[energyforce]

This thread will slowly grow as the buildup continues. The table is a plasma / oxytorch combo. So I thought id start here now that we have finished quite a bit. The buildup is being done by me and danosb on this board.

See the attached pics. Feel free to ask questions. To start off......

3 Ibeams spanning longidutinally at 12 feet. Ibeams are W8x35 which is 8 inch flange, 8 inch web and approx .4 inches thick. There are 4 6x6x3/16 HSS legs holding up each ibeams (12 legs in total). The ibeams are reinforced by 8x1/4" flatbar at each end. To finish the table a 1/8" huge slab of a sheet was thrown on top. All the welds are 3 passes. The top sheet is also welded on to the ibeams.

The legs are to be custom, using trailer ball hitches. This allows height adjustment with swivelling capabilities.

The shaft/pillow block combo and gear rack for the x axis will be mounted on the ibeam. The pics that shows the multiple 9/16 holes drilled onto the ibeam in a straight line is for the 1 inch shafts. The holes are so large to allow lots of adjustment capabilities.

The gantry is fully aluimum and is being built as I write. We should have a "rolling chassis" by the end of Jan or mid feb. The table is going to have a waterbath for smoke reduction which explains the giant slab of sheet on top. The grating is fully 1/4 inch. And for size comparison im 6 feet tall. The table is 12ftx6ft in dimensions producing a cutting area of over 5ft x over 10ft.

We really want to hear your input. This is our first machine.

And for you people who like pretty things, the table is going to be grey and the gantry yellow. :rainfro:

Erik

[DanOSB]

(chair) Erik

fixed the images for you

[jeepn4life]

thats awesome. A few questions. Are you putting the trailer balls on all 12 of the legs? Do you think you need 12 legs to keep it from deflecting? What type of slides are you going to use? What servos? What drive mechanism (rack and Pinion, lead screw, ball screw)

What is your gantry design like? I want to build one about 1/3 the size. i want a cutting area about 4 x 2. Any recomendations on the table material? I bet tha table is not moveable... How much does tha I beam weigh? Are you just bolting the linear rails to the Ibeam? What software and controler are you going to use? Do you plan on having auto height adjustment?

[DanOSB]

yes we are putting all 12 trailer balls on all of the legs as this table is designed to be able to put 6 inch thick sheet (5x10)
we are going to use 1 inch linear shaft for bearings

1200 oz in stepper motors

gear rack n pinion

the ibeam weight 420 lbs each if my memory is correct

going to use gecko for drivers and software isnt set but most likely mach

yes we are considering thc setup

and that black thingy on the last image is the z axis

[energyforce]

I attached two pics of the gantry. Hope this helps jeepn4life. Its purely aluminum for a light design. I have a pic of some guy using a huge heavy steel gantry horizontal span with huge expensive light aluminum vertical posts holding it up?!?! What the heck right? Anyways....

You dont need ibeams that large and that many legs to keep it from deflecting, especially if you are only cutting 1/2" thick sheet. Our table is an extreme overkill, even for 7 inch thick steel. We originally designed for smaller ibeams but the metal supplier didnt have them in stock so we ended up with something larger than anticipated to meet our milestone. You could probably hold 200 tons on it for all I know.

If you are really worried about deflection with your design i dont mind giving you some numbers it if you can send over your dimensions/loads and i can do some calculations.

What kind of jeep anyhoo and what mods? We have some pillow blocks and shafts and rails for sale if you need any. We have a quantity of two shafts that are 1" in diameter, predrilled, and 42 inches in length. I believe we have 2 regular open pillow block bearings to go with them.

Talktocha later.

Erik

[DanOSB]

also if u are considering small table i would suggest look at one of the plan that was posted in here.. its pretty small size and perfect for smaller stuff (1/2 inch or below)

[jeepn4life]

thanks for the info.. I have a 03 TJ, dana 44's front and rear, 4.88 gears, chromoly shafts, air lockers, 4:1 Tcase, NV3550, PSC modified roll cage, custom rockers, TBT front and rear bumpers, Walker Evans beadlocks, 36x13.50 Super Swamper Irok tires, warn 9.5Ti and a customised Full Traction 6" long arm lift...

