brass threaded inserts

[Cooler]

I've been using brass threaded inserts for hardwood. They seem to work well. They are a little slow to install (you have to screw them into a drilled hole) and they are pretty expensive. I've been paying 50¢ each for these.

I can get threaded inserts that were engineered for plastic in bulk directly from the manufacturer. They do not screw in. You tap them into the hole and as you screw in the machine screw it expands the insert so that the knurls on the outside bite into the wood.

Here is the illustration: http://www.tristar-inserts.com/PDF/Tri-S...Series.pdf

I can buy 1,000 of these for less than $150.00 (15¢ each). So it is cheaper and the installation would be much faster.

I received 6 samples in the mail today. The 8-32 insert calls for 0.217" diameter hole in plastic. I will be using these for both end grain installation (3/4" red oak) and face grain (also 3/4" red oak).

Any suggestions on whether I should stick with the .217" diameter drill size (or go smaller).

These are for feet and other accessories that mount under my product so there should be little pull-out or torque on the pieces. I need the screw threads because you can remove the feet and mount other accessories so the threads have to be re-usable.

I like the idea that I can just tap these into place. Screwing in with the ones I got from Amazon.com can be a bit tough to do sometimes.

[Richard D.]

Sounds like they could split the wood when they expand. For feet you should probably be using T-Nuts. I like the ones with the spikes.

$8 for 100 pack on Amazon

[meackerman]

feet generally are placed near a corner/edge. I wonder when the insert expands if it would split the hardwood. maybe you could go with a slightly bigger hole and epoxy them in place....seems some experimentation might be in order.

[Routerman]

You will pull them out of end-grain.

[fixtureman]

we use these for the trade show displays that we build.

http://www.mscdirect.com/product/details...CS_010=93442416

[Cooler]

fixtureman said:

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we use these for the trade show displays that we build.

http://www.mscdirect.com/product/details...CS_010=93442416

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I have those. I used them in MDF and in soft wood. They specifically state that they are not suited for hardwood.

The O.D. of the knurls on these inserts are no larger than the screw threads on the screw in ones. So I would expect the same amount of splitting with either. My main concern is that the inserts will "spin" in the wood as I tighten them. And what size drill to use for the pre-drill.

The manufacturer of the inserts advised me not to use these with pine or other softwood. He said that they have been sold to other woodworkers but they have no feedback at all and can make no suggestions.

I have 6 samples to play with. I don't think these can be re-used. I will try one in the endgrain of 3/4" oak. That is the primary application and then I guess I have to wait until winter to see what wood shrinkage will do to the inserts. Or I can put them in an oven set at 100 degrees overnight to see what shrinkage will do. But first I will have to buy some .217" diameter drill bits (5.5mm = 0.216535").

Any suggestions on that?

[Richard D.]

When the wood shrinks they will become looser. Spitting would occur when the wood swells.

[Willyou]

Looking at the specs, it doesn't appear that they expand beyond the depth of the knurling. In normal use, this shouldn't cause any splitting, but it doesn't provide much bite either. 7/32" (.2187") should be close enough especially if you use epoxy which I recommend in any case. I really like the ease of installation, but I have my doubts about how secure they will be without some help. IMHO, in as much as these are engineered for use in plastic, then give them some plastic.

[Steve N]

Here is the 411 for threaded inserts for wood I am not aware of a brand, or type where end grain applications are suggested. These are used on face grain, note there are some for hardwood, or softwood application. Also note if you find a use for them in a face grain application there is a highlighted line under each type that says "drive tool" Putting one of those tools in a drill press, and having a pre bored pilot takes all of the fuss out of insertion, plus every one of them will be in straight up.

As to your foot, turns to leg, adapts to whatever problem you are using the wrong product for end grain. Richard nailed it, you want T nuts.




With a leveler leg threaded in




Cut away view of install




Pilot hole for bolt to run through, and just squeeze in barrell, tap the prongs home. They tend not to blow out your end grain like a threaded insert will. screw in the leg leveler, or part B of whatever your toy is.

Buying in lots of 1000 or greater they will be way cheaper than threaded inserts.


To attach one piece to another with disassembly in mind your best option will be barrel nuts.








Imagine it buried inside the wood.

[Cooler]

Richard D. said:

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When the wood shrinks they will become looser. Spitting would occur when the wood swells.

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I understand that. I doubt that the wood will crack. The O.D. of the knurls is the same as the threaded version and that does not crack. In any case it would just be a matter of adjusting the drill bit size.

My concern is that in the winter when the wood shrinks and the hole gets larger that the inserts will get loose.

So if I install the inserts now (summer) how do I replicate the dry condition so I can see if it will come loose? Just put it in a room with a dehumidifier? It would take too long.