Wood screw threads

I'm not sure if this will work in your case, however, there was an article in Fine Woodworking(Sept/Oct 1997) on threading wood for machine screws. You just drill and tap the wood just like metal. Here is a chart.
Machine screw sizes Pilot hole sizes Thread hole size
3/8-16 3/8" 5/16"
5/16-18 5/16" 1/4"
1/4-20 1/4" 13/64"
#10-24 13/64" 9/64"
Mark
 
silence dogood said:
I'm not sure if this will work in your case, however, there was an article in Fine Woodworking(Sept/Oct 1997) on threading wood for machine screws. You just drill and tap the wood just like metal. Here is a chart.
Machine screw sizes Pilot hole sizes Thread hole size
3/8-16 3/8" 5/16"
5/16-18 5/16" 1/4"
1/4-20 1/4" 13/64"
#10-24 13/64" 9/64"
Mark
Click to expand...

I have a question on the drill sizes. First, the pilot hole must be smaller that the screw size thread for it to have the threads hold. Question, "How does a 3/8 thread hold in a 3/8 pilot hole." The 5/16 is correct though. Maybe I'm reading it wrong?

"Billy G"
 
Bill,
Looking at the sizes for using machine screw threads in wood I assume the pilot hole is in a different piece to act as a drill guide.
 
I for one enjoy tapping machine threads into hardwood, best to use a polished/ground tap though.
I've made fixtures and repaired items with threads up to 1". If it's a jig or fixture I use mineral oil when tapping, paste wax on finished pieces.
I've even tried threading hickory and maple dowel rods for a clamp, still have to perfect this operation... :biggrin:

_Dan
 
Now see? Who said metal and woodworking don't belong on the same forum? :roflmao:
 
I agree, but a pilot hole in wood must be smaller than the thread size for it to hold.

"Billy G"
 
oughtsix said:
Am thinking about making butt plate screws for an old rifle. Do you make wood screws the same way as metal screws? The one I'm looking at is ~ 6 tpi, but there is a lot of root between the teeth. Is there some trick or is it just basic thread cutting?

Thanks,

-06
Click to expand...

You could also use a threaded insert in the wood and use a machine screw to attach the butt plate.
 
I think somebody confused pilot hole and clearance hole?
 
LOL, a couple of you of caught the mistake of the pilot hole and the clearance hole. The article in Fine Woodworking had it written as pilot hole instead of clearance hole. The writer of the article, editors of Fine Woodworking, and me should had caught that error. Oh well. things happen. and sadly I know better. I'll try to do better next time.
Mark
 
Maybe this will help....the most successful (hobby) wood threading device is the Beal Wood Threading system...it uses a 60 degree V bit in a router with a plastic jig to cut threads in round wood dowels and comes with matching taps...the picture is of two of the taps with a scale so you can see the threads they would make...

The resulting threads seem to be deeper and wider than "standard" machine threads in metal....which would make sense as the strength of the holding power of the thread is the shear thru the root of the thread...

Good luck! and let us know your results....

IMG_0886.JPG
 
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