Thread: how to install steel "T" nuts

Originally Posted by JillB

I have purchased some adjustable glide legs for a laundry cabinet.I also have steel "T" nuts 5/16 inch whitworth thread with 3/8 inch barrel. They are 23mm diameter, and have 4 spikes that hold it in the timber.

My question is, what is the best way to install the steel "T" nuts in 19mm pine, so the spikes are not bent or broken ie., hammer, or press ( which I do not have), or pull them through by tightening a bolt from the other side of the timber, whatever

I am open to all ideas and suggestions thanks,

Jill

I haven't used them all that much, but the ones I used I just hammered in with no trouble.

Peter

I just tap them in with a hammer.

There are a few of options.

If the "T" nuts need to be precisely located, drill some 4mm pilot holes to assure the correct location.

Use a 3/8" (9-10mm) drill bit to clear the body of the "T" nut.

In plywood I usually drill a small pilot hole for the pins of the "T" nut. I usually drill (1/16" drill bit) to half the depth of the pin. Tap lightly with a hammer to start the "T" nut into the holes just drilled.

If you can thread a 5/16 x18 bolt into the back side of the plywood, use that with a washer to pull the "T" nut all the way in. If not use the hammer to tap the "T" nut almost all the way flush with the plywood. The weight of the cabinet should keep the "T" nuts in place.

A word or warning. By design, "T" nuts do not stand up well to lateral pressure, so pick up the cabinet when moving it.

Jill,
As the tee nuts are under the cabinet, there is no need to do more than drill a clearance hole for the threaded shaft of the nut and then pull the nut into position by drawing it in with a bolt and washer. Reason for not tapping it in with a hammer is that if you strike off angle, you could bend the locating spikes, so why take the risk?.

Jerry

Originally Posted by rrich

If not use the hammer to tap the "T" nut almost all the way flush with the plywood. The weight of the cabinet should keep the "T" nuts in place.

A word or warning. By design, "T" nuts do not stand up well to lateral pressure, so pick up the cabinet when moving it.

Am I reading more into this than I should?

RRich, are you advocating that the T nuts go on the surface that the glides mount to?

I have used them in a variety of sizes in model aircraft but always configured so that the wooden substrate is compressed between the T nut and the item being fastened, see diag below. The region where the screw/bolt passes through the substrate should be drilled as a bare clearance hole for the screw, not a clearance for the T nut threaded portion. In this configuration they can carry a considerable side load, in fact they are limited only by the crush strength of the substrate and the breaking point of the fastener.

For the cabinet situation, if at all possible I would mount the T nut and glide onto a piece of timber or sheeting and screw that onto the base of the cabinet so that the fixing screw or bolt does not penetrate through the cabinet base. To facilitate this, a shallow recess can be cut into the substrate so that the top of the T nut is flush with or slightly below the top of the substrate. A shallow relief hole can be drilled up into the cabinet base to accomodate a one or two turn protrusion of the fixing bolt/screw.

I have always drawn the T nut into position from the oposite side with a bolt and nut.

RRich's comments about the weight of the cabinet keeping the T nut in place and poor lateral support suggest that he would drive the T nut from the glide side.

Malb,
I won't answer for rrich who I am sure can explain his viewpoint. However I must point out that all that Jill wants is a simple levelling system for a cabinet involving as little work as possible. Therefore placing the tee nut under the cabinet so that the weight is a locator is good enough. Why build a palace when all you want is a hen house?

Jerry

Originally Posted by jerryc

Malb,
I won't answer for rrich who I am sure can explain his viewpoint. However I must point out that all that Jill wants is a simple levelling system for a cabinet involving as little work as possible. Therefore placing the tee nut under the cabinet so that the weight is a locator is good enough. Why build a palace when all you want is a hen house?

Jerry

Also, it depends on the likely direction of the forces involved. I try to orient it so the force that the bolt will exert on the T-nut pushes or pulls it into the piece holding the nut

It's about 2AM in California, so I'll jump in for Rich.

T-nuts can handle DIRECT lateral load, but when used for levelling screws there's a lot of leverage prying due to lateral load at the bottom of the foot screw. This can easily wrench the T-nut out of the timber. One of the screws may be tight against the bottom of the cabinet, but the others may not; otherwise, you wouldn't need levelling screws, would you?

Joe

Wow! Did I learn lots from this discussion. I definitely would have installed it upside down, until I saw Malb's diagram. Another classic case of a picture being worth a thousand words. Many thanks for all contributions, esp that diagram.

As a result, in each corner I now intend putting two triangular pieces of MDF, one on top of the other and screwed to the underside of the melamine base, with the steel T nut pulled through (by bolt) on one MDF piece, then the entire bolt sandwiched between the MDF pieces - make sense to you? The upper triangle will have a hole for the glide foot bolt to extend into if necessary.

The hole for the glide will be the exact diameter of the glide bolt ( 5/16 Whitworth) to give a bit of lateral support before it enters the T bolt.

Who would have thought something so simple required so much detail to get it right

kind regards,
Jill

Most of the installations I've seen have been inverted from malb's sketch, although the light blue element escapes my comprehension. If the foot screw extends into a part above, it will help to reduce the prying effect. And if the flange of the T-nut is captured between two parts of the structure, it doesn't matter very much how the barrel is oriented.

Often, a T-nut may be used at the bottom of a chair leg for example. In this case, it's best to make the foot screws long enough to laterally engage quite a bit of the hole above the T-nut, to help resist the prying effect.

Joe

Thanks for this comment, Joe. I uderstood the light blue bit was a block representing the actual glide / foot on the end of the threaded leg, located between the board and the ground.

Looks like you are saying that the normal practice is to install theT nuts with the spikes facing upwards, contrary to malb's advice.

Would anyone else like to comment please?

regards,
Jill

My vote is spike up so the weight of the furniture pushes them in further.

Having bolt room is a good idea for the long term durability and sideways stability.


I'm pretty sure I have seen Norm (New Yankee Work Shop) just hit them with a hammer spikes up.

http://www.profhdwr.com/castrlvl.htm

http://www.jamestowndistributors.com...ct.do?pid=1746

malb's sketch is of a situation where the bolt is in tension - ie the two pieces are being pulled together by the bolt and the head of the bolt and the flange of the T-nut spread the load across the outside skins of the two pieces.

If the bolt is in the end of a leg, it is not in tension but is mainly transmitting a force pushing up into the piece to which the leg is attached.

In either case the point is that the T-nut should be oriented so that the major force imparted to it by the bolt is directed axially from the flange in the same direction as the spikes.