# Internal threading tool



## Jmanb13 (Apr 12, 2017)

I have collected quite a few used HSS tool bits from ebay including a bit already ground for external threading. However I am in need of an internal threading tool.

In my previous questions I ended up going with HSS tool bits mainly due to the speed my lathe is capable of achieving (500 rpm) as well as wanting to learn how to grind my own tool bits.

The part I'm going to be internally threading has a bore around 1" diameter.

I've been looking at late tools on the various places, MSCDirect, Shars, CDCO, Amazon, etc.

It seems that about the only tools available for internal threading are tools with carbide inserts.

Are these the only options I have?

Is there any issue with using this with my slower lathe? From my watching of videos and reading, it doesn't seem that threading is done at super high speed anyway.

Any other suggestions or things I don't even know?


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## DAT510 (Apr 13, 2017)

Little Machine Shop has internal treading cutters made from HSS. Both ones that accept HSS inserts and ground HSS cutters. 

http://littlemachineshop.com/products/product_view.php?ProductID=1895&category=-147164245

http://littlemachineshop.com/products/product_category.php?category=-147164245

I bet Shars also has HSS treading tools. 

Hope this helps.


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## mikey (Apr 13, 2017)

Check out the internal threading bars from Micro 100. Their carbide bars are very solid, sharp and cut beautiful threads. I use them for anything small - up to about 1/4-20 or so. After that, I use a Circle Machine inserted tip carbide bar.


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## Charles Spencer (Apr 13, 2017)

I use a carbide insert bar on my SB 9 at slow speeds (back gear engaged).  It works for me.

This is the Chinese boring bar that I bought:

http://www.banggood.com/SNR0016Q16-...urning-Tool-Holder-with-Wrench-p-1061082.html


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## Tozguy (Apr 13, 2017)

Mesa tools, versatile, good quality, good people.

http://www.mesatool.com/products/threading-tools/

I have been using their 1/2'' internal threading tool for external threading too. It allows me to run the lathe in reverse and cut on the backside of the work, going away from the chuck. 

Also, when running in reverse for internal threading I can see the cutting more easily. 

Their inserts don't have to run any quicker than HSS ones. All my threading is done at 65 rpm (slowest available). You do have to start the work turning before the insert touches it (or the insert will chip).


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## brino (Apr 13, 2017)

You could easily make your own boring bar.
1) find a bar that works (ie. fits the hole with clearance and you can hold onto it), 3/4" or 1/2" dia, maybe 6 inches long
2) drill a 1/4" hole clean thru the diameter near one end
3) file that hole square to fit a 1/4 HSS tool bit
4) drill thru the end of the bar into that first hole and tap for a set-screw to hold the tool bit

With these you only need a short threading tool, so one HSS blank could make a couple threading tools.

Above is the simplest version with the tool bit square to the axis of the bar; great for internal threading.
For boring a square bottom hole into a workpiece make the tool bit hole on a 45 deg. angle to the bar axis and put the set screw thru the side of the bar above it. In fact you could put that on the other end of the same bar.

I'll try to remember to get some pics of mine when I get home......

-brino

EDIT: of course you could also save all that filing by using a round tool-bit like a broken drill bit.


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## MozamPete (Apr 13, 2017)

Plus 1 on the Chinese boring bar with an internal threading insert.
Threading is about the only thing I exclusively use carbide inserts for. I mostly use home ground HSS for turning (only using carbide for tough stuff), but for threading - both internal and external - I now use the preformed carbide insert as my go to tool. I'm just using the cheap Chinese stuff (Banggood.com) but it does the job for me with the minimum hassle. And they are cheap, $5 to $10 each is all I paid.


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## Kevin J (Apr 13, 2017)

I also use the boring bar offered by Mesa Tool and I am very pleased with the results.

Kevin J.

EDIT
Forgot to include "in my opinion"


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## Jmanb13 (Apr 13, 2017)

Thanks for the suggestions everyone. I ended up going with the Mesa Tool's bar. It cost a little bit more than the chinese ones, but it also has a grooving tool on the other end, which will help with another project I have planned.


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## kvt (Apr 13, 2017)

I purchased a few boring bars that hold 1/4 inch HSS tools,   The bar,   with the insert cut short to where it just sticks out works great.   I have even done a few backing plates for chucks, and also, spindle spiders using them.   My problem was I needed to do 8tpi which the inserts I found would not do.  So I found my own way.   I even ground my own HSS for it.   Fun trying to get that to work the 60degree fishtail properly.   If I can do it most should be able to do it.


