Cutting sheet steel

In article ,
(Dan Thomas) wrote:

(Veeduber) wrote in message
...
One of the easiest ways to cut sheet 4130 is with a band saw. Use an
old metal cutting blade installed upside down (the teeth pointing up).
Run the saw at normal speed and feed in the material. Keep the
pressure up and it will go (melt) through like you are cutting butter.
Don't pause though, it is not so easy to get started again. Some have
also used the back side of the blade for this purpose with success.

O-ring Seals

---------------------------------------------------

Dear O-ring (and the Group),

I believe you'll find there's a bit more to it than that :-)

First off, the 'normal speed' you're referring to is for a woodworking
bandsaw.
The down-side is that most woodworking bandsaws are fitted with a rubber
'tire' on their driver- & idler-wheels. Friction cutting steel (which is
what
you're doing) will destroy the tire on the driver-wheel in short order.
Bandsaw tires are moderately expensive and can be hellishly difficult to
replace on some saws.

Metal-cutting bandsaws do not use tires. The wheels are sizes so that the
teeth overhang the edge of the wheel, not only for cooling but for clearing
the
swarf.

You can set-up a metal cutting bandsaw for friction cutting if you have the
proper ratio pulleys (ie, increase the blade speed).

The popularity of this method hinged largely on the builder's ability to
splice
their own blades because the original idea was to use common steel
strapping.
Operated at high speed -- and cutting relatively thin stock -- the stuff
does
in fact cut like butter, with a very attractive displace of sparks, too :-)
But the strapping was rapidly consumed and unless you were a dab hand at
splicing, ideally with a Do-All type butt-welder, there was no long-term
advantage over regular cutting.

All of this came about due to the difficulty of cutting relatively hard
steel
in thinner gauges, which loves to strip the teeth off anything. .035 4130,
you
can do pretty well using a regular bi-metallic 32T blade by simply rigging
the
work to feed 'downhill' so that two teeth are in contact with the work.


I used to cut 4130 using the bandsaw method, with a 1/2" bimetal
blade installed the right way, and just letting the teeth round off
the first time I used it. It would cut rather nicely, and didn't hurt
the rubber tire. Keeping the cut straight was the biggest hassle.
There's a German-made friction-cutting tool designed to cut sheet
of all sorts using a steel wheel that doesn't spin but instead
oscillates at a fairly high frequency in an arc of about 20 degrees or
so. I saw it demonstrated on aluminum, steel and even stainless steel.
Really noisy, but a really clean cut, too. No chips. When the section
of the disc doing the work gets a bit dull, you loosen the screw and
rotate it a bit to a sharper section. I am trying to remember the
name, but can't. It was a big hit at our aircraft engineer's symposium
a couple of years ago. Not cheap, but well worth the cost if you're
doing much cutting.
Friction welding of aluminum aircraft skin was presented there,
too, though not demonstrated. Skins are butted together and a
high-speed carbide bit with a flat end and one raised tit are run over
the joint under pressure, the metal heats and fuses, and the alloy is
not affected so strength isn't hurt at all. I don't know how. You get
a flush, seamless joint with far less hassle than riveting. Also very
expensive. I think Airbus is using it on the A380, maybe.

Dan

Dan

I would think that the seam would lose a lot of its basic heat treat
strength, due to the melting/recrystallization.

Orval Fairbairn wrote:
In article ,
(Dan Thomas) wrote:


(Veeduber) wrote in message
...

One of the easiest ways to cut sheet 4130 is with a band saw. Use an
old metal cutting blade installed upside down (the teeth pointing up).
Run the saw at normal speed and feed in the material. Keep the
pressure up and it will go (melt) through like you are cutting butter.
Don't pause though, it is not so easy to get started again. Some have
also used the back side of the blade for this purpose with success.

O-ring Seals


---------------------------------------------------

Dear O-ring (and the Group),

I believe you'll find there's a bit more to it than that :-)

First off, the 'normal speed' you're referring to is for a woodworking
bandsaw.
The down-side is that most woodworking bandsaws are fitted with a rubber
'tire' on their driver- & idler-wheels. Friction cutting steel (which is
what
you're doing) will destroy the tire on the driver-wheel in short order.
Bandsaw tires are moderately expensive and can be hellishly difficult to
replace on some saws.

Metal-cutting bandsaws do not use tires. The wheels are sizes so that the
teeth overhang the edge of the wheel, not only for cooling but for clearing
the
swarf.

You can set-up a metal cutting bandsaw for friction cutting if you have the
proper ratio pulleys (ie, increase the blade speed).

