# What left hand boring bar and inserts for reverse helix right hand internal threading?



## 9t8z28 (Mar 23, 2018)

I Am about to purchase a left hand threading boring bar and inserts to do right hand internal threading using the reverse helix method.  I need to purchase a boring bar and the inserts but I have some questions.  
The thread boring bar I am looking at is a left hand bar that says it accepts ER11 inserts.  I know that ER stands for external thread and IR stands for internal thread but when using the reverse helix right hand internal threading method do you use ER inserts or IR inserts?    The bar I am looking at is in the link below: 
https://www.ebay.com/itm/SNL0012K11...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649


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## Ray C (Mar 23, 2018)

EDIT:  Please see the diagram.

If you have a screw-on chuck, be careful that it does not unscrew.






Ray


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## Ray C (Mar 23, 2018)

BTW, the boring bar you show does indeed take an ER insert.   

Ray


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## petertha (Mar 23, 2018)

I've been eyeing some Asian insert thread tooling myself. Haven't committed yet. For the most part I've had OK success with offshore clones & generally great success with their inserts. But every once in a while, a low quality dud tool arrives. Impossible to tell by a picture. I call those 4140-ish bar stock models. LOL

Anyway, what I think I noticed is they seem to be adopting Carmex type tooling & insert standards. But the problem is you may not see the full compliment of tooling/insert combinations, meaning left/right/inside/outside. I've attached an excerpt from Carmex catalog specific to your question (disregard the highlights). I'd suggest checking Carmex catalogs to at least try & figure out what the cloners were attempting to clone. To complicate matters, sometimes they use different designations. Some are sneaky & either embed or use similar designations to help you cross reference. 
http://www.carmexusa.com/default.aspx?Page=Home

Another grey area aspect is shim/anvils. Carmex has a very complete selection & shows which ones in which applications. Clones might be anywhere from 'no information given', to 'comes with anvil - but no other details'. I noticed some vendors like Shars adopts what I assume is a medium range anvil but I'm not sure if they even stock sizes on either side. Hope this helps. Let us know how it performs,


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## 9t8z28 (Mar 24, 2018)

Ray C said:


> EDIT:  Please see the diagram.
> 
> If you have a screw-on chuck, be careful that it does not unscrew.
> 
> ...


Thanks but this really doesnt answer my question.


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## 9t8z28 (Mar 24, 2018)

petertha said:


> I've been eyeing some Asian insert thread tooling myself. Haven't committed yet. For the most part I've had OK success with offshore clones & generally great success with their inserts. But every once in a while, a low quality dud tool arrives. Impossible to tell by a picture. I call those 4140-ish bar stock models. LOL
> 
> Anyway, what I think I noticed is they seem to be adopting Carmex type tooling & insert standards. But the problem is you may not see the full compliment of tooling/insert combinations, meaning left/right/inside/outside. I've attached an excerpt from Carmex catalog specific to your question (disregard the highlights). I'd suggest checking Carmex catalogs to at least try & figure out what the cloners were attempting to clone. To complicate matters, sometimes they use different designations. Some are sneaky & either embed or use similar designations to help you cross reference.
> http://www.carmexusa.com/default.aspx?Page=Home
> ...


Thanks for the info.  Hopefully someone on here has done the reverse helix internal threading and can chime in on what we need.  I originally found the idea from Joe Pie on youtube.  He didnt explain what bar or insert he used


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## magicniner (Mar 24, 2018)

To cut a right hand thread with the lathe in reverse and the tool moving left to right you use a Left Hand Tool.




For work with bores from 8mm up I use Iscar MGCH 06 and MGCH 08 bars with appropriate holders and partial profile LH inserts

Using the terminology "right hand internal threading using the reverse helix method" will throw a lot of people off as it's not in particularly common use, cutting "away from the shoulder" / "away from the headstock" / "away from the bottom of the bore" and a few variants are far more commonly used amongst machinists.


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## Bob Korves (Mar 24, 2018)

magicniner said:


> To cut a right hand thread with the lathe in reverse and the tool moving left to right you use a Left Hand Tool.
> 
> View attachment 263181
> 
> ...


I use that method most of the time doing internal threads, especially when threading close to an internal shoulder or hole bottom.  Saves using the foot brake, and keeps my anxiety level down...


