threaded rivet nut inserts - what am i doing wrong??

I bought a couple of tools and was excited to use them, this is a great invention.

However, every test ive done into a piece of sheetmetal on the bench has resulted in completely stripping the threads.

I presumed the cheap inserts that came with my (ok time to admit i bought a cheap chinese one, RZX) cheap tool were the problem.

So I bought an additional set of inserts but it is the exact same result.

The instructions that came with the tool are garbage, but all of the reviews are good.

What am I missing?? The only variables I can think of are size of hole and stroke (draw length? not sure what called) of the tool. But I cannot find any guidance online, nor that came with the inserts, as far as X length of draw for Y insert, and none of the 'this is how you use rivet nut tool' instructions ever say anything about it. As far as hole size, I am measuring the diameter of the insert w calipers and using the closest one size up metric drill bit I have - so it is within 0.5 mm, and would seem to be adequate, and have seen users with success online with much more haphazard drill/hole sizing.

any experience or advice??

Can you post pictures of the process / failure?

I have never used one but it might help if someone else has.

I would but not sure how helpful it would be - just pictures of stripped threads and calipers measuring my mandrel (heh heh).

However, I seem to have gotten success through a bunch of trial and error on figuring out stroke, and looking now, the quality brands (ie RIVNUT) do provide tables for optimal stroke. 4mm for a M5 insert is what worked for me.

I guess I will just have to trial and error for every insert size, and every material thickness; which seems... unnecessary. Also makes me nervous as if it is not drawn enough I would guess it is nominally not as tight as could be (?). Meh, hopefully someone one here can still lend some words of experience..

Are you using aluminum inserts?  You need to not pull so hard.  They are pretty fragile.

The first few times I used one, I stripped the threads every time.

But now, I never strip them.  Could be just lucky, or maybe I figured things out.  I have been making sure the threads on the tool are fully threaded, and the nutsert is fully threaded on the puller thingie.  That might be part of it.  But "feel" for when you have completed the pull.  It'll resist you more, and then you strip it.

Which style do you have?  The kind the fits in one hand (like a gun) or the larger one where you have two arms you are trying to squeeze together? It sounds to me like you are using way more force than you need here.

I have the larger one and like you I got a little overzealous with mine, which is also a cheap import and came with no instructions. I actually broke the mandrel on mine (instead of stripping the threads) on my first try.   I ended up finding some online instructions which helped a lot, especially once I figured out how to adjust the working stroke of the tool : https://www.suncorstainless.com/sites/default/files/Rivet-Nut-Tool-Installation-Instructions.pdf

It doesn’t take all that much force to collapse the collar on the rivet nut itself, so I’d say without changing anything else, I’d just stop short of applying as much force as you do now. Once you don’t feel any movement (draw) on the tool, you can pretty much just give it an extra squeeze to set the rivet firm, then unthread the tool. 

The only way I can think to strip them is to keep pulling the drawbar once they are seated.  Can you watch one of your test pieces and see when it seats?  At that point can you keep tensioning it?  If so, that's the issue most likely.

It would be tough to publish a table for stroke when it's entirely dependent on the thickness of the material you are crimping the insert into. 

SkinnyG (Forum Supporter) said:

Are you using aluminum inserts?  You need to not pull so hard.  They are pretty fragile.

The first few times I used one, I stripped the threads every time.

But now, I never strip them.  Could be just lucky, or maybe I figured things out.  I have been making sure the threads on the tool are fully threaded, and the nutsert is fully threaded on the puller thingie.  That might be part of it.  But "feel" for when you have completed the pull.  It'll resist you more, and then you strip it.

These last ones I got are zinc plated carbon steel

so what do you use to gauge when to stop? Just feel? No adjustments to stroke or anything?

Hmm... ok sounds like it's just a feel thing. I guess I was just expecting it to be more scientific/methodical. I'll do some more trial and error but any tips on how you judge it would be appreciated. Makes me nervous just to make sure it is seated well enough and because most uses I won't be able to see the backside so will be hard to tell if it looks adequately 'mushroomed'. 
 

I got the larger one with two arms but quickly found I couldn't get it into a lot of the tight spaces where I was wanting so ordered the hand-squeeze one shortly after so am experimenting with both now

thanks very much for the responses - really looking forward to putting these things to use as I already have 4 or 5 small projects I'm planning on them for 

Makes me nervous just to make sure it is seated well enough and because most uses I won't be able to see the backside so will be hard to tell if it looks adequately 'mushroomed'. 

Generally you don’t have much to worry about with that; rivet nuts are kinda “self tightening” when you add your final fastener and torque it down.  Mostly you just want to be sure it’s in straight, and tight enough the rivet nut itself does not spin when you tighten whatever it is you are bolting to it. It needs to bite into the metal a bit  

But yeah it’s very much by feel. It does not hurt to practice on a scrap of similar thickness before you start setting them blind. I use them all the time and they’ve been trouble free.

Are you stripping them during installation?  If so, stop doing that...gorilla boy.

Or buy a tool with shorter handles.

I typically use 1 size SMALLER drill bit and kinda pound the inserts in.  This helps them from spinning in the bore later on from my experience.

That being said, I got tired of these stripping out and spinning after repeated removals of the bolt.  I went to just using large flange nuts and welding them into the sheet metal after drilling a relief hole with a step bit.

It's the same number of steps (assuming clean metal) and WAY stronger.

I just installed some steel rivnuts a few weeks ago.  No way you strip the threads out on those.  Aluminum; I'm sure could be destroyed with the tool I used.

I do them by feel, it's very easy to pull the threads out. We use the cheap ones at work and use them everywhere. 

One tip is to make sure they are snug in the home before you even start 

Sounds like your just using too much force.... And yeah its kinda a feel thing. A dab of locktite on the outside of the barrell helps them from spinning long term. Also make very sure you dont cross thread them!

Yes, by feel. Get an old panel and practice in a position where you can watch the insert deform. The resistance of the tool changes when things take a set. Learning this is important not only to prevent stripping, but to know when they're properly seated in blind situations. 

Well ok - I guess consensus is in and im gorilla fisting em haha, sounds like they set with just much less force than I expected. Thank you all.

at least that's an easy enough fix, I'll just keep messing with it

one other question while we're at it - it was mentioned using loctite to secure the insert but what about loctite to secure the bolt? I tend to use it a lot and especially on something like this where I would want to be very sure not to overtighten the fastener. I presume no problems as far as it then requiring too much force to remove the fastener and then screwing up the insert set?

Any time the force to remove the bolt exceeds the holding force between the insert and the panel, it's going to spin. I can't say don't use loctite, but I'd use the lowest strength I could find on bolts that I put into inserts. 

FWIW, I had to do a track side repair with a riv-nut once. Since I had not done many prior and the sheet was pretty thin I mixed up a bit of 2 part epoxy for a little bit of insurance. Aside from an inspection and clean up later on I left it as is.

In reply to ol doc gully :

I like to use clear enamel nail polish on the threads of anything that goes into a rivnet. Enough to keep it from vibrating out, but easy to break the bond when you need to remove it.

You're squeezing the handle too hard.  Squeeze it until you start to feel it tighten up, then stop.

gidde up.

thanks again, all.