Newbie- distance z axis can travel

[mostlund]

I see that most home built cnc router tables travels usually about 3 inches on the z axis. Can I make a table to travel/cut 8 inches on the z axis? If so what do I need to do. I basically want to know what the maximum amount of inches the z axis is capable of cutting.

Thanks

[budP]

it cannot cut deeper than the length of the tool

budP

[mostlund]

I'm looking to make a machine that can cut a foam boat plug like this website.

http://images.google.com/imgres?imgu...en-us%26sa%3DN

I thought the amount of movement of the z axis along with the length of the bit(tool), determines the overall distance (height) that can be cut like in the example of the foam boat. Doesn't the height of the Gantry which holds the z axis also determine the overall distance that can be routed/cut?

When you say the "length of tool" are you referring to the length of the bit?

[CarveOne]

The bottom of the router and/or z axis assembly limits how deep the cutter can go into the material no matter what the cutter length is.

CarveOne

[johnmac]

My Z has almost 8" of travel. I built it that way so I can build a removable vacuum bed. Also maybe some other kind of removable bed or fixture as needed. I can also remove everything down to the main bed should I want to cut on something that is extra thick.

The down side to this extra length is the frame must be stronger to prevent flexing.

John

[ger21]

Originally Posted by mostlund Can I make a table to travel/cut 8 inches on the z axis? If so what do I need to do. I basically want to know what the maximum amount of inches the z axis is capable of cutting. Thanks

It's all about clearance. If you're cutting vertical walls, you'll be limited to the length of the cutting flutes of the bit, as the shank will usually mar the work if you try to cut deeper than the flute length. There are tools available to avoid this and cut deeper, though.

If you're cutting nearly vertical, the the collet will limit your depth of cut. If the angles a little greater still, then the bottom of the router, or Z axis will limit your depth. And finally, the ultimate depth limiter will be the bottom of the gantry.

It really depends on what you're cutting, and what tooling you'll be using. Keep in mind that as Z travel increases, the machine will get weaker and flex more. But if you're just cutting foam, it shouldn't be a problem for you.

[harryn]

The comments above are dead on. One other aspect is tool lengths you can actually buy. It is not that easy to get mill and router bits longer than 6 inches, and even 4 is a common limitation.

Industrially, the long "Z like" range you perceive is done in part by having more than 3 axis. Take a look at industrial robots like Fanuc to get some ideas.

If the depth / thickness required is deeper than the machine, then software packages allow sort of a stacking of pieces to get the results needed.

[johnmac]

I just want to mention that I didn't build the 8" Z to cut 8" deep. I bought the assembly I used on ebay. It has 11" of travel, but I an only using 8" or less. With a vacuum table insert, I will have about 5 1/2" to 6" of travel left.

John