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## mksj (Mar 24, 2018)

I do not see that that the OP's question has been answered, and it still seems conflicting as to the the insert/anvil to be used. According to Carmex and a few other references one would use a LH (left hand) internal threading bar with an internal IL (left hand holder) type insert. The EL insert would be for an external left hand thread. The anvil needs to be changed to a negative anvil, the anvil sets the angle cutting into the thread (positive) or away (reverse) from the thread (negative). I would suggest you call one of the manufactures and ask what specific tool holder and anvil would be appropriate for the type/size of threading you want to do. Most of the inexpensive threading tools do not have an anvil under the insert, so I am not sure if they would work for doing reverse internal threading. Carmex is made by Iscar, I have the Carmex IR lay down holder and it works great.  I went with a size 16 insert "AG60" type which has a much wider threading capacity than the size "11" "A60" insert (I have both size bars). The smallest size 16 insert holder left hand internal thread is a SIL 0500 M16 which has a 0.625" shank and the threading shank section is 0.50" with a minimum bore of 0.620". I like the Carmex, but I also find TMX tooling to be very good and 1/2 the price. Which ever you decide, I would call TMX or Carmex for the correct anvil part number for what you want to do before you purchase anything. Also Carbide Depot is a great alternative for both information and to purchase  holders.
http://www.carmexusa.com/content.aspx?file=customerpages/inch_catalog2018.htm
https://www.toolmex.com/itemdetail/6-SIL-500-M16
http://www.carmexusa.com/default.aspx?page=item+detail&itemcode=SIL0500M16


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## 9t8z28 (Mar 24, 2018)

magicniner said:


> To cut a right hand thread with the lathe in reverse and the tool moving left to right you use a Left Hand Tool.
> 
> View attachment 263181
> 
> ...



I know that I need to use a left hand bar but I still dont know what insert to use, one for internal threading or one for external threading and whether the bar can accept either external or internal inserts 

 I looked up the Iscar tool you posted and see that it is a different style of toolholder.  I'm not sure of how its described but the insert mounts vertically on the very end of the bar.  This is different from the laydown as Im sure you know.  This now makes 3 different style insert type thread boring bars that I am aware of.  Joe Pie uses a top notch style which are also very common for grooving or trepaning.  

Your right about my wording.  It does seem to be confussing now that I re-read it after you explained it.


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## 9t8z28 (Mar 24, 2018)

Bob Korves said:


> I use that method most of the time doing internal threads, especially when threading close to an internal shoulder or hole bottom.  Saves using the foot brake, and keeps my anxiety level down...


What kind of threading insert tool holder and insert do you use?


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## Ray C (Mar 24, 2018)

mksj said:


> I do not see that that the OP's question has been answered, and it still seems conflicting as to the the insert/anvil to be used. According to Carmex and a few other references one would use a LH (left hand) internal threading bar with an internal IL (left hand holder) type insert. The EL insert would be for an external left hand thread. The anvil needs to be changed to a negative anvil, the anvil sets the angle cutting into the thread (positive) or away (reverse) from the thread (negative). I would suggest you call one of the manufactures and ask what specific tool holder and anvil would be appropriate for the type/size of threading you want to do. Most of the inexpensive threading tools do not have an anvil under the insert, so I am not sure if they would work for doing reverse internal threading. Carmex is made by Iscar, I have the Carmex IR lay down holder and it works great.  I went with a size 16 insert "AG60" type which has a much wider threading capacity than the size "11" "A60" insert (I have both size bars). The smallest size 16 insert holder left hand internal thread is a SIL 0500 M16 which has a 0.625" shank and the threading shank section is 0.50" with a minimum bore of 0.620". I like the Carmex, but I also find TMX tooling to be very good and 1/2 the price. Which ever you decide, I would call TMX or Carmex for the correct anvil part number for what you want to do before you purchase anything. Also Carbide Depot is a great alternative for both information and to purchase  holders.
> http://www.carmexusa.com/content.aspx?file=customerpages/inch_catalog2018.htm
> https://www.toolmex.com/itemdetail/6-SIL-500-M16
> http://www.carmexusa.com/default.aspx?page=item+detail&itemcode=SIL0500M16
> ...



