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How to make a stringing cutter

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Blog entry by apprentice posted 09-04-2012 01:14 PM 3371 reads 1 time favorited 9 comments Add to Favorites Watch

Here is a step by step tutorial of how to make your own cutters.

First take a length of gauge plate or sometimes called ground stock, do not attempt making it from mild or stainless steel because ordinary mild steel does’nt contain the correct mixtures that aid hardening, like tool steel has.

Here I’m using 15.00×5.00mm gauge plate, drilled a 8.00mm hole in one end leaving 6.00mm of stock at the top side of the hole.

Round over the top of your bar.

Now using a hacksaw or dremel cutting disk, cut down at an angle from the top centre of the bar so that the cut lines up with the indide edge of the hole you drilled at the start.

Leave a gap at the top of around 5.00mm between the two angled cuts.

Next using a saw file, file the vee into one side until you have the two clearing ears, be careful not to file into the opposite edge, leave slightly flat tops to the ears so you can hone them up later.

Your cutter done it is now ready for hardening and tempering.

-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded



9 comments so far

View shipwright's profile

shipwright

5010 posts in 1465 days


#1 posted 09-04-2012 03:30 PM

This is a nice looking cutter.
I understand it and how it works just fine but could you add a photo of it in use to show the position in which it is held / used?

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View apprentice's profile

apprentice

201 posts in 826 days


#2 posted 09-04-2012 04:00 PM

To harden your cutter you will need a litre pot of old sump oil, or brine. The brine solution can be used in place of the oil for the cooling stage, it consists of as much salt you can dilute in solution until no more will dissolve in hot water.

Heat things using a suitable heat source that can reach the magic 880 or there abouts, you can use a magnet to check this, basically when the magnet will no longer stick to the metal, this is the correct temp to dip the cutter into the oil or salt solution, things need to cool down slowly, “do not quench in cold water at the first stage” !.

I use a Rothenburger surefire 2unit using map/pro gas as a fuel, which is a mixture of propane and exetylene, ideal for that little more hitting power, however, normal propane should be ok here as we are only heating a relatively small section, thicker materials will require more heat or a specialist oven if you have one.

So, heat the cutter evenly and gently until the cutter area of the metal is showing a dull red/880, hold it there for a couple of minuites to make sure the core temp is even with the rest of the metal, then with a constant stirring motion dip it into the oil to cool down the metal until all bubbling stops, if you don’t stir, you end up with a jacket of hot bubbles that creates a gas jacket around the hot billet and you won’t get as good a temper into the metal.

Also, old engine oil has deposits of burnt carbon from the combustion process which aids hardening the metal, which absorbs these extra carbons.
Also make sure to buy good quality gauge plate and not Chinese imported material, because it simply won’t take on the desired hardness and result in a tool that will go blunt faster, won’t hold its edge.

Now clean up the blade again until shiny, then adjust down your gun to a small less virile flame and gently heat up the blade again, this time from the opposite end to the cutting edge, and watch as the colours start to form and then run along the blade, when things start running you can back off the flame momentarily to control the speed at which they run….. Do this until the cutter area is a sraw yellow and dip the cutter into plain cold water to lock the colours in, and job done.

The straw colour seen here takes back the brittleness/hardness at the very thin cutting. edge and gives a still hard but more ductile edge.


-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded

View apprentice's profile

apprentice

201 posts in 826 days


#3 posted 09-04-2012 04:08 PM

Cutter in situ on croze, it can also be used in hand routers.

-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded

View Jim Rowe's profile (online now)

Jim Rowe

561 posts in 979 days


#4 posted 09-04-2012 04:41 PM

Excellent pics on hardening.Does the cutter need to be honed to give a cutting edge or is that provided by the v groove?
Jim

-- It always looks better when it's finished!

View Mauricio's profile

Mauricio

6820 posts in 1818 days


#5 posted 09-04-2012 04:42 PM

pretty cool, so the V scores the grove and the other side carves out the groove. I need to try heat temporing one day. Great explanation.

-- Mauricio - Woodstock, GA - "Confusion is the Womb of Learning, with utter conviction being it's Tomb" Prof. T.O. Nitsch

View apprentice's profile

apprentice

201 posts in 826 days


#6 posted 09-04-2012 06:04 PM

Jim

Yes the cutter needs a final honing before use, it is best to form the tool to a relative sharpness, but not razor sharp, otherwise the delicate edges could be destroyed by the hardening process.

Paul

You can see the croze being used in the film link, I have yet to use mine.

Here is another tool which I’m making soon in which the cutter would be fully at home.

-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded

View apprentice's profile

apprentice

201 posts in 826 days


#7 posted 09-06-2012 05:22 PM

The cutter made, here is the body or stringing router. She is made from English holly as is the wedge, it has a full brass sole to extend the life of the tool and will take up to 5.00mm wide cutters.

I still have to make a sellection of different width cutter and the fence, coming soon.

5 hours labour so far.

-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded

View Mauricio's profile

Mauricio

6820 posts in 1818 days


#8 posted 09-06-2012 05:32 PM

Wow, another sweet tool Apprentice!

-- Mauricio - Woodstock, GA - "Confusion is the Womb of Learning, with utter conviction being it's Tomb" Prof. T.O. Nitsch

View apprentice's profile

apprentice

201 posts in 826 days


#9 posted 09-08-2012 06:03 PM

A few shots of the reversible Honduran rosewood fence and mech, this gives a working capacity of an 1-1/4”.

-- http://www.youtube.com/watch?v=qcyhgsGA6mY&feature=player_embedded

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