Suggestions for electronics mounting hardware?

[ClarkusAurelius]

I am starting to get into electronics and need some help finding mounting hardware for mounting to my sleds. Right now I have a mini GPS from Eggtimer but I'm thinking about trying dual-deploy soon and might get other electronics. Any suggestions for a good kit that has multiple sizes/lengths etc.? My struggle is that places like McMaster-Carr have great products but I don't want or need 100 of something. I've looked locally and can't find anything in the sizes I need. Seems like most electronics use 4-40 mounting holes? I've looked around on here an haven't found any suggestions I think might work. I see some options on Amazon which I'm sure are mostly garbage but for what I'm doing right now would be more than adequate, just need a little guidance to select the right thing.

 

[cls]

sparkfun.com has a few 4-40 standoffs, etc. adafruit.com probably does too. jameco.com has all of it and more. I just went to the local hardware store, made my own assortment of 4-40 machine screws, nuts, washers, and coupling nuts. hard to know what you really need, especially when starting out.

1/4" and 3/8" standoffs seem to be enough for rocketry electronics. I have never used the 1/2" and longer ones. seems like most rocketry electronics come with the right standoffs?

BTW there is some metric size (3mm?) that is just a little smaller than #4. the new RPi Zeros use it. very annoying!!

 

[lr64]

I notice that some McMaster-Carr mounting hardware comes one piece at a time, but they're probably cheaper at Digikey.

There's an outfit called Micro-Fasteners, though I haven't bought anything from them. I think they cater mostly to the RC hobby market, or at least they have advertised in those places. Good for screws, washers, etc.

M3 threads are just a little larger than #4, M2.5 are about .014" smaller. Maybe a #4 screw can almost fit in a hole intended for a 2.5mm screw with generous clearance. #2 and M2 are annoyingly close. An M2 screw can almost work with a #2 nut until vibration starts. M5 and #10 are annoyingly close, too. I don't remember if it's 10-24 or 10-32 that almost fits.

I don't know where you can buy small numbers of them, but if you don't like using thread lockers on everything, you might try square cone washers or belleville washers, which can keep things tight even if there's a bit of expansion or contraction. You can get assemblies called SEMS, where a lockwasher, square cone washer, etc. stays retained on the screw. You can also get nylon insert locknuts, which are great as long as you don't use them too many times. You can also get screws with "patches" or coatings that will make them more resistant to vibration. The patches are little bits of plastic set in holes that are a bit more snug than the rest of the thread. One coating is called Vibra-Tite. We used to use that stuff at one place I worked, and at other places I've seen hardware that had coatings which looked similar. Again, I imagine that these work best the first few times and then degrade. Unlike thread lockers, something like Vibra-Tite doesn't make it hard to unscrew the fasteners.

A lot of the fasteners I use come from a grab bag or assortment I got from one of the surplus places. A bit wasteful, as I will probably only ever use a couple of percent by weight. Probably All Electronics, but they are defunct. Other surplus places are Aretronics (where some people from All Electronics went), Electronic Goldmine, and American Science and Surplus.

 

[Sooner Boomer]

#4-40 machine screws and nuts are fairly easy to find (Amazon, local hobby shop), as are plastic and aluminum round and hex standoffs -
https://theelectronicgoldmine.com/products/g25175?_pos=6&_sid=e14a7ffa6&_ss=r
they have more #4-40 hardware. You can make your own standoffs and hardware. A tap set at Ace is about $20. Mine came with a drill bit and a tap for #4-40 to #10. I use Evergreen Plastic tubing to make standoffs. You can also use stacked nuts. Something like this ...

 

[cerving]

We recommend that you isolate all metal hardware from the PC boards using fiber or Nylon washers, or use Nylon hardware. If you look at Sooner Boomer' Eggtimer Classic mounting, you'll see those nuts very close to pads on the board, creating a potential short... putting Nylon washers against the board prevents that.

 

[Steve Shannon]

Missileworks sells kits of standoffs.

 

[KenECoyote]

I've cut up the protective sleeve from the e-matches and used them as standoffs.

I've also used small stirer straws and rubber tubing. Lots of alternatives that aren't conductive.

I often mount my electronics onto wood sleds and I think I got the last screws from Home Depot (pretty much the smallest ones since the heads can't be too big if mounting some Egg stuff). Bag of screws was under 2 bucks.

