3/8-10 modified tap
- Thread starter jkan101
- Start date
In wood it might end up too loose. I use it in phenolic for G10 modified thread. You have to be sure that you don't tap it in too far and not to retap it over and over. I like the shaft and pin to screw together smooth and get a little tighter the last 1/4 inch.....
Kim
It would if you know how to re-bore the hole after tapping.
Bore it less than the minor of the modified pin.
Tap then re-bore to the size of the pin's minor.
The minor of my 3/8 11 tap is only .295.
3/8 10 tap is close to that also.
Better yet, live thread it to the right size from the get go and just follow it with the tap for clean-up.
Atlas's tap has the right pilot so it will less likely walk.
Is that worth $20 more or not ?
You will surely think so after one badly tapped hole.
I center drill the phenolic insert in the shaft and drill it with a 1/4 inch 3 flute solid carbide drill I follow that with a 5/16 3 flute solid carbide drill............. tap it.....
never had a problem..........
Kim
You're using the wrong end mill.
Use 7.8MM end mill.
That way you don't leave a gap between the pin's minor and the insert's wall.
I know what you are saying. I use a phenolic insert in the shaft. I tried the 7.8mm drill and the proper tap from Atlas. It might work in wood but in phenolic it ends up too tight. Phenolic seems to push away from the cutting tool and then comes back and the hole is smaller than 7.8mm. This happens when facing the joint also.....
So I drill and tap all the holes exactly the same whether it's a standard 3/8-10 or a modified thread. I have had no problems and the thread screws together nice and tight. I always wax the pin especially if it is G10.
just my experience....
Kim
Kim,
You can also use a chucking reamer. You can order them in any size in .0005 increments from McMaster Carr. They are about 8" long and have a little flex to them because of the length. They follow the bored hole perfect every time.
I bore the Garolite LE insert to an approximate size about .010 undersize, then have at it with the reamer. Saves a lot of time and is very repeatable.
Rick
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I noticed that also, so I took a 3/8x10 flat minor pin and cut 2 slots in the threads like a tap, and run that thru at the end and it cuts just enough off the hole for the pin to fit perfectly. Usually only phenolic, most woods I use the 7.8 mm drill and the tap does great
Dave
I think that hole on that phenolic insert is not straight when you
drill it with 7.8mm drill.
It's not smaller, it has a slight angle.
If you bore it, it'd be straighter.
Stick a magnetic jewel indicator on the chuck and indicate a chucked up drill blank on the tailstock and indicate it.
I bet that drill blank will show it's off.
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It sounds like you experience the same thing that I do on phenolic......... you just gotta do what works,,,,
Kim