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View Full Version : Help needed - lasering-sandblasting



Fred Ball
03-07-2005, 8:52 PM
Hi folks,

I am a first time member and enjoy reading the forums very much. There are obviously many knowledgeable and experienced laser users here and the information presented is excellent.

I am presently lasering wood, glassware and painted aluminum and I am contemplating purchasing a sand blaster to enhance my glassware. It seems that for a small investment it may help me create better looking glassware.

Any comments would be appreciated.

Thanks

Keith Outten
03-07-2005, 9:49 PM
Fred,

I purchased a blasting cabinet awhile back so that I could offer larger glass engraving projects to my customers. Other than establishing a few techniques with various blasting materials I haven't had time to work with glass much other than to prove to myself that I could do a complex job when the opportunity presented itself. Using a laser engraver to produce a sandblasting mask is the ticket, it allows you to do some very detailed blasting work without having to hand cut custom masks the old fashioned way.

My favorite medium is glass beads, although I have used several types of silica, glass beads provide the best quality in my opinion. I'm sure that there are SMC members who have logged lots of hours sandblasting, possibly they will jump in and share their experience.

Rodne Gold
03-07-2005, 11:28 PM
A blaster is a very hand addition if you have a laser for various reasons. As keith says , you can make masks on the laser for blasting just about anything. For light blasting we use a paper based vinyl transfer tape (the stuff they stick over vinyl graphics to put them in place) and for heavier we use a polyester based sign vinyl (the shiny mirror vinyl)

The principle is to apply the resist to the item to be blasted and then use the laser to vaporise the mask and then blast the item. This way you can get the exceptional detail of the laser and the great effect of blasting.
Using the paper based tape is a little touch and go as too much blasting can wear thru it , but there is a trick.. When the laser engraves the paper away (you can do it real fast) it leaves a glue residue , when blasting you can clearly see the residue "clearing" and as soon as it clears it means you have got a decent blast depth and any much more blasting is gonna wear thru. The nice thing about the paper is that its very cheap and comes off very quickly. The polyester based masks are tacky and the blast pressure actually makes them stick even better so they are difficult to remove after but they can withstand serious blasting.
For carving , the rubber masks used for gravesstones works well.
One can also use cheap sign vinyl as resists , but pvc is not good in a laser (releases chlorine which combines with moisture to form hydrochloric acid) but if there is no fine detail , just use the laser to kiss cut the vinyl and weed and apply it to the substrate - good for stuff like blasting into granite foundation plaques etc , stuff with big lettering)

You can blast many substrates , like wood (when you blast wood you get a wonderful grain structure revealing itself and no burn etc - very much a weathered effect) , glass , metals (stainless gives a lovely matt effect) , perspex (the laser stresses pex pretty seriously when it laser engraves it , blasting doesnt) Marble and granite for much deeper engraving than a laser can do.
In term of sand carving , just apply the rubber or the polyester vinyl and kiss cut it. Lets say you want to do a leaf with veins , kiss cut the outline of the leaf and then the veins , remove only the veins and blast , then remove the leaf and blast. The veins will be deeper than the leaf and the transition between them will be smooth thus you get a carved leaf. You can do as many layers as you want , not just 2.
Blasting will also allow you to frost substrates quickly like glass or acrylic that can be used decoratively or can be painted (frosted acrylic , painted and reverse or front engraved looks stunning) you can also blast and then spray paint the blasted areas before you remove the mask with minimal clean up.

A blaster will make life easier for metal etching. Same principle as sand blasting but what erodes the metal in the clear areas is ferric chloride , the mask acts as a resist. Problem is lasering a self adhesive mask on a sheet of metal leaves a residue on the cleared areas and this acts as a resist to the etchant , a quick blast removes all this and exposes clean bare metal which etches evenly (you can etch metal with a pyrex dish at home - if anyone is interested in the nitty gritty - I will post exact instructions)
Of course there are the usual ordinary applications for a sandblaster in addition to all the above.
We use very fine aluminium oxide grit in our blaster - it allows very fine detail but takes longer to get deeper than other grits
You are going to need a serious compressor for blasting + a dust collection unit and you must put the blaster in an isolated area , it can get messy.
In terms of a compressor , you might need something that is 5+ hp and has a large tank etc - Ie a pretty serious unit if you are going to blast for any length of time or are doing larger surfaces.

Joe Hayes
03-08-2005, 9:05 AM
Currently we are considering adding sandblasting to our line as well. I would love to
hear what brands of equipment the forum users have and why they selected those
over other brands. I keep gaithering info from the companies but it sure helps to hear
from the end users.

Thank you
Joe

Mark Dickens
03-08-2005, 10:11 PM
Hi, Joe!

As I mentioned to you the other night, we bought a PhotoBrasive (made by MediaBlast) CrystalBlast cabinet. We also looked at the Rayzist 2034 automatic recycling cabinet. The main reason we went with the PhotoBrasive set up is that it is a closed system and doesn't exhaust outside the cabinet while you're using it. It also provides one cabinet change of air per second. Since we will have it relatively close (10 feet) to our lasers, I didn't want silicon carbide drifting into the machinery. I know you can vent the Rayzist machine, but I liked the near-HEPA filter provided in the PhotoBrasive machine as well as the reverse-pulse feature which allows you to clean the filters before beginning a project. All in all, I felt that it was the superior machine, but I also know that you don't have to have one to do a superior job....it's all in the operator's hands. Cleanliness was a prime driver for us.

Mark

Rodne Gold
03-09-2005, 6:22 AM
No matter what the filtering system , do NOT site the blaster near the laser or any precision machinery. Grit getting into bearings etc is a major problem. The system is never truly closed , no matter what you do , you will have grit dust etc floating around - even just opening the cabinet or taking the item out will allow highly abraisive particles into the air etc.

Mark Dickens
03-09-2005, 7:14 AM
Appreciate the comment. I will look for another place for it today. Better safe than sorry, especially when you consider that two of our lasers are YAG sub-surface lasers and cost us beaucoup dollars.

Mark

Fred Ball
03-09-2005, 5:30 PM
Thanks everyone!

Great information and it sure helped.

Glenn Palhof
03-12-2005, 11:40 PM
e have a photoabrasive closed sustem,a blast vacume ,gravity tank systems. they all have escaping dust .we have a 4x8 laser, plotter cutter which all require computers to function. keep them as far away as possible.we keep them in a seperate bldg.we have been blasting for over 20 years. buy the best air filter you can wear to protect your lungs.
hope this is of some help
sincerely
glenn palhof