A very basic question on building the Torchmate 1

[justlarry]

Hi,

I have been reading threads here and elsewhere on building the Torchmate 1 CNC table and have a pretty good idea that I can handle this project.

I have the skills to assemble and weld up the table but I have perhaps a stupid question:

Most steel I see and buy is a little bowed or warped at the steel supply house I buy from. Just how critical is it that everything be straight and level when building up the Torchmate 1 ? Is it absolutely essential that the steel I use be straight? It would seem obvious that it would have to be.

Is cold rolled steel the answer and if so is it usually fairly straight? I have never seen or bought this locally. I would have to order it.
This is the only foreseeable problem I do not have an answer to before I take the plunge.

thanks Larry.

[tyler774]

Larry

You are right to be concerned. I have put together a torchmate, could never get it as tight as I would have wanted. If you do buy I would highly recomend incorporating a spring or air cylinder to tension the pinions against the rack. You may want to look into Bishop Wisecarver V-rails for an improvement to the bar stock rails also.

Have a good look at the design of the Dynatorch gantry for ideas, they have a 3D cad model on there site to view.

You can straiten out bowed steel pretty well if you string a taught wire up next to it for a reference. The gap between you measure with a caliper or can get fancy and rig up a jig with a continuity tester.

Thats all I can think of of the top of my head.

Tyler

[justlarry]

Thats a great idea using a taught wire. I never would hav thought of that.

The using a spring on the pinions was somthing I was thinking of to tighten things up a bit. A cheap way to go.

[Ben Olson]

for straightening tubing ( or just about anything that is long , and needs to be straight ) monofilament fishing line is the best , preferrably in a brighter color ( the blue can be hard on the eyes )

just stretch it tight along the tubing ( hold it in place with tape or magnets )

and touch along it looking for the largest gap ( this is the middle of the bend )

if it lays completly flat along the piece ( no gaps ) either the piece is straight or you have to move it to the other side of the tube ( a string will lay tight along the "belly" of the bend )

[justlarry]

I happen to have some flourescent green fishing line! great idea! and checking both sides with it.

The thinnest material I will be plasma cutting will be 1/8 steel and probably up to 3/8 inch with occasinal 1/2 thick, so I am thinking I do not need real micro measureing precision here in the build up but I know its vitally important to be as accurate as possible. The travel speeds should be fairly slow also, although I am not sure that has much to do with it.

Also the shapes I am cutting will be fairly basic geometric shapes of small sizes no more than 2 feet by 2 feet or so and no need for close tolerances in the cuts so if something is slightly off it won't matter THAT much in the final cut out pieces. At least I hope!

My other worry about the TM 1 is the cam roller system used on the Y axis gantry. From other builders here (blackhollow) he posted he had problems cutting circles until he changed the gantry to a rail/bearing block set up. He used a mill to drill and tap the holes on the cold rolled bar to add the rail. I dont have a mill so I dont think i have this option. Just a drill press to work with. so i have to think out a way to attach a rail somehow but shouldndt be too difficult. perhaps sustituting hollow bar and using drill press.
In any case thanks for tips!!, i was worried, Larry.