How to thread ( tap ) a wood thread in metal / steel ?

[Brian Quandt]

I'm looking to connect some steel angle to a piece of plywood (veneered ply, 1/2"), using some brass connectors which I'll grind off the brass heads once the plywood is secured.

Does anyone know where I might find a metal tap which can cut threads for wood-thread type screws? I'm probably going to use a #3 or #4 brass wood screws (or machine screws which are threaded to the head).

Obviously I could use hanger-bolts, and match the steel threads to the machine side of the bolt, but first these are rather expensive, second, I've not found any in brass under #10 in size.

Thoughts?

[John Hays]

Um, why not just epoxy the steel to the plywood and not worry about it... or am I missing the point?

[Jamie Buxton]

Or use brass machine screws. Use a conventional machine-screw tap, which is broadly available. Then grind off the head or whatever you're going to do.

[David Cefai]

If I understand the question properly, you want to end up with an assembly where the thread cut in the steel is all that is "pulling" the steel onto the wood.

If so, I suspect that you will find that the steel will not be very tight against the wood and you will have no way of tightening it.

Could you not countersink the heads into the steel, possibly grinding off any excess brass?

[Rick Lizek]

What you are asking for does not exist. Typically you drill a pilot hole and countersink and use wood screws to secure the angle to the Plywod. You need to rethink your whole process of fastening the angle To the Plywod.

[david brum]

Brass machine screws are available in 4-40 size here. Taps are available at any hardware store.

[Lee Schierer]

You can buy threaded inserts for the wood, drill a clearance hole through the steel and use brass screw to tighten everything up.33191-01-200.jpg The inserts are available from Rockler and others. Installation hint: Wipe the threads across a lump of bees wax before installing the insert into the wood and the installation will be much easier.

[pat warner]

"which can cut threads for wood-thread type screws?"
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Whilst threaded inserts have their place in wood, (especially dense stuff like oak and Jatoba), a tee-nut is a better choice.
The pull strength of screws in ply, (more so with screws as small as yours), is negligible, (~.6x that of wood in face grain). Tapping wood for wood screws, is unknown to this observer.

[Steve Milito]

"which can cut threads for wood-thread type screws?"
**********************************************
Whilst threaded inserts have their place in wood, (especially dense stuff like oak and Jatoba), a tee-nut is a better choice.
The pull strength of screws in ply, (more so with screws as small as yours), is negligible, (~.6x that of wood in face grain). Tapping wood for wood screws, is unknown to this observer.

I've built a few loudspeaker boxes and have used both T-nuts and hurricane nuts to attach the driver to the enclosure. I was never happy with either. I now just use wood screws.