Rick Explains the Different CNC Workholding Invert-a-bolt Fastener Sizes and Functions

Rick Explains the Different CNC Workholding Invert-a-bolt Fastener Sizes and Functions

Hey guys, its Rick at Elijah Tooling. This is gonna take longer than 2 minutes so I’m not gonna do that whole thing, but we had a request recently from somebody who asked us “what do you use all with all those fasteners for? What is the point of having all of these different fasteners?” So I’m just going to go through it. I am going to try to make it as quick as possible, but I am going to try to give you some ideas as to why you might use a particular fastener. 

AA02-015-021 1/2" Invert-a-bolt Fastener "The Classic Fastener"

I’m going to start today with this one. Because this, we call this the classic fastener and it is the most sold product that we have. I also want you to notice that sometimes you’re gonna have some coloration to your parts, so don’t think that we’re doing anything wrong, you can see that some of them have this brownish coloration. Actually, that’s a result of a secondary process that is proprietary, so we don’t disclose what it is, but it’s not really a process in which the colors are gonna come out the same every time. So, I think about it like, maybe, buying a leather coat, it’s a nice high-quality product, but sometimes it looks a little bit different from time to time. What do we use this for?  Well this fastener has a 1-inch outer body, a 1/2" 13 stud that comes up into your part or whatever you’re holding.

You can see that there are several fasteners here that have the same body. That was our goal when we made these, that we would have common fasteners that would fit inside this hole size. So, you can see right here, these two are common and this one is common with several of the fasteners. So this is one of the reasons why we have the different housing sizes. So, for example with the 1 ¼" housing we have a 5/8" stud and we have a ½" stud. In the 1" body we have a half inch stud and we have a 3/8" stud, and we also have some variations of ½".


So, let’s talk about what the classic fasteners used for—it’s used for just about everything and that’s why we sell so many of these.

People will use them for aluminum, a lot of high-speed machining is done holding the parts with this. It’s also used with titanium and steels, and I’ve heard it to be used with just about any material. That half inch stud is very adequate for most applications. But when you’ve got an application where you need more holding force, then we want to move to say the 5/8". And again, you can have your fixture plate set up for 5/8" and you go “oh well I don’t really need that after all”, so you can swap it out with the ½" and it’s the same idea here as well.


So, this fastener has 5/16" hex in it. Which means it can develop significantly greater torque than the one that has ¼". So, check out our website for the specs on that. I want to say that this is like 100 lb/ft and this is 45lb/ft. The bottom line is how much force you can hold with these fasteners or how much weight or whatever it is you are trying to hold is entirely dependent on the hex size. Now that’s when we start talking about something like this.

CNC Workholding Fastener

ELT-A-0875-021 7/8" Invert-a-bolt Fastener

This is the biggest thing we make it is a 7/8" 14 thread and it has a 3/8"s hex in it. So, with this big boy we think in terms of 30,000+ lbs. You want to hold a building? This is your man.

So, lets go through. We talked about the classic, then we have a modification of the classic which is the AA02-015-121 which has basically just a shorter stick out. That’s all it is. It’s going to allow you to use a thinner plate size than you would with this one.

cnc workholding fastener


Then we have of course the premium fastener, we have a whole video on this particular fastener. It’s similar to the classic, but you can already see that it’s got some changes to it, got a different number of holes in the front, it’s also got a seal in the back of this, and the back of it looks different too. So, this is a premium upgrade from this.

Cnc Workholding Fastener


Then we have 3/8", so here’s where you might consider, "hey I might want to use a smaller size if you’re trying to save material", you can get a little bit closer to your tabbing-- when you’re tabbing your picture frames.


And then of course we have this kind of small little guy-- he is going to have the same holding force as this one. They are both 3/8" 16" and they both use a 3/16" hex. So, force wise these can hold the same thing, but the thing that is nice about this fastener this is an AA07 body style, the thing that is nice about this fastener is that you can make a much denser pattern with it. It can go in more places, in other words. Now one thing about it is that is doesn’t have a lot of stick out, so I still thing that kind of more of a medium or light duty because you’re gonna be holding something by just a few threads. Admittedly, I have heard of people actually running titanium parts with this. Cheers to them, but anyway that’s the way I think of that particular fastener. Light-medium duty.

