Air assist/cutting table?

[Deane Shepard]

I am about to purchase a laser for use in manufacturing an electronics product. Fundamentally, I will cut openings in an ABS plastic box to form the case of the unit. I will cut a clear acrylic face to be adhered to the front of the box and then engrave a plastic face plate (probably Rowmark LaserLight).

While the above is the justification for purchase, I imagine that once I have the machine, I will indulge some of my hobbies, like model railroading, pen turning and wood working by using it to cut small wooden parts or do engraving on acrylics and wood for gifts and pens. I am not looking to get into laser services as a business or any form of the trophy/awards type of activity.

I have seen demonstrations, running my jobs, of the Universal M-360 (50 watt) and the Epilog Mini 24 (45 watt). Smaller machines are not an option because of the vertical height needed. When I cut openings in the end of my electronics box, it is over 5" long and must stand on end.

One of the basic differences in the machines is that the Epilog includes the honeycomb cutting table and air assist while the Universal does not. The Universal salesman indicates that they are not required for my job and I believe this to be a true statement, given that we have run my jobs on the M-360 without those features and they did fine.

From everything I have read, I think either machine will do my basic job nicely and asking for opinions on which one to buy is something like asking for religious or political advice but I would appreciate any comments on the truly practical need for the air assist and cutting table features given the planned usage I have described as well as any other advice or comments any of you experienced users might offer. Also, if you think the air assist is truly beneficial, on the M-360, would you choose the computer controlled version or the simple version?

Thanks.

Deane

[Joe Pelonio]

I would never try to cut ABS without air assist, whether computer controlled is just a matter of convenience.

You can get by without a vector grid if you make your own platform to raise the material, but you will not want to cut ABS or anything else on a solid flat metal surface.

[Nancy Laird]

What Joe said!!!

Nancy

[Mike Null]

I agree with the previous statements to an extent. For several years I worked without air assist but I could never do a decent job of cutting without a grid to elevate the material above the table and to reduce the bounceback.

For what it's worth, I do market grids just so you know my bias.

[Rodne Gold]

Why do the face as a 2 part job? You can engrave on solid coloured pex and fill with paint or metallic gilders paste for a stunning one piece fascia.
3 or 5mm or if you really want stiffness , 6mm will be ideal. Rowmark laser engraveables go off with time and deteriorate quick , unless you use stuff with a very thick cap.

[Mike Null]

Good idea, or even try the reverse engravable color filled material.

[Deane Shepard]

I appreciate the feedback and comments.

For my primary job, I am making cuts through four of the six sides of the box and the box is intact as we cut it, so the laser never reaches the table, there is always the other side of the box to block the beam. We dropped a small piece of aluminum inside the box to protect the far side. Based on that, the cutting table is really moot for the main use, but it sounds like it would be a good idea for some of my other prospective uses.

Deane

[Todd Schwartz]

Deane,

My two cents.

Air assist, absolutely. Could not image cutting acrylic without it and it will come in handy down the road as you expand what you are cutting. Would be nice to have the computer controlled version, but that is more of a convenience than a requirement.

Grid table. You will need it eventually. But you have a lot of options when you are ready. You can buy the company version, make your own or get one from Mike.

Todd

[Richard Rumancik]

While the above is the justification for purchase, I imagine that once I have the machine, I will indulge some of my hobbies, like model railroading, pen turning and wood working by using it to cut small wooden parts or do engraving on acrylics and wood for gifts and pens. I am not looking to get into laser services as a business or any form of the trophy/awards type of activity.

. . . .Smaller machines are not an option because of the vertical height needed. When I cut openings in the end of my electronics box, it is over 5" long and must stand on end.

I am assuming that you are satisfied that the electronics business can justify the expense of buying one of these lasers, but if z-clearance is an issue then there is something else you could consider.

You have ruled out smaller machines but sometimes there is a solution to the z-clearance problem. My laser manufacturer specs only a 6.5" thick workpiece but I can mark on a workpiece that is 10.3" high. To do this, I have a special table with a cutout in it that allows the workpiece to drop below the normal table surface. The workpiece can have a footprint of about 24" x 5.5". If I only want to mark an 8" thick workpiece, the footprint can be larger. (There is an z-axis elevator belt under the table that I need to clear.)

If you look at a smaller laser, you will be able to visualize if there is any opportunity to make a custom table to give you more z-clearance to fit your boxes. Some might not allow for much improvement. You might be able to make one yourself or get someone to build one. I built mine of wood; I don't use it that much but if I did I might consider building from aluminum. I would have made a wooden protoype anyway. In your case you might just want to replace the table on a permanent basis. You can build various inserts like solid surface top (to cover the recess when not needed), vector grid, special fixtures, etc.

If you are satisfied with cutting one box at a time even one "pocket" in the table could do what you need. But you might want to make a group fixture.

When calculating maximum workpiece height, make sure you include the focus distance. The maximum workpiece possible is the distance from the lowest table surface to the focus point (not to the carriage assembly.)

Since all your planned uses seem to be smaller stuff and you don't plan to go into the general awards and engraving business it is something to consider if a smaller machine would otherwise work. However if you really need 45-50 watts then you probably need to go to the larger lasers. I would have thought a 30 watt would be adequate for most electronics boxes.

(If anyone is interested I can take a picture of my modified table. It is designed for the Mercury.)

[James Jaragosky]

Deane,

My two cents.

Air assist, absolutely. Could not image cutting acrylic without it and it will come in handy down the road as you expand what you are cutting. Would be nice to have the computer controlled version, but that is more of a convenience than a requirement.

Grid table. You will need it eventually. But you have a lot of options when you are ready. You can buy the company version, make your own or get one from Mike.

Todd
I have a machine without air assist. it is the single biggest regret I have about my purchase, there are so many materials that need air assist to cut properly that I would consider it a must have on any future equipment purchase.
As far as a table choice, I agree with the opinions above.

[Robert Ray]

Hi Deane, If the simple version of air assist is the always on version, that would be my choice because of the pressure burst and possible condensation from compressing and releasing, provided you are using a continous duty compressor pump like a Gast or Thomas.

If you don't want to spend a lot of money on a honeycomb vector cutting table you can use aluminum eggcrate core. Example:
http://www.grandaire-ac.com/product/Eggcrate_Core.asp

I use the eggcrage core with my Venus because there is no honeycomb vector table availavle in that size, and I get really great cutting results with it. Just leaving a small attachment point to your parts prevents them from falling through. I use the 1/2" cell grid, and it works great for Z Scale size materials. I am using the 1.5" lens, and it is flat enough for me to cut with that lens with clean results.

-Robert

[Sandra Force]

I would always get air assist. It will improvve the cuts and make ABS much less of a problem to run. I use the aa on 99% of my projects, with a gauge and valve to increase or decrease the amount of air that I am sending. I have never used a flast metal table due to the amount of cutting that I do. I have both paper honeycomb and Mike Null's lazegrid and love both. If I were doing just engraving I might consider not using a cutting table but they are just too handy and keep the backflash down so well.