"Origami" CNC Plasma Build - folding 1200 x 600mm cut area

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05 Apr 2021 11:06 #204877 by rodw
Not sure about NZ but over here, we need to buy full sheets. Plasmac has a good feature that allows you to sever a sheet so I use that to get rid of the scrap. When I started I cut sheets in half to suit my 1200 x 1200 table but more recently I just index the sheet as required as you get more efficient use of material. If you look around, a few people have modified vice grips so they hook around a slat to hold sheets down to stop warping. You could use those on scraps.

Also from another of your threads, I would just upgrade to V2.9 and run QTplasmac. Once you understand the features, you could use your qtpyvcp skills to flesh out monokrom as I don't think its gone anywhere.

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05 Apr 2021 19:33 #204943 by Joco

Not sure about NZ but over here, we need to buy full sheets.

Depends on the supplier. I can buy full or half sheets. But agree that full sheet is most common.

Plasmac has a good feature that allows you to sever a sheet so I use that to get rid of the scrap. When I started I cut sheets in half to suit my 1200 x 1200 table but more recently I just index the sheet as required as you get more efficient use of material. If you look around, a few people have modified vice grips so they hook around a slat to hold sheets down to stop warping. You could use those on scraps.

I had read about that sever feature which looked rather nice. I will do a snoop for how those vice grips look.

The other part with that vertical table is the need for the extraction fans when inside. Those are big units based on the tube sizes. I did some measuring yesterday and i can actually fit my flipping table in its open position inside the shop if I roll the welding table back a bit. So with a water table installed I could operate in the garage during crap weather. No need to source one or two big suction fans and find a place to store them. Also in the flip table design I worked out where I could put a water tank that could hold the water table fluid. Using low pressure air to push up up into the table and gravity drain. If i can get that all working then I would have a very self contained unit. Yes I know a “pressure vessel”, but for my use I dont have to get it certified and the plan is to use the lowest air pressure I can get away with. Im ok for a slow fill of the table as a compromise on keeping the air pressure down. Hmm, wonder how much pressure would be needed ...

Also from another of your threads, I would just upgrade to V2.9 and run QTplasmac. Once you understand the features, you could use your qtpyvcp skills to flesh out monokrom as I don't think its gone anywhere.

Plan was to use QTplasmac to start I just had some unfortunate experiences yesterday with 2.9pre seg faulting. Nothing to do with QTplasmac. I was running off HEAD so maybe I was a little too bleeding edge. I have also been reading how the plasmac guis hook up to and use the HAL plasmac component. So maybe I will push monokrome forward once I learn more. I really like being able to tweak or build a GUI that fits how I work and the specific design, limits and needs of my kit.

Thanks for responding Rod, I do appreciate the ideas and dialog.

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05 Apr 2021 20:31 #204957 by tommylight
Why not something like the Esab Crossbow ?

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05 Apr 2021 23:41 #204994 by rodw
For the size you are doing, you could use a single inline workshop blower to do a downdraft. Check if Hare and Forbes Machinery House stock them in your country. Not very costly and you just roll out the duct when in use. It might be a lot less stuffing around on a folding table.

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06 Apr 2021 06:53 - 06 Apr 2021 09:54 #205042 by Joco

For the size you are doing, you could use a single inline workshop blower to do a downdraft. Check if Hare and Forbes Machinery House stock them in your country. Not very costly and you just roll out the duct when in use. It might be a lot less stuffing around on a folding table.


Hmmm ... exploring this some more as even though I have a bunch of steel (4 x 4m lengths of SHS65-3) nothing is committed yet. And the more you guys poke me on this the better.

Fan being this one Rod? www.machineryhouse.co.nz/F050
With some of this ducting: www.machineryhouse.co.nz/F051
I think MH in NZ does pretty much all the same stuff as in AU.

Looking at the gantry arrangement on my size I think the best layout would be to have the gantry running vertical.
This way I could still use a full sheet index approach by feeding the sheet through from the side. Heck I could even create sheet supports to hold the part not in the machine. Those could be standalone or on slides into the machine.

If I up scale the machine to being 1.2m by 1.2m cut area on a vertical style table that will create a total out dimension in the order of 1.6x1.6m. However that is still a half sheet machine so if you want to be "efficient" in sheet use I would still argue that being able to feed a full sheet from the side would be easier to deal with on a number of levels. Yes? No? Some big issue with the gantry in the vertical? Somethign somewhere is going to have to over come gravity. It might mean needing a strong motor for that long vertical axis.

