This category is kind of a catch-all for all kinds of 'non-project' stuff, like reference stuff that I find helpful when designing, or a short write up on a general technical topic, like designing with flexural elements or calibrating a displacement sensor...or at least it will be as I populate it :)
If you’re working with thermoplastics (looking at you FDM/FFF printers!) these can be a great option when a fastened joint is called for.
As long as you have good, straight on access to the hole you are wanting to make threaded, heat sets are pretty darn easy to get a functional interface. And with some good practices and a little bit of helpful tooling accumulated along the way it gets easier and faster each time you do it.
The basic idea is that you replace your soldering iron’s tip….oh, yeah, you’ll need a soldering iron if you don’t already have one (don’t worry, it is just a tip change, so zero issue using your regular electronics’ hot pointy stick.) The replacement tip is a cylindrical post, that has an OD slightly smaller than the mininum diameter of the internal thread of the specific fastener.
The below is my go to quick reference when designing parts with heat sets. I’ve used heat sets from various companies, but have found the dimensions here to work across them equally well. I should note, I tend to be pretty conservative on the depths of holes for heat sets wherever possible. So I am less confident in the cross-compatibility claim for that parameter. But for the bore diameter and wall thicknesses I feel very comfortable designing to (kind of the “meat and potatoes” on this for me). On the conservative depths comment, it is a good idea to do so when possible, as it provides room for any overflow, etc. to move out of the way, and not build up. Getting a build up on the leading edge of the insert can quickly result in plastic getting in to and adhering to the threads.
Heat set sizing chart, from here
If you are just looking to get some inserts on hand for an occasional future need, I recommend getting some sort of variety pack like this one. Even though I tend to buy larger quantities of the sizes that I use the most (M3, M4, & M5), I continue to rebuy this set over time because I just love the convenience for one off use.
I have also bought both of these ruthex and Hilitchi assorted kits previously. While I have really been impressed with the fit and finish feel of the ruthex products in general, I still really prefer the absurdly named ‘EEEEE’ ones above :) Always nice to find examples of it NOT being ‘in a name’!
One quick additional note on a design difference I’ve noticed that does seem to group these inserts into two major categories (at least to me). And that is the presence or absence of knurling on just one end, or on both.
When I first started using these inserts, the bulk of what I seemed to find on Amazon were more in the Option B style. My sense is that this was because heat sets weren’t all that well stocked on Amazon at the time, and the ones that I WAS finding were the cheapest of the cheap, which tend to have this general geometry.
The Option A geometry is nice in that the OD of the non-knurled end is (typically) designed to fit the as-printed bore. So if your printer is making holes to size (typically holes are printed undersized and it’s not typically a nice friendly, linear relationship. But good on you if you did the work!) then you can position all of your inserts in place and then just go around and pop em in! However, if you, like me, still tend to just print undersized holes and aren’t too mad about it :) then this feature doesn’t actually work out consistently and can be a bit frustrating.
That being said, I do still prefer the Option A style, but just thought I’d share 🙂
OPTION A
OPTION B
You’ll need a soldering iron/station (well, I guess you COULD use some other hot stick, but I’ll leave that to you).
If you’re in the market for an Iron…
Not at all claiming these are the best things on the market, or even the best bang for the buck. Just examples of tools I have used and liked. If you have some better options you’d like to see get mentioned, drop it in the comments please!
~$50 - Weller 40W Soldering Station - Just a straight forward, reliable (in my experience) soldering station.
~$120 - Hakko Digital Soldering Station - This is my daily driver currently and it’s been great (only about 6 months on it thus far.) Uses a very common, T18 style tips, which also means the heat set tips below are (I think) cheapest in this style.
These folks did a good job of showing the idea, so I’m just borrowing this…
You can get these tips for a range of different soldering irons (or at least I know you can get them for T18, ST, and ET, the ones I’ve needed 🙂 ) They also come in the screw on style shown in the above image, as well as straight body versions, like the ones shown below (never actually seen them called that, just seemed like it kinda made sense)
One comment on what you’ll see below, I made the decision a while back to try to really standardize on metric fasteners wherever possible. So to that end, I have intentionally avoided adding any UN threaded options to my toolbox. No shade at my #lovin folks*, I just don’t have the first-hand info to include anything <shrug>
ADVICE - Be careful to keep the tips clean when you’re using them. It can be very easy when inserting heat sets to get some molten plastic on the tip. I recommend trying to clean the tip with the wire wool and sponge quickly and thoroughly. Plastic burning to the tip will make it much harder to get smooth release of the inserts. It also tends to be a bit of a self-reinforcing challenge, in that zones with burnt plastic coating them adhere better to fresh molten plastic, which then burns also and grows the size and depth of the defect…so on and so forth. So yeah, clean that s****….kind of goes for all of your tools :)
Soldering Tips that I have/have used
For T18/900M/ST Irons:
~$18 - ruthex M2-M8 - These are the ones I’ve been using for as long as I’ve had this Hakko iron. I really like that I can change the tip without having to actually remove the soldering tip from the iron. If you’re going to do a decent variety of thread sizes in assemblies, this is a really nice feature.
~$12 - ShineNow M2-M8 - A cheaper variant on the above. They’re fine, but I do prefer the fit and finish the slightly more expensive ones.
For ET Irons…(if anyone else also still has one)
Please note, I didn’t intentionally find some antique-looking scan for the only Imperial table I currently have in here…honest, I didn’t. I blame Google images ¯\(ツ)/¯ … But I DO find it super fuckin funny :)
https://lightningboltandsupply.com/hex-bolt-dimensions.html