Types of Carbide

[PopcornSutton]

I've been doing barrel work for rifles for about 30 years. A fellow in the tooling industry turned me onto insert tooling, and hooked me up with a holder and threading inserts. The inserts are the "top notch" type and it allows me to thread right up to the shoulder. I got 5 inserts with his stuff and it lasted me a couple decades, but I don't know what TYPE carbide they were. I don't like cutting a "chicken groove" at the shoulder so I use and indicator and when I get to my set point, I pull the half nuts and back the cross feed at the same time. Make a clean end up thread, you can see where the tool pulls out of the cut, there is some variance which is cosmetic.

So, I went looking for replacement inserts, and found the top notch inserts aren't the most popular, but certainly available, but so are the grades of carbide. Kennemetal is a well known brand, so I bought inserts in KC730 type. The first barrel I did with them, I broke two ends, both times at the pull out of the thread. An unmistakable TING and it's gone. I've gone though 4 of the 5 I bought, they aint cheap. So anyone can anyone recommend a carbide type that isn't so fragile? There has to be one since I ran for a couple decades without a break.

 

[RoninB4]

-In

 

[LopezBart]

Try this search on Google: need carbide insert tougher than KC730 carbide

partial results:


To obtain a tougher carbide insert than the
Kennametal KC730 grade, you should transition to grades with higher cobalt binder content or coarser grain sizes, such as KU25T, K420, or KC5510.
The KC730 is a PVD TiN-coated C2/C3/C4 micrograin carbide typically used for finishing and general machining in stainless steels, cast iron, and high-temperature alloys. While it offers high wear resistance, it can be prone to chipping under heavy or interrupted loads.

Recommended Tougher Grades
Tougher grades generally utilize a higher percentage of cobalt binder and/or larger tungsten carbide grains to better handle pressure, vibration, and impact.

Grade	Key Characteristics	Toughness Comparison
KU25T	Advanced PVD coating; higher cobalt content than standard finishing grades.	Higher Toughness: Specifically designed for demanding grooving, threading, and cut-off operations.
K420	Medium binder content with larger grain size; alloyed for steel cutting.	Higher Toughness: Balanced for heavy chip loads in soft to moderately hard steels.
KC5510	PVD TiAlN coated; 6% cobalt substrate with fine grains.	Excellent Toughness: Engineered for productive machining of high-temp alloys with improved deformation resistance.
Sandvik 4335	Heavily alloyed grade for steel turning.	Very High Toughness: Recommended for heavy interrupted cuts and hard materials.

 

[PopcornSutton]

Try this search on Google: need carbide insert tougher than KC730 carbide

partial results:


To obtain a tougher carbide insert than the
Kennametal KC730 grade, you should transition to grades with higher cobalt binder content or coarser grain sizes, such as KU25T, K420, or KC5510.
The KC730 is a PVD TiN-coated C2/C3/C4 micrograin carbide typically used for finishing and general machining in stainless steels, cast iron, and high-temperature alloys. While it offers high wear resistance, it can be prone to chipping under heavy or interrupted loads.

Recommended Tougher Grades
Tougher grades generally utilize a higher percentage of cobalt binder and/or larger tungsten carbide grains to better handle pressure, vibration, and impact.

Grade	Key Characteristics	Toughness Comparison
KU25T	Advanced PVD coating; higher cobalt content than standard finishing grades.	Higher Toughness: Specifically designed for demanding grooving, threading, and cut-off operations.
K420	Medium binder content with larger grain size; alloyed for steel cutting.	Higher Toughness: Balanced for heavy chip loads in soft to moderately hard steels.
KC5510	PVD TiAlN coated; 6% cobalt substrate with fine grains.	Excellent Toughness: Engineered for productive machining of high-temp alloys with improved deformation resistance.
Sandvik 4335	Heavily alloyed grade for steel turning.	Very High Toughness: Recommended for heavy interrupted cuts and hard materials.

Thank you, good info. I will look at these alternatives.

 

[dr_clyde]

This is where a tooling rep will come in handy. Any industrial supply that sells carbide should have one on hand for each brand of tooling they sell.

Their job is literally to match inserts and cutters to the operation you're having trouble with.

I will also say that the Top Notch tools are quite a few years out of date, and you may end up having to buy a new holder.

I know I was looked at very strange when I asked for a Top Notch tool a few years back and was asked why I wanted something so old.

Iscar's Pentacut line is very high quality, each insert has 5 cutting edges to allow you to index the insert 5 times. Which is very nice in a threading application, as they wear faster than a generic turning tool. I use the Pentacut line for all my grooving and threading.

https://www.iscar.com/en-hq/products/threading/thread-turning/pentacut

If you want to stick with the Top Notch tool, McMaster Carr sells inserts individually so you can try out a few different grades before you have to commit to a box of 10 or 12 at $30+/ea. Just match your holder to the insert you need.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[PopcornSutton]

This is where a tooling rep will come in handy. Any industrial supply that sells carbide should have one on hand for each brand of tooling they sell.

Their job is literally to match inserts and cutters to the operation you're having trouble with.

I will also say that the Top Notch tools are quite a few years out of date, and you may end up having to buy a new holder.

I know I was looked at very strange when I asked for a Top Notch tool a few years back and was asked why I wanted something so old.

Iscar's Pentacut line is very high quality, each insert has 5 cutting edges to allow you to index the insert 5 times. Which is very nice in a threading application, as they wear faster than a generic turning tool. I use the Pentacut line for all my grooving and threading.

https://www.iscar.com/en-hq/products/threading/thread-turning/pentacut

If you want to stick with the Top Notch tool, McMaster Carr sells inserts individually so you can try out a few different grades before you have to commit to a box of 10 or 12 at $30+/ea. Just match your holder to the insert you need.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

I know the top notch has been around a long time. The info LB gave on carbide types was good, but matching those types to the top notch didn't work out so well. I will do what you suggest with Mcmaster, didn't know they sell individually. Very worth while instead of committing to 5 pieces.

 

[RoninB4]

-There are other supply houses that sell inserts individually, likely at a lower price than McMaster. Two I just checked are still in business, you'll have to compare what grade/size you want. McMaster was always a bit higher in price when I used to order things.

 

[PopcornSutton]

The only place I've seen that sells smaller quantities is Ebay, but I haven't spent a lot of time looking for them. Ebay's business turned me off years ago, I don't trust them to offer up my credit card.

 

[RoninB4]

I've been doing barrel work for rifles for about 30 years.

The only place I've seen that sells smaller quantities is Ebay,

Two I just checked are still in business,

but I haven't spent a lot of time looking for them.

-So 30 years of barrel work hasn't prompted you to do some reading/research? This is just an observation, not a personal attack.

 

[PopcornSutton]

-So 30 years of barrel work hasn't prompted you to do some reading/research? This is just an observation, not a personal attack.

I stated above, I got many years of service out of the original inserts I had. There was no need to look for replacements until recently. Plus, I no longer have my FFL and doing work for others, so I'm only doing my own and for others that I have previously done barrels for and don't need the receiver to fit it.