To THC or not to THC

[dz1]

I recently finished my CNC router/plasma table. I have been playing with the router for a while and am ready to finish the build by switching it over to handle my plasma cutter.

I will be doing art type cuts in sheet metal, so do not need a absolutly perfect cut. Also I probably wont have that many small detail pierces and all stock will be flat sheet.

I am wondering how sloppy it will be to not use a THC?

I am using a laptop currently as the controller so no 2nd parallel port. For initial layout I want to keep it as simple as possible so I am hoping i wont need a THC off the bat. So before i go spending any more money or resetting the table and tool holder for the conversion I thought I would ask for some feedback from anyone with experience.

Thanks a ton.

btw here is the table build log,

New router build

I can get up to 500ipm on the y, maybe 70 on the x and 12 on the z.
I hope 70 is enough for 16ga.

[Weldtutor]

Originally Posted by dz1 I have been playing with the router for a while and am ready to finish the build by switching it over to handle my plasma cutter. I am wondering how sloppy it will be to not use a THC? I thought I would ask for some feedback from anyone with experience.

I used a floating torch mount with a motorized Z axis rather than an electronic THC. This seems to work quite well for my CNC plasma machine.

Post # 48 at this LINK has pictures of the torch mount.

Other locations in the thread show more construction of the mount, as well as very satisfactory and accurate cuts made with this system.

[dz1]

thanks for the link. That will help allot. Feels much better having some guidence on it from peopel who have done it rather than just guessing and hoping as usual

I dig the floating head, I will see what i can come up with.

I also dig the chain drive, I had seen beetmans table, hadnt seen any other chain drives. at 40-70ipm on my X i am thinking of a redesign. My wiring harness is already set for the x motor on the end plate, so another rack and pinion is out, i was thinking of maybe a double start acme insteadof the ballscrew (which is kinda fine pitched) but chain might do nicely too, only thing i might worry about is back lash when in router mode.

was worried abotu backlash too on the Y in router mode, but the double rack
and fully engaged teeth didnt end up having any problem thankfully.

have you tried yours with a router yet? any noticable chatter from the chain having to fight the cutting forces?

thanks

-Dave

[Weldtutor]

Originally Posted by dz1 I dig the floating head, I will see what i can come up with. have you tried yours with a router yet?

Hi Dave,
No, I have not used my machine with a router.

The floating head, has 4 transfer bearings that roll on the surface of the material being cut.
The idea came from the plans by Mike Laws, that have a link earlier in my build log.

Beetman & I both started our chain driven tables about the same time.

Others were also built by Massajamesb, as well as Smilewizard who switched his from belt drive to chain with satisfactory results.

[dz1]

very cool thanks. will be sure to check out the other threads too.

-Dave

[Degrom]

Originally Posted by dz1 very cool thanks. will be sure to check out the other threads too. -Dave

Hi Dave,

What did you decide on in the end?

[dz1]

oops forgot to update this thread

i really liked the floating head idea, but being rather ughh...lazy I figured
I would start with a solid head first just to get up and running fast

I also decided I would experiment with a mechnical trigger activation
mechanism before popping into my case and voiding my warrenty

here is the torch mount / trigger activator i ended up coming up from trial
and error and from others ideas on teh board

http://cnczone.com/forums/showpost.p...9&postcount=13

the idea for the trigger mechanical thing is from meincer's build
http://cnczone.com/forums/showthread.php?t=31346

I havent used it a ton yet, just had to tear it all down for winter

I have had the tip end up dragging as the metal peels up or bows from teh heat, doesnt drag hard enough to move the work piece yet (just have a weight on it to keep it put so far) I may add in a roller berign design around the cut tip to maybe push down on the metal and keep torch solid mount if need be. the thicker the stuff your cutting the less warp so still might not be necessary for 11ga + will see , it will tell me if its a bad design in time

[Degrom]

Nice build... Must have been a huge learning curve...


What kind of plasma cutter do you have?
Does it start(HF?)?

[dz1]

thanks,

yeah has been lotso work but fun as hell

couple things i had to make work arounds for and couple things i had to ditch and rework, built it for experience/fun so invaluable learning really.

I have a hypertherm powermax 380, 110v, i belive they are not a HF start.

I did use properly shielded wire for teh steppers, i have not experienced any lost steps or drunk motors due to emf. (mcmaster part numbers in the receipts.pdf in build log)

i cheaped out for my limit switch wires and used a foil shielded audio wire...they did pick up noise even from the ac power line going to the router head so I have scrapped limit switchs for now