Z axis length for 4'x8' router mill

[wcarrothers]

Just wondering if anyone had an idea of what the average length seems to be for an Z axis?

I could make it as long as 18" I think but don't know if I should.

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[studysession]

Wow!@ 4'x8' - Do you have pictures?

[wcarrothers]

Not yet. It is still under construction in my mind although I have many bits spread out around my shop to make it happen.

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[mxtras]

Obviously, it varies. Most routers of that size I have seen or run have maybe 4"-6" of travel and have some accomodations to move the spindle up and down a few inches.

Right now, I am using a 5'X12' machine and the Z travel is right at 4". Almost all it was purchased for is for cutting sheet materials such as MDF, ply, etc.

Adaptability is important, I think. If you are going to route flat stuff - like sheet goods, you don't need much more than maybe 2X the length of your average cutting tool. If you are planning to carve blocks of foam or whatever, you need more daylight, but not necessarily more travel. If you are planning to route complex, 3D shapes, design with as much versatility as possible for daylight clearance, spindle position and travel.

Scott

[wcarrothers]

Thanks scott.. I still have to give the dimentions here some thought... Perhaps I will make the Z as long a travel as it can but not perhaps be able to use it all depending on how high I make the gantry.

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[JerryFlyGuy]

It really depends on what you want to do w/ it. I noticed that you call it a router/mill. A router, as already mentioned, usually doesn't have much for a z movement [similar to a plasma cutter] while a mill can be fairly large. I know of one tht is getting built that has 4ft of z travel .

It comes back to what do you want to do w/ it.

Jerry

[andy_ck87028]

When designing a Z axis, bear in mind that it will be at its most inaccurate when fully extended.

An 18" extension will be more inaccurate than a 1" extension (unless you can ABSOLUTELY guarantee rigidity has been solved).

If most of your work will be cutting thin sheet and you have to do it at full extension (ie 18"), then you will be frustrated with the results.

This can be overcome by having a fixed height gantry and variable height table.

Consequently when cutting thin sheet, have the table set high requiring little or no Z extension. Or.... when cutting 3D, have the table set low accepting that there may be a degradation in cutting quality caused by Z flex.

If you have a solid budget, Z flex can be overcome easily, if you have a tight budget, solving Z flex is more difficult.

Good luck

Andy

[wcarrothers]

Ya I figured about the accuracy at full extention and that. But always want to build as big as possiable. You know how that is.

Maybe I will build the z so it could go to 18 but build the supports to 14 or 16. Was thinking I'd have a series of different MFD base tables to adjust the max depth. Perhaps like an mfd top with a grid that would raise it up or something and give you clamping flexiability.

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[andy_ck87028]

Sounds practical to me.

If designing with 18" extension, the snout needs to be pointed.

Therefore you might want to design Z with interchangeable cutting devices.

Some of the guys here have purchased electric die grinders which have skinny barrels.

I am not convinced that a die grinder is good for everything, so I have also designed to allow for a beefy router.

I will probably use a beefy router for aluminium and hardwood and a die grinder for deep profiling.

I think its unlikely that I will need to do full extension work with hard materials, so the issue of flex becomes less of a problem (the harder the material, the bigger an issue flex becomes)

At least by having the two cutting tools, variable height table and big extension, I will have a very adaptable machine.

Have fun

Andy

[ger21]

Think about what you'll be cutting, and the tooling you'll be using. With a router, you'll be limited to probably 3-1/2" depth of cut tooling max. And if you go much deeper, you'll get interference from the collets. Are you really ever going to cut anything over say 6" thick? I'd say maybe 8-10" max clearance under the gantry, with enough travel to get full clearance with the tools you'll be using.
If your not going to use the extra height, you just end up with a more flexible machine.

[wcarrothers]

Ger of course saves me again..

As I'm building the mock up (using 3/4" and 1/2" ply to simulate where I will be using the aluminum) I've been comming to my senses. Becides things on the Z are getting heavy the longer the travel. I'm going to shoot for 10-12" max travel Perhaps I will go to 8-9. I'd say that would be more practical and probably also work better.. Really don't have a plan for what the machine will do though. hehe But hopefully it will look cool..

Just got 2 long lengths of guide chain (that stuff the wires can run inside) to use from work. I was worried how I would end up hacking a way to run the wires but now at least that part will be quite clean..

Probably be a couple months before the project is worthy of pictures (sorry)

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