Rivnut tool

[Dave Plowman (News)]

I have a cheap rivnut tool (4,5 6,8mm) which has been fine for occasional use.

I've got a project coming up which will need lots of 3mm SS rivnuts, and I'll need a new tool as mine only goes down to 4mm. I'm told with the 'universal' types like mine it's all too easy to break the 3mm mandrel, so I'd like one which sets the maximum pull or whatever so this can't happen. There seem to be a bewildering number of designs on the market, so wondered what the experts would recommend? I suppose up to about 60 quid or so.

[newshound]

FWIW I have one of these

which is very easy to use and good for getting into tight spaces. Although it notionally only goes down to 4 mm I don't see why someone practical would not be able to adapt it for 3 mm.

and one of these

which is also very easy to use (I overtightened the first couple because I couldn't believe they were properly set).

Again, not 3 mm. A big plus for these is that the setting tools are simply socket head screws, so easily replaced when worn out. I lubricate these with moly disulphide paste because although they have a bearing to reduce the under-head friction, they rely on the screw to provide the tension, not a separate "pulling" device.

I think you are right to set a budget greater than the £15 or so of the basic pressed steel ones. This one looks as though it might be a bit more solidly made:

[Dave Plowman (News)]

A pal who has a Sealey which does 3mm and is a basic lever type reckons it's the lever action which makes it all too easy to put side load on the thing and break the mandrel. So suggested looking for a screw type one rather than lever. Which might be easier to keep 'square'. Obviously would be slower to use - but I'd rather have reliability than speed.

The cheap lever one I have is Silverline, and I've not managed to break that. But it's not a nice device to use.

[newshound]

I also started with a cheapie. I agree with your mate that you can end up putting side load on the mandrel, I think it is because the "levers" are slightly flexy and this makes it more difficult to control at full "squeeze". Same applies to pop rivets, I find them much easier to get secure since I bought a proper lazy tongs. There are symmetrical "long arm" setters on ebay, but not down to M3.

This is essentially the same idea as the set I showed before (see helpful explanation of the design and working).

As you have a lot to do, it would not be too difficult to make up something like this for M3, but you would be better off trying to find a small thrust bearing than use a brass thrust face. Could always just use a brass washer there, of course.

[newshound]

Use a high tensile bolt or cap screw for setting steel rivnuts; 8.8 would be fine. Oil the thread (moly grease even better).

[Dave Plowman (News)]

Bit more looking came up with this:-

Won't be fast to use - but may be what I'm looking for. Spares seem available too, as well as different size mandrels.

[fred]

Very enlightening Newshound. Its a pleasure to read something written by a man who knows what he is talking about. (not sarcasm, a genuine reflection on your contribution)

[newshound]

Looks good, but expensive. Effectively a version of the "set" which I linked to, there must be a thrust bearing between the mandrel and the "cup". I guess the mandrels, being specialist parts, won't be cheap. The clever thing about the "set" is that it traps an ordinary socket cap head screw and a standard hex driver together to make the "mandrel", i.e. two off the shelf standard parts.

[newshound]

They have a good selection of "inserts" in their shop, and they also sell the Memfast tool which I have.

[newshound]

Thank you. I have picked up such a lot of helpful information on usenet and elsewhere on the net, I like to try to put something back.

[The Other Mike]

For the small sizes, especially in fragile substrates, this type are more controllable than the plier type.

I know this is uk.d-i-y but maybe contract it out to someone?

Or, given the size and possible loadings could you use a rivnut insert and epoxy/hot melt glue it in?

[Dave Plowman (News)]

Appears to be 16.50 for additional mandrel and cap. So not cheap. But if it does do the job well and is long lasting, might be worth it. It's UK made rather than some mass produced far east thingie.

BTW, it's worth looking at the company's Ebay site. All sorts of weird and wonderful inserts. But not cheap.

[Dave Plowman (News)]

That's the one I linked to earlier. But cheaper from Ebay. ;-)

No chance. ;-)

I've used rivnuts before and find them fine. Just want a better tool which will cope with the smallest ones in SS. Most of the cheap ones are only for ally ones.