Rivnut question

[Old tool guy]

I have a need to use a couple of rivnuts, and the bolt size will probably be 5/16” but could vary. Looking at the chart on the rivnut site, for 5/16” bolt the hole in the material needs to be 0.414 to 0.423”. Looking at a drill bit chart, the only size that works would be 27/64” = 0.4219. How critical is the hole size for diy work? Could I use 11 mm bit (0.4331)?

 

[Nutria]

I've used rivnuts some, but not a lot. My guess is that the the slightly oversize hole would be ok-- unless a lot of force would be applied to the rivnut in application.

 

[rlitman]

How much "hole fill" capacity the rivnut has depends on the thickness of the material and the type of rivnut in use. 27/64" is in 115 bit standard sets...

 

[Old tool guy]

How much "hole fill" capacity the rivnut has depends on the thickness of the material and the type of rivnut in use. 27/64" is in 115 bit standard sets...

I have an old 24 hole index that i try to keep mostly filled.

 

[Astro_Pneumatic_Tools]

Your 11mm would likely work okay. Or you could just use our RN516 5/16" riv nuts that are sized for a 11mm or 7/16" drill bit

 

[bdbecker]

I doubt you'll have any issues using an 11mm hole. Just be careful to not over-torque the bolt during assembly and you should be good to go.

(I've dicked around with rivnuts at my day job more than I care to admit)

 

[RoninB4]

-I'll presume this rivet nut is going in sheet metal. A 27/64 drill bit will likely be good but do bear in mind that when drilling sheet metal with a standard twist drill bit the hole often doesn't come out round. Without going into a long explanation of why, the hole will be somewhat lobed (usually 3 lobed) and will seem undersized. A quick pass with a mounted stone in a Dremel type tool or some hand work with a round file will solve that. You can also try a few rapid in/out strokes (while it rotates) to make the twist drill behave as a reamer but that doesn't always work. A regular twist drill bit could be ground with the geometry for sheet metal but that's a lot of work for a one time project. Report back what happens, others will probably want to hear it.

 

[Astro_Pneumatic_Tools]

-I'll presume this rivet nut is going in sheet metal. A 27/64 drill bit will likely be good but do bear in mind that when drilling sheet metal with a standard twist drill bit the hole often doesn't come out round. Without going into a long explanation of why, the hole will be somewhat lobed (usually 3 lobed) and will seem undersized. A quick pass with a mounted stone in a Dremel type tool or some hand work with a round file will solve that. You can also try a few rapid in/out strokes (while it rotates) to make the twist drill behave as a reamer but that doesn't always work. A regular twist drill bit could be ground with the geometry for sheet metal but that's a lot of work for a one time project. Report back what happens, others will probably want to hear it.

Not to pile on, but our TS29 TurboStep drill bits also resolve this issue as well

 

[RoninB4]

Not to pile on, but our TS29 TurboStep drill bits also resolve this issue as well

-Perhaps but I wouldn't consider them a purchase candidate if I wanted to re-sharpen. Not knocking your product.

 

[Old tool guy]

Plan to be installing them in 1” square tube, so wall thickness should not be an issue.

 

[imagineer]

FWIW, I'd forego the "chart" recommendation and simply measure the actual riv-nut barrel. My experience with these are that they're not sized consistently.

Where a proper fit was mandatory, I would measure the riv-nut, go one size under for the hole and then file to fit.
I've also had success drilling a slightly undersized hole and then tapping the riv-nut into place before swaging it.

 

[oldmachinenut]

It may be overkill but I drill the hole undersized and take it to a snug fit with a tapered hand reamer when installing riv-nuts.

 

[66HertzClone]

I use rivet nuts often and I have always used a drill index to find the best size bit to use, and I usually use a stepped bit when using sheet metal.

https://m.media-amazon.com/images/I/717UrWapzQL._AC_SL1500_.jpg

 

[dnschmidt]

Since most rivnuts come from foreign sources (primarily Taiwan) they almost all use metric hole sizes. In your case, as Chris Pettit correctly pointed out, 11mm is so close to 7/16" that the difference should be insignificant. Step drills and turbo bits are clearly the answer for sheet metal as they drill round instead of irregularly shaped holes in sheet metal.

