cutting steel plate with circular saw?

wrote:


Don, very nice, thank you. I will make something similar. I got my plasma cutter to work [somewhat], will ask more in sci.engr.joining.welding.
By the way, you can just apply a light coating of heavy oil (like HD-40 or 80w90) to those things and they will never rust.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
A friend of mine has a metal working wife. He got to buy a plasma machine for her (and gets to use it himself...) She tried tracing around a figure she had cut from 3/4" pine. The pine didn't see the heat. The tip centers inside of the outside barrel that isolates part of the torch electrically.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Pete C. wrote:

-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Igor, I've now made a couple of plasma cutter circle cutters and haven't got a good one yet. I machined one awhile ago from an old brass nut but that plasma cutter has a hot tip (apparently) because enough current flowed through the central bearing to melt it. Back to the drawing board.
What I do right now is to use pieces of scrap plywood in 1/4" or 3/8" thickness (depending on your torch). For cutting an external guide (the kind I prefer) I start by quickly cutting a hole with a small hole saw. Then I figure the radius of the circle I want, including the critical distance from the edge of the guide to the cut edge (this distance you have to determine from experiment, although you can get a pretty close approximation by measuring from the OD of your torch tip to the outer edge of the central air hole) and set a compass to that radius. Then I set the compass drawing point on the edge of the hole I just sawed out and prick punch the circle center with the other end. (The sawn hole is tangent internally to the hole I'm about to draw.) Then I draw out the circle and then cut it out with a jigsaw (which some people call a saber saw depending on geography) and sand it smooth using a drum sander in the lathe.
Then I rip a rough square around this hole and write the designed hole dimension on the plywood circle template. I use squeeze clamps to locate the template and quickly rip out holes with the plasma cutter. It takes about 50 times as long to make the circle templates as it does to cut the metal.
Grant
Ignoramus3975 wrote:

--
Posted via a free Usenet account from http://www.teranews.com


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    (SNIP)     --Oh hey yeah; forgot about those. Saw a demo last year at WESTEC; very impressive! Still I'd hate to have to cut out a circle with one, heh.
--
"Steamboat Ed" Haas : Any Scrabble players
Hacking the Trailing Edge! : around? I cracked 500!
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

First, don't try using an abrasive blade with a circular saw WITH A PLASTIC HOUSING. [You'll melt the poor thing.]
Second, abrasive blades are cheaper than the slotted-type metal blades and do a better job. [BTDT, still have what's left of the slotted blade.]
If you have a circular saw with a steel housing, an adequate guide & clamps, and a couple of abrasive blades then you're ready to begin.
BTW, what size are these sheets?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ben, This is not the best tool for this job. Find someone or rent a plasma cutter. You will be done in minutes whereas with the method you propose will be slow, dirty, noisy, go thru several blades and possibly destroy the saw.
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
circular saws are for woodworking, use either a metal bandsaw (Do-All or Dake) or a plasma cutter.
Tony

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@gmail.com wrote:

With a good table saw and some discipline (ya gotta keep the cut straight) it can be done. The key is a friction blade, looks like a no-teeth circular saw blade, and it literally heats to yellow-heat by friction and pushes through the butter-soft steel. Takes some significant power, though, and makes LOTS of sparks.
You can also get grit-type metal cutting wheels, but they (in my experience) get bound in the cut unless you have good stiff workpieces.
Most folk would do this kind of cutting by oxyacetylene. The OA sparks are less surprising, but there's plenty with any of these three options.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Back sometime in the 70's before abrasive blades became popular and dirt cheap, I bought a metal cutting blade from the Sears Tool Catalog. It fits on a 7 circle saw, and the blade only has four teeth. Well they are not really teeth just slits. The blade is smooth and at four places it has a slit cut into it. I have used it to cut up to 3/8-inch thick steel plate. The way it works is that the blade cuts by friction. The edge touching the metal being cut, gets it red hot or hotter and is pushed away by the blade. The blade doesn't get hot enough to damage it because it only has a small area in contact at any time.
The last two years I have used it a number of times cutting 250-300 gal tanks lengthwise to make large BBQ grills/Pig Cookers. I make one cut length wise down one side which usually takes a couple of minutes to do say a five foot cut. After I weld braces/hinges on, I then cut the sides and front. It works a lot better than a cutting torch or plasma cutter as the edges are smooth and there is no distortion from heat. It is better than abrasive blades, because there is a lot less dust and dirt, it's quicker, and easier.
A couple of buddies have seen me cut with this blade and have made their own metal cutting blades out of old circle saw blades. The just ground the teeth off by reversing the blade in the saw and using it against a grinding wheel. Their blades work as well and my Sears one does.
BUT IT IS SO LOUD THAT YOU CAN FEEL THE SOUND IN YOUR BODY! I wear ear plugs, and shooters ear muffs when cutting with this. Don't try this near a cemetery, you might wake the dead. <grin>
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Beleveve it or not I read about it I think in Mother Earth News, and was just to take a plywood blade lots of teeth no tungsten and just start cutting the teeth will go and the blade will get red hot and start cutting the metal. Have only used it on thin metal, may work with thicker. Noisy though. Ed ke6bnl
Diamond Jim wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's called "friction sawing"

--
Posted via a free Usenet account from http://www.teranews.com


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Mount the blade backwards - especially on thin metals - to prevent it grabbing.
For thin sheet metal, the blade acts like a "nibbler" and may even be sharpened by the experience. <grin>
For thicker metal, it acts as a friction cutter and will last a bit longer if cuts are made halfway to the center about every 30 degrees to keep the center of the blade cooler.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would not use abrasive wheels. I would not use friction blades. I would not use plasma if you want a cut that shows.
You can get a finish cut with a steel cutting carbide blade. There are several manufacturers. DML, Tenryu, etc. I prefer the Morse brand Metal Devil blades. I use it on a worm drive saw. It is best to use an edge guide and keep a steady pressure on the saw. The blades are a bit pricey at about $50, but the resulting cut is excellent.
If you do much of this, it may well be worth buying a dedicated saw made for this like an Evolution. Here is a site: http://www.metaldevil.com/evolution.html These catch all the chips, though the chips from a worm drive aren't bad. If you use it on a table saw, make sure to monitor saw dust and make sure to wear eye protection.
--
~~~~~~~~~~~~~~~~~~~~
DanG
A live Singing Valentine quartet,
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
When you need to cut a panel out of a wreck at the scrappy, nothing beats a good battery powere recip saw.
--
Posted via a free Usenet account from http://www.teranews.com


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.