[Bigtoy302]

After many months or reading and researching I am finally ready to start building a plasma table. So here are the specs.
48.5"X48.5" travel
water tank
369oz steppers
dual drives on the y
Gecko 201 stepper controllers
20 degree 20 pitch rack and pinion
3.75:1 gear reduction
Hiwin 15mm LG rails on the Y and Z
THK HSR25mm rail on the x
CandCNC Digital THC
Mach 3 control.
Hypertherm 1000

The Table will be made from 3x3x.125 square tube so I started milling the cross pieces for the table square and held .001 on length.


Then I started drilling and tapping the holes for the 25mm rail for the gantry.



Next I started on the Z. The Z is .188 HR plate and 15mm Hiwin rails. It will have 6" of travel. The single rail will be used for the floating head for the torch.

[DRL]

Looking good so far. Thanks for taking us along for your build.
DRL

[millman52]

Welcome to the journey. Judging by your having access to a horizontal boring mill. I'd suspect you have access to all the other machine tools, Lathe(s), Milling machine(s), etc to produce a very fine & detailed Plasma table.

Why the small size?

[Bigtoy302]

Why the small size?

I was going to build a 4x8 but I just don't have the shop space and I don't really need anything bigger right now. I know I will kick myself later when I need bigger, but I will build another if it comes down to it.

Oh, I am a Manual machinist in a huge machine shop, so I have access to all the cool machines.

[millman52]

I sort of figured space must be an issue. Other than that it just doesn't cost that much more to go bigger. You might want to try & leave 1 end of the table bolt together. That way if you later want to expand to 8' or even longer length it can easily be done.

It sucks not to have enough room for at least a 4 X 8. That way sheets od stock are economical & you don't first either have to have them sheared in 1/2 or cut them down yourself first.

[lamicron]

Good to have a new build again!!! Fine start too, paint it while building , after done you´ll not want to take it appart ....

[millman52]

Hey Lamicron, Hows your machine running? Sold it yet? Building another?

[lamicron]

Hi Rich! Yes I sold it!!! And sold another 2!! Now Im building two 4x8 and one 4x4 for me, and also one router 4x4, i´m waiting to have the material tomorrow. MAybe start a thread with one of those...´One will be a water table for plasma and a router, i ´ll build it with a rapid table change.
Luis

[lamicron]

Rich, where did you buy your pulleys? I need 3:1 pack. and belts. Can you help me with part numbers?
Thanks
Luis

[millman52]

Rich, where did you buy your pulleys? I need 3:1 pack. and belts. Can you help me with part numbers?
Thanks
Luis

Luis rather than keeping Bigtoy's thread hijacked. Start a build log in: Plasma, EDM and other similar machine Project Log & pm me the link to it or I'll find as I'm on practically every day. I'll look for the information & get back to you there later.

Neil

[lamicron]

Sorry for that, you are rigth.
Luis

[Bigtoy302]

I got a little bit more done today. I got the Y rail holes drilled and tapped, then I welded the frame all together. I still need to weld a sheet on the bottom to form the water tank.



the welds


holes for the rails.

[xtremehobbyist]

Bigtoy,
I recently came across this site. WOW! I have wanted, but could not justify a toy this expensive for a couple years. The prospect of making a plasma table myself has consumed my spare time. Like you, I am reading everything I can find on the subject. I am working out the details now. I plan on starting the build by early summer ('08). I look forward to your updates. I am a fairly accomplished welder myself and I would like to say your welds are impeccable. It looks like we are neighbors too, as I live in southern Oregon.
---Bob

[Jay325e30]

Beautiful welds

[millman52]

Bigtoy,
I recently came across this site. WOW! I have wanted, but could not justify a toy this expensive for a couple years. The prospect of making a plasma table myself has consumed my spare time. Like you, I am reading everything I can find on the subject. I am working out the details now. I plan on starting the build by early summer ('08). I look forward to your updates. I am a fairly accomplished welder myself and I would like to say your welds are impeccable. It looks like we are neighbors too, as I live in southern Oregon.
---Bob

The fun really begins when you start a build.

I was a total greenhorn when I began. I made up some CAD drawings mainly to keep some of my ideas straight. I was lost for quite some time. I really wanted to have most all my parts gathered up before I started.

There are so many things that depends on the part next to it. What do I need to buy so I don't build myself into a corner? Is this heavy enough, Is that strong enough? If I buy this rack & pinion, What belt reduction ratio do I need. Darn I actually would like to have my motors in hand so I can build the drives as small as practical yet rugged & strong.

All these things & trying to think things through to the end took many hours of head scratching & decision making. The time thinking paid off though in not having to un-do progress already made.

Looking back I could easily build a second table. Mine has worked out great so far. If I were to start over there is a few things I'd do different but not many.

[Bigtoy302]

I made some caps for the legs so I could screw so adjustable roller feet in them.


Then I got the bottom of the table sealed off with a piece of 16 gauge. I welded
small beads all the way around and let each one cool to try and reduce warping.


Here are my gantry side plates all cut out.


I then started working on the Z axis acme screw. The bearing blocks where machined for a 608 bearing. The acme screw is a 1/2-10 single single start screw. The nut is a delrin nut from Dumpster CNC.

[Bigtoy302]

Today I had to straighten the table. It had warped about .125 all the way around in the center of the tubes. I did the old heat and quench trick to shrink the top back down. This method worked really good.


Then I mounted the rails and welded the gantry tube to the side plates.



Now after I had the gantry all welded together I totally understand what racking is. I am sure glad I didn't cheap out and not buy a extra motor to dual drive the Y.

[millman52]

Today I had to straighten the table. It had warped about .125 all the way around in the center of the tubes. I did the old heat and quench trick to shrink the top back down. This method worked really good.
Now after I had the gantry all welded together I totally understand what racking is. I am sure glad I didn't cheap out and not buy a extra motor to dual drive the Y.

Have no fear the dual slaved drive will completely eliminate the racking. Mine seemed limp as a noodle. everyone that saw it said it would never work. When you get everything hooked up & power on the motors you'll be amazed how solid it becomes.

Neil

[Bigtoy302]

So, today I got the belt drives, racks and the Z mounted. I Also tested the water tank to make sure I had no leaks. I added some tubes on the bottoms of the legs for more support. With nothing there the table was just to shaky. I still have some finish weld and I still need to make the slat holders, but other wiring and paint it's almost done.

[xtremehobbyist]

Bigtoy,
I don't understand your Z axis. It appears to have 2 slide systems and only one of them is powered. Does the other float? Will it eventually be powered? Your table looks great! One last question, do you know how much the gantry assembly weighs?
Thanks,
Bob