 

[Sooner Boomer]

We recommend that you isolate all metal hardware from the PC boards using fiber or Nylon washers, or use Nylon hardware. If you look at Sooner Boomer' Eggtimer Classic mounting, you'll see those nuts very close to pads on the board, creating a potential short... putting Nylon washers against the board prevents that.

There's actually plenty of clearance, but Cris is right. When in doubt, use a nylon screw/nut, or insulating washers on *both* sides of the board.

 

[tsmith1315]

I thread the mounting holes in the sled and tighten nylon screws directly into it, with nylon spacers underneath.

 

[nevadagold]

https://boltdepot.com/
I buy packs of 100 in various sizes from bolt depot. Cost less than buying small qty at Home Depot or Ace.

for standoffs: https://www.amazon.com/dp/B00MND8DY2?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[kjhambrick]

@ClarkusAurelius --

There are three Grainger locations in Phoenix.

They don't have as large an inventory as McMaster-Carr but ...

You can save a lot on shipping if Grainger has what you need and you don't mind the drive to pick up your order from the store.

HTH

-- kjh

 

[charles.garnes]

Apogee sells an electronics mounting kit and drill and tap set

 

[WizardOfBoz]

I bought some 1/4 (od) tubing from the hardward store and cut my own standoffs. But I didn't have the small 4-40 mounting screws and so it became a cluster ____. Now being held down by ty-wraps.
So I bought some 1/4 and 3/4 nylon hex standoffs and 4/40 screws from Digikey. I did this because the rocketry standoffs didn't seem to have screws that were long enough.... Expensive, but I have 25 of each standoff and 100 screws. I suppose I can buy some 4-40 metal screws as well.
When they arrive, I'm moving my Eggtimer altimeter to a new mount. I use a paint stirrer stick from Lowes, cut down to a useable size. I glue a piece of wood on as a shelf for the battery and hold that with ty-wraps. The idea is that I can shove an altimeter in just about any rocket bigger than 1.5" diameter.
I'll post a pic of the result when I get the hardware.

 

[SolarYellow]

You can get small fasteners in reasonable quantities for cheap on AliExpress.com. It's all metric, but I don't have a problem with that. Keeps me from having to look up number screw diameters again and again.

 

[troj]

Bdale Garbee also sells reasonably priced ($3) nylon mounting sets on his web store.

Lots of options. I can find a lot of the same parts at the local ACE hardware store, as well.

 

[Zbench]

The #4-40 or #2-56 screws in nylon work great. I believe many use them for nose cone retention and are available in packs of 100 from many vendors like Apogee. I like to mount in wood and just drill with the appropriate sized drill and then thread with a tap.

To toughen it up a bit, apply a judicious amount of CA glue and hit with accelerant and then retread with the tap after it cures. Taps that small are cheap and available on Amazon:

https://www.amazon.com/Drill-Americ...p&qid=1720809939&sprefix=#2-56,aps,126&sr=8-3


https://www.amazon.com/BOSCH-BDT440...id=1720810023&sprefix=4-40+tap,aps,188&sr=8-3

 

[tsmith1315]

The #4-40 or #2-56 screws in nylon work great. I believe many use them for nose cone retention and are available in packs of 100 from many vendors like Apogee

I use these:

https://csrocketry.com/recovery-supplies/shear-pins.html

 

[kramer714]

do you have or have access to a 3d printer? Even if it is mounted to a 'sled' it is pretty easy to make a standoff plate, or heck even a full sled.

If you need it, I have the 'bolt patterns' modeled for most flavors of altimeters. Plus i have STL files for many combos of altimeter and diameter.



Mike K

 

[Wayco]

Perfectflite sells these for $1.79:
https://perfectflitedirect.com/products/Mounting-hardware.html

 

[Zbench]

Perfectflite sells these for $1.79:
https://perfectflitedirect.com/products/Mounting-hardware.html

It’s metal though. The nylon screws used for DD have never let me down and are not conductive

 

[OverTheTop]

Keystone Electronics manufacture a great range of hardware. Digikey I think is a major stockist for them. You can usually buy small quantities there.

Check out the Keystone range. They have some good stuff.

