# Threading tool and holders



## Brento (Jan 25, 2018)

Ok so i wanna make a few threading tools. One for metric threads atleast for a 25m X1.5
A internal threading tool
An external threading tool for small threads and for larger threads

I also would like to make a boring/threading bar holder for 3/16 hss stock

(All of the tools will be made from hss)

Does anyone have any drawings for the boring bar or ideas on how to make the tools? I think i have a idea on how to do them but i dont wanna just go grinding and not know what im looking for.


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## mikey (Jan 26, 2018)

ISO metric threads have a 60 degree included angle, just like Imperial threads. Therefore, the threading tools are the same. To grind an external threading tool for this, grind a 30 degree angle on each side of the tool tip and be very precise about it. Also grind a tiny flat at the very tip to prevent breakage.

An internal threading tool is considerably harder to shape/make. There are a number of ways to do this and I've done many of them but to be very honest, you will be better off buying these tools. This especially applies to very small internal threading tools because a steel tool can only hold its accuracy for a short distance. For example, a steel internal threading bar that can cut an M6 thread will be about 3/16" OD at the head. Once the cutting edge is ground, the resultant OD at the neck below the cutting edge will be about 1/8" if you're lucky and the max depth of thread you can cut accurately is about 1/2". A carbide tool can go double that distance, about an inch. Given the limitations of these bars in small holes, I suggest you buy solid carbide internal threading tools instead of grinding them.

As for a boring bar holder, what are you using to hold the bar? If using a QCTP then just make reducing sleeves that fit in your boring bar holder. More info would help here.


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## Brento (Jan 26, 2018)

Well im just starting out right now so i dont have the lathe yet its on its way. I’m kind of just trying to get tools ready and projects lined up to give myself a plan. When the lathe first gets here it will be a basic tool post and i plan to switch it out for a quick change at some point.

As for the boring bar i was talking about the boring bar itself not the holder. Sorry for any confusion


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## ddickey (Jan 26, 2018)

If you're going to grind a threading tool the first thing you should probably have is a fishtail, or make one.


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## Brento (Jan 26, 2018)

I do have a fish tail. I was just getting screwed up with looking online how if you buy a threading tool they have tpi designations so i just wanted to make a tool for the most common threads


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## Dan_S (Jan 26, 2018)

Brento said:


> I do have a fish tail. I was just getting screwed up with looking online how if you buy a threading tool they have tpi designations so i just wanted to make a tool for the most common threads




The different TPI designations, have to do with clearance. Coarser threads have a greater helix angle, and thus require more clearance to prevent rubbing.

Most people will use taps till they get to decent size threaded holes, say 1/2" or so. Then it's usually pre-ground bars like micro 100 makes. beyond that you get into old school boring bars that hold HSS blanks, and then modern insert tooling.


What type of internal threading do you see yourself doing?


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## Brento (Jan 26, 2018)

Well as you said i prob wint be doing and internal threading below a 1/2” since i have taps up to that size.


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## Dan_S (Jan 26, 2018)

Brento said:


> Well as you said i prob wint be doing and internal threading below a 1/2” since i have taps up to that size.




I think you missed my point, how often do you see yourself actually needing to generate an internal thread larger than your largest tap? I've had a lathe for over a decade, and I've had to do internal threading over my largest tap size maybe 3 times. 

Large internal threads isn't that common a task unless your doing a certain kind of work.


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## mikey (Jan 26, 2018)

Brento said:


> Well im just starting out right now so i dont have the lathe yet its on its way. I’m kind of just trying to get tools ready and projects lined up to give myself a plan. When the lathe first gets here it will be a basic tool post and i plan to switch it out for a quick change at some point.
> 
> As for the boring bar i was talking about the boring bar itself not the holder. Sorry for any confusion



Okay, no lathe yet and you're getting ready. Trust me; I totally understand the anticipation and getting ready part. To be honest, I'm excited and happy for you but I urge you to slow down a bit and take your time. Threading is a basic skill on the lathe and it isn't difficult to do but it does take some familiarity with the lathe. Learning to turn an accurate OD and drilling or boring an accurate ID will need to come first.

Can you tell us which lathe you're getting? Do you have a project in mind that requires threading or is this about being able to thread in general? I ask because there is a lot to thread cutting aside from the tooling. 

Dan is right; you can tap a thread. However, there are times when you need a precise fit and a tap my not give you that so you have to cut it. I've done this many times and there are tiny threading bars that will fit in a tiny bore to enable you to cut accurate threads so it's useful to know how to do it. But you are not there yet.

At this point, my suggestion is to get the lathe and the basic tooling you need to get going. Then we can tell you how to make sleeves or a holder for a boring/threading bar or even tell you how to grind one from HSS.


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## Brento (Jan 26, 2018)

The lathe i am getting is the grizzly 7x14. Do i see myself threading more then a 1/2” thread? As of now no. I have threaded before but it was external only and it was on a much bigger machine. I have the hss stock already and just wanted to cut them to have them done. As i said earlier i just wanna get job ideas inline and see what stock i need or how i can plan to do it is all.


