Looking for ideas to make the table adjustable

[wiese]

I am considering modifying my 36X48 table so that it can be raised and lowered to accomodate larger (taller) material. I have considered having the table slide in vertical tracks and placing four cams under the table that would be operated by a locking lever. I have also considered rigging up a threaded feed at each corner similar to what you see on a surface planer. I only need about 6 inches of extra room in the Z direction. Any other ideas would be greatly appreciated.

[davidallen]

I'm trying something similar. I raised the x-rails about 6". to adjust the work surface, I'm building "boxes" to provide an offset table. they can also be used as a plenum for vacuum hold down or provide clamping surfaces for mechanical fixtures.

my main problem is getting the base flat. I'm currently working on an extension to the router carrier to drop it 6" then I'll swap it out and use the orginal one with the boxes

[Brady Watson]

Jay,
Why not raise the rails or the gantry and get a 12" Z axis from ShopBot?

When you say taller material, I hope you are reffering to foam. You will have a hard time finding bits long enough to make use of all of that extra room...plus the forces put on the tool in material other than foam will cause deflection and telegraph to the material.

-Brady

[wiese]

Brady,
Yes, we are machining foam. We hope to create a mold for a fiberglass body that fits onto a high mileage vehicle that our students will take to competition. I should check on the 12" gantry, but I suspect there is no funding for it in our school budget.

David,
I like the box idea. No moving parts!

[Brady Watson]

Jay,
Sounds to me like the path of least resistance would be to hook up with someone who has ArtCAM. From what I understand, there is a slicing feature that will let you machine slices of foam to be stacked up and glued to make the final part.

That is a heck of a lot easier than modifying the table or gantry if that is all you want to do. The other thing, like I already mentioned, is that you will probably be limited to a bit no longer than 5 or 6" long, plus the height of your foam. (maybe less) The slicing idea makes the most sense since even larger bits only have a max cutting length of 3 or 4" and overall 5-6".

-Brady

[gerald_d]

Meshcam (http://www.grzsoftware.com/) now also does slicing of tall models. Amazing power in a simple to use package at only $150. Free 60-day demo available

[wiese]

Brady,
We were planning on doing the slicing in Rhino and using Desk Proto to generate toolpaths. I was hoping to make the slices as thick as possible to minimize the number of seams. I guess it is time to bite the bullet. Thanks for suggestions. I know that whichever way we decide to do it, the students will have fun and learn some good stuff!

[bruce_clark (Unregistered Guest)]

Brady,

I read somewhere that you can use a machine reamer to cut foam. They generally have VERY long cutting faces and you just need to cut fast enough not to overload the teeth.

Again, I would use this ONLY for foam, but they should work and probably be cheaper than a 6" endmill, plus they are generally smaller in diameter than the long endmills. Just remember, I have yet to see an END CUTTING reamer, so it would probably be ruled out for cutting contours but would be great for pockets and cutting thick slices to build up a stack.

Lastly, Mr. Wiese, you might want to consider adding dowl holes in each of the slices so that you can align them a lot easier.

Hope this helps,

Bruce Clark

[gerald_d]

For soft foam, even normal drill bits do the job. A good tool re-sharpener can put a ball-nose onto a drill bit for you. Here (http://www.somta.co.za/dri1.htm) are some ridiculous examples available at the end of Africa. I could buy a 6mm drill with 140mm cutting length, but I would be plain nuts to spin it fast and load the side.

[Brady Watson]

Yeah...a reamer would work and maybe even a drill...however you'll have to ball and sharpen the end to do 3D cutting.

My local tooling purveyor told me that I could get a custom bit for $60 setup (one time fee) and whatever it cost in carbide, HSS (what I would use for foam & long length) and cutting.

If you are planning on doing this type of work, then this is a nominal charge for the right tool...you could build it into the price of the job easily.

-Brady