Cutting Expanded Sheet Metal

[Rambozo]

Here's a go at my video. If I move slow enough like this it doesnt stumble. Everything looks to be working right.
http://www.youtube.com/watch?v=9n32A...ature=youtu.be

And what you are expecting is this...

[xtreme cartz]

And what you are expecting is this...

Yes that is awesome! I at least was hoping it to be as fast as a cut off wheel . I wonder how much the consumable life is reduced using it like that?

[xtreme cartz]

Second question while we're at it, what is better for the tip to be dragged or held slightly off the metal? As much exp metal cutting, I do equal or more 4x8 16ga sheet metal cutting and until I build a CNC I do it all by hand with the plasma or circular saw. I want to build cutting jigs from either 3/16" or 3/8" flat bar that are the same shape as the parts I'm cutting. This way I can just set it on the metal and trace it with the torch to make a perfect part cutout instead of all the layout time it takes with a template, marker and straight edge.

3/16" flat bar puts the tip right on the metal.
3/8" flat bar allows the tip to be suspended nicely in the air, leaving about 1/16" gap between the tip and the metal being cut

[Rambozo]

It appears that Hypertherm also has that feature but they call it grate cutting mode instead of auto refire. Both say it does reduce consumable life, but neither say how much. It just causes the machine to switch back to pilot arc mode when a void is encountered. It sounds like not that hard of a feature to add to a machine. Just a change in the way the transfer works. Maybe it is something you can modify? There are some threads about it on CNCzone.

[Rambozo]

Second question while we're at it, what is better for the tip to be dragged or held slightly off the metal? As much exp metal cutting, I do equal or more 4x8 16ga sheet metal cutting and until I build a CNC I do it all by hand with the plasma or circular saw. I want to build cutting jigs from either 3/16" or 3/8" flat bar that are the same shape as the parts I'm cutting. This way I can just set it on the metal and trace it with the torch to make a perfect part cutout instead of all the layout time it takes with a template, marker and straight edge.

3/16" flat bar puts the tip right on the metal.
3/8" flat bar allows the tip to be suspended nicely in the air, leaving about 1/16" gap between the tip and the metal being cut

Some tips are meant to be dragged while others require a standoff. The problem with a template is that unless there is an insulator on your torch tip, you can't let the nozzle have an electrical connection to your work. So your template would need top be made of non conductive material, or your torch tip. Either way, the lifespan would be an issue. You can do something like Rod did and build a tracer. It's sorta like a manually operated CNC, with you playing the part of the computer. Another thing is to change the size of the pattern so that you can space the torch away from it to increase the life. This limits the kind of pattern, too as you won't be able to have tight curves. It all depends on just what you need to cut. I've always cut expanded metal with a shear, but I remember getting cut from some of the wicked points that could be left depending on the size piece.

If your cutting fast enough, I imagine a piece of 1/4 hardboard or plywood would make an adequate template you could probably increase the life with a flame retardant coating. It'a all about volume, do you need to make 100 parts or 100,000? Also the skill of the operator comes into play. Do you buy a high tech machine to be run by a grunt, or have a real craftsman who can get good results even from basic tools?

[Rambozo]

Here is Rod's tracer.
Much simpler than something like a pantograph but always moves one to one. All you need to do is adjust your pattern for your tracing stylus radius and cutter kerf.

http://www.everlastgenerators.com/fo...hread.php/3196

[fdcmiami]

other issues with expanded metal, grating, ss with directional graining and so on, are how are your cuts going to work aesthetically with the finished product. in the case of the expanded metal if you are trying to lay it in between a preconstructed framework of square tubing where the fit has to be net then you are going to have to make allowances for cutting and fitting; especially when diamond direction comes into play.

it is easiest to work with when you can use some means to negate the danger or unattrativeness of sharp edges and tight tolerancing. i have slotted tubing; bent metal strips to 135 degrees with a knife die and then flattened them onto the expanded metal and tacked the corners; assembled a slotted frame with the expanded in place. with machine guards we would leave a one inch border (most of the time) for the expanded metal to rest in, with the edges of the material out of sight. these procedures allowed for some sloppy cutting tolerances. if you have to cut EM to fit within something you will always be making concessions.

the miller video is impressive but it is a miller video. i would like to have seen a shot of the floor beneath the work table.

[xtreme cartz]

Here is Rod's tracer.
Much simpler than something like a pantograph but always moves one to one. All you need to do is adjust your pattern for your tracing stylus radius and cutter kerf.

http://www.everlastgenerators.com/fo...hread.php/3196

Man that is pretty cool! It traces a part template on the table and is cutting with the plasma at the other end? I've seen coin dies being designed in a similair process going from the scaled up version to make minute details down to the actual coin size... coins being off topic but I always thought it was intersting!