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## kd4gij (Jan 26, 2018)

The 1/2" internal external tool is a good deal and works just fine.
http://www.mesatool.com/products/threading-tools/


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## mikey (Jan 26, 2018)

Brento said:


> The lathe i am getting is the grizzly 7x14. Do i see myself threading more then a 1/2” thread? As of now no. I have threaded before but it was external only and it was on a much bigger machine. I have the hss stock already and just wanted to cut them to have them done. As i said earlier i just wanna get job ideas inline and see what stock i need or how i can plan to do it is all.



Okay, I looked on YouTube for a video for you and found this:






If you are willing to harden and temper your tool, it is easier to make one from O-1 steel. Rather than do a full description of the process, here is one done by a guy already. The process is simple and it works.

https://madmodder.net/index.php?topic=3523.0

After you make one or ten, you'll figure out that it is easier to just buy the thing because whether it is hardened tool steel or HSS, your extension limit is still the same - 4 times the diameter of the bar, and this is 4 times the smallest diameter of the bar. For small holes, this really limits the length of the thread you can cut. Carbide bars can go up to 10 times their diameter and hold their accuracy and that is what I would suggest for internal threading of small holes.


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## Brento (Jan 26, 2018)

Ok my plan is to just make the external tools since that is what i will need when the lathe comes in for a project


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## mikey (Jan 26, 2018)

Okay, I can sort of help you there. See this thread, post 104, re Threading Tool:  https://www.hobby-machinist.com/threads/models-for-grinding-hss-lathe-tools.62111/page-4


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## pstemari (Jan 26, 2018)

With regard to the question about the different inserts for different thread pitches, it's not the helix angle that's the issue, but full-profile vs non-full profile. The full profile inserts have a correct sized flat on the tip for the root and shoulders that cut and deburr the crests. You can also get partial profile inserts with a sharp tip and no shoulders.

From what I've read, helix angles are controlled by the shim seat. You can buy sets of shim seats for various helix angles. I think the usual shim that comes with the toolholder is good for helix angles around 2°, but I won't swear to it.

Sent from my Pixel XL using Tapatalk


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## Brento (Jan 26, 2018)

I made one tonight and finishing another one tmr and ill show you pictures of how it came out. It took a little time to do but i think it came out nice. I still have to break the edges at work on monday. How do you cut your threads mikey do you use the compound at 29 or do you use the cross slide.


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## mikey (Jan 26, 2018)

Brento said:


> How do you cut your threads mikey do you use the compound at 29 or do you use the cross slide.



On my Sherline, I use the cross slide and go straight in. On my Emco lathe I angle the compound at 29.5 degrees. Both work well.


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## Brento (Jan 26, 2018)

I learned with the 29. Is there a better relief angle for one or the other?


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## mikey (Jan 26, 2018)

Not for me. The same tool cuts very clean threads on either lathe.


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## Brento (Jan 26, 2018)

Okay well tmr ill post a picture of how the tool came out and see what ya think


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## Brento (Jan 27, 2018)

Here is one side


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## mikey (Jan 27, 2018)

That's a nice tool and it looks symmetrical. I assume it matches the notch in a fishtail gauge precisely, right? I suggest making the flat at the tip smaller, maybe 1/64" at most. You can also shift the point over to the left to get closer to a thread relief. Be sure to hone it carefully, including the top, and you should be good to go.

Good job, Brento!


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## Brento (Jan 27, 2018)

The other side of the tool im making a smaller cutter for that same reason and for smaller threads. The lighting wasnt the greatest where i was grinding but the sides matched up from what i could see looking by light


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## mikey (Jan 27, 2018)

You should be all set then. Let us know how it goes.


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## Brento (Jan 27, 2018)

What do you hone besides the cutting edge


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## Brento (Jan 27, 2018)

I just reground it to make sure it was 60 it was off just a degree maybe 2 and with doing that made the cutting radius smaller.


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## mikey (Jan 27, 2018)

Okay, looks better with the smaller flat at the nose. 

I hone with diamond stones on both sides and the top. Be very careful to maintain your angles when honing; it is very easy to alter the angle. Just before you finish hone the top, do a light hone on the nose flat and then do the top. The tool should be very sharp and will cut clean threads if your angles are accurate.

Most threading tool charts do not specify the tool shape; it just includes the angles so I don't know what everyone else uses. What I found when using the chart angles on a threading tool is that there were a lot of burrs on the threads so the overall finish was poor. I found, after multiple trials, that a 15 degree relief angle on each side cut the cleanest threads and tool life is very good. My current threading tools are well over a decade old and are only honed occasionally but they cut clean, accurate threads with very little force. Very importantly, they do not deflect smaller diameter work pieces as much as a carbide tool so the threads are more accurate. 

The key advantage to a inserted carbide threading tool, in my opinion, is that you don't have to grind them. Of course, you can also alter the helix angle  on an inserted tool but that is only required on large diameters with coarse threads.


