Large sheet metal circles

[Cass]

yf,
The use of a chop saw to cut circles is a great idea. I can imagine that making a pretty round disk with a pretty nice edge. Probably a noisy, dirty job but effective and a cleaner edge than using a torch. I have cut nice circles with an acetylene torch equipped with a circle cutting attachment that you can buy at a welding supply shop. It is a steel rod with a ring and set screw on one end to hole the torch and an adjustable point on the other end to fit in a punch mark or hole on the other end. With what is referred to as a "drag tip" on your torch you can cut nice circles. The drag tip has the pre-heat holes in a a straight line and it has a small wheel to allow the tip to ride on the material being cut. Works well on mild steel plate with practice.

With regard to jig sawing thin metal l would sandwich it between plywood. Cuts down the noise and vibration, guides the jigsaw blade and makes a cut with less of a burr. Use some spots of spray glue to hold the plywood to the sheet metal. Notice I said "spots" not the whole surface or you will have a lot of trouble getting the stack apart.

[yf]

Yeah.

Cutting discs with the chopsaw makes a very true circle. Very noisy dirty etc.
I also have torch circle cutting attachments.
The circles they produce does not come close to what the chopsaw did. It is basically like cylindrical grinding. Remember, I roughed out with the cutting blade and finished to size with the grinding wheel.

Poor boys cylindrical grinder

[Rotate]

Sorry Les. There are so many Rotozip like tools that are called Roto<something> that I thought that you were referring to these tools generically as Roto-blank. I guesss my ignorance is beginning to show.

Albert


[This message has been edited by Rotate (edited 05-08-2003).]

[L Webb]

That's OK Albert. Most people don't know what roto-blanking is. It is similar to rotary shearing. However, the machine is far superior to those wimpy circle shears.
There is also only one machine in existence. We can cut 1/8 and 3/16 circles up to 39" on it all day long, and fast.
We can also trepan with the same machine.
Les