General Help/Advice Needed

[Robert6666]

I am a 75 years old, retired, fed up and discovered knife making, it has boosted my will to do SOMETHING instead of watching TV constantly.

I have made some knives ALL from heat treating files, some worked out sharp and some NOT very sharp which I se as my problem.

I clean old used files from market type sales

I cut them to length

Put into my home made firebrick propane furnace until bright red, take them out and let cool overnight in kiln dried sand

Mark out the shape and rough grind on a 1 x 30 and a 4 x 36 flat grinder, drill holes for handles

Put back into furnace until bright red, touch with magnet, if it does not stick I put quickly into new car engine oil while stirring, wipe off oil and put back into kiln dried sand overnight.

The next day I rub a file over the blade and find it really hard

Put it into my electric toasting oven for tempering at 1 hour at 400 degrees

When it comes out I bash it with hammer to straighten, OK so far

I let it AIR cool for several HOURS

I now try to grind a FINISHING bevel on a HARD blade on my 1 x 30 using a rough belt then worn out ones,
it will hack through wood really good but not cut paper, it will cut through rope but struggles, it seems to fail on actual sharpness, keen edge.
I sharpen loads of carving knives and they are fantastic.

I know this is a lot to ask but I am desperate for help.

Thank you in anticipation.

[Ed Caffrey]

A couple of likely issues that pop out to me....

1. The material.... Files are a really poor choice for knives, simply because for about the last 20 years, more and more files are case hardened. What this means is that the steel used to make the files is not fully hardenable, but rather some type of a cheaper, mild steel, that has been case hardened. Case hardened means that only a couple thousandths of the surface is hard. Once you grind past that super thin hard "case", you have a low carbon/non hardened material..... not a good thing as far as a cutting edge goes. Unless you KNOW the EXACT type of steel a given file is made of, it's just a gamble as to whether it's actually a high carbon steel....or it's case hardened.
Over the past 2-3 decades, nearly every industry has gone to what's known as "spec manufacturing".....meaning that engineers no longer call for a specific steel type to create a given item....but rather state what the item must do, and how long it must do it, then ask for it to be made of the cheapest material that will fulfill the mission, at the time of manufacture. Sounds crazy doesn't it? But that how things are done these days. An example is auto/truck springs. At one time it was a safe bet that ANY auto/truck spring would be either 5160 or 9260 steel.... these days there are no less than 19 different alloys that auto/truck springs are made of. Files fall into the same mold.... so you never know the steel type you're getting. In some cases it might be usable for blades, but for the large majority, modern files, will be case hardened.

2. Geometry..... The degree of angle ground on the blade and the edge(s), plays a huge part in how well, or how poorly a knife performs. The thinner/finer the blade and edge geometry, the less cutting resistance a blade exhibits. I would suspect that with a 1 X 30 grinder, there just enough power/control to get decent geometry on a blade.

The ONLY way that anyone creating blades can be certain if the end product will be usable or just a "KSO" (Knife shaped object) is to purchase new, known steel. Otherwise you can waste a lot of time on something that simply will never make a decent knife.

[Don Robinson]

What Ed says. Always.

We'll be very happy to help. That's what this forum is about.

Now go buy a piece of real steel.

[Don Robinson]

By the way, forgot to mention that I'm only 83 and enjoying every minute.

[Ray Rogers]

There are other knife makers in the UK, hopefully some will read this and reach out to you.

Whenever we say "buy some steel" most everyone responds that they are on a budget and can't afford it. If you want to make a good knife you'll find a way to afford it, it's really not expensive. Any knife supply place will have small quantities of steel available. Any machine tool supplier or machine shop will have suitable steel and the shops might have scrap pieces you could have or at least they can tell you where to buy it. What you want is a simple carbon steel (meaning with as little alloy as possible) that has very near one percent carbon in it. Your designations for steel are different than ours but over here examples would be 1084, 1095, and O1. Check your phone books and Google search, you should be able to find a knife supply house, metal supplier, or at least a machine shop.

Another thing, motor oil is the worst possible choice for a quenching oil. Get some canola oil from the grocery store and use that instead. Peanut oil is good too but usually expensive.

When you have a piece of good steel it will be flat and straight and soft. That means you don't have to do the annealing step (that step with the sand over night. Sand, by the way, is not good for that. Use kitty litter, wood ash, or vermiculite instead).

Get some good sharp files and use those to shape the bevels on your knife instead of the sanders. A good file will cut that new soft steel very easily and you will get better bevels which will improve your cutting geometry. You want the edge to be about 1mm thick with a nice flat taper down from the spine of the blade. Do your heat treating (harden, quench, temper) and the clean it up and file it down some more making the edge even thinner. Then sand it until its pretty, put a handle on it, and only then sharpen it.

That should get you started ....

[Robert6666]

I am really grateful for your advice, I will purchase some proper steel.

BTW the files I used were very old worn/rusty Nicholson and Firth.

Thank you, any tips appreciated

[dtec1]

when you get your steel let us know...there is more to heat treat than hardness the grain is a factor to and the only way to tell is to harden a piece of steel and snap it in half and look at the grain...so i am sure more than 1 of us wpould be willing to walk you through the heat treaty process using coupons before you make a knife...it will be some trial and error