PDA

View Full Version : Laser Cutting Table



Jim Priest
11-05-2015, 9:30 AM
OEM cutting tables are quite expensive for what they are but I have seen photos of setups that appear to be using fluorescent light fixture diffuser material, the "egg crate grid" type commonly available. Is this a suitable product for use in laser cutting acrylic, wood, etc?

Bert Kemp
11-05-2015, 9:33 AM
Sure they work fine, buy the alum ones at your local borg cut to size and your good.


OEM cutting tables are quite expensive for what they are but I have seen photos of setups that appear to be using fluorescent light fixture diffuser material, the "egg crate grid" type commonly available. Is this a suitable product for use in laser cutting acrylic, wood, etc?

Julian Ashcroft
11-05-2015, 10:46 AM
I use a vent grill as a cutting table, aluminium egg crate in a frame, works fine.

Keith Outten
11-05-2015, 12:24 PM
Another option, this one was machined on a CNC Router from Dupont Corian. Its perfectly flat which is the number one requirement for a cutting/engraving table IMO.

Matt McCoy
11-05-2015, 1:31 PM
Keith, those are really nice.

How heavy are they?

Bert Kemp
11-05-2015, 2:15 PM
Keith do you cut on that corian , does the table get cut down after a while?

Keith Winter
11-05-2015, 11:15 PM
Really interesting table Keith! Does the laser cut into the Corian as you cut, and does it increase fire hazard being made of Corian or the same as steel?

Mike Null
11-06-2015, 6:55 AM
I use the light grids in both powder coated aluminum and in acrylic. Most of my work is in plastic so I prefer the acrylic since there is no bounce back. I use grids with 1/2" square openings and elevate it off the bed by at lest 3/4" preferably more.

In my view both of these are superior to honeycomb grids.

Keith Outten
11-06-2015, 7:49 AM
The 12 by 24 Corian prism table has almost 5000 points. Corian absorbs the laser energy so there isn't any bounce back.
The table is heavy but I have reduced the weight by modifying the supports under the table which also keeps the table perfectly flat.
This design is considered a sacrificial table but I expect it would last for more than ten years if used daily.
Pressure washing is fine and just about any kind of cleaner will work as well.
Corian doesn't catch on fire to the best of my knowledge and I have cut 1/2" thick Corian using multiple passes but the cut is not pretty. Even so there was no flame and I have been laser engraving Corian for almost ten years.

This design excels when cutting very small parts, I made mine to cut letters that I use for ADA signs. You can design your own table in Corel Draw and have anyone who owns a CNC Router machine it for you.

Keith Winter
11-06-2015, 7:56 AM
That's pretty cool Keith! What did it end up costing you?

Keith Outten
11-06-2015, 2:20 PM
My Corian vector table cost me just the labor to build it, the materials were left over from sign projects. Since I own my own CNC Router which is the only machine required to build these I had no financial investment.

Kel Kodama
11-07-2015, 7:38 AM
I have been using a cheap DIY pin table and it works great. Buy a perforated metal sheet (e.g. on McMaster-Carr or Amazon) and slotted spring pins:

$25 http://www.amazon.com/gp/product/B000H9QGDY?psc=1&redirect=true&ref_=oh_aui_search_detailpage
$9/250 http://www.mcmaster.com/#98296a883/=zpes9o

Gently hammer in the slot spring pins, preferably on top of a flat piece of metal, to get it to bottom out accurately.

Mayo Pardo
11-09-2015, 1:38 AM
Keith that corian table looks great!
I think your count is a little off though on the number of points?
If the short side is 12 inches, and there are 48 points, the long side being 24 inches with the same spacing would have 96 points, so 48x96 = 4608.

Did you use a 1.5 inch 90 degree V-bit?
I've made similar patterns in HDPE cutting board material and never thought of doing the same in corian -
I have scraps big enough to experiment on so I think I'll make one this week!
Are the supports underneath necessary - the 1/2 inch seems really rigid but maybe once all those grooves get cut in there's the risk of it snapping off?

Keith Outten
11-09-2015, 5:17 AM
Mayo,

I believe your right, I'll have to go back and look at the drawing to verify the number of prisms. I believe I used a 60 degree router bit.

The sports are necessary because you remove a considerable amount of material. Although Corian is a very hard material the supports will make sure that the table remains perfectly flat. Corian has a tendency to curve if too much of the thickness is removed.

Once the table is machined I then glue the supports on the bottom. The last step is to put the vector table back on the CNC Router face down and machine the bottom of the supports then verify that the table is flat within a couple thousandths or less.

Darren Wilson
11-10-2015, 4:09 AM
Wow, Awesome table Keith.

Daz

Keith Outten
11-10-2015, 12:41 PM
Thanks Darren.

The pictures above are of my third vector table or version 3. The first version was two pieces of Corian glued together which made the table one inch thick without any supports. I added supports under the second table which was one half inch thick which was much better for several reasons not to mention that the surface of the vector table was above the laser table so I could use tape or clamps to hold material down. In version three I moved the supports at the ends which made it much easier to lift and install on the laser table.

