Black Friday Deal got me :)

listing said 4A max and said it was an upgraded version i have not picked up any power supplies yet. usually China ratings are exaggerated so i never go to the max. i think the motors are rated at 3 A. I will keep that in mind regardless. maybe i will get some sort of manual with them when they get here? I will have to wait and see. but if i smoke a $7 drive it won't hurt to bad

I've been gathering and planning quite a bit. My motors and drives came in yesterday and another batch of goodies should be here in the next few days.

I'm still working on my finished plan but have a much better idea of how thing will look coming together.

But with a floating head with a magnetic breakaway and about 5 inches of Z travel i came up with this so far.

 

I started to actually do some work but it was short lived but when Christmas and new years gets here i will have a lot more time to build things. But as of now i have a gantry beam and 1500mm rail to mount on it and all the bits to build the Z axis so it a start my lead screw for my Z needs to be cut down to fit the build. 4 start screws are limited in choices for some reason.

but everything is built around 3 inch square aluminum tubing. came across a drop of this for the gantry beam as well. i'm using 12 mm round rails for my Z. also decided to change some things on my floating head concept. after looking at it for a while i seen a better and easier way to do it  

   

So I picked up a self-centering 4 jaw chuck. it's not very big but will hold 4 inch square tubing from the inside. i was looking at several ways to make a steady rest for longer tube but the draw back is you have to have around a 6" bore to pass 4" square tube through. bearings beyond 90mm ID's are very expensive. i might have found a work around but i have to test a small design and scale it up if it works. A steady rest for round tube is pretty easy but the square tube gets a lot more involved unfortunately. it would be nice if a cheap self-centering programable clamping system could be don cheaply but that solution is yet to be found
i have an idea for that too but until you build and test it out all it is an idea but if that would work the little chuck would get phased out  

 

also add the Longworth chuck to your list
www.carbatec.com.au/article/266/how-to-make-a-longworth-chuck
Not sure if it does square and rectangles

A couple of photos of Joey's setup.
He's running Qtplasmac. The rotary is attached to the gantry. I think he must use another unpowered chuck to hold the other end.
you can see his table is not exactly a hobby one

   

i was thinking Pneumatic clamping of some sort that could be controlled by Linux CNC. i was wondering if something simple like regulating air pressure between two independently could be a simple solution for calibration of the center line ?

just some more progress on the Z axis

what i was thinking was if you had a way to control clamping independently and had the pass through requirements you could have a tube feeder and not need a 24 foot long machine to work with a full length of tube. space saving in a good way i think.

been looking into this and i think it can be done but it is not cheap project off the shelf options are either through the roof in price or yet to be discovered. even making the stuff myself is going to be expensive by my standards and could see costing around $400 per chuck. So that being said i think i will start with a rotary union to see if i can pull that off and go from there without that the whole idea goes out the window

You could make up some machined blocks for your 4 jaw to hold rectangular tube centrally. eg 3" x 2" would need 2 x 1/2" blocks to make it a square.