NeoPixel string blade assembly Part II - Wrapping May 6, 2017 15:24:34 GMT -5 Corran Horn, Wildcard, and 4 more like this
Post by naigon on May 6, 2017 15:24:34 GMT -5
NeoPixel/WS2812 string blade assembly part II - Wrapping/diffusion
How to properly install a string/strip into a blade
This is the second part of the NeoPixel tutorial, though this actually works for any type of string blade, be it NeoPixel 5mm strings, NeoPixel “skinny” strips, and even old-style ladder strings.
- Male ¼” Stereo jack
- Male 1/8” Stereo jack
- 330ohm 1/4watt resistor
- 28 gauge wire, Teflon coated/PTFE
- 1/16” packing foam completely white
- Clear gift wrap
- Scotch or similar clear tape
- 40” LED diffuser
- 1” thin walled blade tube
- 1” blade tip
Step 1 – Add the connector
The male connector will need to be added to the blade. This will be for PWR, GND, and DIN of the blade for a WS2812 style blade, OR just PWR and GND for an analogue blade. I will concentrate on the former here since that is what my products natively support.
Before you start, check if the cover for your connector fits over the entire strip assembly. If it does not, either modify it to slide over the entire thing, or push it up enough that it can be assembled in the future, as once the wires are on it can only be applied from the other end. I just cut off the skinny back of mine so the entire thing could slide over the blade.
First, I attached the 330ohm resistor directly to the DIN pin of the first LED, which is pointing straight down from the blade. I did this using some heatshrink that fit the wire. Then the other end of the resistor is connected directly to the middle pin of the connector. If using a mini connector, you might need to use a wire here as the resistor may provide too much thickness to fit in the smaller barrel.
With the resistor connected, I used a piece or red 28AWG PTFE wire, and then hooked it up to the positive rail; for the 5mm straw-hat blades, this will be the right-most rail with the DIN pin facing up. This needs to get connected to the tip or bottom most connection point of the connector.
IMPORTANT – you MUST have PWR at the tip or else it is possible that a short can occur when inserting the blade. However, if you put the male end on the saber and female end on the blade, then you need power at the BASE of the male connector, which is the outer-most connection of the female connector. I highly recommend if you are confused to use a male connector on the blade, and power should be at the tip of this, exactly as I have in this tutorial.
Then, the GND black wire was connected from the GND rail of the string, which is the left-most rail of the 5mm straw-hat string when DIN is facing up. This gets connected to the big ground connector of the ¼” male stereo or 1/8” male stereo jack.
Figure 1 - Connector completely wired. In this pic DIN is facing DOWN, so connectors look reversed. Resistor is hooked to the top-most look; GND is connected to bottom GND.
Finally, apply the cover for the male stereo jack. Mine fit right over the string after I cut off the back so I just slipped it down at the end. This is fine as we only need some material in the widest spot to act as a holder for the housing that will be made at a later step.
Figure 2 - Cover screwed on the male connector. Notice that the back has been cut off so I can easily slide it over the string.
Step 2 – Wrap the string/strip in foam
Once the blade is completed with the connector, the first step is to wrap it up in the thin foam. The main reason for this step is to protect the strip from impact; this foam should NOT be considered a source of diffusion, as foam diffuses unevenly and harshly. This is way I do NOT recommend using the MR/Hasbro foam of the foam sold at TCSS as it is very thick and is too aggressive in the diffusion.
First lay your blade out on the floor, and cut a piece of foam to length of the blade. It is okay if your foam is not as long as the entire blade, it can be pieced in one or two sections, as the next couple layers of diffusion will hide the seam.
Figure 3 - Cut the foam to match the length of the blade. It is okay to piece it in 2-3 pieces as the horizontal seams will be hidden by the outher diffusion layes, as long as the two are pieced tightly together.
Once it is laid out, the critical step is to get it cut the correct width. The width should be cut such that the foam wraps around the string and the vertical seam meets together when pulling tightly. It’s important that the foam be taught to prevent the string from slipping underneath the foam.