The popularity of this method hinged largely on the builder's ability to
splice
their own blades because the original idea was to use common steel
strapping.
Operated at high speed -- and cutting relatively thin stock -- the stuff
does
in fact cut like butter, with a very attractive displace of sparks, too :-)
But the strapping was rapidly consumed and unless you were a dab hand at
splicing, ideally with a Do-All type butt-welder, there was no long-term
advantage over regular cutting.

All of this came about due to the difficulty of cutting relatively hard
steel
in thinner gauges, which loves to strip the teeth off anything. .035 4130,
you
can do pretty well using a regular bi-metallic 32T blade by simply rigging
the
work to feed 'downhill' so that two teeth are in contact with the work.


I used to cut 4130 using the bandsaw method, with a 1/2" bimetal
blade installed the right way, and just letting the teeth round off
the first time I used it. It would cut rather nicely, and didn't hurt
the rubber tire. Keeping the cut straight was the biggest hassle.
There's a German-made friction-cutting tool designed to cut sheet
of all sorts using a steel wheel that doesn't spin but instead
oscillates at a fairly high frequency in an arc of about 20 degrees or
so. I saw it demonstrated on aluminum, steel and even stainless steel.
Really noisy, but a really clean cut, too. No chips. When the section
of the disc doing the work gets a bit dull, you loosen the screw and
rotate it a bit to a sharper section. I am trying to remember the
name, but can't. It was a big hit at our aircraft engineer's symposium
a couple of years ago. Not cheap, but well worth the cost if you're
doing much cutting.
Friction welding of aluminum aircraft skin was presented there,
too, though not demonstrated. Skins are butted together and a
high-speed carbide bit with a flat end and one raised tit are run over
the joint under pressure, the metal heats and fuses, and the alloy is
not affected so strength isn't hurt at all. I don't know how. You get
a flush, seamless joint with far less hassle than riveting. Also very
expensive. I think Airbus is using it on the A380, maybe.

Dan

Dan


I would think that the seam would lose a lot of its basic heat treat
strength, due to the melting/recrystallization.

A PDF on stir/friction welding from NASA.gov
http://makeashorterlink.com/?E472217A6


ww

I have purchased a number of items from Harbor Freight, and have
generally been satisfied with them. No question about these things
competing with top of the line merchandise, but for items that I
only use occasionally they are good enough. Two items that come to
mind are an angle grinder for $20 and an electric hoist for $60.

I'd suggest that you visit the store and decide which items you
would want to buy. Then if you are not in a hurry, get on their
mailing list and wait for what you want to come up on sale.
Sooner or later just about everything they sell is offered at
big discounts - often 50%.

David Johnson

I'll second the opinion about the quality of modern cars. I have
been astonished by the almost trouble free experience I've had with
my '92 T-Bird (bought new). At 11 years and 135K miles, it still
has the original belts, hoses, ignition wires, etc. Two of the
original tires went 77K miles. The only repair needed was the
"idle" servomotor that went out at a few years ago (the car ran
fine, but "idle" was about 1800 rpm).

David Johnson

"Aardvark" wrote in message ...
Orval Fairbairn wrote:
In article ,
(Dan Thomas) wrote:


snip
I used to cut 4130 using the bandsaw method, with a 1/2" bimetal
blade installed the right way, and just letting the teeth round off
the first time I used it. It would cut rather nicely, and didn't hurt
the rubber tire. Keeping the cut straight was the biggest hassle.
There's a German-made friction-cutting tool designed to cut sheet
of all sorts using a steel wheel that doesn't spin but instead
oscillates at a fairly high frequency in an arc of about 20 degrees or
so. I saw it demonstrated on aluminum, steel and even stainless steel.
Really noisy, but a really clean cut, too. No chips. When the section
of the disc doing the work gets a bit dull, you loosen the screw and
rotate it a bit to a sharper section. I am trying to remember the
name, but can't. It was a big hit at our aircraft engineer's symposium
a couple of years ago. Not cheap, but well worth the cost if you're
doing much cutting.
Friction welding of aluminum aircraft skin was presented there,
too, though not demonstrated. Skins are butted together and a
high-speed carbide bit with a flat end and one raised tit are run over
the joint under pressure, the metal heats and fuses, and the alloy is
not affected so strength isn't hurt at all. I don't know how. You get
a flush, seamless joint with far less hassle than riveting. Also very
expensive. I think Airbus is using it on the A380, maybe.

