Going to put some expanded metal on my slats

[motoguy]

I've got an order for a couple hundred small parts to be cut from plates of 3/16" mild steel. I've previously nested these parts into "waste" areas on other jobs, so I know these have a tendency to tip/fall when cut. In addition to the torch hitting the tip ups, it also leaves a nasty gouge on the part, as it rolls into the still firing plasma arc.

Based on:

http://www.plasmaspider.com/viewtopic.php?t=16497

http://www.plasmaspider.com/viewtopic.php?t=14675

and

http://www.plasmaspider.com/viewtopic.php?f=3&t=14577

it seems that some heavy, non-flat expanded metal on top of my slats can/will go a long way towards alleviating the tip-up issue. I'll be cutting these at 45A on my PM85. I'm curious if those of you who used expanded metal in the past are still doing so, and if you still like it. I seem to recall a couple of folks tried it, and found it to me more trouble than it's worth (parts welded to the expanded metal via dross). Any tips or tricks would be appreciated.

[OTHill]

Still using it and loving it. No tip ups ever not one torch crash in several years.

[Stout]

I have very good results bridging parts by leaving a 1/16" tab on the parts so they all stay connected. Just put a bar on the bottom and connect a bunch to the bar. Easy to handle and minimum cleanup. Just break them off and finish with a flap disc. Also reduces the number of pierces.

[little blue choo]

I have very good results bridging parts by leaving a 1/16" tab on the parts so they all stay connected. Just put a bar on the bottom and connect a bunch to the bar. Easy to handle and minimum cleanup. Just break them off and finish with a flap disc. Also reduces the number of pierces.

Great idea Stout. I will remember this tip.

Thanks
Rick

[iron2]

I put expanded 3/16th heavy before I added HTC to machine and it worked great for quite some time. Good idea.

[_Ogre]

you think cutting on a $60 sheet saves money?
cheaper way is to eliminate the tip up interference
i could care less if i have a tip

pierce near the next part, cut steel back towards the tip up, end at pierce near next part, rapid travel over virgin steel and pierce near the next part
sheetcam won't set the pierces this way, you need to set every pierce where it works for you
a few minutes moving pierce points will save you tons of scrap, including the $60 expanded metal that will eventually end up scrap

if your cutting 100s of parts, do it in runs of 25 and add a bit of g-code to end at the next run of 25 pierce: table stops, you check for nasty tip ups, push go
works for big parts too: these are 7x7 base plates
here i cut 3 rows of 15 base plates; stopping at the next start, check cut quality, if all is good, push cycle start again

[motoguy]

I certainly understand that cutting on a $43 sheet of expanded steel isn't saving money...however...it was an amazing experience! I've grown used to "babysitting" my machine while it's cutting. I'll be the first to admit that has more to do with my experience level than anything, but it is the fact. THC doing something I wasn't expecting, parts tipping up, getting a 0-30 error, etc. Something. Cutting these 350 parts on the expanded sheet was...amazing. LOL I pushed "Run", the machine cut for 1.5 hours, and I literally needed to do nothing. I watched it for a while, then eventually realized it was going to be fine. I went outside and started assembling my parts tumbler (cement mixer) while it finished cutting. Single-button-press cutting is a new thing to me.

I thought the expanded metal performed amazing. Obviously, no tip ups. The expanded stuff was through-cut in some areas, where my hole/curve rules slowed the cut speed down to 40/60/80%. The rest of the area, though, it was not cut through. It lifted off as a nearly intact 4x8 sheet. The EM was not welded to my parts...my parts picked right off. The EM was not welded to my slats when I went to remove it (well, no more than any other sheet), and it popped right up.

I certainly need to experiment more with cut layout, to try to minimize tip-ups in the cut path. That is a better solution. With a tight nest of odd shaped parts, I'm not sure how to go about it. My tip-up issue was rarely a traverse issue...it was usually an issue of the tip-up being within the torch diameter while cutting the next part, and having a "glancing blow".

Either way, I'm very happy with my expanded metal experience on 3/16 @45 A. The slower used when I cut some 1/4" material tended to cut up the EM, though.

[islander261]

Hello

I cut all art stuff with lots of small drop out parts. Tip ups used to be a real night mare. I had to stand by the table with a rod to push them out of the way to prevent torch collisions. Now I use a piece of 6GA unflattened expanded steel on top of the slats. No tip up problems! I replace the piece about every three months (it really looks bad when I am finished with it). I figure it is just part of my consumable cost, it certainly saves a bunch of my time. The way I look at it $70 every three months just gets lost in the noise. I weld the expanded metal to the slats to keep it flat, just small tacks so I can break them with an air chisel when it is time to replace the expanded metal. Ok, I don't cut thick stuff, only 14ga to 10ga and mostly using Finercut consumables at 45A.

John

[Diesel]

I have very good results bridging parts by leaving a 1/16" tab on the parts so they all stay connected.

Very good thinking!
Just like an injection molded scale model parts kit.

Regards,

Matt