I dont expect toc cut anything thicker than a 1/2". I guess I would like to make a table that can cut at least a 4x2" sheet and up to a 4x3" sheet. I figure most of its time will be doing 3/16 or 1/4 stuff... I am trying to decide what size material to make the frame out of. I like your I beam design... I dont have any way to check, but can you recomend a Ibeam size and corner post size to make the table out of? I dont want it TOO over killed. It would be nice it is could be moved with a small forkift... Plus the Ibeam idea makes a nice place to mount slides and since they are sort of covered, they should help keep dust off.

I am looking at some INA or THK slides. Not sure if I shoud mount them on the center piece of the I beam or on the bottom piece...

[jeepn4life]

Another quick question, do you think you need 1200 oz motors to move the light AL gantry arround? I was hoping with mine I could get away with the 600'sh motors... I also was going to use a gecko, which one were you going to use?

I was confused about one thing though. I have SolidWorks to make 2d drawings of the parts I want to cut. I need a CNC software like MACH2 or whatever right? Once I have that software is that it or is there another piece to the puzzle. I mean the motors go to the gecko, how does the computer talk to the gecko?

I am going to buy these rails I think unless you tell me not to http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1 and there is a matching pair that is shorter for my y axis... I was going to go gecko and Mach2 (gecko recomended it), and 640 Oz motors. I was undecided on the drives.. Rack and pinion is probably pretty easy. With those big motors are your going to direct drive them or gear them back? What rack and pinions are you going to use

[energyforce]

thanks for the info.. I have a 03 TJ, dana 44's front and rear, 4.88 gears, chromoly shafts, air lockers, 4:1 Tcase, NV3550, PSC modified roll cage, custom rockers, TBT front and rear bumpers, Walker Evans beadlocks, 36x13.50 Super Swamper Irok tires, warn 9.5Ti and a customised Full Traction 6" long arm lift...

Nice Jeep. I have mog404's, hydro steer, recentered hummer beadlocks with cutdown mag runflats. Im never gonna put these things on anything!! No time and no shop yet. I may sell my hydro steer if someone would by it all just so that i can get what i paid for it back.


I dont expect toc cut anything thicker than a 1/2". I guess I would like to make a table that can cut at least a 4x2" sheet and up to a 4x3" sheet. I figure most of its time will be doing 3/16 or 1/4 stuff... I am trying to decide what size material to make the frame out of. I like your I beam design... I dont have any way to check, but can you recomend a Ibeam size and corner post size to make the table out of?

I dont want it TOO over killed. It would be nice it is could be moved with a small forkift... Plus the Ibeam idea makes a nice place to mount slides and since they are sort of covered, they should help keep dust off.

I am looking at some INA or THK slides. Not sure if I shoud mount them on the center piece of the I beam or on the bottom piece...

I can recommend an ibeam size, you will probably only need 2 ibeams and not 3 and they would be a LOT smaller than the ones we have. You want some clearance for the bearings too so they need to have some web height. Any ibeam that you can find that is small enough to just allow enough cleanracne for your bearings will definataly be strong enough!

I think slides would be more difficult to work with than shafts because of thant extra degree of freedom you would have to otherwise worry about (pillow blocks can rotate on a shaft but thk bearings on slides cannot) But I have no experinece in this area... we will let u know how well the shafts work for us ....

[jeepn4life]

any comments on the stepper motors of other questions I had?

[ger21]

I was confused about one thing though. I have SolidWorks to make 2d drawings of the parts I want to cut. I need a CNC software like MACH2 or whatever right? Once I have that software is that it or is there another piece to the puzzle. I mean the motors go to the gecko, how does the computer talk to the gecko?

Mach2 (I'd go straight for Mach3, it's a free upgrade to Mach2) sends signals to the Geckos to move your motors. If you can save 2D .dxf files from Solidworks, Mach3 can turn them into G-code to run your machine, but with limited functionality. A more powerful option would be to use a CAM program to make your G-code. SheetCAM has plasma features included, and works great with Mach2/3. You can even buy them as a package. www.sheetcam.com

[DanOSB]

if your whole gantry weight less than 40 pounds u are just pushing the motor limits and if u are going to zig and zag u will miss some steps but if u make it 20 pounds for a to z inculding torch then it should be okay.. i would still suggest get some gear reduction.. saw bunch of them on ebay.. for me im going to run 1200 motor with 5 to 1 gear reduction and 20 degree and 16 pitch (1/2 inch face) and 1 inch pinion (thats what we are leaning toward to so far.. not decided yet.. havent purchased those too..


also your jeep sound like a nice one..

for me i drive full size chevy with d60 and 14 rear disc all corners and detroit both front/rear 410 gears wtih 38 michelin military tires.. they are same height as 39 boggers

[jeepn4life]

sweet rig, where are you located?