Any views on the amount of back lean needed? Of course some toggle clamps at the top for sheets would allow an angle very close to 90. 75 to 80 perhaps?
Edit: Looking at the specs of the BurnTable's vertical slopin table, given 30" footprint from wall and a 60"x60" cut area the slope of the work surface looks to be around 60 deg. Put another way the angle at the top of the triangle is 30 deg. Doesn't seem as aggressive as I would have expected it could be.
a 21" (crica 530mm foot print) gives a 70/30 deg split. but perhaps not stable enough.

Hmmmm .... maybe I will hack a model up and post here for some rock throwing .. I mean constructive advice. ;-)

Still need to hunt down those clamps Rod mentioned.
Last edit: 06 Apr 2021 09:54 by Joco. Reason: Added extra info after picking apart specs on BurnTable per video linked by Rod.

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06 Apr 2021 06:57 - 06 Apr 2021 07:42 #205045 by Joco

Why not something like the Esab Crossbow ?


I had thought about that approach. But the gantry models are ultimately more compact in operation and pre setup.
In short, looked at, considered design options, considered operational area needs, setup and the like and decided wasn't enthused enough to want to make it happen. This vertical table idea is starting to grow on me. Especially as I am starting to see how I could have it permanently setup inside with little need to move it. Although I am still likely to put it on wheels as the option/ability to do the workshop waltz is pretty important.

Cheers.
Last edit: 06 Apr 2021 07:42 by Joco.

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06 Apr 2021 09:33 #205057 by Joco
On clamps for plasma tables I found ths thread on a website that seems to have an awesome list of clamping approaches. Love it.
Saving these off for later reference. Just be aware you have to be logged in to see the images.

www.plasmaspider.com/viewtopic.php?t=15287

Cheers - J.

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06 Apr 2021 11:00 #205072 by rodw
Yup you found them!

I'm a bit rusty on the resolution of forces but w sin(theta) and w cos(theta) comes to mind for resolving forces to the X & Y direction for a force w acting at angle theta (where theta is the angle of the lean.

There is not much difference in forces required per motor to move the whole gantry with 2 motors then a torch lifter with one motor.
In one design I have its 142 N split over two motors vs 56 N for one motor.

But lets just assume direction of travel is dead vertical. The additional forces in newtons for gravity will be 9.81 * the weight in kg.

I think you could upgrade your gantry end motors to small NEMA 34's and run the gantry up and down I upgraded my original Stepper online motors (on a 48 v power supply with DM542a drivers)
www.omc-stepperonline.com/nema-34-steppe...86x98mm-8-wires.html

to Moon ML34HD0L4700 motors. (64V AC = 90 volts DC approx with LAM DS1076A driver)
www.moonsindustries.com/p/nema-34-standa...0-000004611110010545
These are more expensive but lighter and way faster! Seems like they would be OK on 48V
The following user(s) said Thank You: Joco

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06 Apr 2021 21:08 - 06 Apr 2021 21:18 #205189 by Joco
Arrgghhh to many choices. :pinch:

On the vertical table I like the space saving angle of it alot but the mess side of it worries me. The downdraft style tables with anything less than some SERIOUS suction don't seem to get that great press. It's not to say it can't be done, just a DIY path on fume based extraction does not seem to be as well trodden and documented as the water table path. Probably because the water pattern is well proven and solves the vast bulk of the fume/dust issues in an effective manner.

But happy to be educated otherwise.

Thinking about my planned usage model some more, while I will be able to cut outside during the summer planning on that in the winter in NZ is a failed plan at the start. I'm in Wellington and we like our southerly gales here in the winter. Think horiztonal rain and I am not exaggerating. Plus my main garage doors are south facing so venting out will just result in stuff being blown back in - :blink: So being able to cut inside is gonna need to be on the design requirements list. Obviously I could wait on the weather but that's gonna limit things a lot in winter which take a chunk of the fun out of things. I did some measuring and I can push the (on wheels) welding table back and be able to open up the fold/flip table for use and still have room to move about and be able to use the welding table.

Anyway, from a dirt/dust angle I am less convinced the vertical table will be as effective given my limitations. :(

But if I am missing something please let me know.

Note: I'm refering to "down draft" in a hobby setup context not the industrial grade systems. They clearly work else there would be no market for them.
Last edit: 06 Apr 2021 21:18 by Joco.

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06 Apr 2021 21:29 #205191 by rodw
I think most commercial tables are downdrafts. I suspect the reason why you don't see many DIY versions is likely due to lack of Output pins or the ability to zone the table based on torch position on the Windows based CNC environments. Neither is a problem with Linuxcnc and the right mesa card.

In fact there is a thread by txrone here who has an 8 zone downdraft using a component I wrote.

I always wanted the spaceship to be a 2 zone downdraft using one of the fans I shared with you but in the end, creating a water tray was so much easier.

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