A little help regarding 440 C please

[stich]

I have a S&W HRTDR in .25" 440C that I'd like to remodel. It's a nicely conceived inexpensive 6.5" recurve blade, and these changes will really improve it. I want to grind a finger choil into the bottom of the blade just outside the handle, more or less .8" wide and deep. There is about 1.3" from the handle to the beginning of the sharpened edge in which to fit it. I started on it with a dremel, but won't finish the project in this lifetime at that rate. I also want to drill several holes as large as possible in the tang in order to remove weight from the rear and shift the balance point farther forward. Here are my questions, and if you have any pointers, suggestions, or tips, please feel free to advise. I have a 4" sidegrinder, jig saw (scroll saw?), dremel, and drillmotors. I'll purchase the necessary blades/bits.

1) What tool and abrasive bit or blade would you use to cut or grind the choil? And is a +/- .8" diam. half circle about the right size for a choil? The 440C is mostly .25" thick in this area until you approach the sharpened edge, where it begins to taper down. This is wasted space as is, hence the choil for choking up and greater blade control.

2) Will regular type high speed drill bits work to drill the holes in the tang, and what speed (rpm, fast/slow) on my drill motor or jig saw should I use? What is the minimum edge width of steel I should leave after drilling? In other words, if my tang depth is 1" should I drill a .75" hole and leave only .125" at top and bottom? 3/16ths? Again, the tang is .25" thick. If a hand held jig saw will work, I will just drill starter holes and hog out even more tang with the saw. I want to reduce as much weight as possible. What type jig saw blades might cut 440C? I'm guessing the RC is 57-58. I wonder how many sq" of .25" thick 440C equals an ounce? The balance point is right at the forefinger now, so every little bit will help.

I think I will really like this knife when I'm done, and it's not bad now. Thanks in advance for any pointers.

 

[J. MacDonald]

I wouldn't recommend removing over half the width of the tang for fear of overly weakening it. Drilling .250 stainless that's treated to RC57-59 is going to be quite the task. Forget about HSS drills, you need solid carbide. You might be able to squeeze by with cobalt drills, but I'd go straight to carbide. What your trying to do will be quite difficult with hand tools, you really need at least a drill press for the drilling portion of the job. Cutting the choil you desire is another challenge entirely. It would be easy while grinding it to overheat the steel and ruin the heat treat. It would be best to mill it, again with colid carbide, but this will still be a pain in the arse if you have the equipment. RC57 is really very hard steel and it takes a lot to cut it, especially cleanly. You might just consider getting another knife that's more to your liking.

Can't answer the question as to weight per sq. in. of .250 440C

John

 

[Jason Cutter]

I did try something similar years ago. John's suggestion that you get another one you like is probably the best way to get a knife that suits you. However, if you are still interested to modify the knife, here are some ideas / precautions.

The steel is hardened / tempered already - so whatever you do, be it grinding , drilling, you have to be careful not to ruin the heat treatment. This is less of a problem, say if you are grinding in a choil, but heat travels very quickly from an overheated area towards the thin parts eg.- the blade.

Grinding with a small tool like a Dremel is an exercise in frustration unless you have lots of time, patience and plenty of sanding drums to replace worn one. You WILL go through MANY if you try to grind in a choil. I would suggest carefully and slowly cutting in a contour with an angle grinder with an abrasive disc. But you have to be very careful about overheating the steel and the piece should preferrably be kept cool regularly or all the time with a water spray / dunking in cold water. Then refine the contour with a Dremel.

Drilling hardened 440C steel - I wouldn't even bother, with the investment in carbide bits and the techniques required, the $$ could better go towards a new knife. I'd find some way around drilling new holes. Regular HSS drill bits will NOT work well at all or for very long.

Sorry to be a dampener, but what you are planning is quite difficult. Most of the things you are after would be done prior to heat treatment. I'm also not familiar with the sidegrinder thing, if its a belt grinder of some sort, it could be used somehow. Jason.