The Stovebolt Site Forums The Shop Area The Tool Chest tap advice???

I need to thread a hole but unsure what size drill bit to use.I need to tap it to 3/8 coarse thread.I know 3/8 fine thread uses 21/64 drill bit,would the coarse be the same?

Thanks!

Great chart, Cletis!! Maybe we can get Peg to stick it up on the Tech Tip or Links page??

Every tap you buy has the needed drill size etched on it.

That's what I use to think also but the new 3/8 tap I bought did not list drill size.

It's been a while since I bought one so it's possible some manufacturers have done away with the practice. It's probably a cost saving measure and/or so they can sell you a chart. I'll have to look at the taps next time I go to the hardware store.

My 5/16NC tap was never returned, and the replacement has not a single mark anywhere on it. Bought at my local lumber shed, it was Vermont-American brand, it looks funny compared to the others in my set-different cut on the flutes & has an odd shiny look. Maybe China built?

Just google "tap drill chart" and you'll get dozens of them.

Wow! Mark sent me this thread. I CALLED these folks (couldn't believe they didn't have an email address) to see if we can use their chart. Left a message. They had some other cool thing on their site. Not sure if it's helpful for truck restoration. But looked like neat engineer-speak stuff.

Hopefully, they'll let us use the charts. If they won't ... well ... maybe our Tech Tip will be just "go Google!"

Stay tuned.

Peg

Cletis said a mouthful. In the time it takes to post a tap drill question on the old 'Bolt', a Google search would have turned up dozens of hits. If you can think of it, you can find it doing a Google search...bedbugs to brass tacks, vitamins to Viagra...who puts all that stuff on there anyway?

Stuart

Amen to that. Google just amazes me. I learned more from reading on line stuff about what was wrong with me than I did from the doctor.

And if it's on the Internet, it's gotta be the truth, right?

(Well, at least we don't get a bill from the big www!)

Peg

Free charts are usually available from sellers of machine tools, and their accessories. Fuchs Machinery, MSC, and Productivity, (Omaha area) all have them. I have also picked them up at trade shows, such as IMTS in Chicago, etc.
I have seen drill sizes listed on taps, but not very often.

John

a lot of cutting tool catalogs have charts in them in the back with dec equiv. and everything. hr

Check out MSC direct,free Catalog,if they dont have it you dont need it.

All my taps have the drill sized marked on them. Maybe I'm just lucky. I keep forgetting to stop at the hardware store to check the new ones.

I ahve seen taps that the drill size (and tap size for that matter0 was etched on so lightly that you couldn't even read it unless the light is just right. And these weren't even off brand taps, the were Matco! Most taps, if the don't say it on the tap itself, will have it on the package/storage container that it comes it.

I think that if you talk to your hardware stores, parts stores, Snap On, Matco, MAC toolguys, etc. Many times I have been "given" some really nice cards or wall posters for my garage that list drill and tap sizes.

I got my best one from a welding supply shop.

Where would our community be if we didn't bull over things we could have found on google?

Chester,

I am in complete agreement. My comment was meant to be a friendly tip. When you need a speedy answer to a generic question to finish a simple task, Google is a excellent resource.

Stuart

Google, Yahoo, etc. That's where I usually head first when I have a question about something. Although I rarely do it because I know everything!!!

I also use a product called Tap magic. prevents gauling and broken taps.

On the subject, I lost my bottle of cutting oil somewhere in the garage. Has anyone seen it? Forgot where I bought it. Sears maybe? I have CRS...

I agree that MSC is a great source, used to buy most of my taps and drills there when I had a shop.We put lables on the face of those plactic drawer cabinets with the tap size over the drill size ( 10-24/ #25) so you dont spend time reading the chart!!
Tap Magic is great for ferrous metals, and Alumatap for non ferrous. If you put 1/2" or so in a clear 35mm film container you can just dip the tap in it and it will coat the tap plus float away most of the swarf(metal chips) between uses. You can also use a little spit in an emergency - better than tapping dry!!