 

[Wayco]

It’s metal though. The nylon screws used for DD have never let me down and are not conductive

I'm glad that you have had no failures with nylon screws and nuts. I can't say the same. They really don't earn the title "hardware" in my mind.
I won't go over all the failures I have had with them, but there were enough to take them off my list of items I use in my avbays. I would say that the standoffs I get from perfectflite have never let me down. Most of my dual deploy rockets have Stratologgers in them for the same reason. If I did have an issue with shorting out an altimeter or any other circuit board, I would check out the circuit board first.
Sharon and I fly a lot of dual deploy rockets, having two L3 fliers in the family gives us a lot of opportunities to evaluate the stuff we use. I would love to hear from anyone who has had an issue with metal standoffs, and will adjust my attitude based on real life instances of such failures. Or not, I'm an old guy and it's hard to change my mind without documented facts to prove otherwise.

 

[Titan II]

Never had issue with metal. I drill and tap sled for 4-40 screws and frequently use cut e-match sleeves like noted in post 7 for stand-offs.

 

[pbahorich]

I typically buy my small screws from a local Ace hardware store. They have an entire aisle of fasteners including 4-40, 2-56 and smaller. If you can't find it ask since they have people available and eager to help. Much different than the typical warehouse style hardware stores most common these days. You can buy one at a time out of little drawers. They even carry aluminum nuts including the 1/4-20 I sometimes use on my av-bays.

 

[SolarYellow]

It’s metal though. The nylon screws used for DD have never let me down and are not conductive

That may depend on what kinds of motors and rockets you fly. I would not use nylon with high acceleration. A shortish 38mm airframe with an I200 or even H180 would make me very nervous using nylon screws.

 

[jhornsby3]

I used the nylon 2mm and 2,5mm standoff kits from Amazon. Worked great for all of my Eggtimer stuff. They hold tight. Are cheap. And when I had a rocket come in ballistic because of failed J-Teks, the stand offs sheared saving the electronics.

 

[ClarkusAurelius]

Thank you all for all the great suggestions! It turns out that Ace IS the place with the helpful hardware folks. I have found it difficult to know what to get when I don't even know what I'm going to need in the future. Part of my problem is that I need to see these items in person to get a gauge of what I need. I went to my local Ace and the were very helpful and I found all of the 4-40 hardware I needed including nylon washers and standoffs for a few bucks. They have even smaller stuff and metric so I think that will set me up for now. I have an Ace that's only a few minutes from my house that I've been to but hadn't thought to check the nuts and bolts. Had a pretty crappy day today so reading all of your helpful suggestions and finding the parts I needed was a little boost for me.

 

[cerving]

I used the nylon 2mm and 2,5mm standoff kits from Amazon. Worked great for all of my Eggtimer stuff. They hold tight. Are cheap. And when I had a rocket come in ballistic because of failed J-Teks, the stand offs sheared saving the electronics.

That's one reason I like Nylon hardware... it will shear instead of your circuit board if you land hard.

 

[Handeman]

That's one reason I like Nylon hardware... it will shear instead of your circuit board if you land hard.

I understand your thinking about using nylon mounting screws, but do you really want the mounting screws to shear and let the circuit board fly around inside the bay and pulling on all the wire connection points?

I had a lawndart once where the mounting board broke between the altimeter and the battery where the rocket folded. The 9V battery was poured out of the remains of the av-bay in about a dozen pieces. The altimeter stayed attached to the mounting board and I'm still using it 10+ years later. If it had come loose, I'm sure it would have been poured out of the av-bay with the battery, or at the very least, ripped the wire connectors off the board.

 

[SolarYellow]

Thank you all for all the great suggestions! It turns out that Ace IS the place with the helpful hardware folks. I have found it difficult to know what to get when I don't even know what I'm going to need in the future. Part of my problem is that I need to see these items in person to get a gauge of what I need. I went to my local Ace and the were very helpful and I found all of the 4-40 hardware I needed including nylon washers and standoffs for a few bucks. They have even smaller stuff and metric so I think that will set me up for now. I have an Ace that's only a few minutes from my house that I've been to but hadn't thought to check the nuts and bolts. Had a pretty crappy day today so reading all of your helpful suggestions and finding the parts I needed was a little boost for me.

Lots of people like their spray paint, too.