Buy the thread tap kits, which will probably be 5 m/m X .80 m/m and 8 m/m X 1.25 m/m and the correct drills will be included(or at least the size will be on the package).
I see in the chart posted above that there are different pitch sizes (meaning different hole size before tapping)
Thats a good rule to know but my problem is that I don't know what is the more common pitch for M6.Chalo wrote: ↑May 20, 2018 3:09 pmThe general rule of thumb is to subtract one thread pitch from the diameter. Metric fasteners make it super easy, because both those dimensions are right in the name. So the tap drill for M6x1.00 is 6mm minus 1mm. But it works just as well for inch sized fasteners, e.g. the tap drill for 3/8"-16 is 3/8" minus 1/16", or 5/16".
If you know your drilled hole is likely to be wallowed out, like if you're using a handheld drill, then maybe drop down a few thousandths to the closest smaller size.
Well, I am sending the 3D file to a CNC shop but I have to have holes so they will know where to make the threads so I rather have the holes the right size.ferret wrote: ↑May 21, 2018 7:31 amHi rg12.
1. If you are having the part made by a machine shop than you should specify the thread you need and have them drill and tap the threads. They know what hole size to use.
2. There are countless charts on the internet, for example:
3. The pitch for an M6 thread is 1mm, and the hole should be 5mm.
Thanks so much!ferret wrote: ↑May 21, 2018 9:39 amIt is common practice to send the machine shop a drawing of the part which will have important dimensions marked appropriately even when the part will be manufactured by a CNC program based on a 3D model.
M6 pitch is 1 mm. This is the thread used in mountain bikes (and practically everywhere else).
There is a 6mm fine pitch metric thred (MF6) which has a 0.75mm pitch. It is almost never used.
Avner is right. I have only ever seen 6mm metric fine thread on a few old cable adjusting barrels and on clamp bolts in old road bike levers. It's so uncommon that my first impression is always that I'm looking at 1/4"-28 UNF thread.