Mark,

He's got a left hand tool and in post #3, I told him he needs an ER type insert.   Depending on what company you're dealing with, the terminology is different but anyhow, ER (external right) is the same geometry as IL (internal left).    In post #7, Mcingineer, zoomed-in on the cutting diagram from the picture I posted.   The boring bar he showed does not accommodate a shim -it's just a simple LH bar.  I think he said it takes an ER11 size insert which are the little small ones like this:  https://www.ebay.com/itm/10-16ER-11...660631?hash=item283c516b17:g:yrEAAOSwa81XSPi7

If he lived nearby, he could drop over and I'd hand him a couple...  In my original post, I started to describe how all the orientation works for threading but, I ran out of time.

Ray


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## mksj (Mar 24, 2018)

If you use a lay down insert tool, then you need an insert specific to the holder you are using. So the four types of inserts and holders indicated by manufactures would be left and right hand, external and internal. So for a left hand internal threading bar, you would use a left hand internal insert. The left hand internal holder for lay down inserts has a different shim depending on if you are threading into the the work or away from the work. So if you use a lay down internal left hand boring bar threading threading outward, you would need the negative shim plate and you would use an 11 IL A60 or 16 IL AG60 depending on the size insert that the boring bar takes. With lay down insert holders you need four different bars and insert types to cut all external/internal and left hand and right hand threads.

The top notch and other vertical inserts (on edge inserts) use just one insert for all four scenarios, so something like a TNMC insert can be use in an internal or external holder. Also you can look at Mesa Tools which sells there own variant where both insert and holder can be used for any of the above scenarios for $44.
http://www.mesatool.com/products/threading-tools/

Ray, you may be able to interchange inserts as you mentioned, but it doesn't follow with what is indicated by the manufacture.  I am aware of the difference between the internal and external insert, say right hand insert is the direction of the cutting tip. But the lay down inserts that I also have a cant to the vertical cutting edge in addition to the seat angle which tilts into the direction of cut. All I am recommending is that he call one the manufactures (or Carbide Depot) and see what they recommend. I understand that a right hand external insert may work in an internal lay down threading tool holder, but it may not be ideal. My Carmex right hand internal threading holder does not have a seat, but the left hand internal does so the insert seat angle also may be a factor. Bottom line is I do not have a clear answer and I am only pointing out what is indicated by the manufactures.

Also, I find a lot of misinformation and pictures on the posted specifications, so when in doubt, I have called the manufacturer or in this case I would check with Carbide Depot specific to the lay down threading tool holders, inserts and shims if needed. One can also use an on edge type of insert, although I find the TNMC type can be a bit more fragile and there are some limitations as to the size of the holder. The Top-Notch are more robust but also a wider insert.


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## magicniner (Mar 24, 2018)

9t8z28 said:


> I looked up the Iscar tool you posted and see that it is a different style of toolholder.



I mentioned it only as many seem unaware of the tooling and that it can be used for LH & RH threading, grooving and boring on the lathe and for grooving on the mill, it can also be used for thread milling on a CNC Mill


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## Jimsehr (Mar 24, 2018)

I would not even have to think about buying that tool . For that price it is a throw away if it don't work. When I was in business the insert used to cost that much.  Buy it and try it. And if you can hold part in a collet and don't worry about chuck unscrewing.


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## 9t8z28 (Mar 24, 2018)

Thank you to all who have posted and been patient with me.  I am catching on to the different types of inserts and insert holders that can be used.  I am looking for the cheapest way to go about this and that may not be possible or practical.  I may be better off with one of the other types of bars and inserts mentioned here.  I was hoping that I could put together a bar and insert for under $30-$40 and that may get the job done but I also may be better off spending more for a better tool that can not only be used for threading but can also be used for grooving and or maybe trepaning. 

 I am unemployeed right now and just started going back to school for machining.  I am taking a government funded metal working training program.  Its designed to get more people (high school students all the way to seniors) back into the manufacturing industry.  I was skeptical at first but now that I am just going on 4 weeks in, I have come to realize that it is a very in depth program that gives you the tools and a hands on experience into all aspects of the trade.  So far I havent learned a whole lot more than what I have already taught myself.  I do need to touch up on my Trigonometry but I get the basics on where its used.  Sorry for going on like that!  All I wanted to say was I was on a tight budget and I went on to give you guys more info than you needed!  
Thanks again to all who commented.  This forum and the people are really helpful and patient.  Its a pleasure to be here and ask questions and read your comments.  Even if my issue isnt always solved I get different outlooks on what I am seeing and a different way to look at my issue or what it is I am trying to do.  Thanks!


