Inside threading, can you recommend some tooling?

[WobblyHand]

Threading with the tool upside down, on the inside of the back is less stressful, the tool comes out of the work as it cuts, rather than having to stop before it crashes. With the spindle turning toward you, (conventional) you cut the same direction as when threading outside.

Small bore. Start with a 3/8" HSS tool blank and remove (slowly) all the stuff that isn't a cutting tool. You'll have to be exceedingly careful to leave the threading tool on the end, but it's worth it. You won't be leaving more than 1/2" of thread, so get a narrow grinding wheel, or spend a lot of time with a 3/4" wheel.

I have made a threading tool from a No 0 center drill, captured in a piece of drill rod for ID work, too.

It's all good experience.

A year ago I ground a trepanning tool and a crude grooving tool to make my led spindle light. Had a devil of a time with the groover. Didn't have the correct tools for the job really. But the HSS tools I made did work and the spindle light was finished. Don't have a small bench grinder or a decent rest for the grinder. It's the rest for the grinder that makes things easier. The sheet metal rests on common consumer grinders are a joke, they vibrate like mad, aren't even level, and are difficult to set.

But making a tool and using it is satisfying. I'll poke around and see if I can cobble something together.

 

[WobblyHand]

Ok, for threading outwards, RH (conventional thread) two ways:
1) Spindle reversed, tool down, cut inside of bore closest to you ("LH style tool")
2) Spindle reversed, tool up, cut inside of bore away from you ("RH style tool")
I think the second one is easier, better visibility
-M

I think I understand, but, if you could find a picture it would really help. Up and down, what do you mean?

Suppose we have a normal ground HSS threading tool made from a blank and are using it for outside threading. Up means the flat is on top? And the relief on the sides is on the bottom?

 

[markba633csi]

Yes, up means flat on the top- like a conventional HSS tool mounted normally

 

[WobblyHand]

What size? What material? I'm assuming that you will want thin walls, so I would do it with a very sharp HSS tool set in a boring bar. I would also do it blind. This is a skill that you will need if you're using a lathe, so practice it now and become proficient at it.

Size, presume you mean ID. For what I want, 0.75" and up. Material? Workpiece or? For the workpiece, I'll practice on 6061, but would like to make it out of 304. Thin walls.

 

[WobblyHand]

Yes, up means flat on the top- like a conventional HSS tool mounted normally

Ok. I do have a carbide micro 100 like threader, but I have to check if it's LH or RH. But I really don't want to use it until I am past initial ineptness But at least I can check the handedness.

 

[WobblyHand]

Bokum makes HSS threading tools with 3/8 integral shank, form relieved, grind only on top, lasts for many years with normal use, not sure if they make a left hand tool.

They sure don't make it easy for folks these days. Their threading tool catalogs are not online, only boring tools. Looks like their website hasn't been updated since 2011. Their boring bar catalog uses a URL which is obsolete and has been taken over by an internet squatter. Weird.

 

[WobblyHand]

If you are flank feeding angle the compound 29.5* in the opposite direction from what you use for external threading. If plunge feeding it makes no difference how the compound is set.

I am with SKL001 on the tooling, a boring bar with a 60* tool bit. I prefer this over carbide insert tools.

If you are determined to use carbide check out Banggood for internal threading bars.

Micro 100 sells internal threading tools in HSS.

What does Micro 100 call them? Can't seem to find them. I just downloaded the 2021 catalog and didn't see them.

Where can I find a boring bar with a 60* HSS tool bit. These are small HSS blanks, like 1/4" square and smaller? Where do you get them. Don't know what the correct name is for a search.

For flank feeding (what I normally do for external threading) do you mean -29.5* from the perpendicular to the spindle axis? External threading would be +29.5* CCW from perpendicular.

 

[Janderso]

They snap real easy if you bump the bottom

Yes they do.......

 

[Nutfarmer]

Joe Pie has a good U Tube video on threading away from the head stock with the tool bit upside down with the lathe in reverse.

 

[WobblyHand]

Joe Pie has a good U Tube video on threading away from the head stock with the tool bit upside down with the lathe in reverse.

Watched it a couple of times! Not sure about the tooling, which is why I'm asking these simple questions.