[nokode]

Hi all,

in the process of defining the final size for my machine, and considering that bigger = more expensive, i'm trying to build the smaller, yet usable table size possible for my projects. So, here a standard size for wood and mdf boards is around 1200 x 600mm, but probably the wider material i will machine is somehere around 800 and 900mm, for house doors.

I plan to do also add signs for shops and so, and that's a problem because those could become really long. Now, my question (finally lol):

Is it possible to machine a long piece (longer than the cnc table) by segments? machining a segment, then by some form of marks, or holes for positioning or something else, stop the work, advance the material and continue machining, keeping the two segments in perfect aligment??

Like to read your comments/experiences.

Thank you again.
Rui

[ssutton]

Yes Possible, no not easy. My machine has a 49.5" X 49.5" cut area. I solve most of the indexing issues in CAD before I go to CAM. The workflow makes much more since that way.

Scott

[nokode]

Yes, i forgot to mention, but dividing the work into separate files (those segments) should be done previously. My problem is really how to align each part of the work into the same board when i move it, to make it seamless those connections.

Thanks.

[acondit]

Your machine needs to have pretty good accuracy and repeatability to do this. I cut a couple holes for machine dowels in my table for one setup (a flip over part that had to be machined on two sides). Another time installed a fence and an index piece to index a long set of parts. Look here at posts 97, 113 and 114 to see how I did it.

[ssutton]

Just as acondit said, repeatability is going to be the key. My machine is set up with solid state home sensors so my 0,0,0 position is very repeatable. If you can, drill a hole in the first file, then using a positioning tool like you can use with "Big Tex" Blue screen in Mach you can find the material position again once you move it. You should probably use a fence of some sort to keep things square and then all you have to find in the materials X position relative to where you left off in the first cut file. Again, it can be done I have not yet found an easy way to do this, still trying new things. If someone has any novel way of doing this please speak!

[JC50]

I did something similar a couple of weeks ago. I cut a 55" piece on a 44" bed. As mentioned before, I clamped down a straightedge for a fence (48" brass edged mason's level). This made it easy to move the piece and not change my Y axis zero setting. I then (very carefully) measured and rezeroed my X axis for my next cut. Turned out much better than I expected.

[jcoats]

It may seem hokey, but go take a look at the ShopBot Buddy machine. It uses a 'stick' (rack mounted on the bottom of a spoil board) that keeps the board alligned. That machine is effectively a fixed gantry machine. The 'stick' that comes with the machine is only about 24" long, but can purchase up to a 120" long stick.

Just a thought and a way to 'rethink' our normal solutions.

ShopBot Buddy
is their current page about them.

[RomanLini]

It's not that hard, if you have an edge guide that the work butts up against then there is only one axis where it moves. Then you can get the machine to drill a hole for the next guide peg which sets the amount of movement in that direction.

I've done it on my little machine with that method, using a couple guide holes and contersunk brass screws for the alignment (brass countersunk screws are cut on a lathe and act as accurate cones, locating into the guide holes).

It helps if you have ability to home the machine to an accurate position (my machine does) but it's not necessary, if you don't turn the machine off or crash it.