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## magicniner (Mar 24, 2018)

If you'd started with budget constraints I'd have suggested making a tool from Silver Steel or HSS


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## Bob Korves (Mar 24, 2018)

I have many boring bars and threading tools, of all types, most ground decades ago by unknown machinists.  Got them dirt cheap in tool lots.  Why start from a square blank when you can find one in a couple minutes that is very close to what is needed, and the grinder is nearby to modify them as needed.  I find the good old USA HSS better than new imported stuff today.  I have not seen any new high quality HSS, but I am sure it is available if you have enough money.  Why bother when there is so much good used HSS for sale cheap.  Most everyone has gone to carbide, which is good stuff, but I like to keep my quiver full of arrows for all circumstances, expected or otherwise.


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## 9t8z28 (Mar 24, 2018)

magicniner said:


> If you'd started with budget constraints I'd have suggested making a tool from Silver Steel or HSS


It can go both ways.  If I said the sky is the limit then I would have everyone telling me to call Kennametal or Sandvik, tell them what I need and they would sell me 8 bars for internal, external small to large threads left to right and then all of the grooving and trepaning inserts to go along with it.  Oh and not to mention it would have to have through coolant as well.  Lol
I have a piece of Mo-Max set aside for my last resort.  I don't want to use HSS.  I want to use carbide inserts.


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## Ray C (Mar 24, 2018)

Here are a few choices.   Could not find a 12mm (1/2" equivalent) but found some in 10mm (3/8") and 16mm (5/8").


https://www.banggood.com/SNL0016Q16...-p-1161645.html?rmmds=search&cur_warehouse=CN

https://www.banggood.com/SNL0016Q16...-p-1153642.html?rmmds=search&cur_warehouse=CN

https://www.banggood.com/S10K-SCLCL...-p-1129429.html?rmmds=search&cur_warehouse=CN

Ray


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## kd4gij (Mar 24, 2018)

Mesa Tool has a 1/2" threading bar that will thread any way you need.
http://www.mesatool.com/products/threading-tools/


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## 9t8z28 (Mar 24, 2018)

magicniner said:


> If you'd started with budget constraints I'd have suggested making a tool from Silver Steel or HSS


It can go both ways.  If I said the sky is the limit then I would have everyone telling me to call Kennametal or Sandvik, tell them what I need and they would sell me 8 bars for internal, external small to large threads left to right and then all of the grooving and trepaning inserts to go along with it.  Oh and not to mention it would have to have through coolant as well.  Lol
I have a piece of Mo-Max set aside for my last resort.  I don't want to use HSS.  I want to use carbide and inserts.


Ray C said:


> Mark,
> 
> He's got a left hand tool and in post #3, I told him he needs an ER type insert.   Depending on what company you're dealing with, the terminology is different but anyhow, ER (external right) is the same geometry as IL (internal left).    In post #7, Mcingineer, zoomed-in on the cutting diagram from the picture I posted.   The boring bar he showed does not accommodate a shim -it's just a simple LH bar.  I think he said it takes an ER11 size insert which are the little small ones like this:  https://www.ebay.com/itm/10-16ER-11...660631?hash=item283c516b17:g:yrEAAOSwa81XSPi7
> 
> ...


Sorry for questioning you but I want to be clear.  In post #3 you said the bar I posted a link to takes ER inserts and above in your post# 12 you said I need ER inserts.  But then you said ER is the same geometry as IL.  Do I need ER or IL inserts and if I need IR inserts will they work with the bar I posted a link to?  Or,,  should I forget about the bar I posted a link to and go with something else?


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## 9t8z28 (Mar 24, 2018)

Ray C said:


> Here are a few choices.   Could not find a 12mm (1/2" equivalent) but found some in 10mm (3/8") and 16mm (5/8").
> 
> 
> https://www.banggood.com/SNL0016Q16...-p-1161645.html?rmmds=search&cur_warehouse=CN
> ...


