Pressure pot vs. siphon

[Dan Hintz]

A potential upcoming job would likely require a sandblaster setup (probably a days worth of work, maybe a weekend)... I don't currently own one, but the job would more than pay for a decent setup. This will be for selectively removing thermo-hardened paint from glass.

For those that sandblast from time to time, do you find a pressure pot better due to the lower air requirements, or is a siphon perfectly workable? The cabinet is cheap (the sub-$200 HF version should be plenty), and I can get a siphon in the $100 range, but all I've seen so far for pressure pots are in the $600+ range... seems steep, especially if the siphon will be fine if I'm not using this setup daily. I'll be using a 33gal Sears compressor... 8-9 CFM at 90psi won't be a problem, though I imagine it will run more often than I would like.

Also, suggestions on a better gun than what comes with the HF cabinet are appreciated.

[Mike Null]

Dan

By all means buy a pressure pot. A siphon system which is probably included with the cabinet is sloppy and inefficient. You can buy quite good pressure pots at Harbor Freight under two hundred dollars. Further, you will be surprised at how many engraving type things you can do with it. Also important is buying the right medium for the job. I prefer silcone carbide and for glass and crystal I like 150 to 180 grit. Your other choice is aluminum oxide which I've found to have a nuisance of a static electricity problem.

Gary Hair does a substantial amount of blasting so I consider him to be an expert on the subject.

[Dan Hintz]

Mike,

I could have sworn HF sold a small pressure pot, but I couldn't find it until after posting this thread (is was listed as a " media blaster", and their search function sucks)... for around $100, it may be worth a try, even though it gets somewhat mixed reviews on their site. So for about $300, I get a cabinet and pressure pot... it looks like both come with guns (of some form or another), but are they worthwhile to use? I intend to do small items, but having never done it before I don't know if the supplied 1/8" nozzle is still too wasteful of air or if it will be acceptable (like shooting a fly with a shotgun).

I was already leaning towards the carbide, but the specific grit was up in the air.

[Gary Hair]

Mike - thanks for the compliment. Even thought I tend to be *slightly* opinionated, I'm still learning.

Dan,
I have two of the HF $199 cabinets, 199 on sale anyway, and a 6' x 8' blast room. I have three different pressure pots, two 40# to do pavers, rocks, granite, etc., and a 20# for glass. I run HF 70# AO for the rocks and I use 180# SiC for glass. You can almost always buy the 40# pots for less than $100 but it looks like right now they are not on sale. The better bargain would be the 110# pot for $129. They have their 70# AO on sale for $39.99, you can't beat that price. Search for "abrasive" and you'll find mostly everything they have.

As for nozzles, it depends on the size of the object you are blasting and, more importantly, the capacity of your compressor. 9cfm @ 90 is bare minimum and you shouldn't use anything larger than a 5/64" nozzle and even with that your compressor will be running a lot. Here is some info I posted previously:

I have a 5hp, 60gal, 15cfm @ 90psi compressor and it's barely adequate for doing anything other than glass. I have a 12.5hp, 175psi, 26.2cfm compressor that I am rebuilding and it will keep up with me for almost anything I want to do. Plus, being gas powered, it's portable so I can take it anywhere I need to go. Unless you plan on blasting with a tiny nozzle, 1/16" or less, at low pressure, 25psi or less, you just can't get away with a $300 compressor.

Here is a good budget for the most basic items:
Compressor - $2,500 (EatonPP10V120Y1)
Cabinet - $220 (HF number 93608)
Pressure pot - $150 (HF part number 93889)
Dust collector - $130 (HF 31810)
Nozzle - $40 (granitecitytool.com 3501-0002)
Nozzle holder - $40 (parts list on cuttingedgesandcarving.com)
Blast media - $40.00 (HF 99945 - on sale now for $40, otherwise $50)
Stencil - $113 (pacificcoastpaint.com Anchor #116, #117 - same price but medium tack)

There are other misc. bits and pieces you will need, but this list would get you started.

You'll notice that I put the compressor FIRST - it is the most important thing to spend money on and not go cheap. The rest of the equipment isn't that expensive and can be upgraded if you need to later, but you don't want to buy a cheap compressor, burn it out, and have to buy another one.

Gary

[Dan Hintz]

Thanks, Gary!

At the moment, I'm stuck with my Sears 33gal compressor... it's rated at a mere 5.1 CFM @ 90psi, but that should limp me through for at least this project if I keep to a small nozzle. I realize I may have to blast in short bursts to let the compressor catch up and cool. If I get another compressor, it's probably going to be a scroll type for the reduction in noise level and increased CFM. The current need is for removing a few square inches of thermoset paint from glass tiles (tough stuff, the laser won't even mar it!).

I can't find anything on the Cutting Edge Sandcarving site... most of the links just sit at the Home page.

Everything is about what I expected except the stencil material... I'm not doing granite headstones, so is a 33mil resist really necessary? That's expensive stuff. I was thinking something more like Laser Tape from Ikonics... 4mil seems a bit thin, but again, having never done this before I don't know how fast the material wears through. The Anchor material costs $113 for a 15"x30' roll, whereas the Ikonics stuff costs $149 for a 12"x100' roll (and I was thinking more like the 6"x100' roll for $75)... not a huge price difference, but it all adds up in the end. Can the Anchor stuff be laser cut? If not, it's a non-starter.

[Gary Hair]

Dan,
You can use a lot of different materials for your stencil and, no, 33 mil is not necessary for your project. The laser tape may work, it's pretty durable even at 4 mil. If you buy a 6" roll of it and it doesn't work, I'll buy it from you. The Anchor stencil is laserable, that's about the only way I cut it. I have a plotter but it seems that most of what I do has too much detail for the plotter so I laser it. The Anchor rep I talked to a while back said all of their stencil is polyester based, so it's all laserable. I think they have a 10 mil stencil that would work fine for you, just don't get high tack, it's a real pain to remove from glass.

There is a lady in your area that is on the sandcarving forum all the time, she might be able to help you out if you need some hands-on help, otherwise I'm glad to help.

I'm not sure what you meant about the CES site?

Gary

[Dan Hintz]

Any idea what the lady's name is for a quick lookup, just in case? (I assume you're talking about the CES forum). The CES site tabs up top mostly ended up doing nothing. The gallery took me somewhere, as well as the forum tab, but the home, products, etc. tabs took me to the same page... Home.

Good to know about the high-tack being a pain to remove. I was going to choose it over the medium tack thinking it would provide better security against edges lifting as I cut, but if you think the medium-tack is acceptable in that regard, I'll go that way. And 10mil sounds like a very good compromise.

[Gary Hair]

I don't know her last name, "Kiko B., Chevy Chase, MD" is what's in her profile. Click on the "Forums" tab and you'll get to the forum, the home page you went to is the home page of the person who runs the forum and they are two separate things. Sorry I neglected to mention that but I get there from a shortcut on my favorites bar and haven't been to the home page in at least 3 years...

For glass you could probably even use low tack, as smooth as it is almost anything will stick to it. As long as you keep the nozzle moving and 90 degrees to the surface, you'll have no problems with blowouts.

Gary