 

[rlitman]

-I'll presume this rivet nut is going in sheet metal. A 27/64 drill bit will likely be good but do bear in mind that when drilling sheet metal with a standard twist drill bit the hole often doesn't come out round. Without going into a long explanation of why, the hole will be somewhat lobed (usually 3 lobed) and will seem undersized...

Yes, and in the case of a rivnut, that's a GOOD thing. The more the hole is out of round, the less likely the rivnut will be to spin. They actually make hex rivnuts if you have a way to make hexagonal holes.

 

[strength_and_power]

Undersized and tapped in. McMaster sells to nuts of various flavors and grip ranges.

 

[rlitman]

Not to pile on, but our TS29 TurboStep drill bits also resolve this issue as well

For a rivet set in sheet metal, where the roundness of the hole matters, I too have used step drill bits to get a perfectly broached hole in one operation. It's a great choice, and if I did more sheet metal work, I'd be really tempted.

But for a rivnut, the trilobular mess made by a twist drill is a bonus. Roll with it. Kind of like how trilobular screws are less likely to back out of holes.

 

[MovingAlong]

Looking at a drill bit chart, the only size that works would be 27/64” = 0.4219. How critical is the hole size for diy work?

Looks like a bit is cheap enough off Amazon..

Curious though, how would the application (diy) change the hole size requirement?

 

[KnurledNut]

I've been using the Dorman rivet nuts and both 5/16 and 8mm call for 7/16 or 11mm, and has worked fine for me.
I can buy them locally as needed and the quality has been satisfactory.

 

[WhataTool]

Yes, and in the case of a rivnut, that's a GOOD thing. The more the hole is out of round, the less likely the rivnut will be to spin. They actually make hex rivnuts if you have a way to make hexagonal holes.

Non round HARDWARE is certainly less likely to rotate.
Putting round hardware in non round holes just means less engagement.

Rivet crimping that outside surface on less surface area is not an advantage.

 

[Jlanciani]

A #58 drill is .420"

 

[Old tool guy]

Curious though, how would the application (diy) change the hole size requirement?

i don’t know … it’s not a structural application, or something that gets permitted and inspected.

 

[dnschmidt]

A #58 drill is .420"

Wrong. a #58 drill is 0.0420". Zeros after periods matter.

 

[bugnut]

Plan to be installing them in 1” square tube, so wall thickness should not be an issue.

You are using 1" square tubing but you did not mention the wall thickness. The wall thickness is the most missed variable in all of the answers above. If the wall thickness is thicker than light gage sheet metal than a different set of answers are applicable.

The application of wall thickness determines the rivnut required, the hole diameter and the drilling method.

My $ .02 worth YMMV

 

[finn]

-I'll presume this rivet nut is going in sheet metal. A 27/64 drill bit will likely be good but do bear in mind that when drilling sheet metal with a standard twist drill bit the hole often doesn't come out round. Without going into a long explanation of why, the hole will be somewhat lobed (usually 3 lobed) and will seem undersized. A quick pass with a mounted stone in a Dremel type tool or some hand work with a round file will solve that. You can also try a few rapid in/out strokes (while it rotates) to make the twist drill behave as a reamer but that doesn't always work. A regular twist drill bit could be ground with the geometry for sheet metal but that's a lot of work for a one time project. Report back what happens, others will probably want to hear it.

A step drill should work to make a round hole….if you can control the plunge.

 

[GeoBruin]

A separate consideration, and it depends on what tool you're using to I stall the rivnut, but the mandrel on the riv nut puller may bottom out in 1" tubing preventing you from inserting it all the way. You may need to make a puller from a bolt and a couple nuts.

 

[liliysdad]

A separate consideration, and it depends on what tool you're using to I stall the rivnut, but the mandrel on the riv nut puller may bottom out in 1" tubing preventing you from inserting it all the way. You may need to make a puller from a bolt and a couple nuts.

You can get around that by using a spacer, like a nut, in between the installing tool and the rivnut.

 

[bwringer]

FWIW, I'd forego the "chart" recommendation and simply measure the actual riv-nut barrel. My experience with these are that they're not sized consistently.

Where a proper fit was mandatory, I would measure the riv-nut, go one size under for the hole and then file to fit.
I've also had success drilling a slightly undersized hole and then tapping the riv-nut into place before swaging it.

Same. The riv-nuts I have didn't come with a drill size recommendation, so I just measure and grab the right or closest size from the drill index, and go for a tight fit.