The Bar in the first link uses ER inserts.  The bar in the second link uses IR inserts.  The bar in the third link is not even a thread turning bar or insert.  I saw these on bangood but I still don't know what will work for reverse helix threading away from the headstock.  Were you just giving me options to try or you were recommending a bar and insert that will work?


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## Ray C (Mar 24, 2018)

9t8z28 said:


> It can go both ways.  If I said the sky is the limit then I would have everyone telling me to call Kennametal or Sandvik, tell them what I need and they would sell me 8 bars for internal, external small to large threads left to right and then all of the grooving and trepaning inserts to go along with it.  Oh and not to mention it would have to have through coolant as well.  Lol
> I have a piece of Mo-Max set aside for my last resort.  I don't want to use HSS.  I want to use carbide and inserts.
> 
> Sorry for questioning you but I want to be clear.  In post #3 you said the bar I posted a link to takes ER inserts and above in your post# 12 you said I need ER inserts.  But then you said ER is the same geometry as IL.  Do I need ER or IL inserts and if I need IR inserts will they work with the bar I posted a link to?  Or,,  should I forget about the bar I posted a link to and go with something else?



Here's another way to answer the question...

Please look closely at this picture of the Shars tool:  http://www.shars.com/products/index...rs/1-2-x-7-lh-internal-threading-boring-bar-1

It is a left hand tool very similar to the one you posted in your original link.  You'll notice that Shars tool takes a 16er ag60 insert.  I've got no less than 4 different LH boring bars and they all take ER-type inserts. 

Also look at post #7.  To use a LH threading bar, this is the best way to make the cut.   I've done in many, many times.  You will need to make a starting groove inside the bore.   Since you're starting-out and don't have grooving tools, just use the tip of your threading insert to dig a groove.

Ray


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## 9t8z28 (Mar 24, 2018)

kd4gij said:


> Mesa Tool has a 1/2" threading bar that will thread any way you need.
> http://www.mesatool.com/products/threading-tools/
> View attachment 263256


  Do you have this tool and have you used it for what I am trying to do?


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## Ray C (Mar 24, 2018)

9t8z28 said:


> The Bar in the first link uses ER inserts.  The bar in the second link uses IR inserts.  The bar in the third link is not even a thread turning bar or insert.  I saw these on bangood but I still don't know what will work for reverse helix threading away from the headstock.  Were you just giving me options to try or you were recommending a bar and insert that will work?



The bar in 1st link would work but it has a 16mm diameter (maybe too big for what you need).  

The bar in the 2nd link has a typo.  It is a LH bar and therefore needs an ER insert.  

The 3rd bar... Sorry, I must have cut/paste wrong.  Forget that one.

Ray


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## kd4gij (Mar 24, 2018)

Yes I have that bar and yes used it like you want. it comes with both left and right handed inserts. One of each. you can also get grooving inserts for it.


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## Ray C (Mar 24, 2018)

Anyone still in doubt, please go here and read the wealth of information in the section about Thread Turning Inserts.  You will see the relationship between EX-RH, IN-LH and IN-RH, EX-LH spelled-out in black and white.   http://www.carmexusa.com/content.aspx?file=customerpages/inch_catalog2018.htm

They only fit one way and there's only 2 combinations for flat type inserts.   The main difference between various styles is if they're full or partial profile.  Some also have different top angles for chip-breaking purposes etc.  For manual machining, you don't need to get too fancy...

Ray


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## petertha (Mar 26, 2018)

kd4gij said:


> Mesa Tool has a 1/2" threading bar that will thread any way you need.
> http://www.mesatool.com/products/threading-tools/



I was looking at that Mesa myself but noticed the min bore is 0.710". The minimum for 11-series internal style like OP showed is 0.47". The 8-series is 0.31" ... just mentioning in case this also factors into the decision.


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## petertha (Mar 27, 2018)

If you end up getting insert & anvil overwhelmed (as I became), these might be an option. 
https://www.carbideanddiamondtoolin....Threading.Tool.060.to.490.Min.Bore.Series.30
From what I can visualize, should work right to left in forward rotation or upside down left to right as you are wanting - so long as your toolholder / tool post can re-position it vertically which is another thing to watch out for. A thicker shank tool upside down means the toolholder must be able to compensate 'up' sufficiently so the cutter tip is on center bore. Check your setup that you can do this. Bigger lathe + smaller shank shouldn't be a problem, but the revers may not be true

Homebrew variation
http://madmodder.net/index.php?topic=3523.0


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## magicniner (Mar 27, 2018)

petertha said:


> From what I can visualize, should work right to left in forward rotation or upside down left to right as you are wanting



You'd think so wouldn't you?


