Welding Tips and Tricks

Ok. Started building my CNC plasma table. I am building this on my spare time on what time I have, esp. with a 2 year old girl and one more on the way (boy). I figure this may take till at least next spring to be complete $$.

Ok got the gantry kit and making the table.



Drilling and tapping 64 holes for the Y-axis.


Rails bolted to the top tubing.




Main frame and water tray cross members.


Quick mock up of gantry set up. I have some adjusting to do. Not a big deal.

Back on track. Got the crossmembers done. Even with a messed up thumb I was able to fully weld all the crossmemebers for the water tray supports.

Made some bases for the legs. These will accommodate the machine feet I am getting from McMaster. This allows a strong base as well as leveling that machine. Made some plates up and welded nuts to the back side. These nut are called center locking. They are deformed a little in the center to allow them to lock. More to come.





This is not the leg. Just a scrap piece the same dimensions as the leg.

Hey,

Thanks for the great submission. Congrats on the awaiting arrival, Keep up the good posts,

Mick

I love the table and can't wait for more updates.....

So I made a little holder to hold a magnetic indicator to check the runout of the track. I got .003" in almost 8 feet and that is not even fully bolted down. See pic.

Is that good or bad? (sorry)

weldin mike 27 wrote:Is that good or bad? (sorry)

LOL. Well considering some particular human hairs are about the same I would say that is great for a striaght cut.

Made upright for the water table because there could be a lot of weight on this thing. Fully welded them in today. I had to use the creaper and do some overhead welding because I did not feel like tipping this thing on its side. It is getting real heavy.I am also going to make some diagonal bracing to the center of the crossmembers. Also found a computer tower I had. Just have to tweak it a little and get the software loaded on it.

Good stuff. Keith fenner on you tube has videos of his plasma setup, which looks home/shop made. The torch is a hand one hose clamped on to the cutting carriage.

weldin mike 27 wrote:Good stuff. Keith fenner on you tube has videos of his plasma setup, which looks home/shop made. The torch is a hand one hose clamped on to the cutting carriage.

Keith Fenner's is actually a PlasmaCam(tm) set up where he modified it with his touches, venting system, breakaway torch..etc.

I got my 4 x 8 gantry kit from Precision Plasma. The controller set up will be from CandCNC.com and will be running the Bladerunner dragon kit with the 620oz stepper motors and 3/8" shafts. The plasma cutter will be a BIG hypertherm. Total cost by the time I set up my cable management set up and other misc costs will be around $10k. Instead of buying toys to play with like I have in the past, it was time to buy something to make money and then in turn get more toys.

that was an excellent posting. i love the pictures and you also did good explaining what/how you did. the machinist at work crashed our south bend lathe this pm and broke the teeth off a gear. do you think one of these computer driven plasma rigs could cut a new gear in 1/2 in material?

Wow 10k, You can buy pre made ones shipped to your door for less. I was shopping around in the last while for tables, and found 1 company that was really cheap. and another that was pretty good.

Trucut plasma tables: http://www.trucutcnc.com/build.html
Shopsabre: http://www.shopsabre.com/plasmas.html
and Burntables: http://burntables.com/

When you say a Big Hypertherm how big? 200amp? 400amp? or big for a garage like a 105?

jwmacawful wrote:that was an excellent posting. i love the pictures and you also did good explaining what/how you did. the machinist at work crashed our south bend lathe this pm and broke the teeth off a gear. do you think one of these computer driven plasma rigs could cut a new gear in 1/2 in material?

depending on the software tool pathfinding, the speed of the stepper motors/Servos, the torch tip, and technology of the machine, I would say yes and no. a 50k machine could probably make the part with no cleanup at all. a 10k machine would waste your time. if it is too slow coming into and out of the corners, it will ruin the inside valleys of each tooth on your gear. If the machine can't anticipate the arc voltage and respond with proper torch height distance then you will have a big wide kerf cut on the bottom side of the gear. and cheaper tables wont usually have the proper backlash reduction capabilities to be doing the constant in/out in more than one direction at a time, especially if they are belt driven.

Oddjob83 wrote:

jwmacawful wrote:that was an excellent posting. i love the pictures and you also did good explaining what/how you did. the machinist at work crashed our south bend lathe this pm and broke the teeth off a gear. do you think one of these computer driven plasma rigs could cut a new gear in 1/2 in material?

depending on the software tool pathfinding, the speed of the stepper motors/Servos, the torch tip, and technology of the machine, I would say yes and no. a 50k machine could probably make the part with no cleanup at all. a 10k machine would waste your time. if it is too slow coming into and out of the corners, it will ruin the inside valleys of each tooth on your gear. If the machine can't anticipate the arc voltage and respond with proper torch height distance then you will have a big wide kerf cut on the bottom side of the gear. and cheaper tables wont usually have the proper backlash reduction capabilities to be doing the constant in/out in more than one direction at a time, especially if they are belt driven.

oj83- thanks. that more than answers my question.

Tjschur wrote:

weldin mike 27 wrote:Is that good or bad? (sorry)

LOL. Well considering some particular human hairs are about the same I would say that is great for a striaght cut.

Give Mick a break... It's metric in his world...

.003 in 8' for a home-shop project is impressive, and then some!

Steve S

With the price of a Hyperthern PM105 my whole set up comes very close to $8800.00. I have an excel spread sheet that I keep track of every single item on this build. So I figured in some misc. costs and figure about 10k, by the time I am done. I did scope out some of them listed on the above links, however shipping these things is very high and figure, just build one the way I want it.. I already have a PC, monitor, mouse, etc.