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## 4GSR (Apr 13, 2017)

One thing I don't miss is grinding my own threading tools.  I don't have a steady hand anymore and blind in one eye and can't see out of the other, too.


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## brino (Apr 15, 2017)

Here's the pictures I promised in post #6 above.

This one has a set screw in the end of the bar:






This one has the set screw on the "top" of the tool bit:






I thought I had one with the tool bit at 45 degrees, for boring flat bottomed holes, but I cannot seem to locate it.

-brino


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## Doubleeboy (Apr 15, 2017)

I second the Made in Oregon Mesa threading tools.  They are good quality, not expensive, the inserts can be found on ebay pretty cheap.  I have numerous hand ground HSS bits that I have used for 40 years, just recently tried the Mesa tools , I like them alot.


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## Jmanb13 (Apr 18, 2017)

Doubleeboy said:


> I second the Made in Oregon Mesa threading tools.  They are good quality, not expensive, the inserts can be found on ebay pretty cheap.  I have numerous hand ground HSS bits that I have used for 40 years, just recently tried the Mesa tools , I like them alot.



I got my tool and immediately dropped it and broke one of the tips. Then on my first threading attempt I messed up and broke the other tip  Yay learning!

Do you know what I need to search for on ebay to find the inserts? The only ones I can find are the triangle looking ones.


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## Tozguy (Apr 19, 2017)

I buy them from Mesa, a box of ten of each LH and RH. Seems like chipping the one supplied with the tool is a common entry fee. Now I know how to make them last.


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## cascao (Apr 19, 2017)

Harold hall has nice how to grind hss boring tools
http://www.homews.co.uk/page237.html


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## ericc (Apr 19, 2017)

When you are just starting out, it is most economical to start out with something quick and homemade.  Stefan has a good design on Youtube, but you have to be careful using this for threading tools.  The angle of the cutter should be no more that 30 degrees.


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## Jmanb13 (Apr 19, 2017)

brino said:


> Here's the pictures I promised in post #6 above.
> 
> This one has a set screw in the end of the bar:
> View attachment 231452
> ...



I'm probably going to take a stab at making one of these as well


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## Silverbullet (Apr 19, 2017)

You can use old center drills as cutters when ground right . Then the hole only needs to fit no square filing. Works for me


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## brino (Apr 19, 2017)

Today I stumbled across some boring bars on Harold Hall's site, see photo 3 here:
http://www.homews.co.uk/page140.html

They could also be used for internal threading.

I like that his bars that have the cutting bit at 45 degrees, also have a flat at 45 degrees on the end of the bars....presumably for the set-screw to hold the bit.

-brino


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## darkzero (Apr 20, 2017)

Jmanb13 said:


> I got my tool and immediately dropped it and broke one of the tips. Then on my first threading attempt I messed up and broke the other tip  Yay learning!
> 
> Do you know what I need to search for on ebay to find the inserts? The only ones I can find are the triangle looking ones.



IIRC those Mesa threading inserts are proprietary, he has them custom made. I use Nikcole Mini Sytem grooving tools & their inserts look similar but the cutting edge is on the top of the inserts rather than close to center on the Mesa inserts.

EDIT: Found this comment by Mesa Tools:

"Hey guys... I do have my inserts custom made for my tools.
I have been dealing with a new supplier for several years now, and the quality is top notch.
Nikcole Mini Systems has a good variety of inserts that do fit my tools......JIM"

And just a FYI, since he said the Nikcole inserts fit (I didn't expect that), the Nikcole inserts are much more expensive. Mesa's inserts ars priced pretty well.


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## Jmanb13 (Apr 20, 2017)

darkzero said:


> IIRC those Mesa threading inserts are proprietary, he has them custom made. I use Nikcole Mini Sytem grooving tools & their inserts look similar but the cutting edge is on the top of the inserts rather than close to center on the Mesa inserts.
> 
> EDIT: Found this comment by Mesa Tools:
> 
> ...


