6" CNC Router?

[matt]

Does anyone out there know of a small (not cutting anything with a wide footprint) CNC Router that can cut through a 6" laminated hardwood block?

[Prometheus]

Not offhand, but the "laminated" part gives me pause. If you have, or intend to purchase, CNC equipment for whatever it is you're up to, why not cut the unlaminated pieces individually with the CNC router, then glue them up in a jig? Even if you can find a cutter that is 6" long and suited to the task, it's going to cost one heck of a lot more than the equivilent 1" bit.

After all, the point of CNC (as I see it) is that it makes repeatable manufacturing easier. Any CNC machine should be able to make as many hardwood cutouts as you like that are virtually identical. So you make a bunch of them, then laminate the finished parts. If they need to be contoured on the Z axis, draft each part accordingly.

If you're making one-offs, you may not need a CNC router at all. Grizzly sells X-Y tables that you could attach to a bench with the router mounted above it to make an accurate wood milling machine. (an old drill press could be excellent for this if you remove the head and replace it with a router- it might even work with the drill press chuck, but the bearings aren't designed for that use) Manual machines are just as accurate as their CNC counterparts- they just require more attention and effort when making a lot of identical product. Instead of hitting "start" and letting it go, you need to set up each operation and use hand cranks to make things happen- but truth be told, that's a lot more fun than production CNC work.

[Steve knight]

the problem is the cutter length. there are some endmills that long but they can be fragile. the shopbot has 6" of z travel. is this something you will be doing often?

[Morris Dovey]

| the problem is the cutter length. there are some endmills that long | but they can be fragile. the shopbot has 6" of z travel. is this | something you will be doing often?

Yabbut 6" of travel isn't 6" of cutting capacity if there's a need to move the tool above the workpiece. For that you'd need to be able to raise the spindle at least 12" in order to move a 6"-long bit over a

6"-high workpiece.

FWIW, ShopBot offers a z-axis extension that'll provide the 12"; but the down side is a reduction (~50%) in z-axis precision along with a (perhaps significant, depending on application) increase in gantry flex.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Steve knight]

your right I had not thought it out much. well when I get my machine it will be easier to picture. Plus a 6" bit would flex too. so it

[Morris Dovey]

|| Yabbut 6" of travel isn't 6" of cutting capacity if there's a need || to move the tool above the workpiece. For that you'd need to be || able to raise the spindle at least 12" in order to move a 6"-long || bit over a 6"-high workpiece. || || FWIW, ShopBot offers a z-axis extension that'll provide the 12"; || but the down side is a reduction (~50%) in z-axis precision along || with a (perhaps significant, depending on application) increase in || gantry flex. | | your right I had not thought it out much. well when I get my machine | it will be easier to picture. Plus a 6" bit would flex too. so it

It will flex some; but it's unlikely that anyone would plunge a bit 6" into a workpiece and attempt horizontal movement more than once - 6" CEL bits are a tad pricey to replace. :-)

My rule of thumb is to make deep cuts in passes no deeper than the diameter of the bit; and if a smooth wall is needed, rough cut a little shy of the finished dimensions (by perhaps 1/10 of the bit diameter) and then make a final (outline) finish pass at full depth - and when I want /really/ smooth edges, I make the finish pass twice to minimize the effects of bit/machine flex.

A good general rule of thumb is to work with the least possible amount of tool hanging out of the collet - even (perhaps especially) with a long z-axis.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA