Left Hand Laydown Threading Bar Question

[MrWhoopee]

I just bought a left hand inserted threading bar for internal threading from the inside out (backside, reverse rotation). The correct insert is a 16IL-AG60. It appears, with possible exception of the top rake, that insert is the same as a 16ER-AG60. Am I missing something?

 

[graham-xrf]

I just bought a left hand inserted threading bar for internal threading from the inside out (backside, reverse rotation). The correct insert is a 16IL-AG60. It appears, with possible exception of the top rake, that insert is the same as a 16ER-AG60. Am I missing something?

That confuses me. But looking at the part numbers, one is coded "IL" compared to the other coded "ER", clearly suggesting "internal left" and "external right". The difference might be in underside clearance. Inside a small bore, it might rub. Surely two part codes mean they are definitely different in some way.
I don't think you are missing anything. I would also wonder about that.

 

[LEEQ]

I recently went through the same thing. After much looking I felt like there was a fair amount of evidence that an internal left insert is the same as an external right insert. I bought the internal left and internal right threading tools as well as the external right and external left. I purchased some internal right and external right inserts. I have used internal right inserts in a lefthand external tool upside down to cut a right hand external thread away from the chuck. I used the same method to make a plug gauge. I then threaded internally as you suggest( in reverse, tool upright, cutting the far side of bore, feeding away from the chuck) with the external right insert in the internal left tool. All of my threads seem to be great. I can't find anything wrong with them. I used these methods to produce a 1/2 20 external thread finding my desired over the wires number with the machinery handbook 23. I then purchased a nut and tested the fit. All was well. These experiences suggest to me that I am getting away with what you're contemplating. I might be cutting a misshapen thread, but they seem to fit commercial stuff when cut to a class 2 with the inserts and methods mentioned. I would love to hear from an authority. I couldn't find mention of any IL inserts most places I looked either. I also use the threading tool to find my over the wires number and set my handwheel to zero when threading away from the chuck externally. I just use the threading insert to make my undercut and measure with one or two wires. When I am at the proper number I set the cross slide to zero and know how deep to go. I read up on these methods, but my confidence in trying them came from watching it in action thanks to Joe Pie. All of my measuring methods and threading tricks come from him. I just took a leap on the bangood threading tools and the insert guess. Good luck and keep us posted

 

[LEEQ]

Oh, also. I believe these inserts top rake goes straight back. As in not higher on the chuck side or the tailstock either one. Just slanting back straight unlike your average hss right hand cutting tool. My biggest concern was helix angle. I thought and researched till my head hurt and then bought the righties. If they aren't right for everything, they are at least right for half of everything, right?

 

[BGHansen]

I put a 16ER-AG60 insert under a microscope and it looks at 50x to be perfectly straight up/down on the nose. So no side relief angle. I guess they could tip the insert some in the holder to get some relief, but that'd change the 60 deg. angle some (?).

Picture immediately below is a close-up of of a RH external threading tool and what I bought as a LH external threading tool. Set them on a flat plate side by side. Could be my old eyes, but the cutting edges sure look parallel to me.

Bottom photo is a composite of the same tool holders on a flat plate with a square at the cutting edge. Not the side relief angle I was taught to grind on a threading tool.

I suspect in actual use a 16ERAG60 insert works for both RH and LH threading. The 16IRAG60 just mirrors the profile, so would "probably" work for both LH and RH internal threads. Pretty sure the 16IR is what I stuck in the LH external tool holder.

Bruce

 

[MrWhoopee]

The difference might be in underside clearance. Inside a small bore, it might rub. Surely two part codes mean they are definitely different in some way.

I had thought about clearance under the cutting edge. I went out and shot some pictures of the LH bar with ER insert and RH bar with IR insert.

First end view of LH bar with ER insert


RH bar with IR insert


Face view of LH bar with ER insert


and RH bar with IR insert


The inserts appear to have the same rake and clearance angles.

Maybe the only difference between ER and IL is the price. I'm running the ERs, I already have them.

 

[graham-xrf]

The inserts appear to have the same rake and clearance angles.
Maybe the only difference between ER and IL is the price. I'm running the ERs, I already have them.

The actual cutting parts of the inserts seem functionally identical.

 

[SLK001]

Maybe the only difference between ER and IL is the price. I'm running the ERs, I already have them.

I believe that the only difference is that they are mirrors of each other.

 

[LEEQ]

I think we're in agreement that the er and il are the same, not mirror image. Conversely the internal right should be the insert that fits the external left tool holder.

 

[LEEQ]

I'm glad to see others have scratched their heads over this one. I would love to talk to someone who sells the nice name brand stuff I can't afford. See what their take on it is.