Once the foam is cut to the appropriate width and length, use the clear tape to wrap it around the string. Pull and use tape in spaces of about 4mm apart, as it is better to have it tight. The tape should be long enough to give a good hold but doesn’t need to wrap around the foam.
Figure 4 – Starting to tape the foam around the string. Notice the tape is being applied in about 4-8mm spacing, enough to keep the seam tight.
Continue down the string until the entire thing is covered in the foam. For any horizontal seams, make sure to press it up tightly to the previous piece, and use tape around the entire seam to keep it from slipping.
Figure 5 - About half-way done, with the start of the second piece. The horizontal seam is barely visible, so it will not show under the primary diffusion layers.
Step 3 – Wrap using the standard wrap.
At this point, the foam tube will be much smaller in OD than the 40” LED diffuser is in ID. To fill the space and to add a bit of secondary diffusion, the standard clear gift wrap will be used around the foam.
The hardest part about this step is finding a clean area to apply the wrap. A hard-surface is better, but I just used the carpet area in my den after a quick vacuum. Simply put the roll out, place the foam strip on top, and start rolling slowly to ensure no wrinkling and that the wrap is applied evenly at all ends. It should be fairly tight as well, but it’s not like the foam where it is critical to be insanely tight, so it is totally fine to have just a little play.
Figure 6 - Starting to wrap the string assembly in the transparent gift wrap.
I just rolled a bit and kept checking until it seemed it would be a snug fit inside the tube, and then cut off the excess. This was only like 2 ft of wrap for me. Don’t worry if this assembly is a bit loose in the blade, as the adapter added in the next step will keep the assembly from backing out of the blade.
Figure 7 - About 3/4 of the way wrapped. I was careful to make sure the ends were wrapping straight, and just kept checking with the tube until it would fit.
Finally, cut off the film when it looks like it will be a very tight fit. If at this point it won’t quite go in, you can still unroll from your assembly and cut some more until it does fit. Again, it doesn’t need to be a super tight fit as the next step will keep the assembly secure.
Step 4 – Adapter
The final step is probably the one that will need some more research for those of you that don’t own a lathe. This is to create an adapter for the connector that will lock it in place at the bottom of the blade, effectively keeping the entire thing secure.
I used delrin stock lathed down to fit the inside of the 40” LED diffuser, and then used the tailstock with the drill bits to drill a hole so the connector’s housing fit snuggly. After this, I drilled and tapped 3 4-40 set screws into the housing so I could lock the connector on it.
Now, the next step I would do a bit differently. Here I actually drilled and tapped the blade, drilled one more hole in the connector so I could use a longer screw, and then secured the final assembly this way. The issue is that the stress of the screw in the blade caused it to get hair-line cracks. Fortunately they are hidden inside the emitter when inserted but it concerns me a bit.
Figure 8 - Adapter I made on the lathe. 3 set screws at 60 degress hold this on the male 1/4" connector.
What I would do instead is just drill the blade with a bit larger hole then the 4-40 screw, insert the entire assembly, and then through that drill and tap for the 4-40 in the black adapter. This way more of the stress would be on the adapter which is thicker and can handle the load. It’s okay if there is a slight wiggle, as this is just to force the ¼” male connector from sticking in the hole when pulling the entire blade.
Figure 9 - Installed with the set screw through the blade. You can see the cracking on the blade – to prevent this I think actually just having a hole in the blade and the set screw in the adapter would be better. It won’t be able to back out once it’s installed in the saber anyways, so only needs to keep the blade from sliding up.
For those without a lathe, my hope is there will be some washer that is about the right size that could be drilled/filled by hand, but I haven't searched. I do also hope that someone that can 3d model will just model this part for both the 1/4" and 1/8" connector to fit inside the 40" diffuser, then it would be a ready part to drill and tap.
After this you should have a secured blade that is ready to plug into your saber!