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

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9t8z28

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

Ray
 
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,

SNAG-3-23-2018 0000.jpg
 
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

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

Tool.jpg

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.
 
Last edited:
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

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.
Click to expand...
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...
 
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

Carmex Example.jpg
Laydown Threading inserts 16 AG60 .jpg
 

Attachments

  • Carmex Thread Turning Inserts Technical Section.pdf
    1.2 MB · Views: 14
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

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.
Click to expand...

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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