I need to make some knives for cutting custom wood moldings. See this
for typical profiles:
http://www.wmooreprofiles.com/crowns.htm

The knives for my machine are cut from 1.500"x.250" tool steel, length
is .750" longer than the profile to be cut (biggest I need is 6.250"
long!). Commercial ones are heat treated to Rockwell 55-60, last 5000 to
10,000 feet before sharpening. I only need 100' to 1000' so I don't need
quite the hardness although full hard is nice for keeping a clean cut.
Warpage is a real problem, the gibs that hold these 8 oz chunks of steel
at 3600rpm depend on flat surfaces to grip.

I have access to a very accurate heat treat oven but it is not
atmospheric controlled. I can also access a surface grinder to clean up
scale and warpage BUT the gibs quit working if I go down too thin.

I grind smaller knives all the time, no huge deal to get the shape I
need on the grinder. This is the first try at these larger ones.

-What steel to use? A2, O1, W1 are all available
-can I get by with out heat treat? (Highly desireable to not deal with
warpage and scale) If so, what grade of steel?
-Can I wrap the blanks in a carbon steel package rather than the
expensive SS foil? (Some .008" steel could be flat formed around the
blank with crimped edges)
-How about just hardening the cutting edge? Rough cut, harden, temper??,
finish grind the last .010"

These custom knives are killing me for short runs to match some existing
woodwork. $200 cutter for 100' of molding.

In article t,
says...
I need to make some knives for cutting custom wood moldings. See this
for typical profiles:
http://www.wmooreprofiles.com/crowns.htm

The knives for my machine are cut from 1.500"x.250" tool steel, length
is .750" longer than the profile to be cut (biggest I need is 6.250"
long!). Commercial ones are heat treated to Rockwell 55-60, last 5000 to
10,000 feet before sharpening. I only need 100' to 1000' so I don't need
quite the hardness although full hard is nice for keeping a clean cut.
Warpage is a real problem, the gibs that hold these 8 oz chunks of steel
at 3600rpm depend on flat surfaces to grip.

I have access to a very accurate heat treat oven but it is not
atmospheric controlled. I can also access a surface grinder to clean up
scale and warpage BUT the gibs quit working if I go down too thin.

I grind smaller knives all the time, no huge deal to get the shape I
need on the grinder. This is the first try at these larger ones.

-What steel to use? A2, O1, W1 are all available
-can I get by with out heat treat? (Highly desireable to not deal with
warpage and scale) If so, what grade of steel?
-Can I wrap the blanks in a carbon steel package rather than the
expensive SS foil? (Some .008" steel could be flat formed around the
blank with crimped edges)
-How about just hardening the cutting edge? Rough cut, harden, temper??,
finish grind the last .010"

These custom knives are killing me for short runs to match some existing
woodwork. $200 cutter for 100' of molding.


If the furnace is good for 1750F, I'd give A2 a shot. It's inexpensive,
relatively easy to work, dead simple to harden, and dimensionally stable
in heat treat. McMaster has the SS tool wrap in small rolls ($20-30) and
small bags (as low as $2 ea). Or you can pack the part in cast iron
borings in a suitable container. Worst case is you may have to touch up
the edge to remove any decarburized suface.

My biggest concern with A2 for short runs is whether the edge will get
hot enough in use to draw the hardness back. As long as it doesn't
exceed 450F, which seems unlikely if the cutters are sharp and you're
milling pine or the like, I'd expect it to work OK.

For longer runs abrasion resistance is probably more important than
hardness. There's a huge difference in the abrasion resistance of
something like M4 compared to A2 at equal Rockwell hardness.

Ned Simmons

Ned Simmons

How about buying hardened stock and carefully grinding it without
destroying it's temper.

Thanks Ned,

snip


If the furnace is good for 1750F, I'd give A2 a shot. It's inexpensive,
relatively easy to work, dead simple to harden, and dimensionally stable
in heat treat. McMaster has the SS tool wrap in small rolls ($20-30) and
small bags (as low as $2 ea). Or you can pack the part in cast iron
borings in a suitable container. Worst case is you may have to touch up
the edge to remove any decarburized suface.

I guess I just wan't thinking about McMaster, the stainless bags are
just the right size. Can they be reused once or tweice? Would you use
the oversize (.015" over the nominal .250") material and surface grind
or will the pieces come out clean?

Heat treat regimen something like: 1750 for 10 minutes, air cool on a
brick, temper at (??) for 10 minutes, cool on a brick???


My biggest concern with A2 for short runs is whether the edge will get
hot enough in use to draw the hardness back. As long as it doesn't
exceed 450F, which seems unlikely if the cutters are sharp and you're
milling pine or the like, I'd expect it to work OK.


I can't see the temp being a huge issue. The molder has power feed, very
little chance of just sitting in one spot and rubbing.

For longer runs abrasion resistance is probably more important than
hardness. There's a huge difference in the abrasion resistance of
something like M4 compared to A2 at equal Rockwell hardness.


Yep!!, the first pieces I need are all pine. If it works, there are
several runs of cherry in the plans. THAT stuff is ABRASIVE!! But still
relatively short runs, no more than low hundreds of feet.