Dan

Dan


I would think that the seam would lose a lot of its basic heat treat
strength, due to the melting/recrystallization.

A PDF on stir/friction welding from NASA.gov
http://makeashorterlink.com/?E472217A6


ww


The Eclipse 500 is using a patented stir weld process...

--
Dan D.

Aardvark wrote in message .. .
Orval Fairbairn wrote:


I would think that the seam would lose a lot of its basic heat treat
strength, due to the melting/recrystallization.

A PDF on stir/friction welding from NASA.gov
http://makeashorterlink.com/?E472217A6


ww


That's the process. The metal, as they say, does not actually melt,
just plasticizes, and doesn't lose its strength.


Dan

It appears that my previous thank you note didn't get through. Maybe
it's a appropriate, 'cause now I get to thank everyone on Thanksgiving.
The generosity of members of this list is boundless. I actually had
several people volunteer to cut the sheet for me. I declined those
offers because of the shipping cost and difficulty of communication (and
I really do want to keep the 'I built that' element as much as possible).

I have an inlaw that has access to a portable plasma torch. I'm going
to get the sheet laid out and get up with him. I had actually forgotten
all about this particular resource until someone here mentioned it.
However, I'm still of the mind to hold back at least one piece so that I
can give that friction cutting method a try. Just 'cause I LIKE to see
sparks flying.

Beyond that, I've had dozens of occasions to recieve excellent
information from this newsgroup, both as direct responses to questions
I've posed and in responses to others...even from old curmudgeons(sp?)
like Barnyard Bob. Regardless of the amount of bickering and
namecalling, I firmly believe that everyone here has the goal of
building/help build the safest possible airplane at the least expense of
time, effort, and dollars. When I come flying into Sun'n'Fun or Oskosh
in a few years, you can all rest assured that you had a hand in getting
me there.

Thank you.

(PS - If I crash and burn on test flight, then it's all on my head.)

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

I used a table saw and later a radial arm saw with abrasive cutting wheels
from the local lumberyard/hardware. Works just like cutting wood, but
noisier and smellier. Be careful cover the wood table (if the saw table
isn't metal) with a sheet of metal or the sparks will cause charring. I've
cut up to .120 4130 this way and it works fine.

I wouldn't use this method for huge projects, since the grit is messy and
hard on the saw if you don't clean it well, but for the occasional part, it
worked well, cutting straight lines and fairly quickly.

"Ernest Christley" wrote in message
. com...
I've got some .035 4130 that I have to cut elevon ribs from. 2 inch on
one end, 3/8ths on the other and about 16" long (each one is a different
length). The small end fits against a run of tube, the thick end against
the elevon spar. Both ends have to be shaped appropriately. The sides
of the long runs need to be perfectly straight. I've seen a lot of
options on how to cut aluminum, but the info on steel seems to be more
limited. Here's where I'm at so far.

A shear big and strong enough to handle the job is currently out of my
budget. (though, I keep hearing that the economy is coming back around)

Harbor Freight has a $35 cutting tool that can handle the job according
to the advertised specs. It sorta, kinda looks like an angle grinder,
except that it has a short arm and a reciprocating tooth out one side.
I figure I can drill a 3/8" hole, clamp a 2x4 to each side of the sheet
as guides, and just make a run with the cutter. Anyone have experience
with these things? Do they leave a clean edge?

Another option is to pay a machine shop. If I can find a good shop, I'm
sure to get quality work, but I can't say that I did it and I won't have
a tool afterward. I'm saving that as a last resort.

Are there any better options?

--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber

Ernest Christley wrote in message .com...
I have an inlaw that has access to a portable plasma torch. I'm going
to get the sheet laid out and get up with him. I had actually forgotten
all about this particular resource until someone here mentioned it.
However, I'm still of the mind to hold back at least one piece so that I
can give that friction cutting method a try. Just 'cause I LIKE to see
sparks flying.

Might be a good idea to cut one piece with the plasma torch,
another with a saw, clean and polish the edges of both, then bend them
to see what the crack resistance is like. Plasma heat is big-time hot
and might drive lots of carbon (from slag) into the edge of the steel
and make it brittle. If so, it would be wise to cut a little oversize
and grind to final size.
I spent many hours cutting all sorts of metals with a plasma
torch some years ago. What a great time-saver. Of course, these were
feed-mill parts, not airplane parts, and nobody cared what happened to
the edges of mild steel.
I understand that the plasma flame is hotter than the surface of
the sun, which is something like 10,000°F. The interior of the sun, of
course, is much hotter than that.


Dan