Cnc Workholding Clamp Fastener


3/8" is always going to be like medium duty, the ½" heavier duty, and then you’re 5/8" and of course your 7/8" really heavy-duty holding power.


Now, I do have another fastener here that looks a lot like the classic if you put them up here together. You may not be able to tell the difference, but the reality is this is an all metric fastener-- it has a metric thread on the outside, it has a metric thread on the stud, and it has a M6 hex wrench bit it’s driving here. So, if you need a metric solution, then this is your fastener. It’s called an IVB-M12x1.75-021 by 1.75 that’s the pitch on the threads.


What have we got left?


We have the t-slot fasteners, and they are very similar to the classic in that they have a ½" 13 stud, they have a ¼" hex, but you probably-- or you may have noticed when I picked it up this is a quarter turn, this one as well is a quarter turn fastener. This is used in and M16 or an M18 slot. So, this allows you to use the fastener directly without screwing it into a fixture plate. So, that’s what’s cool about them. Holding power is medium to heavy holding power.

T-slot fastener


So, that is kind of the scope of our standardized work inventory stock fasteners.

Then I just wanted to take a second to talk about parts we call “discontinued”, but what it really means is we don’t stock them—but we make them. So, I thought I would just run these by you, just in case you are that customer that we are going to be able to sell thousands of them to and then they will move over to this category.

Invert-a-bolt hybrid fastener

So, for example this one is a hybrid. We call it a hybrid because it has an English thread on the outside but a metric thread on the inside. So, this is an M12 by 1.75 and has an M6 hex. There’s two of them that stand up like this and you can see that they’ve got this quite a lot more engagement than these other ones. And so, these two fasteners are very similar, except for one of them has more engagement than the others. I have to stick it up like that, but you can see that one is 15 mm engagement, and one is 20mm engagement. These are the O71s and the O81s, they have the same 1-inch hex and a 1-inch 12 outside thread, but they’re taller. We have a particular customer that loves those and we love selling them to them! They have been using them. I believe they’re used on skins, but anyway… Not human skins, aircraft skins.

discontinued metric fastener

So, lets talk about this is another metric fastener an M16 fastener and it is again. It’s in a, this is an all metric fastener, as well as a metric outside body M16. Discontinued, but the idea here is that we make these things. The only qualification that we have is that you’ve gotta buy 100 of them if you want us to make one that we don’t regularly stock.


Here is a much bigger 5/8th's and this particular fastener was created to go into t-slot fixtures, so that’s interesting. It was in essence a direct connect to a plate from the t-slot fixture. Let’s see, this is the 031 and so its very similar to the 021 except for this one has the 5/16" hex, so it creates more torque like I said. This has a ¼" hex. So, the 031 is 5/8" but with a 1/4" hex.

And we have, what do we have here, this is another hybrid in which we had a M6 stud, I’m sorry, an M6 hex, with an M12 stud, but it has a 1-inch body on the outside, English/metric, so very similar to this one, English/metric, except that it is the same height as the classic. And its part number is AA02-330-021.

And the last one that I want to show you is constrained in the sense that it’s a shorty. I think of it as a shorty and it sits in a 1-inch plate. And one of the things that I forgot to mention here is these will go in a 1 ¼ inch plate, and these will go in a 1 ½ inch plate. This is the only fastener that we have that goes into a 1-inch plate. It has a half twenty stud, so it’s got more thread and it has the 1-inch 12 outside thread. But here’s the thing, but we in the very near future are going to be redesigning this to make it a quarter turn product, so we will be able to incorporate some of the new features that we have: quarter turns, some of the new features as far as materials that we changed here, for the fastener that goes into the 1-inch plate. So, it’s an AA02-005-001. It will be converted to a -021, will be its designation. So, anyway, that one gets sold a lot too, surprisingly, that’s the funny thing about these discontinued products. We tend to sell or resell them; it’s just that we don’t have the quantities that we would like to see for a stocked item.

I hope this has been informative for you, if you have any other questions, I am happy to answer them. This was specifically a request that we received. If you have any requests for us, we would love to answer those, and they might get on the video!

Hey, until next time!

-Rick Miller 

Chief Executive Officer at Elijah Tooling


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