First Try at Metric Threading

I’ve found the hardware from the store is a bit looser than the specs call for. I made a table locking bolt for my mill and used a nut to test, it didn’t fit and needed to chase it with a die.
 
My fat belly bumped the cross slide handwheel and moved the cross slide in .0006” right as the spring pass began. That’s not good.

I was watching to see how many chips I got on the spring pass. I should have looked at the DRO sooner rather than later.
 
I used my Shars 0-1” screw thread mic, and measured the pitch diameter to be 9.329 mm.

I won’t even put a nut on there until I see 9.160 mm.

Here’s a picture of what it looks like after you dial in the cross slide .0006” too much on a spring pass.

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OOOOH, the dreaded belly bump, I hate that, done it too....
 
I got the pitch diameter down to 9.126 mm and I need to go to the hardware store to buy an M10-1.25 nut.

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mikey said:
So, what happened with the torn, chattering trailing edge?
Click to expand...

That was for an M14-2.0. I did not have a nut to test it yesterday afternoon so I turned it down to this M10-1.25.

At this point, I have a full selection of M4 through M18 bolts, many in both fine and coarse. I will try to make it so this thread is not redundant.

The M10-1.25 nut fit:

image.jpg
 
So, I ask again, what happened to the torn trailing edge? Is the issue resolved and if so, what did you do to resolve it?
 
mikey said:
So, I ask again, what happened to the torn trailing edge? Is the issue resolved and if so, what did you do to resolve it?
Click to expand...

I did not resolve it. I turned it down to 10 mm. My afternoon blew up yesterday with family stuff, and by the time I was able to regroup the hardware store was closed and I just started over with M10-1.25.

I had chosen M14-2.0 without owning such a nut. Also, the first attempt was awful. I was dialing in .010” on the compound most of the time, and we wonder why it tore. Sometimes you just need a fresh start.
 
Try angling your cutter like I mentioned and see what happens. The other option is to grind a decent threading tool and give that a try. If you do this, use 15 degree relief angles and I bet you won't have any torn threads due to helix angle issues.
 
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