I would assume the PP50 is not designed to be dragged? I remember it came with a wire clip thing to go on the end of the torch to keep it off the workpiece. I usually hold the torch off the workpiece as it seems to cut healthier but it could just be my imagination.

[redbeard]

I would assume the PP50 is not designed to be dragged? I remember it came with a wire clip thing to go on the end of the torch to keep it off the workpiece. I usually hold the torch off the workpiece as it seems to cut healthier but it could just be my imagination.

Dragging just decreases consumable life because of the molten metal splashing back. I usually drag for .125 or less, and use a standoff for thicker stuff.

[xtreme cartz]

other issues with expanded metal, grating, ss with directional graining and so on, are how are your cuts going to work aesthetically with the finished product. in the case of the expanded metal if you are trying to lay it in between a preconstructed framework of square tubing where the fit has to be net then you are going to have to make allowances for cutting and fitting; especially when diamond direction comes into play.

it is easiest to work with when you can use some means to negate the danger or unattrativeness of sharp edges and tight tolerancing. i have slotted tubing; bent metal strips to 135 degrees with a knife die and then flattened them onto the expanded metal and tacked the corners; assembled a slotted frame with the expanded in place. with machine guards we would leave a one inch border (most of the time) for the expanded metal to rest in, with the edges of the material out of sight. these procedures allowed for some sloppy cutting tolerances. if you have to cut EM to fit within something you will always be making concessions.

the miller video is impressive but it is a miller video. i would like to have seen a shot of the floor beneath the work table.

I can tell you know about the fun of working with EM! It's different for sure. I prefer working regular sheet metal... much less of a headache. Welding em to 1 1/4" x 16ga round tubing is a b**** with getting the v's just right. As a bonus you have to make sure to penetrate enough without burning through the thin wall tubing while welding and penetraiting into the vee. The cuts have to be within 1/8" tolerance all around or else the radius of the round tubing leaves the em either short or overlapping with a gap inbetween the tubing and sheet metal. There are times when the V's dont run straight across the sheet metal due to how they manufacture the sheets. Bugs the hell out of me when I have to skip to another set of Vees to keep the parts dimensionally accurate. You also have to watch out for getting a line going down half of a V, those are terrible to weld.

[xtreme cartz]

Dragging just decreases consumable life because of the molten metal splashing back. I usually drag for .125 or less, and use a standoff for thicker stuff.

Ok I have noticed that happening when I do drag it. I'll probably make the templates to hold the torch up then. I've lost the manual to my machine. I'm sure these answers were in there but I appreciate all the advice!

16 ga sheet metal, how many amps and psi? I like to move fast lol I have found running at 35 amps seems to work well.

[Rambozo]

I've lost the manual to my machine. I'm sure these answers were in there but I appreciate all the advice!

http://www.everlastgenerators.com/manuals.php

[fdcmiami]

I can tell you know about the fun of working with EM! It's different for sure. I prefer working regular sheet metal... much less of a headache. Welding em to 1 1/4" x 16ga round tubing is a b**** with getting the v's just right. As a bonus you have to make sure to penetrate enough without burning through the thin wall tubing while welding and penetraiting into the vee. The cuts have to be within 1/8" tolerance all around or else the radius of the round tubing leaves the em either short or overlapping with a gap inbetween the tubing and sheet metal. There are times when the V's dont run straight across the sheet metal due to how they manufacture the sheets. Bugs the hell out of me when I have to skip to another set of Vees to keep the parts dimensionally accurate. You also have to watch out for getting a line going down half of a V, those are terrible to weld.

you can buy slotted tubing. tubing with a channel in it.

[Rambozo]

I've tried a 7 1/4" metal circular saw with a carbide blade before and its great for solid sheet metal and tread plate (although I prefer the plasma for this), but when it comes to the expanded metal the saw pulls up the edges of the metal too much and gets bound up.

One thing that will help with that is to make a zero clearance insert for your saw. You will lose the ability to angle the blade, but it will prevent the binding and pulling of the ends. This is often done to prevent tearout in plywood, too.

[xtreme cartz]

ok, have you considered contacting a sheet metal shop and paying the shop rate for the use of the shear? if you are cutting that much material (it seems, working the numbers quickly, that there is quite a bit of waste) you would be far better off having your rectangles cut and doing the details yourself.

Thought about this alot today and it seems to really be the best route to go for now with the quantity we are doing. I remember we were given fairly decent rates for parts I've had cut in the past. Maybe with quantity they can do even better. If I can find a place that will do the exp metal too, the time saved alone would be worth while not to mention cost of consumables and cut off wheels. Sheet metal is just a small part of the picture. I would actually have time freed up to do everything else!

[JBnID]

You need a power shear for the straight cuts and a hand notcher for the corners and odd angles. Or contract with a CNC plasma outfit to supply your blanks.