As far as the motors, how do you calculate what the motors can do? Don't know what my gantry would weigh, but I am sure it wont be super light. I will try to make it as light as possible since it doesnt have to hold any weight except torch,

You think the 600 size motors are too small for that huh? Can you educate me on how to select a motor for a gantry size? I guess with the gear reduction you basically get rid of the fact the pinion is traveling a larger distance per revolution? Would a piece of all thread be a better choice for my 4'x4' table? That way the motors would turn 10 times per inch of travel... instead of 1" or more per inch of travel with a rack and pinion?

Hey, another question, if you have gear reduction or not makes a big difference of the number of steps you have to make to tavel one inch... Does the software take care of that for you? Let you input the number of steps to travel a given distance?

Since I have a handful or smart people responding to this thread, I'll try my luck again. Why do you say not to use just Mach3, what functionality to you not get that you need.

Last one for tonight, I promise. do you have the your plasma torches riged so the CNC software can turn it on and off? If so, I have hypertherm 600, and I know it should be as easy as opening up the torch and soldering in a wire or 2, but one issue I have been wondering about is the auto shut off for air. When I use my cutter, I pull the trigger air flows, plasma starts and I cut. When I stop of let off the trigger the air keeps going. If I hit the triger again, the plasma doesnt start again, it just shuts off the air and then starts the plasma again on the next pull of the trigger. Is there a way to program in time delays before it trys to start the plasma again so I can wait for the cool down air to stop before it starts another cut?

[energyforce]

I think 600ozin should be just fine for your application.

At 1200ozin with our pinion (rack and pinion) and 5 to 1 reduction should give us somewhere around 750lbs of force! But of course the motor wont run at this torgue all the time, depending on how fast its moving (look at the graphs that is supplied with your motor) and how much voltage you put into the motor. So if our motor was pumping out 600oz in we would have half of 750lbs being put onto our gantry.

No reduction = 1 step to move distance A
5:1 reduction = 5 steps to move distance A
No reduction = torgue T
5:1 reduction = T x 5

If your driver and motor will not give you the accuracy you need i.e. .01 of an inch or .001 (whatever you want) then its a good idea to get a reducer. The reducer also increases your torgue. The motor probably is too fast anyways so the reduction will help you gain some good torgue and reduce the speed and decrease your stepping distance meaning more cutting accuracy or increased resolution.

I think im talking too much and the pros here are probably gonna start criticizing me and telling me im all wrong so ill jsut wait and see what happens. After all im learning too....

Ive been at school all day and my brain is just dead! WE are building a gearbox right now and im just burned out mathematically.

[DanOSB]

well lots of tables are using 200 oz in motors with some reduction.. and there is quite lot of nema 23 frame for gearhead that are cheap on ebay that you might want to consider instead.. lets say u get 20 to 1 gear ratio means 20 times 200 oz which means about 250 lb which is plenty for a smaller table and build your gantry with 2080 tslot or something or light 2x4 alum tubes

we are located in bc canada (im in langley)

about plasma.. i dont know about the 600 verison.. but im sure u can get machine torch which i beleive will control the oxygen valve but i know for bigger verison has a switch for on and off on the panel so i guess it controls at the panel or something..

we are focusing on flame torch and once we get plasma we will get machine torch and its ready for cnc setup

[DanOSB]

forgot to add this.. if u have more reduciton u will have more power but the table will be moving more slower.. so have to caculate the rpm and the reduction.. to make sure u can accomplish the speed you want to have for cutting

[jeepn4life]

Instead of using gear boxes for gear reduction ,what about just using a acme screw or something. If a pinion has a circumfrance of 1 inch, then you turn one rev to go 1 inch on the rack. If you have a gear reducer 5:1 then 5 reves per inch. With a screw with 10 TPI, you would have 10 revs to go one inch. hell, a 20 TPI would be twice that. and Back lash on a 20 TPI threaded rod shouldnt be too much I would think...

[jeepn4life]

What speeds are you guys looking at for cutting. My cutter for 1/2" needs like 20 IPM but for 1/8 it can cut 250IPM....

[DanOSB]

i have the numbers somewhere here.. but from like 2 ipm up to 500 ipm i beleive

[jeepn4life]

Do you guys like the round rails or the flat rectangular THK style rails?