Another MM as Plasma Table
 

Time to get on with a Plasma Table.
The initial specifications are as follows
Cutting area : 1850 x 6100mm
Fume control :Water bed with down draft fan using this type of fan.
Stepper Motor :86HS9801
Motor Driver : TinyDriver
Motor Power supply voltage : 48Vac
Grate surface height : 600mm
Structure : 75 x 50 RHS nominal thickness 3mm
Torch Height Controller :- CandCNC DTHC-3000
Motion control software :- Mach3

u want a cutting area of 1860x6100mm and only use 50x75 RHS tubing, is that not gonna be a bit flimsy??

My maths says its ok. I'm surprise too :)

How many legs to the floor?

The biggest load is going to happen when somebody drops the steel plate onto the table . . . . .

only 4 legs.
The side rails will be truss beam made out of 2 parallel 50x75 RHS with the top & bottom 200mm apart... :)
My calculation load is for 50mm thk 6'x20' MS plate. but 25mm is about the thickest sheet which may go in.
There will be a rolling gantry for hoisting the plate to the grate.
Sorry, I'm just too lazy to draw at the moment. That will come as the build progresses.

Ken try with this THC,
http://www.agelkom.com.tr/prod02.htm
as the Cand wont send you one piece outside USA, and this is what some others recommended to me, and I ordered one for a friends plasma.

Danilo, thanks for the pointers :)
Interest!
The Agelkom work differently from the Cand. Agelkom use capacitive sensor to dictate the torch height where Cand control the torch relative to the plasma current & play with the voltage... which is more suitable... that is a question...

If the acceleration of the machine is slow the when cutting on corners the sensing voltage rises or lowers (I can't remember) due to slow cutting speed causing the torch to dive into the material the same thing happens for crossing over a cut. The Agelkom Cap04 sensing ring could/can get in the way but it isn't really an issue.

Antony, thanks for the heads up.

Delaying my THC order turn out to be a blessing :D

Also learnt that Agelkom is coming up with a new product with voltage control + capacitive sensor...
So now is Cand Vs Agelkom.

Would most appreciate more suggestions :)

Ken,
You could do that now with a Agelkom CAP 04 and a voltage divider sensing the arc voltage via a micro (did some one say Auduino?) to handle the logic.......... would it be nice? yes, is it necessary? not sure.

Anthony

I have a pic (microchip) to do that. Hovever on the mach2 manual, there is a free schematic (if you have buyed mach*) that does a pretty good job.

I am aware of the Mach2 THC but do not have enough info to get serious with it. BTW, I'm using EMC2.

Good luck Ken!,
Just find the THC on ebay, search for proma-elektronika.pl

I just made some first cuts with oxy fuel, man thats scary ! what a flame and it really cuts the hell out of that sheet metal.
Ken, consider the oxy fuel attachment its nice to have it arround in addition to plasma.

Yes, did keep oxy-acetylene cutting for thicker steel plates, hence the table is designed for 50mm MS plate :) For what I understand cost benifit of plasma cutting is best below 12mm MS plate.

hello Ken, did you get the Tiny step 's :)

Been busy moving to a new location. Can't start work on the plasma table at the old place.

New place has 1100sq.ft floor space with a 700sqft mezzanine floor.

not a lot of space to work with but that will do for now.

Attachment 12869

Most of the moving jobs are done, what remains are the details.... :mad:

Attachment 12871

The steel stock came in too :D

Attachment 12870
& gave my MM a new PC cab salvaged from wooden crate I made for the shop move. ;)

Now I can start work on the Plasma table.

These BOB & Driver came in from http://www.tinycontrols.com/
:D:D:D:D:D:D
Attachment 12879

They are really Tiny!!! Can fit in my palm! :D:D:D
I can now use a 400x400 control panel with plenty of space to spare! :D
Attachment 12882

Here I place a a steel ruler to give a good perspective of the actual size.
Attachment 12880
Attachment 12881
Attachment 12880

Great stuff!!!

Stay tune, the build is now officially in motion!!! :D:D:D

I raise you one ...My UIM-ROBOT drives are even smaller .:D

Hi Ken,

I have mounted the Tinysteps on a 1mm thk aluminum sheet with a 90mm fan behind, they don't heat up, just luke warm -

I work them up at 50V DC and 4 A - we have smooth motion.

Regards
IRfan

Irfan, thanks for the heads up.
I am considering off the shelf 48Vac tranny.
50Vdc, give around 35~36Vac transformer which is also available off the shelf :D :D

about the THC
 

Hi, I'm too looking for a suitable THC. I'd like to use my licensed MACH in combination with Agelkom or Proma-elektronica.
Did I understand correctly that you need only this one component from Proma-elektronica to make a reliable THC?
By the way I use a Hypertherm Max100.

Have a look on www.cncdirect.co.za THC available there.

http://www.cncdirect.co.za/htm/mach.html

Some update on my build.

Finally grounded all the rails.


This time round, I went with the P38 sand paper with steel support disc.
The sand paper support disc cost less than US1... so I got a few more just in case anything went wrong...
Verdict. Easier to handle & no worries over flatness when using grinding disk.
Attachment 13098

The results are better than my 1st time round & sand paper method give better control over depth, I just set the final grinding depth on the grinding jig & went through all the rails without any further adjustment.

Couldn't resist spending extra-time to grind the rails nicely this time round... Not difficult, just dirty & laborious.

Attachment 13096
Attachment 13097

PS, yes the stack of plywood in in the way of this built... Gotta get rid of them tommorrow.

Hi Claudia,
Long time no see. For the THC, I'd placed an order for the Cap 04 by Agelkom. Still waiting for delivery...

The built progress is slow, but moving nevertheless,

Did some modification to the table, using 50x100x3.2mm thk RHS instead of the channel. The cross bearer is bolt on. These modification added more work than I wished for.

The table is suppose to take 5 ton static load according to my calculation.

Pix of the current state of the built.
Attachment 13257

another
Attachment 13256

My version of bolt on joint with locator/stopper.
Attachment 13258

Hi Kent.

What type of work are you going to do with this new machine.

Wishing success.

Guillermo.

I honestly haven't a clue what I'm gonna do with it... :o
Surely it will be good for something when its running :D

Built mine with no plan in place Now use it daily

al

Some progress

The installed Rails are aligned & shimmed

Table is painted with hammertone finish

The Gantry & Car are assembled & painted & glazed in 2K auto paint
Attachment 13423
Attachment 13421 Painted in automobile 2K paint
Attachment 13422

I am using the new Intel Atom board D425KT mobo.
I packed the board with only 2Gb 800MHzDDR3 ram & uses a Seagate 160GB SATA hard disk (this is the smallest hard disk I can find off-the-shelve in a hurry) and a economical off-the-shelf PSU with the largest fan that I can find (in a hurry).
I heard & read lots about nasty things that plasma fume caused when they get to the electronics. Hence a seal chassis is called for (well almost seat, but not ventilated that is for sure) another 400x500x200deep off-the-shelve control panel is called for the duty.
This improved atom mobo draws 25~30W at max load & has a huge processor heat sink with very long fin. This should improve its processor's passive heat management, by right more the improved mobo is better suit in a sealed environment which I have in mind. The hard disk should emit more heat than the mobo :p
I may connect an additional fan if internal panel temperature exceed 60deg C during actual operation.

Here is the pix of the Work in progress
Attachment 13424


##PS, It is not my intention to go compact on the electronics, i.e. the PC & motor control system. I don't see any advantage in do so a part from reducing the actual panel cost.