The software and operating system is available for free.
http://www.linuxcnc.org/
https://www.youtube.com/watch?v=BraEMAu5UkY

Finding a low latency computer system can be very inexpensive.
http://www.robotshop.com/en/roboard-ncb ... oller.html

Building the table with motors, etc. can be done for under $1,000
A plasma cutter can be bought for the same.

G-Code can be created using a free program called 'Blender' http://www.blender.org/
Blender is available for Windows, Mac and Linux. and is used for many applications
such as 3D printing, 3D visualizations and movies and much, much more.
http://www.youtube.com/watch?v=No4XrqG0HaM
http://www.scribd.com/doc/119014583/Ble ... -Modelling

Movies
https://www.youtube.com/watch?v=1XZGulDxz9o
https://www.youtube.com/watch?v=eRsGyueVLvQ

The world is changing as we know it. These tools are available for free.

You make it all look so easy, but the accuracy continued throughout all this fabrication is amazing.

There's a lot of skill and experience lurking behind this work. It is a fine example of what causes me to stir starting welders to get on to building stuff (especially work that must be square, plumb, in the same plane, etc) as early as possible. "Welding" just ain't melting and sticking steel together.

Full of admiration.

PS Enjoy the kids.

Oh yes this is an impressive build, and .003 over 8' is amazing. our manual mills at our shop are damn near perfect if they are .003 over 1'. This is also a project I'd care to not attempt, as only one of the factors I have never received any material over 4' that didn't have a warp in it in some direction. that and the effort to build one with time and materials, actually using the software, cause you get what you pay for in that respect, in my scenario I'd be better off spending 12k for a used 5x10 and maybe updating the control if the machine is too old and picking a plasma cutter of our choice.

Me and my boss have seen a fair number actually run and trade shows and some used tables and the best factors we have found are:

Servo motors, steppers can get pretty warm and burn out faster and have a finite number of positional coordinates. servos have an almost infinite number and are built to run back and forth for long periods, as well as have much higher travel speeds.

Linear Rails: they run like butter and are more accurate than other generic roller styles.

Helical/planetary gearing helps eliminate backlash, belt and (ugh) bicycle chain designs are very prone to loosening over time.

One piece designs are more ridged especially if you plan to use a water table, the whole thing may just warp to conform to the floor it is sitting on, then add several hundred pounds or material to cut(depending on what you are doing of course). So a 6 - 8 leg design would be primarily (although you can do more) for sheet metal only.

Water tables help stop distortion in isolated locations of parts where the torch spends a lot of time and the heat has no where to go. Downdraft are ok if you have a self contained fume extractor. if you vent outside your sucking your heat away.

If you desire to do thick parts, unless you predrill a hole or edge start everything, your pierce cut is your main limiting factor. Other than getting a Mag drill for these scenarios there is no cure other than getting a more powerful plasma cutter.

I could go on, but my brain has stopped working and these topics are best with the spoken word.

I will be tracking this topic, as i'd love to know everything you do on your path to a good table. and I wish nothing but the best.

Oddjob83 wrote:One piece designs are more ridged especially if you plan to use a water table, the whole thing may just warp to conform to the floor it is sitting on, then add several hundred pounds or material to cut(depending on what you are doing of course). So a 6 - 8 leg design would be primarily (although you can do more) for sheet metal only.

Water tables help stop distortion in isolated locations of parts where the torch spends a lot of time and the heat has no where to go. Downdraft are ok if you have a self contained fume extractor. if you vent outside your sucking your heat away.

If you desire to do thick parts, unless you predrill a hole or edge start everything, your pierce cut is your main limiting factor. Other than getting a Mag drill for these scenarios there is no cure other than getting a more powerful plasma cutter.

I could go on, but my brain has stopped working and these topics are best with the spoken word.

I will be tracking this topic, as i'd love to know everything you do on your path to a good table. and I wish nothing but the best.

Can you elaborate on one piece design. Not sure what you mean by that. I did also add gussests and extra bracing to my table in case I plan on using thicker plate. Right now this table will hold my F250 superduty dump bed truck. I am also running a water table. Thanks T.J.

I dont have this table, but its just an example, a one piece box style.

http://www.shopsabre.com/shopmasterpro10.html

yes no doubt your table can handle the weight. Sorry I was all hyped about plasma tables when i was posting last and i was on a rant or sorts. lately my boss has vetoed the plasma table this year, but he had me do a bunch or research only to decide that the table we want to get he has to see in person first in Minnesota. and he doesnt have the time and i dont have a passport. Also Shopsabre isn't going to be at fabtech canada this year. Otherwise I am sure we would be getting one in march.

So I have shut my enthusiasm off after the let down, i cant even recall what kind of frame of mind i was in when i made all those posts. If anyone has any more questions about what i posted I let you know incase i glossed over stuff.

More done this weekend between umteen million projects. I got some castors and made some plate with a 1/2" bolt welded to the plate. This allowed me to screw them into the bottom of the legs. It rolls nice. The castors are rated a 330Lbs each. I am going to later plasma cut out some castor mount and also act as feet for leveling. Also ordered a Hyperthem PM, torch and the new Bladeruner ethernet system.

I would have to agree with Oddjob83 that one of the biggest limitations CNC plasma has is piercing heavy plate. On the predrilling note, I imagine this would work great but does anyone have firsthand experience with it?

Ok this has been buggin me for the last few hours now. CNC plasma is great but why not step it up and go water jet? Been looking for a pump that will work but havent had any luck. the way i look at it is go big or go home.