Frusturated!

[iron2]

OK so this weekend I wasted 4-2x4 sheets of 14 gauge trying to cut out a sign. Sign was to be 46x23. My slats are 3 inches apart running parallel and when cutting letters they will drop leaving a partial sticking up which then of course the cutting tip hits and drags the sheet thus ruining the entire process. No money to be made on this project.
Any ideas for an efficient layout for laying my sheets on? I am thinking a 2"x2" grate may work well just not sure where to look for one. Any pics out there of your table I could take a look at? Any ideas would be welcome.

[TJS]

Look for expanded metal at your local steel supplier. Get the flat stuff not "raised".

[iron2]

Excellent thought of that didn't know if it would work, thanks for that.

[Metriccar]

I'd imagine the expanded metal needs to be replaced often? It seems like it would burn that along with the part you are making. Tip ups are a part of life for me so depending on what I'm cutting I'll know I need to watch it. Especially for smaller sheets that weigh less and will be dragged. My machine has an ohmic sensor so if the tip comes in contact of metal during movement the machine will stop and give an error. Doesn't mean I will not worry about issues from tipups though


Expanded metal if it will last would be great for catching parts that fall through.

[iron2]

Was afraid of that so I went and picked up some 3lb expanded metal which is about 3/16" thick and will see how it works. As long as I can level the bed out, it's not the flat but we'll see. Maybe the extra thickness will carry it for awhile. Thanks for the reply's and input I appreciate it.

[grindergary]

I use expanded metal, not the flat but it works well for up to 45 amps. I use it to cut 16 gauge metal and have it last a long time. The 45 fine cuts work very well and don't cut thru the expanded metal. I will check later and let you know what size I used.
Next time, I will try flat.

Gary

[OTHill]

I use raised I think it's called 1 1/2 10 ga.. Mostly I cut 3/16 and lighter at 45 amps. I use it till the holes are almost plugged up.I think it lasted at least 9 months. Probably average a couple hours a day cutting. No crashes in all that time. I took out 4 out of five slats. Don't need them any more.NO MORE WORRYS about tip ups.Don't think it will work well with a lot of heavier cutting tho.

[_Ogre]

not sure how to do it in torchmate, but in sheetcam i sequence my starts to avoid running over a tip up
if your cutting to the right, start the cut on the right so that if the part tips up your tip won't contact the part as it moves to the next cut start

tip ups always happen so plan for them

[jimcolt]

Same as Ogre, If the cutouts are sized so they may tip, then I am sure to manually choose the sequence and cutpaths wisely to ensure the traverse does not run over tip ups. I use Plasmacam, which also has a collision feature....if the torch hits a tip up the motion immediately stops and does not disrupt anything. simply clear the obstruction and reset the fault, and resume cutting.

You can also tab your parts so that they do not tip....very commonly used when cutting small parts.

Jim Colt

[Stout]

Likie Jim said. Tab the parts. In Turbonest I can set the overtravel on the lead out to a negative value. So the part does not fall free. Might be something to research with your CAM provider.

[iron2]

Thanks to all for the insightful help. Appreciated

[jbc28]

I tried flat expanded metal today without success. My parts were basically welded to the expanded metal with dross. I was cutting fine cut at 45 amps.

[urbnsr]

I use the 3/4" 9ga raised expanded and run mostly 3/16" at 65 amps and some 11ga at 45 amps. It lasts longer than I thought and in the end it adds under 3 cents to the cost of each piece I cut: Well worth it!

HTH
Paul

[OTHill]

Definitely try the raised. been at it over a year and only on my second set.

[islander261]

Hi

Use the RA type expanded metal, not the flat stuff. I use #6RA and haven't had a tip up problem since I started using it. Helps with having to fish small parts out of water tray as well. You may need to tie wire it down to slats because it isn't real flat as cut.

John

[Team Tracker]

Not sure of your controller and software but ours and many others will have settings that raise the torch up a user specified distance before traversing to the next profile which is very helpful to solve this. Call your manufacturer and they may be able to help.

[vmax549]

There is really no way to know when drawing or caming whether a piece will tip up. It depends on HOW the material lays on the slats. IF you suspect it will tip then stand by with a pair of piers ready to remove the tipped up piece.

You did not think that it all cuts hands free did ya ?? Some do ,some don't.

(;-) TP

[jimcolt]

There is high end CAM software (ProNest2015 from Hypertherm) that has collision avoidance capability. You can have 1000 parts nested and it will never traverse over previously cut parts that have the possibility of tipping. The software even controls the retract distance of the z axis (height control) to save time and further avoid collisions. This software is configured for high end industrial applications as it has a lot of other modules and features that suit 3 shift high productivity applications. Hypertherm has a couple of lower priced CAM packages as well that have some of the same features.

Jim Colt Hypertherm

[iron2]

Haven't been able to check in lately but thanks to all who responded to my frustration. The info has helped a great deal. I am curious as to the ohmic sensor. Not really into spending another $3500 on my system but maybe this sensor could help out. Anyone give me an idea of what they would cost to install? The drop outs have pretty much been cured with the expanded 3/16" but catches can still happen and if I can save a sheet from annihilation with the ohmic sensor that would be great. Any help appreciated.
Iron2

[Metriccar]

As mentioned earlier I have an ohmic sensor on my Plasmacam. While it will sometimes stop when coming in contact of the metal, it can also keep going and drag the metal on smaller pieces. Just yesterday I was cutting about a 15"x40" sheet of 14 gauge that had a tip up and instead of stopping it dragged the metal. For example sometimes the tip up metal can hit the torch above the shield with the sensor and just keep going without getting an error. Oh mic sensors are no substitution for watching the machine and pulling anything out that would hang it up. Furthermore while I do not have a water tray from what I understand if you have a water tray the water can splash up and fool the sensor. I can tell you while the sensor will catch some, it will not catch all. If your goal is to leave the machine unmanned be prepared to go back and turn it on when the sensor stops because a piece of metal tripped it off before it fell through. From what you describe for your situation I don't think it will be worth getting ohmic sensor for $3500 for a solution to tip ups unless you are looking for superior thc and consumable life. The expanded metal grate sounds more promising as well as cheaper

I think the sensor from candcnc was only a few hundred and if it had a stop feature for coming into contact during axis movement, I do believe it would be worth it.

[jimcolt]

Ohmic sensing is part of the cnc machine's torch height control sensor. It is not designed for collision avoidance, rather, it is to accurately locate the surface of the material before each cut cycle. Some machines use it as a backup collision sensor, however I would never recommend it as the best method for this purpose. In my opinion all cnc plasma machines should have a torch collision breakaway mount that saves the torch, the machine and the part you are cutting from damage.

Some torch height systems are compatible with ohmic sensing, check with your system manufacturer.

Best regards, Jim Colt Hypertherm

[iron2]

Great, Thanks