In article t,
says...
Thanks Ned,

snip


If the furnace is good for 1750F, I'd give A2 a shot. It's inexpensive,
relatively easy to work, dead simple to harden, and dimensionally stable
in heat treat. McMaster has the SS tool wrap in small rolls ($20-30) and
small bags (as low as $2 ea). Or you can pack the part in cast iron
borings in a suitable container. Worst case is you may have to touch up
the edge to remove any decarburized suface.

I guess I just wan't thinking about McMaster, the stainless bags are
just the right size. Can they be reused once or tweice?

In order to quench the part you need to get it out of the bag quickly,
otherwise the bag may prevent the part from cooling at the proper rate.
I suppose you could get the bags large enough that you could snip off
the sealed end, leaving enough for another use, but in my experience the
foil takes a beating at A2 temps. You also want to minimize the amount
of air in the bag, so an oversize bag is less than ideal. Wrapping the
part in brown paper helps to consume any oxygen in the bag and also
helps to prevent the part sticking to the foil.

Would you use
the oversize (.015" over the nominal .250") material and surface grind
or will the pieces come out clean?

If you seal the bag or foil pack carefully and use the paper wrap you
shouldn't see much decarb, certainly nowhere near .015 inch.

Heat treat regimen something like: 1750 for 10 minutes, air cool on a
brick, temper at (??) for 10 minutes, cool on a brick???

The usual recommendation is "cool in still air". I'd avoid setting the
part on anything that would tend to cause uneven cooling and increase
the chance of internal stresses and distortion. If you can put a hole in
one corner you could fish the part out of the foil with a wire hook and
hang to cool. However you decide to handle the part, it's a good idea to
do a practice run cold, perhaps with aluminum foil. You don't want to be
scrambling for another pair of pliers while the part is cooling in the
bag.

More heat treat info, including tempering temperatures, here...
http://www.crucibleservice.com/produ...ming/index.cfm

Ned Simmons

Thanks.

Ned Simmons wrote:
In article t,
says...

Thanks Ned,

snip



If the furnace is good for 1750F, I'd give A2 a shot. It's inexpensive,
relatively easy to work, dead simple to harden, and dimensionally stable
in heat treat. McMaster has the SS tool wrap in small rolls ($20-30) and
small bags (as low as $2 ea). Or you can pack the part in cast iron
borings in a suitable container. Worst case is you may have to touch up
the edge to remove any decarburized suface.

I guess I just wan't thinking about McMaster, the stainless bags are
just the right size. Can they be reused once or tweice?


In order to quench the part you need to get it out of the bag quickly,
otherwise the bag may prevent the part from cooling at the proper rate.
I suppose you could get the bags large enough that you could snip off
the sealed end, leaving enough for another use, but in my experience the
foil takes a beating at A2 temps. You also want to minimize the amount
of air in the bag, so an oversize bag is less than ideal. Wrapping the
part in brown paper helps to consume any oxygen in the bag and also
helps to prevent the part sticking to the foil.


Would you use
the oversize (.015" over the nominal .250") material and surface grind
or will the pieces come out clean?


If you seal the bag or foil pack carefully and use the paper wrap you
shouldn't see much decarb, certainly nowhere near .015 inch.

Heat treat regimen something like: 1750 for 10 minutes, air cool on a
brick, temper at (??) for 10 minutes, cool on a brick???


The usual recommendation is "cool in still air". I'd avoid setting the
part on anything that would tend to cause uneven cooling and increase
the chance of internal stresses and distortion. If you can put a hole in
one corner you could fish the part out of the foil with a wire hook and
hang to cool. However you decide to handle the part, it's a good idea to
do a practice run cold, perhaps with aluminum foil. You don't want to be
scrambling for another pair of pliers while the part is cooling in the
bag.

More heat treat info, including tempering temperatures, here...
http://www.crucibleservice.com/produ...ming/index.cfm

Ned Simmons

On Sun, 08 Jan 2006 16:58:56 GMT, RoyJ wrote:

-What steel to use? A2, O1, W1 are all available

If you're going to make it yourself I'd stick with the simplest steels
that are most forgiving to work with. That would be 5160 or 1080,
1084, 1095. These high carbon steels are forgiving and will harden
rather easily.

-can I get by with out heat treat?

No. Annealed steel will be way too soft.

-Can I wrap the blanks in a carbon steel package rather than the
expensive SS foil? (Some .008" steel could be flat formed around the
blank with crimped edges)

If you wanted to go to all the trouble... you could theoretically
build a sealed box, place your blade inside, spray a bunch of WD40 and
weld it shut. You put that whole thing in the oven... when the WD40
combusts it burns the oxygen in the box and you've got a controlled
environment. But you've also caused yourself a lot of new issues...
Foil is much easier.

