Developing my own digging tool.. Tell me what you think..

[Lee-MI-MI]

For a tool holder, I use a Klien number 5129 flashlight holder. It has a bottom but it is not closed off so any dirt just falls through. I do not know how to post a picture but go to their web site and look at it. It does not have any way to hold the digger in so it is possible to fall out if you turn it upside down. I have never had my digger come out while using it.

For a source of tempered steel try leaf springs from old light weight cars. Another source is rotary lawn mower blades.

I am sure you can buy untempered tool steel that can be tempered when you are through. Do some reading on how to do it. Basically you heat it to some temp, usually judged by the color, then dip in oil. Water will chill it too quickly and cause it to become brittle.

Mild steel will not be tempered well but it can be case hardened. That leaves a softer core but a very hard surface that can hold an edge very well. You heat it to a cherry red then rub it in carbon/graphite until it is no longer red. Not sure it this would be good for a digging tool. Very good for knives.

Check local commercial welding/fabricating companies for information about tempering. If they cannot do it for you, they may be able to refer you to someplace close by. Something all old time blacksmiths could do as part of their trade.

 

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[Number9]

If you're going to make a digging tool to sell you need to consider many things.
The metal you use needs to be as easy as possible to fabricate.
The metal must be at a reasonable price and easy to obtain.
If the metal in the standard form meets the requirements you need to do the job,
this will lower your cost by not having to do extra steps, such as post heat treat.

Just remember, when a metal is used because it is the best for one application,
it may be a poor choice when used in a different way. 440C stainless makes a nice blade for a knife because
it is hard and will hold an edge. But shove it into the ground several times and you will see it will chip from hitting rock.
When making a digging tool you need the metal to have a high "fatigue limit". The highest load that can be repeatedly applied without breaking a material is known as the fatigue or endurance limit. AISI 4130 alloy steel shines at 130 ksi, over three times greater than the next closest alloy, 440C stainless steel. That's the reason many knife blades break when they are used as a pry bar!

I would consider using 4130 because it fits most of the requirements for a digging tool for resell.
If I make a digging tool for myself, it will be made from Grade 5, titanium. But I wouldn't be making it for resell!

 

[NWGA-RelicHunter]

Thanks for the replies and suggestions about types of steel guys. I'm familiar with the hardening and tempering process, and the different types of steel. While using items such as leaf springs, driveshafts and lawnmower blades etc and hand heat treating each one would probably be fine for making a few tools for your own personal use, it just wouldn't be feasable for producing a large quantity. In order to keep the cost of the tool low and competitive with other digging tools, I would need to get these produced in large quantities at a single location. In order to do that, you would need to cut them from flat stock on a cnc plasma or laser, form them on a press, harden and temper them by the batch in a large oven, etc. True, I could do it myself one by one, but it would be much more costly and time consuming without having all the proper equipment and materials.

NWGA have you heard the storys of the cannons in your graveyard down there?

Yep, Myrtle Hill Cemetary. Located right accross the river from the old foundry which manufactured cannons. Apperently archaeologists used some kind of ground penetrating radar and located some large cannon shaped object at the cemetary. Rumor has it that they burried some cannons there and dumped several more into the river to keep union troops from getting their hands on them. I've detected "near" that area and made some pretty nice finds.

 

[Tnmountains]

yes a nice historical area. Keep us updated on your tool. Might have to give it a try up here around Chattanooga

 

[Number9]

I'm familiar with the hardening and tempering process, and the different types of steel.

What type of steels were you considering and the hardness and range of temper?

 

[NWGA-RelicHunter]

What type of steels were you considering and the hardness and range of temper?

Well I would like to use 4130 chrome moly. That would definitely be ideal for a digging tool. But heat treatment for 4130 requires a furnace to reach 1600+ degress. Thats the problem. I don't have access to such a furnace, and I don't want to do these individually by hand because no two of them would be the same hardness (this would cause inconsistencies and quality problems). The steel has to be cut and formed before it can be hardened and tempered.. So thats why I'm trying to find a company who can do everything in house at a single location. Otherwise I would have to have the steel shipped to me so that I can cut it and form it, then shipped to someone else for the hardening and tempering proccess, and then shipped back to me again for final assembly, packaging and distribution. There's no way I could keep the price competitive if I do it that way.

 

[NWGA-RelicHunter]

Tank, Jeff & Minningtown,
Your prototypes shipped out yesterday. Should be there within a week or two.

