1" x 8 tpi spindle tap question

1” x 8 tpi is a standard bolt thread for metal. I doubt, if a specialty wood thread existed, that it would use the same identical description as a metal thread. Bellow are standard metal tap and drill sizes.

INCH SIZES -
NATIONAL COARSE

TAP SIZE———DRILL SIZE
1/4-20———————#7
5/16-18——————-F
3/8-16———————5/16
1/2-13———————27/64
5/8-11———————17/32
3/4-10———————21/32
7/8-9————————49/64

1-8————————7/8

1-1/8-7——————-63/64
1-1/4-7——————-1-7/64
1-1/2-6——————-1-11/32

You are in luck. As you can see, the drill size for a 1”- 8 thread is 7/8”. That is a standard Forstner or Brad point drill size.

I saw on Woodcraft’s site they are suggesting tapping a hole in wood to match the standard thread of a lathe spindle, so YES!, this is in fact a standard metal thread size. It is so you can remove the chuck and just screw the wood workpiece onto the lathe in place of the chuck.

-- Michael :-{| Diapers and politicians both need to be changed often; and for the same reason.

I recently checked into it for my Jet Mini lathe with a 1×8 TPI headstock. After talking with Jet and McMaster Carr, they recommended this, but I haven’t ordered it yet and don’t know if the “pitch” of the threads would be correct or not.

http://www.mcmaster.com/#2521a581/=cz5j9e

don’t know if you want to spend that much either, but we got the tap & dye set (1×8TPI)—from Grizzly, I think—anyway, the threads the tap cut were not compatible with my lathe headstock.

It is a metal tap to match the metal threads. I have one but have not used it yet. I believe the instructions do say 7/8 bit but I would have to go look when I get home.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

Thanks guys, i actually called Craft Supplies USA today and spoke with a rep and to reiterate what you guys are saying, the rep said the particular 1×8 spindle tap in question does utilize a 7/8” pilot hole.

So there i go!

Thanks again, Chris

-- Chris Harrell - custom callmaker "Quacky Calls" Eastern NC. http://www.quackycalls.com

The 1×8 tap does use a 7/8” bit, a brad point is much better choice, and you can buy it,( and odd sizes) from Beall Tool
The tap you are looking to purchase, has a removable guide on the end,that guides the tap straight
I have made, and tapped wood nuts for 1/2”, 5/8”,3/4”, 1”, 1 1/4” and 1 1/2”, wood bolts.
IMPORTANT: When tapping in wood, clamp in vise to avoid splitting

-- E J ------- Always Keep a Firm Grip on Your Tool

“IMPORTANT: When tapping in wood, clamp in vise to avoid splitting

—E J”

THanks EJ, with this tidbit i will not have to go through the school of hard knocks in this area. Chris

-- Chris Harrell - custom callmaker "Quacky Calls" Eastern NC. http://www.quackycalls.com