Rivnut Tool

[Bpk9p4]

My team has been using rivnuts for the past couple years and we love them. I was wondering if any other teams use them and if so what tool do they use to put them in. We currently use a hand powered rivnut gun https://www.grainger.com/product/POP...AS01?$smthumb$

It works great but is hard on your hands after a while and prone to lots of error. Has anyone used an power tool rivnut gun?

[topgun]

Think about what the rivnut is doing, and how you can make your own tool.

Drill a close fit clearance hole for the size you are using in a piece of thicker steel. Put a bolt through the hole, screw the rivnut on the other side so it's tight. Place the rivnut in the mounting hole where you want it and use a powered drill to turn the bolt. Tightening the bolt will pull the rivnut bending portion tight to the mounting hole.

[nirmatt_1690]

If we need to put more than just a few, we use a pneumatic gun.

[Jon Stratis]

We've always used a wrench-driven tool, McMaster PN 96349A380.

[ollien]

Originally Posted by Jon Stratis

We've always used a wrench-driven tool, McMaster PN 96349A380.

Does this work for the non-self aligning rivet nuts?

[GeeTwo]

Initial results of rivnut pullout testing: (Due to budget constraints, only doing 10-32 steel thin-wall large flange inserts this year; if we're happy with the results, we'll expand our options next year).

I drilled a 19/64" hole using a drill press and inserted an SKL 10-32-130 steel thin nut with large flange into each of three pieces of aluminium:

• 3/4" x 1/8" bar (Ace Hardware, looks like 6061, pictured above)
• 0.1" wall Vex 1"x1" tubing (I used a factory hole as a pilot)
• ~1/16" wall channel (sold as 1/2" plywood edging, also pictured)

I then centered a 1/2" hex nut over the rivnut (large enough hole for the rivet to pass freely), added three steel 1/16" thick fender washers, and inserted a 1" stainless 10-32 cap screw (allen drive). I did not have a 3/8" to 1/4" adapter handy, so I could not use my torque wrench, so I used my shortest 1/4" ratchet driver. In each case, I tightened with my index finger and thumb against the adapter socket. In each case, I was using roughly the same amount of torque (to within perhaps 50%) at failure. I shall repeat these tests with an adapter so I can measure torque, and with the longer rivnuts in coming days.

Each setup reached normal (tee-handle) torque with no noticeable deformation or stress relief (that is, yielding or breakage) of any part. On applying additional torque to failure, each case had a somewhat different failure mode. Consult the attached image for clarification.

1/8" bar - the bar did not noticeably deform on a large scale, but the small crimped area of the rivnut reamed its way through the aluminum to a depth of about 0.1" (I was able to put the versaframe tubing wall between the stock and rivet flange with no difficulty) when the machine screw sheared at the head end of the threads. Because the failure was through reaming not bending, I expect that if the force had not been applied normally to the surface, far less force would have been required to pull the insert from the material. I definitely intend that we shall use the longer .225 rivets for aluminum of this thickness. In steel, it is entirely possible that the stock would have held the rivnut to a rather greater pull out force.

0.1" Vex tubing: The crimped area of the rivnut was adequate to hold in the aluminum. However, the wall of the tubing was deformed (volcano style) until the hole was large enough for the insert to be pulled completely clear of the tubing. It appears that a longer rivnut would provide minimal additional capacity, though I shall test this when the longer inserts arrive.

1/16" plywood edging: The aluminum yielded "volcano style" to a height of 1/16" on one side and 7/64" on the other, then the machine screw broke at the top of the treads on the insert, presumably from the bending torque.

Curiously, the VF thick wall tubing deformed much farther than the hardware store grade aluminum bar and plywood edging.

Edit/Addition:

Originally Posted by Fusion_Clint

Ok,

Having never used a rivnut before, I started looking on youtube and came across this. https://youtu.be/3Og-tHIR_0I?t=66

For those of you that have rivnut experience, what are the cons of using this method?

Originally Posted by RoboChair

Installation is time consuming and rather annoying. Anything larger than a #10 rivnut takes some considerable muscle and/or the use of a cheater bar(s).

I will add testing this method (with 10-32 thin wall steel inserts) to my next round of tests. It seems to me that you can get better torque with hex head bolts 1/4"-20 and larger than with any normal #12 and smaller heads. I am also concerned that applying torque to the threaded part of the insert during the crimp might result in a weaker/twisted crimp.

[cbale2000]

Not to get too off-topic, but as someone who had never even heard of Rivnuts before seeing this thread, I'm curious... What are the actual benefits of using a Rivnut? Most of the application examples I've seen so far look like it would have been far simpler and faster to just use a regular bolt+locknut.
You don't appear to be saving space since the rivnuts still stick out, and for that matter the rivnuts also appear to create an additional space on the front side of the material that wouldn't have otherwise been there.

Am I missing something here?

[Ari423]

Originally Posted by cbale2000

Not to get too off-topic, but as someone who had never even heard of Rivnuts before seeing this thread, I'm curious... What are the actual benefits of using a Rivnut? Most of the application examples I've seen so far look like it would have been far simpler and faster to just use a regular bolt+locknut.
You don't appear to be saving space since the rivnuts still stick out, and for that matter the rivnuts also appear to create an additional space on the front side of the material that wouldn't have otherwise been there.

Am I missing something here?

The way I understand it, the point is that the nut stays there when you remove the bolt, so it's better if the nut would be in a hard to reach position. Essentially, it lets you tap a threaded hole into a piece of sheet metal that would otherwise be too thin to tap.