I tried selling the vector tables, the first one was destroyed by UPS even though I shipped it in a custom plywood box with plenty of interior support and padding. Apparently a UPS fork lift drove over the box and busted the box and the vector table into several pieces so I gave up, there isn't any way to protect a precision table from being damaged if the shipper is going to be so irresponsible. What makes this design especially nice is that they are flat and they will stay flat throughout their service life time.

I have parts cut for two more tables, one I have promised to Mike Null and one for my laser engraver.

Darren Wilson
11-11-2015, 1:45 AM
Hi Keith,
Sorry to hear UPS destroyed your hard work, hope they paid for it.

I have a good size slab of .5" Corian, I just might throw it under the Gerber and try my luck. I don't think I have enough to make the supports, do you think I could get by with some Aluminium Box? Would you go any closer on the peaks, maybe .125 or are you happy with .25"?

Thanks,

Keith Outten
11-12-2015, 3:13 PM
Darren,

Using a 60 degree router bit at the depth necessary to get the maximum number of prisms and keep the depth of the prisms as deep as possible the spacing is based on the geometry. If you try to get a closer pattern you will have to change the depth. I tried to get as much depth as possible to allow some air movement under the material to carry away the smoke and prevent flaming.

I expect you can use an aluminum box for a frame but it would have to be pretty heavy material to keep the Corian flat. I don't know what the difference in thermal expansion is between Corian and aluminum, it may be insignificant. For my money using Corian for the frame structure was pretty easy, you can use epoxy to adhere the table to the frame, no fasteners are required.
.

Dave Sheldrake
11-12-2015, 5:55 PM
difference in thermal expansion is between Corian and aluminum

not enough to worry about Keith :)

I love the look of those tables...the number of problems they would solve beggars belief.

Henri Sallinen
11-13-2015, 5:09 AM
Since no-one has asked this yet: Isn't it a problem that the bed isn't hole based? I'm thinking about the vacuum/exhaust. What problems might you encounter if the suction isn't based partly on the idea, that the air flows through the table from top to bottom?

Keith Outten
11-13-2015, 7:52 AM
Henri,

I haven't experienced any problems with this design. I created this table specifically to cut letters and icons for ADA signs because the text is so small there is a problem using the more traditional tables when the letters fall down though the grid. The ADA plastic is 1/16" thick.

I have cut hundreds of thousands of small letters and numbers using the first and second versions of this table over the last five years so the concept is proven to be a good option for this task. I won't say that this design is the best for every job but for very small items it works extremely well. I should note that my laser doesn't have a vacuum system so a downdraft isn't relevant. It is possible to adjust this design by drilling holes between the prisms, the supports under the table would be able to maintain a vacuum from the bottom.

The edges of the table are perfectly square with the rulers/guides on the laser table to maintain alignment.

Henri Sallinen
11-13-2015, 7:59 AM
Keith:

Nice to hear! This really is a new kind of approach to the laser cutting tables. I'm currently in search of aluminium egg crate core from the UK for our replacement bed.

Graham Taylor
11-17-2015, 5:01 AM
I have been quoted 420 for a new honeycomb table for my Speedy 300 which seems rather steep. I will be using this one just for cutting Mylar and my existing one for wood, acrylic and all the other dirty materials.

Are there any cheeper options out there or does that price sound about right?

Henri Sallinen
11-20-2015, 3:43 AM
Graham: You can order they honeycomb separately, if you're a DIY kind of guy. The search term is "aluminium honeycomb core" for honeycomb or "aluminium egg crate core" if you're looking for a square type of cutting table used for instance in the new Epilog Fusion machines.

Keith Outten
11-20-2015, 7:16 AM
Vector Tables are generally very expensive. The first one that I purchased from Epilog many years ago was $600.00 US for a 12" by 24" table that was actually 11.5" by 24" so a quarter sheet of plastic didn't fit the table as it should have.
The replacement table that Epilog sent me wasn't flat, it was an 1/8" out of tolerance so I had to dismantle it and correct the problem.

IMO a vector table has to be perfectly flat or its useless.
.

Graham Taylor
11-20-2015, 11:40 AM
Graham: You can order they honeycomb separately, if you're a DIY kind of guy. The search term is "aluminium honeycomb core" for honeycomb or "aluminium egg crate core" if you're looking for a square type of cutting table used for instance in the new Epilog Fusion machines.

Henri,

I had seen the honeycomb core previously in this thread (I think) but didn't know about the egg crate core.

The thing putting me off, as Keith has pointed out, is the fact that it has to be perfectly flat and I don't think I would be able to achieve this. I may have a look at my existing table and see if it is possible to just replace the honeycomb.

My reason for wanting another is so I can keep it just for Mylar and I don't have any down time cleaning the one I have if I need to cut some mdf and/or acrylic which we seem to be doing more and more lately as we have developed our own range of products.

I think I will do a google search to see if there are any precision metal working businesses near me so I can take the table to them and see if they could make something similar.

Thanks for the help, it really is much appreciated.

Graham

Henri Sallinen
11-21-2015, 4:36 AM
Graham:

You're welcome! The honeycomb might be a bit problematic to get shipped dead on flat, but I think the egg crate core might be something that could be shipped/handled/inserted perfectly flat because of its more rigid structure. See what the local metalworkers have to say. They might have a completely different viewpoint on this problem!