Ok cool! Thanks. I'm going to practice my threading a little more before I start using 8 dollar inserts and breaking them . They worked great until I got my thread slightly off by accidentally bumping the crossfeed handle with my stomach

That and dropping them on concrete floors tends to cause problems too


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## NortonDommi (Apr 23, 2017)

And my 2c worth is..
                                    Like many others I don't have a tool & cutter grinder and the smaller the pitch the more accurate you need your cutter. Not a problem if you have the appropiate tap handy but I'll give an example.  Yesterday I decided to make a MDF disk for the polisher as I had seen on U-tube a way to hone the edge of knives, scissors ect.  The left hand side of the polisher has a 5/8" U.N.C. left hand thread, a new intermediate tap,(all that was available), was NZ$207 + G.S.T. of 15% .
  I had saved up and bought a SNR 0010K11 threading bar and a couple of inserts for a good price especially for a project. I've fortunately got a camlock chucking system on my lathe and following good advise try to always thread away from the chuck, in this case as it was left hand no problems.
  Job was done quickly and accurately and I spent time honing every knife I have. Mum's happy with the scissors too.
  My point is this. No matter how good we think we are sometimes the small expense of buying a purpose made tool is cheaper than doing it yourself,(doubley so if you're half blind), that is not to say you do not need to know how!
  Threading bars made for threading inserts can also be used for grooving inserts i.e. circlip grooves and are in the investment catagory in my view.
  - Barry


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## benmychree (Jun 10, 2017)

brino said:


> You could easily make your own boring bar.
> 1) find a bar that works (ie. fits the hole with clearance and you can hold onto it), 3/4" or 1/2" dia, maybe 6 inches long
> 2) drill a 1/4" hole clean thru the diameter near one end
> 3) file that hole square to fit a 1/4 HSS tool bit
> ...


Another way to make boring bars is with Sturdy brand square hole sleeves; they will fit in a reamed hole and can be silver soldered in the hole.  Another alternative is Bokum brand internal threading tools and boring bars; the smaller sizes are integral tip and shank in HSS or brazed on carbide, the larger sizes are screwed into shanks and come in various sizes and styles; they are all sharpened (only) on top of the tool, as they are form ground on the cutting faces.


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## joshua43214 (Jun 10, 2017)

Threading inserts are about the only carbide I use.
I am a real lover of HSS, but inserts are the way to go for threading.
I got a cheap left hand (I thread internal from the inside out in reverse) bar direct from China for about $15.00.
The low quality bar is more than rigid enough for fine threads, and I almost never cut coarse threads.
I am still using the same cheap Chinese insert too. I did buy a good one from MSC, but havn't needed it yet.


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## benmychree (Jun 10, 2017)

joshua43214 said:


> Threading inserts are about the only carbide I use.
> I am a real lover of HSS, but inserts are the way to go for threading.
> I got a cheap left hand (I thread internal from the inside out in reverse) bar direct from China for about $15.00.
> The low quality bar is more than rigid enough for fine threads, and I almost never cut coarse threads.
> I am still using the same cheap Chinese insert too. I did buy a good one from MSC, but havn't needed it yet.


You say that the low quality bar is rigid enough ----  So far as modulus of elasticity is concerned (the ability to resist deflection) all steels, hard or soft, carbon or alloy, have nearly the same modulus value; a hard alloy bar will not perform any better than a soft mild steel bar; the only way to achieve added stiffness it to increase the diameter, and small increases make a large difference; I read that an increase of 1/4" to a 1" bar will increase its stiffness or resistance to deflection by a factor of five.   This comes from the book "Tool Steel Simplified"


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## Jimsehr (Jun 10, 2017)

The Bangood bar and ten inserts go for $27 dollars shipped. That gives you 30  sharp cutting  edges.  #snroo10k11
Jimsehr


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## joshua43214 (Jun 10, 2017)

benmychree said:


> You say that the low quality bar is rigid enough ----  So far as modulus of elasticity is concerned (the ability to resist deflection) all steels, hard or soft, carbon or alloy, have nearly the same modulus value; a hard alloy bar will not perform any better than a soft mild steel bar; the only way to achieve added stiffness it to increase the diameter, and small increases make a large difference; I read that an increase of 1/4" to a 1" bar will increase its stiffness or resistance to deflection by a factor of five.   This comes from the book "Tool Steel Simplified"


Thanks for the added info. In my mind I was comparing it to a solid carbide bar.
I use a shop made insert holder for external threading. Made it from mystery metal for the exact reasons you state. No need to get fancy steel unless I am worried about the insert itself damaging the base holder. Took less than an hour to make, figure I can always make a new one if the seat gets buggered.


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