Sandblaster Advice

[Andrew R Stewart]

So as I enter another season of my frame tinkering I get more tired of hand sanding everything prior to brazing. Sure the big and consistent surfaces like tubes are fast enough but those convoluted things (braze ons, fork crown interiors and more) are annoying me more then they use to. I see these bench top small cabinets which don't cost too much (less then a nice paint job). So my perfect world sees one of them and a not too costly compressor (120V) would let me clean off small parts at a slow but less physical pace. My cynical world sees questions and less then hoped for results.

1- do these little cabinets require a dust collector to not pollute the room they're in? What goes in must come out. I see references to using a vacuum cleaner as a outlet device.

2- At the cost I can afford I suspect that I'm looking at siphon fed gun/nozzle. My understanding is that this is a far slower/less media delivery compared to pressure pot designs. But since I don't fully understand the "plumbing" of a PP design I don't know how a small cabinet might be set up with a PP. Any thoughts or...?

3- The only blasters I've used are on either end of the spectrum. Doug Fattic's very nice, large capacity, massively compressored, big enough cabinet for a tandem, unit. And a non cabinet, hand held, jug and gun combo done outside. Doug's unit is a dream to use. The outside/hand held one was effective enough but the neighbors complained about the sand blanketing their flower beds. Hence the thought of a small cabinet. Thoughts here?

4- I have a date with a third party blaster soon. (Sounds like a opening line to a racey novel). I have collected all the bits of two frames that I will hate to sand to prep. Drop outs, reinforcing rings, home made braze ons, crowns, seat clamp rings. The guy has an hourly rate that I don't want to incur too often so some of the bits will sit around for a number of weeks+ before their brazing. At one time years ago Fred sold PickleX and claimed it reduced formation of oxide during storage of freshly cleaned steel. Any current equivalent? Navel Jelly? Need to clean off the phosphate "coating" before brazing?

Thanks for any insight and guidance. Andy (who has NRPS "Portland Woman" playing right now)

[Mark Kelly]

Can't answer the Qs re blaster cabinets, but here's a tip to prevent anything oxidising: remove the oxygen.

Use a sealable container large enough to hold the parts, make sure the jar doesn't have a plastic lid or rubber seals (eg a jam jar is fine, a "le parfait" jar is not). Drop in a couple of oxygen absorbers and stick the lid on. Job Done.

Stick the rest of the pack of absorbers in another jar or two, making sure they fill the jar as much as possible. The packs usually come with a little indicator pill, put that in the jar with the spare packs.

[Eric Estlund]

Blast cabinets are great things, but pre-braze prep isn't were I would use one. I am not a fan of floating filler across a toothy blasted surface, either for sweat or fillet joints. It can be done, but I prefer to work over a mechanically cleaned bright surface.

[dbohemian]

Blast cabinets are great things, but pre-braze prep isn't were I would use one. I am not a fan of floating filler across a toothy blasted surface, either for sweat or fillet joints. It can be done, but I prefer to work over a mechanically cleaned bright surface.

I agree 100%. I have a couple of brazing texts that explain it the same way. A blasted surface is difficult to braze compared to a 80-120 grit sanded surface. Try it for yourself. The media blaster for me is more of a brute force, final clean, paint prep tool.

[Eric Estlund]

Oh, and since I skipped actually talking about cabinets- my advice would be to get the biggest one you have room for. Small cabinets (table top) are frustrating and ineffective for bike work. I'd rather not have one than have one that was too small (and hence have gone without while I rehab a larger one). Don't forget that big cabinets also generally need a real compressor on them. A small compressor is almost as infuriating as a small cabinet.

To address an early question of yours- there is no reason to prep parts for brazing if they are going to sit for any length of time. Prep them to a mechanically bright finish and braze same day. Even if you do the lion's share of the clean up and fitting earlier, make sure to give them a good, fresh hit before moving forward day of.

[echelon_john]

I built mine with a kit from TP Tools (Build-Your-Own Skat Blast Cabinet Kit - Foot-Pedal Operating System - TP Tools & Equipment) and the accessory vacuum (VAC-45 HEPA Vacuum - TP Tools & Equipment)

Cheaper than buying a built unit, and you can make the thing whatever size you want. Mine was 48" wide x 30" deep x 30" high from the roof to the mesh working surface. I could turn all but the very largest frames around inside.

The vacuum system worked VERY well and there was never any appreciable dust outside the cabinet, other than the tiny amount that would cling to the door and spill when it was opened, but between adding a deflector at the bottom of the door and giving a good thump before I opened it (and keeping the fan running when the door was opened) dust was never an issue.

The directions are very clear, and if you have ANY wood fabrication skills (cutting a straight line) it will be an easy Saturday project.

Biggest piece of advice is that, with any siphon system, your air can NEVER be too dry. I ran two dryers; one right at the compressor, another at the drop line to the cabinet. Keeping the air dry maximizes the effectiveness of the blasting and saves the headache of continually removing the hose from the gun and "back blasting" to clear out the siphon.

Oh, and get a bigger compressor. 80gal min. And wear ear protection if it's in the same room. ; )

[jon_norstog]

Sandblasting is an operation that maybe best left to others. Look around, like a tombstone dealer, they blast all the time and have walk-in blast cabinets. When I was building in Pokatello, Walker Monuments would do a frame for me for $12. if you can find a deal like that, take it!


The worst thing about blasting is getting a snootful of silica dust. Silicosis, anyone?

Good luck!

jn

"Thursday"

[Mark Kelly]

Can you still buy silica based blasting media? They haven't been available here for years.

[e.Gellie]

.........your air can NEVER be too dry. I ran two dryers; one right at the compressor, another at the drop line to the cabinet.

Hi John,
can you share more detail on your air dryer setup?

[echelon_john]

Sure. Just a couple similar to these:
Airline Filters:Excelon® General Purpose Air Line Filters for Partical and Water Removal in Compressed Air Systems - F72G-2AN-QE3
or these:
Husky 3/8 in. Standard Poly Bowl Filter-HDA70603AV - The Home Depot

Key, I think, is one near the compressor and one near /at the drop to the cabinet.

Hi John,
can you share more detail on your air dryer setup?

[Eric Siepmann]

You can also use baking soda for media as well. I had good results with it on Birmabright when restoring my 1966 Land Rover. I'd also look into dry ice blasting as well if there is anyone near you doing it. They use it in conservation quite a lot and they can dial the results to the material, such as canvass, wood, or steel. Might be pricey for your own cabinet though.

[Curt Goodrich]

80 grit aluminum oxide is what I use. Works great. No need to over think this.

[echelon_john]

Skat-blast is another good choice. Lasts forever, relatively inexpensive.

[DeeDub76]

Also some additional good info in this related thread.

http://www.velocipedesalon.com/forum...ets-41679.html

[Andrew R Stewart]

So here's an update. I ended up buying a SBC 420 cabinet then called Mike Tacoma at bro-Blast for some upgraded bits. I assembled and modified the cabinet WRT the Pro-Blast kit. It works great! I am running 80 grit garnet, maybe only 10 lbs worth, at 75 PSI supply.

I started a thread over at Bike Forum's Framebuilders. It's not finished as I have a couple of installments yet to write... but there is more detail and photos if that stuff turns you on. Andy

https://www.bikeforums.net/framebuil...ndblaster.html