# Home made dovetail cutter



## BillWood (Oct 29, 2014)

Hello,

I thought this was clever

http://www.opensourcemachinetools.org/archive-manuals/Dovetail_Cutter_explanation.pdf

Am a little confused - should I be able to do this by turning a piece of drill rod or silver steel in my 9" Hercus (equivalent to 9" south bend)

Should I use a HSS cutter or something different to cut drillrod/silversteel ?

When I buy a piece of "drillrod/silversteel" how do I ensure that I'm not being sold a piece of toolsteel and the shop assistant doesnt know the difference ? Does toolsteel come in big round rods ?

Any good links or previous threads that clearly summarise the differences ? Google does show some confusion on these issues - below is my current understanding

Silver Steel = British word = Drill Rod in USA
Drill Rod = American word - see above

I can buy Silversteel or Drillrod and make other tools with it on my 9" lathe - need to do some heat treatment after I have finished turning then I sharpen on a grinder ?

Tool Steel - Same as HSS ? 
HSS - High Speed Steel - what my cutters are made of and I buy them as small usually squarish section blanks approx 3-4" long

In any of the above categories there can be slight variations in various elements such as chrome vanadium carbon etc.

I have seen some suggestions that Tool Steel is a generic term that can include Silver steel, drill rod and HSS under one broad term.


If this is all covered in a FAQ then Ive missed it and please point me there.

Bill


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## Andre (Oct 29, 2014)

I made one exactly like it for cutting 11mm scope ring dovetails in a part. Made from a piece of junk hex key, worked great. Want a picture?


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## BillWood (Oct 29, 2014)

Andre said:


> I made one exactly like it for cutting 11mm scope ring dovetails in a part. Made from a piece of junk hex key, worked great. Want a picture?



Yes Please Andre,

So Junk Hex key is a source of steel that I can use to make cutters ?

What other types of junk can be used to make cutters ?

Bill


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## Andre (Oct 29, 2014)

BillWood said:


> Yes Please Andre,
> 
> So Junk Hex key is a source of steel that I can use to make cutters ?
> 
> ...




 Long story short (I actually did type a long story, but I'll post it later in another thread showing the usefulness of old hex keys) I have a friend who always has junk Allen wrenches that I happily dispose of :biggrin:

Other things to make cutters from: Hardened dowel pins, injection molding ejector pins, anything hardened or hardenable basically.  

Pics tomorrow


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## Andre (Oct 30, 2014)

Darn, I'm so sorry! I forgot to take a picture of the dovetail cutter while in the shop today. 

I'm really sorry, I'll get them to you ASAP! (probably tomorrow)

Sorry bout that.


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## Terrywerm (Oct 30, 2014)

Bill, it looks like you have it pretty well figured out. Yes, Drill rod in the US is pretty much the same thing as silver steel in Great Britain. If there are any differences, they are very slight. 

Yes, you can use drill rod/silver steel to make cutting tools such as a dovetail cutter.  It can be cut easily using HSS tools in its annealed state, which is the way it is when you purchase it.

Tool steel is a very generic term, and it can mean drill rod, HSS or other alloys, as you have already seen.

Drill rod / silver steel are steels that can be hardened and tempered through the use of a heat treating process. This process requires heating the part, then quenching it in the proper medium for the type of steel that you have, then heating it gently a second time, but only to a specific temperature to set the temper. Here in the US, drill rod can be obtained in a variety of types, such as W-1 which is a  water hardening rod, meaning that water is used as the quenching medium.  There is also O-1, which is an oil hardening rod, using a special type of quenching oil, and there are some air hardening types as well, where they are simply quenched in the surrounding air.  There are other types as well, but I have laid out the basics here.

Andre's suggestion of using old hex keys is not a bad idea, but annealing them before machining is the way to go.


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## Andre (Oct 30, 2014)

terrywerm said:


> Andre's suggestion of using old hex keys is not a bad idea, but annealing them before machining is the way to go.



I didn't anneal mine to make the cutter. Just cut the short end to length and grind the profile, just be careful to not get it too hot as to ruin the hardening. 

These cheap hex keys that come with guitars are in fact hardened, surprisingly. Not as hard as name brand keys but still hard enough for a seldom used cutter.
I have however annealed them in the past on the stove to machine a miniature hexagon cannon barrel. Worked like a charm.


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## Andre (Oct 31, 2014)

Here are the pictures as promised. Again, sorry for the delay.

The larger one is the dovetail cutter and the smaller was a from an odd job. Had to deburr the underside of a 1/4" hole inside 3/4" square aluminum tubing. Couldn't reach in with a file so I had to be creative. 







Notice the chip breaker, it helps give the edge a more positive rake angle and reduces the power needed to drive the cutter. Not that my mill is running out of power but the lower needed power for the cut the better. The back of the tools is nothing special, just some relief. 

I drove these tools with a jacobs chuck. They are a hex size where the diameter over the points won't fit in one of my 1/16" separated collets. If I remember correctly it was between 3/16" and 1/4". Wouldn't stretch a 3/16 collet enough and a 1/4" wouldn't shrink enough. So drill chuck it was.

If you use a drill chuck, make sure there is a drawbar holding it in the taper, or in my case a straight shank in a collet. Also take light cuts, drill chucks aren't meant for milling. Just be careful and you'll be fine.


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## BillWood (Nov 1, 2014)

Andre and Terry, Many thanks for the replies

Bill


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## Terrywerm (Nov 1, 2014)

Andre said:


> I didn't anneal mine to make the cutter. Just cut the short end to length and grind the profile, just be careful to not get it too hot as to ruin the hardening.
> 
> These cheap hex keys that come with guitars are in fact hardened, surprisingly. Not as hard as name brand keys but still hard enough for a seldom used cutter.
> I have however annealed them in the past on the stove to machine a miniature hexagon cannon barrel. Worked like a charm.



Ah yes!! I guess I wasn't thinking only along the lines of grinding a hex key to shape as a new tool. To grind to shape, annealing certainly would not be necessary, but to machine it in the mill or lathe would be a different story.


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## Eddyde (Nov 1, 2014)

In a pinch you can also use router bits on metal, just use a slower feed and lots of coolant. You can also regrind the rake if necessary.


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## iron man (Nov 1, 2014)

Or for $13 you could just buy one and avoid the hassle.

https://www.grizzly.com/products/Dovetail-Cutter-3-8-x-60-/H2955


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## Andre (Nov 1, 2014)

Eddyde said:


> In a pinch you can also use router bits on metal, just use a slower feed and lots of coolant. You can also regrind the rake if necessary.



I did this a few times using a dovetail cutter. Worked great.


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