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## Dan_S (Jan 27, 2018)

@Brento Do you have any hones to use on the cutting edges?


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## Brento (Jan 27, 2018)

Dan - I have no diamond files now its on my amazon wishlist but at the bottom but im going to take it to work and hone it on monday.

Mikey - im not sure what my relief angle is exactly but ill know more on monday. When honing you are really doing it to just break the edge of the sharp grinding burrs correct? Ive never honed before.


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## Dan_S (Jan 27, 2018)

Brento said:


> Dan - I have no diamond files now its on my amazon wishlist but at the bottom but im going to take it to work and hone it on monday.



You don't need diamond for HSS, cheap aluminum oxide or silicon carbide stones will work perfectly well assuming they are flat.


if you want some cheaper diamond cards, take a look at these. I used them exclusively for several years until i could afford something bigger/better. I still use them regularly as some times they are easier to manipulate than bigger stones.
https://www.sharpeningsupplies.com/DMT-Diamond-Card-Sized-Sharpener-P19.aspx


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## Brento (Jan 27, 2018)

I am looking at the set the is shaped like a hand file i do have polishing stones and a few hard edm stones as well


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## Brento (Jan 27, 2018)

https://www.amazon.com/dp/B000UVS62S/_encoding=UTF8?coliid=I2BHZT7TA81XO5&colid=3P5OH34AB7CHJ&psc=0


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## mikey (Jan 27, 2018)

Brento said:


> Mikey - im not sure what my relief angle is exactly but ill know more on monday. When honing you are really doing it to just break the edge of the sharp grinding burrs correct? Ive never honed before.



When honing, you are trying to remove the grinding marks left by the wheel or belt and creating a flat plane on each face of the tool. When you do this, the intersection of the planes on the tool are razor sharp and the tool cuts well.

Diamond cards or plates will remain flat over years of use and that is what I use and recommend. The credit card stones are fine for most tools. I use a medium, fine and extra-fine to hone my tools after grinding and the extra-fine after each use. I would buy the ones that Dan linked to. You can get them on Amazon.


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## Brento (Jan 27, 2018)

So the ones i picked out dont bother with? I figured those were good bc they were a little more versatile


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## mikey (Jan 27, 2018)

I have those plastic one, too, but the credit card ones have a steel backing and will not flex - important when trying to keep a surface flat.


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## Dan_S (Jan 27, 2018)

Brento said:


> So the ones i picked out dont bother with? I figured those were good bc they were a little more versatile



I would personally pass on them, as I've used that style before as it was hard to feel when the the tool bit was properly seated on the surface of the hone. Grinding on the periphery of the wheel produces what it is commonly called a hollow grind (arc). When you hone, you want to make sure you are touching the top and bottom of the arc, if your not you can start rounding over the edge of the bit, or altering the angle.

As Mickey said, a properly ground and honed tool is razor sharp.

The photo below shows the side of a honed bit. you can see the original grind in the middle of the bit and then the honed faces at the top and the bottom.


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## Brento (Jan 27, 2018)

Do you have to get the grind marks out fully or just enough at the top where the tool is cutting?


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## mikey (Jan 27, 2018)

A diamond stone cuts fast and if you register the tool properly, the face will cut both top and bottom (if using a bench grinder) evenly. Don't worry; its easy. Just keep the face of the tool flat on the stone and let the stone cut; it will cut very fast. Use the medium stone to get the coarse grind marks off and switch to the fine stone until you create a homogeneous surface, then do the same with the extra-fine. Use water to lube and don't get in a rush. You'll get the hang of it quickly.


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## Brento (Jan 27, 2018)

Okay sounds great ill have to hold off on getting the diamond files unfortunately.


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## Dan_S (Jan 27, 2018)

Brento said:


> Do you have to get the grind marks out fully or just enough at the top where the tool is cutting?



You just want to get the marks at the cutting edge, maybe a 1/16" wide or so. Getting a completely flat face top to bottom, would require a lot of honing. It goes really fast at first because your honing a very small area, but as the honed spot grows it will take progressively longer.


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## Brento (Jan 28, 2018)

After doing the threading tool im wondering what i should make with my other blanks i have 3 more 3/8 and a 3/16 coming


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## mikey (Jan 28, 2018)

How about a general purpose right hand turning tool?


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## Brento (Jan 28, 2018)

Well i picked up a set of insert tools for 30$ but that would be nice to do as well


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## Brento (Jan 28, 2018)

Ik my set did not come with a boring bar so i was thinking of using the 3/16 as a insert then make a holder later on


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## mikey (Jan 28, 2018)

Okay, have fun and keep us posted on how things go, Brento.


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## Brento (Jan 29, 2018)

This is wat i was able to do during lunch.


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## mikey (Jan 29, 2018)

Looks good to me!


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## Brento (Jan 29, 2018)

The tip radius looks good?


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## mikey (Jan 29, 2018)

Brento said:


> The tip radius looks good?



Near as I can tell. You did a good job with that tool.


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## Brento (Jan 29, 2018)

Awesome now on to the smaller side ill post up when thats done


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