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Does a K&M Carbide Cutter Wear?

Kyle Schultz

Gold $$ Contributor
I'm referring to the cutter; not the pilot.

If I adjust the tool to give the desired loaded round neck diameter, run a hundred cases or so, and then stuff a bullet and check the diameter, sometimes it seems the loaded neck diameter may be slightly larger. Either it's my sloppy measuring or the cutter isn't taking as large a bite.

I can't imagine brass wearing down a carbide cutter but then again who would have thought a piece of Styrofoam could knock a hole in the space shuttle wing. So I ask...
 
Looks like yer gonna keep lookin' fer the problem my friend. Ain't no brass case ever wore out a carbide cutter. Best of luck ......
 
I have found that taking two cut passes on each neck helps consistency. The last cut I make is about .001.


Your K&M should adjust to cut .0002" with each click. Now, two ten thousandths is mighty small, and should have little, if any. bearing on the final result. And as Lapua 40x says, no carbide cutter will wear out on soft brass necks. I always run mine down the neck a second time.
 
After the cut, it doesn't hurt to spin the case while applying a bit of that green scouring pad stuff that you can steal from the kitchen.
 
Review your process. You must keep the turning tool and brass at as close a constant temp as possible. IMHO a carbide mandrel helps in that attempt....not so much for the carbide cutter. HSS cuts brass just fine.
 
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I have a dumb question and only ask since I did it myself with the K&M cutter. Did you take it apart and put the cutter back in oriented differently than when it was delivered to you?
 
I have a dumb question and only ask since I did it myself with the K&M cutter. Did you take it apart and put the cutter back in oriented differently than when it was delivered to you?

I did to clean. The K&M website has pictures on how it should be orientated.
 
I leave 4 tenths on after 1st turn job, shoot-em then the turn off the last .0004" off. I take my time on the last turn and it works well and nothing gets hot. That gets me my most accurate neck.
 
Get rid of the K&M neck turning tool and get yourself a better one. You will have many, many headaches with it. Been there, done that.
 
Get rid of the K&M neck turning tool and get yourself a better one. You will have many, many headaches with it. Been there, done that.
There is a learning curve with all N T tools. IMHO, the advantage of the K&M is that is is inexpensive compared to the rest of the field, and therefore it is affordable to buy a dedicated tool for each operation- be it different calibers, or one set up as initial cut and one as a final cut. Pretty much meaning -set it up once and forget it. Inexpensive, yet is capable of cutting of producing case necks to accurate dimensions repeatedly.
 
There is a learning curve with all N T tools. IMHO, the advantage of the K&M is that is is inexpensive compared to the rest of the field, and therefore it is affordable to buy a dedicated tool for each operation- be it different calibers, or one set up as initial cut and one as a final cut. Pretty much meaning -set it up once and forget it. Inexpensive, yet is capable of cutting of producing case necks to accurate dimensions repeatedly.


With a quality turning tool, you dont need two passes. A quality tool doesnt heat up. And the learning curve us diminished. Cheap turned out to be super expensive and time consuming. K&M does turn cases but not consistent and not fast enough.
 
I can turn a couple of thou' off a Lapua .308 case in one pass in approx 35sec including loading the case in the 'chuck' (although I have a Sinclair case holder) and putting the finished case in the loading block with the K&M. It will hold tolerances as good as I will ever need. In example, yesterday morning I turned 100 cases that were converted from .308 to 6.5 creed (necks turned down from 0.018" to 0.014" at conversion) and fired twice. I then did a final turning yesterday to get them down from 0.014 to 0.0125". Once I had the K&M dialed in (took less than 5 minutes to set and check on a Sinclair ball mic set-up) the first case and the last case were exactly 0.0125" + or - 0.0001" neck wall thickness at 4 ninety-degree checks on every 10th case. I don't know how I could get tolerance better than that on rifle brass...or why it would even matter. If you can't get less than 0.0005" tolerance with the K&M too you may be doing something incorrect.
 
As was previously said, you need to keep the tool at as constant a temperature as possible. The K&M tool is a great little tool, but it is little & light weight with very little heat sink capability. It will help to get an accessory handle to absorb more heat, and a carbide mandrel to reduce turning heat. Make sure that your pre-turning neck mandrel is the correct size for the turning mandrel; they have to be matched in order to get the proper fit. The neck sizing mandrel normally is about 0.0008" bigger than the turner mandrel to get this fit, but that may not be correct for any particular application. K&M sells custom ground mandrels to accomodate this variance, so if the fit on your turning mandrel is too tight after pre-sizing with the standard Expand iron mandrel, you may need to get a custom sized Expand iron mandrel made. I had to do that with some of my 20 cal wildcats, and it worked very well. I think you could call K&M to discuss your problems and they would help you work out the best solution.
 
Make sure you get the silver wheel tight that holds the cutter in place after you adjust for your thickness. Sounds like the cutter may be backing out on you some. I started dipping necks in WD-40 before turning and using a carbide mandrel and they don't heat up like they used to.
 
Make sure you get the silver wheel tight that holds the cutter in place after you adjust for your thickness. Sounds like the cutter may be backing out on you some. I started dipping necks in WD-40 before turning and using a carbide mandrel and they don't heat up like they used to.
^^^
I use lanolin 'butter'...I dab my finger tip in it and apply a very light coat on the neck once spinning in the chuck and then feed in the cutter (like you would if using Imperial Die Wax). I have the aluminum large holder, which I HIGHLY recommend for comfort and stability as well as its heat sinking capability. With this set-up I have not had any heat issues and turn non-stop...usually 100 cases in a batch before I get hand cramps. The carbide mandrel will keep the heat out of the tool body/handle better than the HSS one as carbide will reject the heat produced and it will mostly be absorbed by the brass case and chips. Everytime you change to a new case you are, in effect, adding a fresh heat sink. I will add that the finish is also excellent with the lanolin lube. I turn at 140rpm (a somewhat arbitrary speed...because that is the speed of the gearmotor that drives my homemade case prep center) which turns out to be a good surface speed for an efficient feed rate/depth of cut yet produces a very fine finish.
 

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