 

[Dedimus]

I would use that weapon in battle

 

[PAmike]

back to your tempering problem. If you are welding the handle to the blade you will want it tempered afterwards. case hardening is another option that works very well.

 

[Number9]

I believe if I was thinking about making a tool for resell, I would try to design a digging tool that could be made without having to heat treat the metal after it's formed... unless I had all the equipment to do the required work "in house". When you get a subcontractor to complete any step in a products development, you loose total control over the quality of that process and also cut into the profit you would gain...
That is the reason I suggested using a steel that wouldn't require to be heat treated after the tool is made.
4130 (Chromoly) Normalized Alloy Steel would be a steel that could be worked and still maintain the properties needed to make a digging tool similar to the Lesche Digging tool without the extra expense of heat treat.
4130 can be welded without having to have a treatment after welding on metals that are about 1/8"(10ga) or less and still give a strong bond.
A digging tool must have some flexibility and yield, yet still maintain it's shape after repeated use. If the temper is to high the metal will be giving up the yield for hardness that would lead to the possibility of the tool breaking and not flexing under a heavy load.
If you don't know what the combination of "strength", "flexibility", and "yield", looks like under a heavy load this should explain it.

 

[Juanmoretime]

What a fine knife to wear into a bar!!! Lol!!!

 

[NWGA-RelicHunter]

Number9,
Thanks for that info. I really would love to be able to produce the digging tool myself without needing any outside help.. The only thing I want to make sure of is that I can produce a high quality tool that is equal to (or better than) the Lesche in strength and quality. Otherwise, its not worth doing (IMO). Lesche uses hardened and tempered 4130 .120 (11ga) for their blades.. You are correct, their is a fine line between making a blade too brittle with the heat treating process and too soft (not hardened or tempered) which would just allow it to bend with too much pressure. I don't want these blades to bend, like the el-cheapo diggers on the market. I don't want them to break easily either. Its going to take a little (a lot?) experimenting on my part to find the perfect combination of yeild and hardness. I will definitely take your advice and try to find a steel that will do the job without needing to be hardened and tempered. If 4130 turns out to have the right combo of flex and hardness without needing to be heat treated, great. Thats what I'll use. But if it doesn't work out and I can't find something that will fit the bill, I'd rather give up on the idea completely than produce an inferior product.


Someone mentioned case hardening the mild steel that I'm currently using. That may work OK for putting an edge on it, but it won't do much for overall strength as case hardening only hardens the outside (case) of the metal.

Going with a thicker steel to improve strenght isn't really an option either, as it would make the tool too heavy.

Thanks again for the comments and suggestions guys.

 

[extractor]

bump How is it going. Have ya been able to get it into production?

 

[NWGA-RelicHunter]

bump How is it going. Have ya been able to get it into production?

Unfortunately no. I have been in contact with a few companies who offered to produce it, but the $$$ it takes to get started (buying samples, initial purchase, etc) is just beyond what I can afford right now. The old saying "it takes money to make money" is 100% correct.

 

[Born2Dtect]

TANK69,

Is the picture in post #15 of you in the old "Colorado River" in Yuma?

Ed D.

 

[Night Stalker]

Ok, you talked me into it...........I'll be an official tester! I want one of those

 

[db1guy]

I would make the handle a bit longer for leverage,, also I would give this digger a shot if youd like a field tester, I d be happy to compare it to my skydriver,my favorite coin tool.Looks like you have a good adaptation there, is the material thermoplastic or metal? Or combination? Thanks! 1guy

 

[halfstep]

For a blade to be tempered, it must have enough carbon in. Then when you temper it, you take the blade to a specific temp and then quench it to harden it. Then you reheat to a lower specified temp to draw it back from being too brittle. You can draw it back enough to make the steel springy then reheat the edge and requench it. This produces a strong edge with a flexable backbone. This would be time consuming but would make the best blade.
The use of 4130 chrome allows for a hard blade that is wear resistent. Using a leafspring out of a small vehicle would make a great digger knifer steel. It is a spring steel. You can get them at junkyards pretty cheap and find the size you need to keep from having to do a lot of work on it. You can find the width and thickness you needs and then just shape the blade. A good nickel steel would make a flexable wear resistent blade as well.
Your digger looks like a good design. I would like to see a set of teeth on both sides with a slight tooth offset like a saw blade. This will make it cut.

 

[olepossum]

hook me up i will test one for you with the nw missouri winter diggin

 

[jeremy]

Awsome digger