Single Point Threading Between Centers

[erikmannie]

Beautiful threads! Nice work. Single point threading gets a lot faster after the first 10-20 times you try it. Starts to become routine.

For chamfering the corners of a hex head, I like to use a threading tool. Each side is a 30 degree chamfer tool and you can hit both edges in the same setup (assuming of course the dog wasn't there). It ends up looking pretty darn close to factory.

I did that at the beginning and end of the threads. Thanks for the tip.

 

[erikmannie]

I had a problem. I saw that I was able to make cuts as deep as .20 mm (10 divisions on the metric scale). After taking my son to work and then returning to the project, I dialed in 10 divisions on the Imperial scale. This is 30% more of a cut, and it busted my threading blade. Look at this carnage:

 

[erikmannie]

I will try to recover from this, but I think part of the OD is gone.

This is why I can’t have nice things.

 

[brino]

Erik,

I think we can blame your son for this one for "taking you out of the zone".

That's the type of tool that just gets ground flat on top to present a new edge, right?

-brino

 

[erikmannie]

My Dad came over, saw this & said that I have scrapped the work. Just as a learning experience, I am going to try to recover.

I grabbed this 60° preground HSS bit, and I put it in the tool holder so that it fits into the threads that I have cut so far. My half nut remains engaged.

Looking at the photo up close, I can see that I need to make an adjustment.

 

[erikmannie]

Erik,

I think we can blame your son for this one for "taking you out of the zone".

That's the type of tool that just gets ground flat on top to present a new edge, right?

-brino

Yes, it must be ground flat on the top, just as it came from the factory. That’s what the mill & carbide end mills are for.

 

[erikmannie]

There we go. Hopefully the fishtail on the tailstock quill is good enough. At present, the OD of my threads are serrated.

 

[erikmannie]

Well, at least I crashed into the dog driving pin.

 

[JRaut]

Yes, it must be ground flat on the top, just as it came from the factory. That’s what the mill & carbide end mills are for.

You sure about that......???

Dressing it flat using a grinder (or belt sander if you've got one) is the way to go for these.

Trying to do it on the mill sounds like a recipe for disaster.

Well, at least I crashed into the dog driving pin.

Oops...

+1 for just holding it in your 3-jaw.

 

[erikmannie]

Using a hammer and a bench vice, I temporarily fixed the offset dog driver pin bracket. It will be re-engineered.

I carefully made some cleanup passes, and I went in another .10 mm (in two passes). I tested the nut, and it was too tight.

I wanted to file the OD, but since the half nut remains engaged I had to move the tailstock quill all the way out (6”) and do the filing as the carriage advanced.

Here it is before I clean it up more.