Treadmills? If you Google Thread Mills they will offer to “correct” your search to treadmills. Only in the last two months has Google caught on to the term “thread mills” and begun to return websites offering this tool. Google still features a picture of a treadmill to remind you of your potential spelling error.
So why does a company that knows threads best, because they manufacturer non-standard, special taps every day, want to offer thread mills? It goes back to the same thinking of when your only tool is a hammer, every problem looks like a nail.
We have “new hammers” at North American Tool. There are very few hard and fast rules that lead you to a special tap or thread mill, but here are some of the considerations.
- Do you have a three axis CNC programmable machine? If the answer is no, go back to taps.
- Do you have the same pitch for a variety of hole sizes? An 8, 12 or 20 pitch thread mill will handle a variety of hole diameters. This characteristic may also reduce the number of setups required for a job.
- Does your shop have a limited number of threading jobs, but typically not the same pitch? A single profile thread mill often can perform many pitches within a given range.
- Does the part you are threading have a relatively thin wall being threaded? Thread Mills are an excellent solution for this situation because they put less stress on the part as they thread.
As all North American Tool thread mills are manufactured with micrograin carbide, they are typically more rigid than HSS taps. This can be a good thing for tougher materials or a bad thing for materials that require some “give” when being machined. Usually HSS or HSS-E are more forgiving substrate materials for taps.
One can also make the argument that superior thread quality can be realized, particularly with the application specific thread mills (e.g. Aluminum or Exotics). Sometimes taps are forced into hole diameters that are not optimized for threading or not as round as they should be.
Whether you need a special tap or thread mill, remember the best threading solutions come from the people who know threads best.