Quadrature Encoder - Bonding Acetate (?) to Clear Styrene Sheeting?
xanatos
Posts: 1,120
I have printed out several quadrature encoder wheels on laser-printer transparencies - came out great. They are a little flimsy, though, so I want to bond them to some clear styrene sheeting I got from the hobby store (Evergreen Scale Models, Item # 9007, 0.015" thick (0.4mm)) - and I want the bond to be clear, and to last/not peel, not yellow, etc.
What's a good glue to use? 5 minute epoxy? Super Glue? Silicone Sealant? ... For some reason I don't feel "intuitively secure" with any of those choices... :-)
Thanks!
Dave
What's a good glue to use? 5 minute epoxy? Super Glue? Silicone Sealant? ... For some reason I don't feel "intuitively secure" with any of those choices... :-)
Thanks!
Dave
Comments
Transparencies are glossy & reflective. Are you using reflective sensors? If so, did you test them together yet? Many times IR doesn't behave like you expect.
Edit: you did say clear, so likely you're using a break beam sensor. The Scotch 77 glue and translucent double sided tape won't be perfectly clear, but may work for you.
Yes, break-beam sensor (OPTEK OPB826, DigiKey), IR. Hoping the toner isn't transparent to IR... :-)
Dave
If you'd like, email me your artwork and a mailing address, and I'll cut one that's truly opaque on my laser cutter. No charge.
-Phil
You may be surprised. 940 nm IR blasts easily through black opaque-appearing photographic negatives (the exposed end bits after development). That stuff used to be highly sought after to filter out visible light and let IR pass through unfettered.
PS: This is all true, but I mainly replied just to use the word "unfettered" in a sentence.
Phil, you are an awesome human being! Thanks so much, I'll email you. Also - just in case anyone else on the forum can benefit from the quadrature encoder patterns I'm using, I'm uploading the file here. One file is the small 1" round, the other are 2" rounds... hopefully someone can benefit. NOTE: Apparently the forum re-res'd the file... the original was 300DPI, with a single small wheel being 1", and the larger wheels being 2". If anyone wants the full res, PM me.
Dave
These patterns were generated (singly) by WheelEncoderGenerator.exe and Codewheel.exe, both available as free downloads. I just replicated them in PhotoShop for this project since I thought there was a chance I might mees a few up :-)
Pic attached... I had NO IDEA how I was going to attach these things, and saw some hugely bulky arrangements on a few sites... this is sleek & sexy! :-) OK, I'm a geek, sorry :-)
Dave
I am just curious, how are you going to do this. Could your method be used to generate PCB positives?
Bruce
Dave
BTW, unless your IR sensor filters for only IR any visible LED would work.
Duane J
Could you post a photo just the item that you got from Ace Hardware so I know what I am looking for Thanks
They're called Tee Nuts. The one pictured above in use on my encoder wheel assembly is "1/2" - but it measures about 0.56", and I would guess that measurement may vary by manufacturer and batch - they don't appear to be a work of precision engineering, but they can be used in one! :-)
Picture attached here is of a single Tee Nut like that I used above. They come in 1/2", 3/4" 1", etc. The 1-72 screws work perfectly in the pre-drilled brad holes on the 1/2" version (and the center shaft hole is pre-tapped to 6-32 threads)... 2-56 fits the 3/4", and I'd guess 4-40 on the 1".
I had originally bought a dual-position optical interruptor sensor for this project and that housing does indeed filter for only IR, but I have 1000+ green surface-mount LEDs looking for something to do, and I'm thinking that they would work very well in this application... and eliminate the issues around IR transmission through a printer copy. Phil Pilgrim has made me a truly wonderful offer, cutting out a few of these for me out of Delrin on his laser cutter (which will also eliminate any IR transmission issues!) and those will probably be what I use in the actual item I'm trying to complete by 11/1. But after that... I want to get more into robotics, and I see a lot of these types of things in my future, plus visible light streaming out of things like these just plain looks cool... :-)
Dave
The disc itself is 1/32" acetal. I've added a hub, made from 1/16" acetal. The disc can be sandwiched between the hub and T-nut. Two hole circles are included in each part: one set for a #1 screw OD and one set for the root diameter of #1 self-threading screws. The T-nut and hub can be installed as I've shown above or the other way with the hub on the outside. The advantage to having the hub on the inside is that the tips of the self-threading screws face the shaft, rather than outwards. In order to provide additional clearance for the T-nut and hub, I've increased the OD of the disc to 1 3/8". That separates the ID of the inside track from the hub enough that the hub doesn't have to squeeze into the sensor frame.
-Phil
Dave
-Phil
And.....I love T-Nuts also.
Fantastic quality - and not only that, I discovered that the transparency black-areas weren't a problem - they block IR just fine. The real problem is that SO DO THE CLEAR AREAS! :-)
Ya saved me, Phil! Thank you so much!
The pictures show the encoder wheel mounted to a Tee Nut and shaft with a collar that serves as a bearing. You can also see the dual-sensor optical interruptor I'm using. The system is programmed and reports in feet and inches perfectly... now I have to make the PC Boards... :-)
Nice, nice work, Phil!
Dave
-Phil