-How about just hardening the cutting edge? Rough cut, harden, temper??,
finish grind the last .010"

If you use one of the simple steels I mentioned before, it is actually
possible to harden just the edge using nothing but an oxy-fuel torch
and a quench tank. You can see a video of this process he
http://www.pozadzides.com/bladesmith.../hardening.htm

Select the link called "Part 1 - Mike Hardens with Oxy Torch". We
took that blade, sharpened it, put a handle on it, chopped wood, bent
it and generally tested the crap out of it. It was not as good as
having done a full heat treat, but it still passed all the tests.

John P.

I was a custom knifemaker for 15 years, did some bookbinding knives,
woodworking knives and carving tools, did dies for leather welt splitters,
did all kinds of crazy stuff.

I completely endorse both of Ned's posts, he is right on the money from my
point of view. I think A2 is probably the sweetest spot in terms of relative
ease of use, relative ease of availability, good result etc etc. Heat
treating foil is great stuff. One thing to watch for in heat treating A2 is
that there are two tempering temperatures that give quite good toughness,
while most of the range between yields markedly less toughness. I'm away
from my technical references, but i believe a two hour draw at 430 F, cool,
then second two hour draw at 430 will be close to optimal. Sub-zero after
the hardening would be good, but is not absolutely mandatory.

Adam Smith
Midland, ON

"RoyJ" wrote in message
k.net...
I need to make some knives for cutting custom wood moldings. See this for
typical profiles:
http://www.wmooreprofiles.com/crowns.htm

The knives for my machine are cut from 1.500"x.250" tool steel, length is
.750" longer than the profile to be cut (biggest I need is 6.250" long!).
Commercial ones are heat treated to Rockwell 55-60, last 5000 to 10,000
feet before sharpening. I only need 100' to 1000' so I don't need quite
the hardness although full hard is nice for keeping a clean cut. Warpage
is a real problem, the gibs that hold these 8 oz chunks of steel at
3600rpm depend on flat surfaces to grip.

I have access to a very accurate heat treat oven but it is not atmospheric
controlled. I can also access a surface grinder to clean up scale and
warpage BUT the gibs quit working if I go down too thin.

I grind smaller knives all the time, no huge deal to get the shape I need
on the grinder. This is the first try at these larger ones.

-What steel to use? A2, O1, W1 are all available
-can I get by with out heat treat? (Highly desireable to not deal with
warpage and scale) If so, what grade of steel?
-Can I wrap the blanks in a carbon steel package rather than the expensive
SS foil? (Some .008" steel could be flat formed around the blank with
crimped edges)
-How about just hardening the cutting edge? Rough cut, harden, temper??,
finish grind the last .010"

These custom knives are killing me for short runs to match some existing
woodwork. $200 cutter for 100' of molding.

I stopped to check on the heat treat oven, found out that there is a
"lifetime" supply of the foil in the cabinet next to the oven.

I just took a look at the toughness chart. Wow! is there a valley
inbetween the peak at 500 Degree F temper and 1000 degrees F. I can
easily do the 500F point, including the double temper and cyrogenic
inbetween. Liquid nitrogen.

Adam Smith wrote:
I was a custom knifemaker for 15 years, did some bookbinding knives,
woodworking knives and carving tools, did dies for leather welt splitters,
did all kinds of crazy stuff.

I completely endorse both of Ned's posts, he is right on the money from my
point of view. I think A2 is probably the sweetest spot in terms of relative
ease of use, relative ease of availability, good result etc etc. Heat
treating foil is great stuff. One thing to watch for in heat treating A2 is
that there are two tempering temperatures that give quite good toughness,
while most of the range between yields markedly less toughness. I'm away
from my technical references, but i believe a two hour draw at 430 F, cool,
then second two hour draw at 430 will be close to optimal. Sub-zero after
the hardening would be good, but is not absolutely mandatory.

Adam Smith
Midland, ON

"RoyJ" wrote in message
k.net...

I need to make some knives for cutting custom wood moldings. See this for
typical profiles:
http://www.wmooreprofiles.com/crowns.htm

The knives for my machine are cut from 1.500"x.250" tool steel, length is
.750" longer than the profile to be cut (biggest I need is 6.250" long!).
Commercial ones are heat treated to Rockwell 55-60, last 5000 to 10,000
feet before sharpening. I only need 100' to 1000' so I don't need quite
the hardness although full hard is nice for keeping a clean cut. Warpage
is a real problem, the gibs that hold these 8 oz chunks of steel at
3600rpm depend on flat surfaces to grip.

I have access to a very accurate heat treat oven but it is not atmospheric
controlled. I can also access a surface grinder to clean up scale and
warpage BUT the gibs quit working if I go down too thin.

I grind smaller knives all the time, no huge deal to get the shape I need
on the grinder. This is the first try at these larger ones.

-What steel to use? A2, O1, W1 are all available
-can I get by with out heat treat? (Highly desireable to not deal with
warpage and scale) If so, what grade of steel?
-Can I wrap the blanks in a carbon steel package rather than the expensive
SS foil? (Some .008" steel could be flat formed around the blank with
crimped edges)
-How about just hardening the cutting edge? Rough cut, harden, temper??,
finish grind the last .010"

These custom knives are killing me for short runs to match some existing
woodwork. $200 cutter for 100' of molding.