Honeycomb table

[pete hagan]

I'm ready to replace my laser cutting table with a honeycomb grid but need some advice. The table I currently have is about 1" in thickness aluminum and two different styles of table surface, flat 1" wide strips and thin rails on the opposite side of table with a triangulated webbing (see picture below). When I'm cutting sheet acrylic I found that I really could do better with a honeycomb table because my table creates to much flash back causing small points of stress and dots of super heated resin along the edges creating a cleanup issue.

My table size is 600mm X 900mm or slightly smaller than 24" X 36". The support structure is made from angle iron like a bed frame with about 1" lip all around for placing the table on. There are no supports within the field, ie no cross members in this table frame. I am concerned with the sag from this large of honeycomb panel.

Those with a honeycomb table can you tell me what thickness it is and if you have any supporting cross members on your table frame?

Thanks

Pete

[Joe Pelonio]

Mine's a metal frame with support around all edges and up the center. The honeycomb is about 1/2" thick. There is droop (or wear) over time that leaves a low spot on the left half. What I do is rotate once, then when both sides have the depression I turn it over to the other side. Seems to last me about 2 years and the replacement was $40 last time.

[Keith Outten]

I made my own vector table recently. I machined a piece of Corian with my CNC router using a 1/4" square grid pattern that left me with a flat, very dense prism surface. The material rests on top of each prism which are sharp and I have not seen any flash back as yet. I actually have better support than my old 1/2" aluminum grid.

I still have a couple of things to do to improve my Corian vector table and a bit more testing but so far it is the cats meow :)

.

[Michael Kowalczyk]

Hey Keith,
Did you use a V bit? Any Pics?
Thanks,

[Keith Outten]

Michael,

Yes, I used a 90 degree V-bit. The resulting prism rows both in the X and Y directions allow maximum air flow under the material, just about unrestricted. What I found is that too much of the material is machined away so I had to glue two pieces together to keep it flat. I think ordering 3/4" thick Corian will solve the problem and allow me to machine a little deeper as well. I have a idea that the horizontal rows (X direction) don't need to be machined at all just the Y rows for air movement. I will machine another table as soon as I can as another test table. I have also had some friendly advice from Mike concerning a very easy way to add material stops that can be rotated out of the way when they aren't needed. When I have tested very thin stuff like laser lights I found that using the new table flat allows me to run tape from the top surface over the edge of the table and it holds the material flat for engraving. Having an adjustable stop will allow me to keep this new ability and be able to have the stop fence when its needed.

Corian eliminates the flash back problem because it cuts rather than reflect the energy. The damage is minimal so the table should last for many years and it cleans up real quick...much easier than aluminum.

I'll keep you posted.

.

[Michael Kowalczyk]

Hey Keith,
Thanks for the reply. great idea about only V cutting 1 axis. Less turbulence and quicker evacuation. How far are you peaks apart?
I understand your need for thicker material. I use 1/2" HDPE for some grids and I cut them 3/8" deep by 1/2" wide and wondered why they were curling in on me. Here's a thought on the materials stops. A few 5mm stud offset shelf brackets.

Thanks,

[Bob Cole]

The Corian idea sounds intriguing. The ULS manual states to raise acrylic at least .5" off the honeycomb grid to eliminate the flashback. This definitely works, but much harder to line up the piece since the grid stops are only 1/16" thick. I've been eyballing it, but I might need some glasses since not always lined up correctly.

I was wondering if there was a good material that wouldn't flashback and would allow the airflow for vectoring.

[Bill Stein]

I have also had some friendly advice from Mike concerning a very easy way to add material stops that can be rotated out of the way when they aren't needed.

Mike,

Would you be willing to share this information with the rest of us? I need to add stops to my homemade table but I have never been able to come up with an effective method. It sounds like you have.

Bill

[Keith Outten]

My Corian grid is based on 1/4" spacing so the prism points are very close together. This provides excellent support and keeps very small parts from falling through when they are cut in most cases.

For material stops a simple tab screwed to the back and left side of the table will do the trick and still leave most of the material edge open for tape when its needed. The small tabs can be losened and rotated upward to use as a fence or downward to keep them out of the way. This was Mike's suggestion, I don't think he would mind me sharing the idea.

I'm already upset that I paid $600.00 for a table that isn't near as good as the one I built :(

.

[Bill Stein]

DOH!

That's too easy . My problem is that I'm always looking for the hardest way to accomplish something:) . Thanks for the information.

Bill

[Ed Newbold]

I made my own vector table recently. I machined a piece of Corian with my CNC router using a 1/4" square grid pattern that left me with a flat, very dense prism surface. The material rests on top of each prism which are sharp and I have not seen any flash back as yet. I actually have better support than my old 1/2" aluminum grid.We would LOVE to see a photo of it, Keith. I need to make a new table too. Thanks,

[Bill Cunningham]

A quick effective cutting table is simply 1/2" x 1/2" aluminum vent fire grid .. I have been using one piece 12 x 24 for 3 years now. It's a little brown in places, but the laser won't affect the aluminum, it just burns off the paint. It's stiff enough to support a good weight, with only a small block under each corner, and sometimes one in the middle, keeping it off the table.. It comes in pieces 2' x 4' so I have enough left for 3 more pieces should the current one ever fall apart on me..

[Stanley Waldrup]

Do you have a source for the grid?
Stanley

[Bill Cunningham]

Just about any heating contractor or sheet metal shop will have it, or at least can get it.. They can even cut it to size for you.. I got mine from a local sheet metal shop. It's a 1/2 x 1/2 grid 1/2" high, and the metal is about 1/32" thick.. I can't remember what I paid for it, but I do remember thinking wow, thats cheap!

[AL Ursich]

WOW.... Great tips... I might be able to cut the table on my Sears CompuCarve.... Wow.... I don't have a table yet.

Thanks Guys.... The stops are just pieces turned up side down?

AL

[Keith Outten]

We would LOVE to see a photo of it, Keith. I need to make a new table too. Thanks,

Ed,

As soon as I get the new improved vector table machined I will post some pictures. I hope later this week.

.

[Tod Landis]

A quick effective cutting table is simply 1/2" x 1/2" aluminum vent fire grid .. I have been using one piece 12 x 24 for 3 years now. It's a little brown in places, but the laser won't affect the aluminum, it just burns off the paint. It's stiff enough to support a good weight, with only a small block under each corner, and sometimes one in the middle, keeping it off the table.. It comes in pieces 2' x 4' so I have enough left for 3 more pieces should the current one ever fall apart on me..

I want to use your recommendation, but I am having difficulty pinning down where to purchase... and you clue me in?


Tod

[Bill Cunningham]

I got mine from a sheet metal shop that does industrial ductwork

[Henri Sallinen]

Bill: Might the material be called "aluminium egg crate core"?

[Craig Matheny]

Aluminium egg crate core is just that it is used primarily to make a structural panel of high strength with very low weight used a lot on planes.
Bill: Might the material be called "aluminium egg crate core"?