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jimmy482
08-12-2011, 08:54 PM
Should I use a 3/4" spade or forstner bit to countersink my tee nuts? Are they about the same since I need to stop at about 19/64" to be flush. The spade goes all the way through and the forstner stops at 3/8".

DATo
08-12-2011, 10:44 PM
No offense Jimmy but I am having trouble understanding your question. I sent it, exactly as written, to my local chapter of MENSA and four guys head's exploded. I got a note back saying that this is a question that can only be answered by a politician, a Buddhist monk or Rod Sterling.

Now as I read it you have some very small (1/4") T nuts which are tapped 8-32. If you run a 3/4 spade or "forstner" through it I can only conclude that you will wind up with a negative 1/2" T nut ... which can only exist in the Twilight Zone. (This is apparently where Rod Sterling comes in.)

I honestly am not trying to offend you but perhaps if you could clarify your question we can be of more help.

TGTool
08-12-2011, 10:59 PM
Pure speculation here, but I think the OP may be talking about those threaded inserts that you can put in wood parts to provide a steel threaded hole. It's a stamped part shaped like a top hat with an extrusion for the threaded hole which is probably the 1/4" he mentions with the 8-32 tapped through the center. The flange (brim of the hat) has prongs that dig into the wood to prevent rotation. So, if he wants this recessed he'd drill a #19 hole (clearance for the #8 screw) followed by a 1/4" counterbore for the threaded section, followed by his 3/4" spade or forstner bit to sink the flange below the surface.

After all of which I have no particular advice on what bit to use. If he has access to a machine with a depth stop I should think either would work.

Lew Hartswick
08-12-2011, 11:01 PM
He's talking about woodworking t nuts ( I THINK ).
I've used a forsner bit to counterbore for the flange mostly but I also
have used a "Speedbore" (trade name of someone) with excelent
results for that job.
...lew...

Bill736
08-12-2011, 11:20 PM
I prefer to use the Forstner bit first, since the center spur leaves a small centering hole for the other bits to follow.

oldwing
08-12-2011, 11:38 PM
7/8" or 1" Forstner first, to the depth of the flange, followed by 1/4" counterbore. The spurs from the flange will hold it in position.

darryl
08-13-2011, 01:39 AM
I've picked up the odd set of speed bits with the idea in mind that I'd make the custom tool I needed from the appropriate one from the kit. I have a few that I've all but removed the point on, or ground the point to act as a pilot bearing in a pilot hole. The steel is usually fine for wood, plastic, or aluminum. These are usually made for counterboring, or making a recess for a washer, etc.

jimmy482
08-13-2011, 06:38 AM
7/8" or 1" Forstner first, to the depth of the flange, followed by 1/4" counterbore. The spurs from the flange will hold it in position.

Oldwing you think 3/4" isn't big enough?

DATo
08-13-2011, 07:05 AM
Pure speculation here, but I think the OP may be talking about those threaded inserts that you can put in wood parts to provide a steel threaded hole. It's a stamped part shaped like a top hat with an extrusion for the threaded hole which is probably the 1/4" he mentions with the 8-32 tapped through the center. The flange (brim of the hat) has prongs that dig into the wood to prevent rotation.


Woah!!!! OK that makes sense. I was thinking "machine shop" T nuts. My apologies Jim. I don't know a hell of a lot about woodworking. Built a birdhouse once when I was a kid. The city condemned it [:-(

jimmy482
08-13-2011, 07:10 AM
No offense Jimmy but I am having trouble understanding your question. I sent it, exactly as written, to my local chapter of MENSA and four guys head's exploded. I got a note back saying that this is a question that can only be answered by a politician, a Buddhist monk or Rod Sterling.

Now as I read it you have some very small (1/4") T nuts which are tapped 8-32. If you run a 3/4 spade or "forstner" through it I can only conclude that you will wind up with a negative 1/2" T nut ... which can only exist in the Twilight Zone. (This is apparently where Rod Sterling comes in.)

I honestly am not trying to offend you but perhaps if you could clarify your question we can be of more help.

http://http://www.homedepot.com/h_d1/N-5yc1v/R-202704505/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 Dato the tee nut is about 3/4 inch wide. I think the 1/4 inch is the suggested depth of the countersink.

jimmy482
08-13-2011, 07:15 AM
Woah!!!! OK that makes sense. I was thinking "machine shop" T nuts. My apologies Jim. I don't know a hell of a lot about woodworking. Built a birdhouse once when I was a kid. The city condemned it [:-(

Why did the city condemn your birdhouse?

RussZHC
08-13-2011, 09:08 AM
Have used them a bunch and may have been doing something wrong (not sure what though as they have all done what they are supposed to do), but are you sure you need to countersink/counterbore?

Use the "advantage" of wood over metal, drill through whatever that small diameter is (and its OK if its not exact on the smaller side, e.g. if the actual measurement is say 7/32nds you can drill 3/16ths), place the insert in said hole, hammer it in so that the teeth catch...this may leave just the thickness of the "top hat" proud of the surface (if the wood is really, really hard that bit I supposed you could counterbore but it would be quite large and barely break the surface and use a more exact measurement drill) but, from what I have seen, when you tighten whatever it is you are threading in, it pulls that "top hat" part flush (there is a bit of compression of the wood, even if you are doing it on an end grain).

That's if you are using it in that direction (full through) and it acting as a bit of a clamp. From what you have said, it sounds more like you are using it "opposite", so you need to drill down only just far enough so if the fastener you are using is longer than the body of the "T" fitting it can have some clearance (so as not to act as a pushing tool to push the fitting out on tightening the bolt/whatever). Hammer the insert flush...again, unless the wood is ridiculously hard...we've hammer them into some pretty hard maple as example.

The place I have seen them used most often was on the bottom of wood framed chairs/upholstered furniture so screw in legs could be used. I've used them "flipped around" (first method I describe above) to hold much heavier items, typically rails or shelf supports (you can go right across the shelf space with a round threaded rod and screw it into the mate on the opposite side)
Using a few much larger ones to hold my vice to wood bench top since flat washers on the underside were just a bit too large a diameter.

Carld
08-13-2011, 10:09 AM
:D don't feel to bad DATo, when I read the thread I was puzzled and thought, I'll wait to see what happens. I wasn't quite sure whether he was doing wood or metal.

boaterri
08-13-2011, 11:07 AM
Forstner bit for the counter bore, brad point for the thru hole.

Rick

oldwing
08-13-2011, 03:50 PM
Oldwing you think 3/4" isn't big enough?

The last Tee nut I set in had a 7/8" flange. If a 3/4" works, use it.

jimmy482
08-13-2011, 09:09 PM
The last Tee nut I set in had a 7/8" flange. If a 3/4" works, use it.

Was the tee nut you used #8-32? I checked it with some measuring tape, and it was either exactly 3/4" or very slightly over 3/4".