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## mksj (Mar 28, 2018)

I was ordering some Carmex 16 IR AG60 inserts and was reviewing their online information. If one is using lay down inserts evidently their are differences between both internal and external inserts as well as the holders. So although an ER insert may work in an IR tooling, it imay not be ideal, this may be manufacturer specific. A common problem with any insert threading tooling is the minimum diameter, even with an 11 IR A60 the minimum internal diameter one can thread is about 5/8".


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## Ray C (Mar 28, 2018)

If the OP is still pursuing that bar, then, he'll need ER inserts.  If you look at the bar, it has a flat and the seating portion of the insert appears to be at at 7 degree (or more) angle.   If he used a Carmex IR insert that would give him about a 20 degree positive face angle which is far too aggressive.  It would put excessive pressure even with light cuts and bend the bar way too much.   This is specifically why I recommended an ER for that bar.   

I have about 2 dozen different threading bars and holders (actually, probably more than that).  At times, I've probably used the "wrong" carmex insert as per their recommendations.    I've probably used "normal" inserts in Carmex bars....   For many years, I always did threading with hand-ground HSS.  About 10 years ago, sharpened carbide became readily available.  Like all manual machining, you use the tool in the way you best see fit.

Ray


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## 9t8z28 (Dec 8, 2018)

Just giving an update:
I purchased the left- hand bar that I linked to in my opening comment.   So far it has worked out great.   I just used it to thread an M20x.5 test piece for my Hemingway rotary broach.   ( I wanted to practice on scrap before I tried to thread the actual part).    I started out with a threaded relieve at the back of the bore.   I then set up a stop and threaded in reverse at 650 rpm.   I made a mistake while calculating the thread relief and did not go deep enough but the insert did not mind at all and cut without any issues.  The threads turned out great and fit my male M20x.5 retainer that I previously made. 
Some were commenting that this bar might not work because it was a copy and the bar did not use an anvil/shim to set the insert at the correct angle (positive/negative).   That may still be true but the threads turned out excellent for a hobbyiest. 
Here is a picture of the ID threads.   For some reason at the bottom of the bore the thread crest looks flat but at the side they look sharp.   This is the Camera doing this and is giving the appearance that the threads were not cut on the same centerline as the bore.   I assure you this is not the case.   I should have taken a better picture.


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## tommyiw (May 13, 2022)

Ray C said:


> EDIT:  Please see the diagram.
> 
> If you have a screw-on chuck, be careful that it does not unscrew.
> 
> ...


Hi, would you mind sharing where you get this pic?


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## 9t8z28 (May 14, 2022)

tommyiw said:


> Hi, would you mind sharing where you get this pic?


I didn't post the pic but I believe its from the Carmex website.


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## mksj (May 14, 2022)

Information/picture is from Carmex, although information has been updated. Carmex tooling/inserts are made by Iscar.


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## Parlo (May 15, 2022)

I've never seen inserts used to cut on the trailing edge - away from the chuck. There is no clearance on the trailing edge as they are tilted the wrong way in the toolholder. Threading away from the chuck looks cool, but not for insert tooling.


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## 9t8z28 (May 15, 2022)

Parlo said:


> I've never seen inserts used to cut on the trailing edge - away from the chuck. There is no clearance on the trailing edge as they are tilted the wrong way in the toolholder. Threading away from the chuck looks cool, but not for insert tooling.


Left hand and right hand bars are commercially available with the appropriate inserts for threading in all directions for left hand and right hand threads


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## Parlo (May 15, 2022)

9t8z28 said:


> Left hand and right hand bars are commercially available with the appropriate inserts for threading in all directions for left hand and right hand threads


I haven't looked into what is now available, I do know that left hand and right hand threads whether internal or external can be produced cutting towards the chuck but with the rotation reversed, always on the leading edge of the insert.
Tip: If I have to cut an external left hand thread, I use my standard right hand boring bar on the o/d up side down, towards the chuck in reverse.


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