back springs

[just bob]

If you have a knife with a broken back spring and want to replace it what kind of steel is it you go buy and where do you get this at?

[coffeecup]

For the last replacement backspring I made, I got an assortment of spring stock from Brownells. http://www.brownells.com/.aspx/pid=2621 ... RING_STOCK

Depending on the knife, you may need something wider. Brownells has it if you look around enough, or search on "spring stock."

Don't forget that the spring will have to be hardened and tempered after making it. Before going to that trouble, you might want to look around for a parts knife.

Good luck!
Jim

[knives-are-quiet]

Finding another knife like the one in question with say "a broken blade" and using the spring from that one would be the easiest way.
You cut out that temper hardening process.

J W

[just bob]

I'll update this. I bought 3 knives that were just alike. Only 1 of them had a good backspring. It was 3/4 x 5½. I didn't have any springs that long to try and make others from. I don't want to buy and stockpile parts I will never use again. I did a little digging on the Internet and found what type of steel to use on these. Actually steel from a lawn mower blade is a type of spring steel and I thought suitable for my purposes. I was really happy when I went to the salvage yard and found one just the thickness I needed for 50¢.

The first pic shows the 2 blanks I cut from this

Then clamped together with locking pliers and used the good spring to get the hole locations.

Clamped back together and ground to near finish size. I want to dry fit these before I say they're done. I will finish them on the belt sander.

Don't know if I changed the temper of the steel with the drilling and grinding or not but decided to try and harden them a bit. Here is the procedure outlined in Ben Kelley's knife repair book. Heat until cherry red with gas torch - emerge in oil - rub with emery cloth - then place steel on a 1/4 inch steel plate that has been heated on a hot plate - When the steel changes to a dark blue color remove it and wipe it with oil.

I don't have a gas torch so here is what I did. I removed one burner from my gas grill and placed the springs on the open flame. I let them go for about an hour and they still weren't cherry red, but they were very hot (well done?) I then emerged them in oil and rubbed with steel wool. While they were heating I did have a thin steel plate on the other grate heating. I placed the springs on that and never did see them turn blue. Maybe I didn't get them hot enough? They did turn a dark color and appear different after the heat treat. A picture shows this and also the dry fit to the knife I'll put them in.

[just bob]

More pics. The first pic is after an hour in the grill and then just placed into the knife to see how close it was. I think this will work. They may fall apart like a $2 lawn chair, but so far - so good.

[CCBill]

...Hi, Bob...
Keep us updated on this project. I'm interested in how it turns out.
...CCBill...

[glennbad]

Very cool, that you are making your parts. I haven't graduated to that yet.

I will also be watching this thread for updates.

Glenn

[knives-are-quiet]

I've made a few springs of my own and never even bothered with the tempering.
Grinding, dipping in water, grinding, dipping in water over and over. Not letting the steel get too hot worked well for me.
Still have the knives with the springs I made and use them often. Have had no brakeage issues.
Heat treating is more of a concern when severely reshaping the blade and the cutting edge.
Just converted a 10 inch high carbon stainless steel Kershaw Chef's knife into a 4 1/2 inch Bushcraft knife with a convex grind. Used my backyard barbecue to heat the blade and let it cool slowly which anneals the steel (softens it). Cut , shaped , grinded and sanded. Then heated the blade up again till red hot. Then dipped in oil. Tempered the blade in my kitchen oven at 450% and let cool repeating the process three times.
Tested it by striking the hidden tang area with a hammer very hard a few times.
Didn't chip or brake.
This Bushcraft is pretty much done and will have taken me 4 days to build. Just a few finishing touches and learning how to sharpen a convex edge and I'll post pictures tomorrow.
I didn't photograph this time as this knife was a rush build.
I'm going on a camping trip next week and need the knife done. Photographing everything would just make everything take twice as long.

By the way, J - Bob, that spring looks perfect.
And I'm sure it will work just fine on that knife.
It will once again have a mighty snap.
Excellent job and post pictures of the finished product.

J W

[just bob]

I got one of these knives buttoned up this morning. The inspiration came from this web site. There is a Russell for sale with stag handles in one of the stores. I got this stag on ebay. I have 2 more of these to do and am going to do one in sawed bone and am uncertain on the other. The knife I just finished has excellent walk & talk and half-stops. Maybe the world's first Briggs & Stratton / Russell Barlow hybrid? I'm still not too good at finishing a knife up, I fear cracking the scales trying to get them too tight. There is some slop at the butt end of this knife. I am going to practice on some junk and maybe come back to this knife later. I'll post more pics when the other 2 are finsihed.

[knives-are-quiet]

Hey, J - Bob~
That knife is absolutely beautiful.
I wouldn't worry about the little gaps here and there.
I have an original green river easy open with ebony handles.
It has gaps that were there from day one.
Stag is a little more forgiven than bone is.
But you still need to be careful when pinning.

Excellent job~
We need to see more of your work.

J W

[orvet]

Nice work Bob.
Do keep us posted with further developments.

[muskrat man]

most quality lawnmower blades and saw blades (like those from sawmills) do not need to be retempered for a backspring as they are spring consistency from the start. As long as you keep it cool by dipping in water while grinding you won't have to bother retempering.

[just bob]

Got another of these knives done today. I also got the inspiration for this knife from this web site. I saw the pearl handled Russell that was the Board of Directors knife in an auction. This is one of the pen blanks that was 1" wide. It is their version of imitation MOP. I have one more of these knives to do and have the original back spring left to work with. The two I made seem to function just fine. I hope to do the last knife in black pick bone - if I can find it.

[knives-are-quiet]

NICE!!!!!!!!!!!!!

[just bob]

Since the subject of this thread is back springs I'll post this here. My brother collects these leg knives and has over 300 better knives. This is one of those cheapo knives that are all over ebay. This knife was never used or carried. It was only opened to clean and oil. Both back springs on it broke in no time. I took it apart and they are .070 thick and look to be pot metal. In fact they look to be the same material that those cheap fingernail files are made out of? If you send these back for reapir there is a $7.50 S&H fee. When you include your original postage the repair isn't a bargain at all. It's cheaper to buy another - and maybe they know that.

[orvet]

And people ask me what the difference between a US made Schrade and one made in China?!

[just bob]

Got the last one of these 3 knives done and don't want to sound boastful, but it is my best work to date. Found the bone scales at the Lexington knife show and wish I would have bought more. They were at a good price with no S&H and that goes a long ways. I also made the back springs for the little leg knife from an old kitchen knife that was the right thickness. Even it it's an $8 knife I'll include a picture. I have also found out how to drill back springs and hard steel. If you heat it red hot with one of those gas torches that they solder with ($25 at Menards) and let it air cool you can drill right through it. I wasted a dozen drill bits before I discovered this.

[orvet]

I get used carbide drills from the local flea market (3 for $5). The drills are from the circuit board industry. Goes through the steel like butter and doesn't mess with the heat-treating of the steel.