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Author Topic: better to ask first than pay later  (Read 2504 times)

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better to ask first than pay later
« on: June 03, 2009, 08:28:46 PM »
im a newbie with enoght exsperiance to be dangerous. 10 years ago i was a sheet metal engineer i worked with autocad and programed lasers and turret presses as well as many other cnc machines. im now a industrial e&i so thats the dangerous part

i want to build a plasma/oxy cutting table. i dont need 0.001 accrucy i just need it to look like it was machine cut rather than hacked out with a chalk mark and gas axe

now for the free advice.
i would like the table to be able to cut a 8x4 full sheet up to 12g stainless steel or up to 1" with oxy i know this will present problems as plasma requires high speed and oxy cuts alot slower so i might have to forgo the oxy and one day invest in a larger plasma that can handle 1" neatly. the table will need a water tray as my wife will get upset if i set fire to the workshop again.

so questions.
1/ i would like to make the gantry over the 8' side of the table this allows me to load material easier with out having to drag it over a slide rail. if the gantry was made from alluminum and kept light weight is this possible (2 steppers on this axis)
2/ using slides and linear bearing what should i use for the drive (cheap is nice as long as it works) chain-tooth belt-gear rail-ball screw i would be happy with +/- 0.3mm
3/ as the manual points out the best place to work out the size of the steper motors required for a gantry is to ask the forum as its a grey art of acceleration and over run as the axis is not having to work on the material but it does have to move fast
4/ anyone ever worked on a flooded plasma table? does it require a special torch to cut with its tip in the water? does it affect the ampage required to cut dry material.

any advise would be welcome as i would rather start right then end up with a bunch of parts that carnt do the job.

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Re: better to ask first than pay later
« Reply #1 on: June 07, 2009, 12:25:39 PM »
Before you go buying anything and for what it is worth, I would suggest that steppers will be far too slow for a table that size and you will be disappointed with the time it takes for the rapid positioning moves and that servo motors are the way to go.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.