 

[Old tool guy]

Same. The riv-nuts I have didn't come with a drill size recommendation, so I just measure and grab the right or closest size from the drill index, and go for a tight fit.

Good point, but i was going to order a couple of drill bits at the same time so i wouldn’t have to go looking at the hardware store.

 

[tarbellb]

A separate consideration, and it depends on what tool you're using to I stall the rivnut, but the mandrel on the riv nut puller may bottom out in 1" tubing preventing you from inserting it all the way. You may need to make a puller from a bolt and a couple nuts.

You can get around that by using a spacer, like a nut, in between the installing tool and the rivnut.

Also. You can also get around it by not fully threading up the rivnut and squeezing the till engagement

I did a ton of 3/4 x 1 1/2" sq tube like this


But step bits bottomed out....

 

[Old tool guy]

Also. You can also get around it by not fully threading up the rivnut and squeezing the till engagement

I did a ton of 3/4 x 1 1/2" sq tube like this


But step bits bottomed out....

You’re supposed to grind off the tip …

 

[Jlanciani]

Wrong. a #58 drill is 0.0420". Zeros after periods matter.

Woops, my bad. Apologies all.

 

[whateg01]

I doubt you'll have any issues using an 11mm hole. Just be careful to not over-torque the bolt during assembly and you should be good to go.

(I've dicked around with rivnuts at my day job more than I care to admit)

I never know how tight to pull the rivnut to set it. The amount of torque they can handle would depend on how tight it fits the hole, but it's there a standard for what they should be able to hold?

 

[Old tool guy]

 

[whateg01]

That's all well and good but how do I measure upset load, which I believe means the amount of force to install them, during installation with either the typical tool or with a bolt and washer that is often used?

 

[Old tool guy]

there a standard for what they should be able to hold?

I was answering your last question.

 

[RoninB4]

A step drill should work to make a round hole….if you can control the plunge.

-Yeah a step drill may very well make a hole that's "more round" but the steps are set diameters. So you can go from too tight > too loose (Lautrec) and plunge control is indeed important. Step drills also can't be re-sharpened and that makes them a disposable cutter. Yes you can sorta "fake" a resharpen in the gash but you've changed the geometry and it doesn't cut nearly as well as original geometry. If the step drill has one of those crappy coatings on it that makes it even worse for resharpen or when the coating comes off. A lot of homeowner types use them and that's ok by me, field service types might use them too for expediency. I don't object to whatever solutions people use for their situations in their universe. As a former toolmaker I feel step drills are a decidedly inferior cutter and I don't own one. I have plenty of other options for making a hole whatever size/shape I want to. Step drills are for those that don't have, or choose not to have those options. We all do with what we have. JMO

 

[bdbecker]

I never know how tight to pull the rivnut to set it. The amount of torque they can handle would depend on how tight it fits the hole, but it's there a standard for what they should be able to hold?

Regarding how tight to pull the rivnut, for a home-gamer, I'd focus on the installed length dimension provided by manufacturer to verify that you are installing them correctly. In a production setting, we have documented setups for the rivnut gun itself to speed up the process, but always verify the gun is working correctly with physical measurements prior to, and at periodic intervals during, the job. The rivnut manufacturer should also be able to supply information regarding pull out, sheer, and torque resistance. We typically check installed length and torque resistance because that is what our customers spec on their prints, but will do other checks if required.

The pneumatic installation guns we use have stroke and torque adjustments, but it's on a numbered scale, not a defined torque value like on a torque wrench.

 

[whateg01]

Regarding how tight to pull the rivnut, for a home-gamer, I'd focus on the installed length dimension provided by manufacturer to verify that you are installing them correctly. In a production setting, we have documented setups for the rivnut gun itself to speed up the process, but always verify the gun is working correctly with physical measurements prior to, and at periodic intervals during, the job. The rivnut manufacturer should also be able to supply information regarding pull out, sheer, and torque resistance. We typically check installed length and torque resistance because that is what our customers spec on their prints, but will do other checks if required.

The pneumatic installation guns we use have stroke and torque adjustments, but it's on a numbered scale, not a defined torque value like on a torque wrench.

I'm guessing since there's not a standard thickness or length, or seems that way, that info might be hard to get for Amazon versions. I pull on the installer until it feels "about right", which I'm willing to bet is probably too much.

 

[cherrybomb]

Asking for a friend,wouldn't it make sense to practice a few different drills and techniques on a practice piece?