My team has used rivnuts a few times in the past. This year we used them to attach our main breaker because the frame member we wanted to attach it to was surrounded by other components so we couldn't get a wrench behind it to hold a nut. There was probably another way that would have worked just as well, but we have found that aluminum rivnuts work well and are fairly easy to install for low-load applications. We have also used steel rivnuts for higher load applications, but they tend to be harder to install (and remove when they inevitably break) and not be as strong as a regular nut.

[FrankJ]

Originally Posted by cbale2000

Not to get too off-topic, but as someone who had never even heard of Rivnuts before seeing this thread, I'm curious... What are the actual benefits of using a Rivnut? Most of the application examples I've seen so far look like it would have been far simpler and faster to just use a regular bolt+locknut.

Lots of applications where you cannot get to the back side to use a nut and the material is too thin to thread.

[RoboChair]

Originally Posted by GeeTwo

• 3/4" x 1/8" bar (Ace Hardware, looks like 6061, pictured above)
• 0.1" wall Vex 1"x1" tubing (I used a factory hole as a pilot)
• ~1/16" wall channel (sold as 1/2" plywood edging, also pictured)

If your ACE is selling 6061, good for them! But I would bet you $10 that it's 6063 and I HATE that stuff, super gummy and nowhere near as stiff.

Please don't buy hardware store aluminum. Please.

[GeeTwo]

Originally Posted by RoboChair

If your ACE is selling 6061, good for them! But I would bet you $10 that it's 6063 and I HATE that stuff, super gummy and nowhere near as stiff.

Please don't buy hardware store aluminum. Please.

This was all just scraps from my garage. For structural robot parts above the drive train, we use versa frame and 6061 channel (and a small amount of tubing) usually from Bayou Metals. When I do the more complete testing, I'll be sure to get some 6061 scraps from the recycle bin at the robot workshop.

Gummy? Would you please elaborate?

[Munchskull]

Originally Posted by GeeTwo

Gummy? Would you please elaborate?

When you machine 6063 Aluminum the chips tend to reform and stick on your end mills and other cutters.

[GeeTwo]

The longer (.225") rivnuts arrived a couple of days ago, and I spent some time today in testing. I'm planning a white paper to be out before kickoff, but here's the gouge:

• I began by inserting the machine screw "dry", and tightening with a T-handle (I did not use arm strength; with limited hand strength, I can get to about 2 ft-lb with a T-handle). Unless that failed, I then disassembled the test unit, sprayed the threads with WD-40, and re-assembled for higher torque tests. All tests utilized new (or lightly stressed) stainless 10-32x1" allen-cap-head machine screws; I expect these to be a bit stronger and more consistent than "plain steel" machine screws.
• In 1/16" 6063 aluminum, I only tried the short rivnuts, because the longer ones would clearly not grip. The maximum torque supported with lubricated threads was 4 ft-lb, which theoretically corresponds to a clamp load of over 2200 pounds, which should have broken the machine screw. However, the failure mode was the rivnut pulling out of the aluminum through a "volcano" deformation.
• In 0.1" versaframe tubing (6061), the short rivnut performed sililarly to the 1/16" case above. The long rivnut secured tightly originally, and supported a torque of up to 6.5 ft-lb for several full revolutions. Failure was due to shearing of the machine screw near the head. After failure, there was definite visible deformation of the surface (~1/16"), and the rivnut was loose in the hole after failure of the screw.
• In 1/8" 6061-T5 C-channel, the short rivnut pulled out easily with about 2ft-lb of "dry" torque (provided by an Allen T-handle; torque estimated by hand). Note that in the preliminary test, I had applied far greater clamping force to the tool than should be required; in this case, I applied forces similar to those necessary to clamp in thinner material.
• In 1/8" 6061-T5 C-channel, the longer rivnut supported a maximum torque of about 6 to 6.5 ft lb. Failure was due to shearing of the machine screw, and there was no discernible deformation of the aluminum.
• In 1/8" 5052 plate (particularly, an AM-14U2 end plate), the behavior closely matched the 6061-T5 C-channel above in both cases.

Bottom line: Use the longer (.225) rivnuts in 0.1" and thicker material. TBD if a spacer or gusset will make mounts in VF thick wall tubing more secure.

Caveats: Due to budget limitations, we decided to try rivnuts this year in a very limited case. As we use 10-32 bolts for the majority of our structural work, this was the single thread we decided to experiment with this year.

Originally Posted by Munchskull

When you machine 6063 Aluminum the chips tend to reform and stick on your end mills and other cutters.

Thanks. I have noted that sometimes holes drilled in 6063 are not as large as the drill bit would indicate; I presume this is somehow related to "gumminess".

[Fusion_Clint]

Geetwo,

Help me understand your test. It seems that you are torquing the screw in the mounted rivnet to see when it will fail/stripout, is this the case?

Considering that the recommended torque for a typical 10X32 screw application is in the 30 In Lbs range, reaching from 48 to 80 In Lbs in most of the material is fairly impressive. http://www.federalscrewproducts.com/torque-chart.htm

[GeeTwo]

Originally Posted by Fusion_Clint

Geetwo,

Help me understand your test. It seems that you are torquing the screw in the mounted rivnet to see when it will fail/stripout, is this the case?

Considering that the recommended torque for a typical 10X32 screw application is in the 30 In Lbs range, reaching from 48 to 80 In Lbs in most of the material is fairly impressive. http://www.federalscrewproducts.com/torque-chart.htm

Yes. As described several posts above, I was using a 1/2" nut and three washers against the stock so that I was pulling on the rivnut, not simply tightening against the flange.

I had already noticed that the stainless machine screws supported several times the rated torque, even a good bit over grade 8. What I found even more impressive was that all of the shear failures occurred at the same torque to within about 10% (my measuring precision with this tool at that torque). Further the torque on the threaded portion was probably quite a bit less than the torque I was applying, due to friction between the head of the screw and the large washers.