Joys of glass blasting

[RiskyBusiness]

I finally got my homemade bead blast cabinet up and running this weekend. I should probably write an article about my lessons learned, but in the mean time here are a couple of pics of the change of surface on my carb bowls. I am not going to do the carb bodies, just the bowls and tops. To many potential issues with the bodies.





Here's my home rolled cabinet:



The bowls had soaked for 2+ days in carb cleaner prior to blasting. You can see the difference. I figure I will blast a lot of parts before this is over.

[Artic_rider]

I know what ya mean Risky, lucky enough to have one at work, and I tell ya, it's sure a hell of a lot easier then the alternatives, and since I'm doing the ground up restoration this winter...yehaw.

[ivers]

Nice

What kind of blasting pot did you use?

By any chance did you get away with a cheap Harber Freight style pot?

[AKMac]

Impressive results! I've always wanted a setup like that at home.

BTW is that purple power I see in one picture?

[RiskyBusiness]

Ivers: I did, indeed, use a cheap Harbor Freight Pot. Here's a pic:



I think it is
this model

It is slow and takes some tinkering to keep it running, but I am really happy with it on small parts. The single largest problem with blasting is moisture. I found that using glass media makes the process much less sensative to moisture. In a perfect world I would rig up a dryer between the blaster and the compressor. The cheap little dryer you see in the picture is useless. For the volumes used in blasting I need something the size of a truck radiator.

AKMac: That is TOTALLY Purple Power. I buy that stuff by the gallon!

[Jerry]

AKMac: That is TOTALLY Purple Power. I buy that stuff by the gallon!

I buy it in the spray bottle, works well on the XJ engine, particularly if the engine is warmed up a bit. Spray it on, let soak for a few minutes, rinse off with hose. Does a nice job.

[ivers]

great! i like cheap, i think i'll set something similar up for a few winter projects of mine.

besides it might give me an excuse to buy another air compressor!

[Bud Manley]

Any chance you can get a parts list together with along with prices and instructions for box building etc...?
Include links for online sites.
Please list any problems encountered.
This report will be due two weeks before Christmas.

[RiskyBusiness]

Bud, that's a darn good point. I will put together full description prior to Christmas. I learned a few things that could be useful to someone else putting one together. In the mean time, here's a list of some of the big "ah-ha" points:

- Don't expect a shop vac to suck the sand out and recycle. A shop vac cannot handle the volume of media. It is, however, a really good idea to have a shop vac connected to the cabinet while running as it keeps the dust down.

- No need to seal off where the hose enters the cabinet. Make the hole fit snug and just slide it through. This will allow you to control how much hose is in the cabinet. I fixed a coupling between the inside hose and the outside and I regret it. I have too much hose inside my box and its like wrestling a snake.

- Put a slope in the bottom and a collection bucket below that. I am retro fitting this using a 4" dryer vent. I have made a false floor using expanded metal. This helps with collection which can be a slow process.

- Screen the media when you recycle. Failure to screen will result in wood chips and lint getting caught up system. I spent too much time cleaning my hoses of little wood chips before I bought a screen. An expandable window screen works very well.

- Be patient when doing this. Blasting takes time and patience. Getting all the angles on complex and large parts is hard. I just did the rear wheel off of my Beemer and it took waaaay longer than anticipated.

- Pay for good media. I have been using glass bead media from Northern Tool. It costs about a buck a pound but it is worth it. Sand has health issues and most media is very sensative to moisture. The glass has worked very well and I am happy that I paid $50 for two 25 pound buckets.

Here are some quick links that I can scratch up:

Here is a cabinet design to knock off.

You saw the pot in my prior post. Here are the
gloves .

Here's the media.

Here's my little red compressor that could .

In case you are wondering, I have a lot of stuff from Northern mainly because there is one near my house. I drive within a block of it every morning and afternoon. Sometimes it sucks me in.

And here are hand buckets!

The hand buckets are critical. This design provides the precise diamater to match the gloves above and also has lids to keep critters out of the gloves. Nothing worse than sticking in your hand and finding a spider or a mouse! Just drink the contents and cut the bottom out. Be sure and have chips on hand!

[RiskyBusiness]

I forgot these items:

Plexglass: bought at Home Depot for <$10.

Internal light: I used a cheap halogen shop light. I recommend a shop light on each side of the interior of the box. It is VERY hard to blast away a shadow. I tried.

[prometheus578]

Time for questions from the studio audience.

Not being a proficient sandblaster, I have a coupla questions.
From your photos.... what is the purpose of the "Pot"? From what I see.. it has an airline going to it, and by the looks of the white powder on the top, you pour the media in there. so what we have then, is a pressurized container of sand, which you then spray with. Hhmmm...
I recall blastering years ago... the cabinet had a mesh floor for holding the target objects, and underneath that was a sloping area where all the sand fell and was concentrated after doing its business. The pick-up tube for the sprayer was mounted in that area, so that it would cycle back up with out having to strain and refill anything. Would that be more convenient that filling a pot?
As I've toyed with the idea of making my own, I'm following your adventure with great interest.
As dust is a great challenge and reduces the visability in the housing, with my sand falling to the bottom, I planned to have an outlet mounted in the upper housing to attach a shopvac. Between the blast cabinet and the shopvac, along the route of the hose, was to be a cylinder holding a vacuum cleaner bag to further trap the dust and airborne particles.
A question I had was about the mounting of the gloves, but you've provided a wonderfull example of an expedient, yet tasty application.
Just reread your post.. I can only imagine that the "wood chips" you refer to are from when you accidentely blast the walls of the cabinet. I'm not rich enough, nor talented enough, to build this thing out of metal, but as I planned to build out of wood, like you did, what would be wrong with lining the box with pieces of sheet metal or aluminium(which ever is cheaper or available, and screwing them to the wood? Like from an old washer and dryer which I have around, or using the old outer skin of the hot water heater in the garage which is now pissing all over the floor and needs to be replaced?

[RiskyBusiness]

Lining the box with metal would solve a lot of the wood chip issues I have had. An easier way of solving this is to build the whole thing out of MDF. MDF is made of small enough particles that it just dusts up and does not splinter the way chip board does. Mine has both since I had a lot of chip board around.

In terms of the pot vs. the siphon approach: The pot is pressurized from the top to improve media flow. I presume that a unit with a non pressurized pot feeds the aggregate using Bernoulli's Principle... just like fuel inside carbs. A pressurized pot is more like fuel injection. With a pressure pot a small amount of pressure comes from inside the pot forcing the media into the fast moving air at the bottom. Look at the plumbing on one of these and I think it makes sense.

[2fast]

Dang it, I never thought about having my own blast cabinet till you posted this. Now I won't be able to rest until I have one. I love what it did to your carbs, and I have many similar projects that this would be really cool for. Thanks, I think.

[prometheus578]

Geez, and I thought that I was the only one that qoutes Bernoulli

"Son... see that pick-up truck carrying that mattress on top? Watch what happens when he hits 65 MPH!" Same goes for pick-ups with bedliners not bolted down. (Just trying to make my sons more observant drivers by using applied physics)
"Son.. d' you see the Mammary Glands on the Susie in the Mustang?" (If one uses medical terminology, I feel that Father/Son bonding is enhanced )
Blast pot seems ok... it's just that there was an old bead blast/ siphon gun laying around work that I'd adapt to my purpose and save bucks.

[RiskyBusiness]

When given the option between a pressure pot and free... always go with free. It's like my favorite type of beer... FREE!