another try

[jdaniels]

all right guys i posted in another section yesterday and i think it was the wrong one as i didnt get any response.

Sunday afternoon i decided to make a knife. I have been collecting knives for a while usually just cheap ones but recently i have started to buy better folders. I read somewhere that lawnmower blades make good knives(I have plenty i have a lawn biz) Any way i make the knife sunday afternoon is a few hours. All i had was an angle grinder with a cutting disk and a grinding disk. Sunday night i found this site and i think it is great. I have already found out how much i did wrong and i have plenty of ideas for the next one.

I would love to post pics but i dont think i can. This knife is in no way one I would say is awesome but it looks more like a survival knife. I think it would be great to be lost in the woods with.

Any way i have tons of questions about metal grinding but i am looking at old posts and what i dont find there i will be sure to ask. This is a great site.

Can anyone comment on what i could do to the blade to preserve it I know its heat treated but is that good enough and what about rust and all that stuff.

 

[John Andrews]

Welcome,J.! You have come to the right place, guy. I suggest just keeping the blade clean and oiled with mineral oil or such. Otherwise your blade will rust pretty easily. There is an earlier post we discussed about oils for blades. It is a recent one and shouldn't be hard to locate.

 

[Matt Shade]

Welcome aboard, sounds like your already hooked so I'll spare you the warning

You have a benchgrinder don't you? What do you sharpen mower blades with? I make all my knives on an 8" bench grinder. Its dirty, but fast and you can get great results with a little practice.Biggest downside is that you don't have as many grit selections, so you have more finish work after grinding.

 

[jdaniels]

matt
do you have a pic of how you have your banch grinder set up. I do have one but it is a 6". But i have found i had better results with an angle grinder. It gives me more control. Do you put your bevel on the blade with the grinder. Also do you drill your profile and cut it out with a hacksaw or bandsaw. Then use your ginder to take the rest of the metal off. Another question while i am at it. If you use old car springs how do you get the bend out of them and do you anneal them. first or just go at them. Thats all for now but i have lots of ?s stil

 

[Matt Shade]

I use a plain old 8" craftsman professional benchgrinder. I have used a 6" and it worked fine other than the clearance between the wheel and the motor wasn't as much as I would have liked (that only seems to be a problem on that particular brand of grinder too-cummins mac)
I have the work rests set pretty much perpendicular to the face of the wheel (in terms of the up and down tilt) with as little space between it and the wheel as possible. Then I grind the blade edge up, using a pretty basic hollow grinding technique. There are alot of tips and tricks listed in various threads that you should be able to find with a search (there are also archives of years past which are full of good info) Basically you start grinding the bevel, and carefully work side to side and you should have a groove pretty soon that you can feel the wheel fall into. Then just vary the amount of pressure you put towards the edge or spine of the blade to adjust how steep the bevel is, and taking your time, you should be good to go.

The main thing is taking your time, and PRACTICE, don't expect the first time or even the 10th time to be perfect! Keep a bucket of water handy to dip the blade in from time to time too.

Oh yeah, on profiling. I generally just use a hack saw (got a high tension one from sears for $20, and have found starret blades to be the best) I tried drilling and didn't think it was necessary (I've only worked with fully anealled barstock though, cuts easily with a hacksaw) For wide curves you can cut from the side almost up to your pattern in several places, then cut each section out individually.Tight curves I just grind in. Once I've cut as much off as possible I grind it down to the profile on the benchgrinder and the edges up on a disc sander (you could also do that with a file, the bench grinder leaves a very small cant to the edges)

I don't know much about the leaf springs, they definitely need to be annealed/normalized to straighten them and prevent warping when you harden the blade. You can probably find some information on that if you do a search, and you can also post a thread on the subject. Feel free to start a new thread for each group of related questions you have, ie. heat treating, grinding etc. Its easier for folks to pick out your questions and try to answer them.

 

[rlinger]

Welcome aboard!

I cut my profile the best I can with a band saw (just a glorified hacksaw I guess). I have been finishing the profile with files and then sand paper backed by a sanding block to keep things perpendicular.

I started out with a 1 X 30 inch belt grinder for grinding the blade bevel. They are normally not expensive and not too hard to find. Harbor Freight sells one for 50 to 60 bucks (they have a web site too).

I'd say with your shop back ground we'll be seeing pictures of your knives before too long. Sounds like you are good with machinery. I think you'll do well.

Roger