.2mm tap drill) holes at 90° and tapped for 10-32 set screws.

Next we filed approximately 12.5mm or 1/2" of the drive gear axles flat to fit into the output shafts.

Mounting the gearbox was pretty straight forward. We found center between the two plastic end blocks and spaced the mounting holes off from the paperwork supplied with the gearbox. As noted in the pictures above, we used nutserts to mount it but a better option is to just use bolts from the bottom with nuts on top as there isn't enough rooms for the allen wrenches on top.

Next the holes for the drive shafts will need to be relocated in the plastic end blocks. We butted the bearing housing of the gearbox up to the base plate which put our holes 44mm or 1.73229" back and 57mm or 2.24409" up. Your locations will probably vary, but that is a general starting point.

Once that is done place the drive shafts throught the plastic block holes and secure to the output shafts. We put a drop of Loctite on the output shafts where they enter the gearbox and on the drive axles where they enter the output shafts. We then changed the drive gears from the stock 11 tooth gears to the 25 tooth gears. This required adding about 5 links on each side. Our spacing is 2.8" or 71mm out from the outer edge of the plastic end plates. This cut the open close cycle from around 8 minutes (sorry, don't know what minutes are in metric.) to just about 3 minutes.

Next we trimmed out the access holes for the bottom and top for the gearbox. We 3d printed a raised cover for the gearbox (Upside down in the photos) and a raised switch mount. The leads off the manual control switch would other wise hit the left side drive axle. An option would be to remote the switch down where it would be more convenient during normal operation and put a cover over the hole.