Hey Mark! I don’t know what your needs are but you will find several main types of taps for different applications....pic below.
I don’t have experience with taps from some of the machine shop companies but have only used generic taps so far for my projects, I would expect the taps from machine shop suppliers to be of a higher quality than some big box store or discount store varieties.
You might look at Little Machine Shop, Victor Machinery, or Emco for some choices.
If Ken V. was still active here, I’m sure he would be able to answer your questions.
Are you looking for recommendations on where to purchase a 3/8 -16 tap? Or the kind of tap? Do you need a die to go with it? Is it to be used in pen making?
You can find taps on Amazon if your only going to buy one, or possibly ebay. Victornet.com carries all kinds of taps and dies. Make sure you buy one made from High Speed Steel, (HSS).
If this is this is for taping wood and acrylics for bottle stoppers, go to Lowes or Home Depot and pick up one. No need for anything expensive, I use one out of a Harbor Freight set of tap and dies, as they wear out, I replace them with good ones from a local machine supplier.
Agree with Dogcatcher - for wood or plastic stoppers, a standard tap from Ace Hardware or Home Despot is fine.
Generally, taps at the hardware store are tapered taps - this presents a minor challenge when threading a blind hole for stoppers because the tap will stop at the bottom of the hole. You can purchase bottoming taps that will thread all the way to the bottom of a blind hole from specialty suppliers, but because the market for them is smaller, the price will be higher. There are three ways to get around this problem:
1. Just don't use one, and accept that the threads toward the bottom of the hole will be more shallow. The effect will be that the grip on the threaded stud on the mandrel or stopper will increase as it is screwed further into the hole. In the case of wood, that's not a bad thing, but the added stress could crack plastic.
2. Ideally, the depth of the threaded portion of the hole should equal the length of the threaded stud that will screw into the hole. So if you drill the hole deeper than that depth, and use a tapered tap to thread the hole, you can make the place the taper beyond the end of the stud. That's OK for plastic provided its not translucent - it could be ugly if you could see the hole through the plastic.
3. If you make threaded inserts (discussed here) that you the glue into an oversize hole in the wooden blank (easy in wood, more difficult in plastic), you can avoid the taper altogether even when using a tapered tap. That's because when you make threaded inserts, the hole you are threading is not a blind hole, and you can run the tap in as far as necessary to get full depth threads over the entire length of the hole.
I’m below kitless now but aspire someday. For now I need to thread bottle stoppers in acrylic. A local winery called Friday and asked me to possibly sell to them. I arrived and they took almost all of my reserve acrylic stoppers, cutting boards, wood coasters and cheese cutters. I need to get to work.
Thanks for all the suggestions. Usually better tools that cost more win if I can justify the cost with reduced errors and a better product.
If I were going into production, I would buy high quality. Your time and the quality of your product is worth more than what you would save on the price of a cheap tap. Good taps make a big difference.
For me a high quality HSS tap is made in USA, Japan or Germany. Never from China, India or any other east asian source. Eastern Europe can be hit or miss and I don't take a chance on them anymore.
If you are going to tap on the lathe then you might be able to use just a bottoming tap with some practice. A plug tap is probably your best all around tap if you are going to get just one, you aren't doing it by hand and you aren't comfortable starting with a bottoming tap. If you are going to tap by hand then get a taper tap.
I like MSCDirect as a source for taps. They are clear on what is USA made, ship fast and have a wide selection. While I could probably save a buck or two by shopping around, it's not worth my time. But, that's just me.
Just another set of opinions for you to consider....
If you going to make high dollar wood stoppers, I highly suggest using the threaded inserts on those, with instructions to remove the wood before washing. I made my own inserts using 1/2" aluminum rod that I drilled and tapped.
Marketing, tip, I also made the silicon stopper versions, these were the el cheapo versions that I made out of maple and other domestic hardwoods. I would give the vineyard owners a couple each time they made an order. Soon I was selling more of them than the metal versions.