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Thread Like Summary
BSA_WM20, Chip H, George Kaplan, Magnetoman, NYBSAGUY
Total Likes: 17
Original Post (Thread Starter)
by Magnetoman
Until three years ago I had easy access to a media blasting cabinet, and it was quite useful at times for my motorcycle work. Although I managed to do without a cabinet since then, a new restoration changed that. This thread will describe the modifications and measurements I made to upgrade and optimize a blasting cabinet for motorcycle restorations, resulting in significantly improved performance over that possible with a "stock" cabinet. Although there are youtube videos and written descriptions of blasting cabinet modifications, this thread will contain relevant information I haven't seen anywhere else. As always, corrections, additions, and helpful comments are appreciated.

As for media to use in the upgraded cabinet, there are at least a half-dozen types that are appropriate for various motorcycle-related purposes, each available in a range of grits, and each optimally used at different pressures. So, a discussion of topics related to media will follow later in this thread.

The cabinet

The first photograph shows the contents of the 80-lb. box containing the top-loading media blasting cabinet I bought on Amazon.

[Linked Image]

It took approximately 8 hours to assemble it to the point shown in the next photograph, where it is sitting on a plywood base with four wheels that I added to make it mobile.

[Linked Image]

It didn't take eight hours to assemble because I was particularly slow or ran into any problems; there are just a lot of pieces to bolt together.

After assembly I caulked all the seams with RTV to keep media from escaping onto the floor via small gaps between the pieces of sheet metal. Also, since I didn't want the cabinet to move when I was using it, I used four locking-type wheels that I bought at Harbor Freight. It's possible that it would be fine if just the two front wheels were lockable, but the difference in price between locking and not-locking is small.

The blasting cabinet I had used for a number of years was side-loading and it always dumped some media on the floor whenever the door was opened, which is why I bought a top-loading cabinet for my garage. The lid has an opening that's 32½"w×~17"d, and the inside is 34"w×22"d×14–21"h. For scale, the next photograph shows a BSA plunger rear frame in the cabinet.

[Linked Image]

As this shows, there shouldn't be too many items on a motorcycle that a cabinet of this size wouldn't be able to handle. Although a smaller cabinet would take up less room in the garage, anything much smaller than the one I bought would be limited in what it could be used on.

The cabinet came with an LED light that thus far has been sufficient. However, eventually I might add additional lights.

The next photograph shows that the screened "floor" of the cabinet has a wide ledge around the edges, as well as wide supports for the screen.

[Linked Image]

It turns out that the total area of the ledge and supports is sufficient to accumulate the equivalent volume of approximately 8 lbs. of aluminum oxide during operation. If only 8 lbs. were in the cabinet, which is a common size this media is sold in, this means having to stop periodically to wipe it into the hopper. After having discovered this, I added another 8 lbs. of Al oxide. A different medium with lower density (e.g. walnut shells) also would accumulate on the surfaces, but its greater volume means it would reach a thick-enough layer to slough off into the hopper by itself and keep the media feed mechanism at the bottom from becoming starved.

[to be continued]
Attached Images
Liked Replies
by quinten
add a street 90° at the bottom and a few inches of pipe
and move the valve out from under the tank , to the front edge of the tank near the door .
still have to bend over to open the valve ... unless you add a 2 ft extension as a vertical handle

I think most people are guilty of not draining compressor tanks often enough .

( ... that compressor closet looks like a good place for snakes )
2 members like this
by chaterlea25
Hi MM and All,
Having in a past working life opened literally hundreds of air receivers for annual insurance inspection I feel safe to say that the plug on MM's
compressor tank's large plug has been sealed with anaerobic "goo"
Applying the oxy torch was the only way to open those plugs along with the 6 foot helper LOL

An automatic condensate drain as below saves bending down or remembering to drain the tank
"Harbor Freight Automatic Compressor Drain Kit Item 68244"
At $10 I could do with one myself !!

2 members like this
by Tridentman
Have to disagree ref brush painting.
After soda blasting I immediately hose down the parts vigorously.
I have had no problems with brush painting afterwards using the normal process of passivation (which I guess does include an acid) then POR-15 coats and then top coats---all by brush.
As to killing vegetation--dont know.
I do my blasting in the road outside my house and the hosed water goes straight into the municipal drains.
The last time a cop stopped and asked what I was doing I told him that I was cleaning the road as it looked rather dirty.
He drove off no doubt convinced that all Englishmen are mad.
Which of course to an Englishman is the ultimate compliment!
2 members like this
by Magnetoman
Originally Posted by Chip H
Quite a plummer's night mare you've got there MM.
Really? It could be a few inches shorter if I had shorter pipe nipples on hand but, other than that, it's hard to see how it could be any less of a nightmare given the need for the components that it incorporates.
1 member likes this
by Stuart Kirk
Stuart Kirk
Aircraft Tool Supply sells a very compact right angle air drill. It uses thread in bits which are available in different lengths. I have some that are only 1/2" long.
1 member likes this
by George Kaplan
George Kaplan
Originally Posted by Magnetoman
So, I'm open to suggestions... no, I mean, I strongly encourage suggestions. Please.
Having faced some similar problems recently (large immovable nuts) here is my two cents worth.

A long lever is essential (or a big impact gun but there is no clearance for one of those here). I would argue that 3 feet long lever isn't long enough, do you have anything to make it 6 feet? I have a piece of scaffolding tube for such situations.

A shock would help get it moving. Would it be possible to rig something up so you could hit the end of the lever with a 14 pound hammer?

Is it fixed with high strength Loctite? I would hope it hasn't given that it needs 500 American degrees of temperature to release it so lets rule that out given that its a pressure vessel.

I also assume that its not a left hand thread, there is no reason for it to be one.

I know that the above is stating the obvious but sometimes its worth stating anyway.


P.S. I just remembered that when I have used pipe sealant in the past (I use Delta 888) that also makes fittings very hard to remove if left for a few years. Maybe that is what was used? It would make sense given the application.
1 member likes this
by quinten
use a coupling nut welded to a base
and some all thread ...
to make a small , short screw-jack , with a pointy poker tip .

screw-jack the pointy tip... right up into the rusty hole

[Linked Image from]

[Linked Image from]

or 3 mini jack scews could lift the whole compressor tank higher off the ground
1 member likes this
by Deadstiffcatt
A large Allen head wrench (key) with the head sharpened?

Place wrench at slight angle at bend point on wrench, with shorter pointed end wedged into center of opening.A large enough wrench could be placed on the ground, a shorter or smaller one could be placed on a few hunks of metal to elevate it to wedged position. Using a cheater bar, apply downward pressure on longer arm of wrench to use bend point as a pivot. Can tap cheater with a hammer. This might work to break obstruction free......once nut is removed.
1 member likes this
by Magnetoman
I machined a point in a piece of ⅜" stainless rod long enough to grab with pliers in case it wedged itself in whatever was blocking the drain.

[Linked Image]

However, that wasn't necessary and the blockage was no match for 10 tons of Porta Power strength. I think it was roughly 9.9 tons more than necessary.

[Linked Image]
Attached Images
1 member likes this
by quinten
add a street 90° at the bottom and a few inches of pipe
and move the valve out from under the tank , to the front edge of the tank near the door .
still have to bend over to open the valve ... unless you add a 2 ft extension as a vertical handle

I think most people are guilty of not draining compressor tanks often enough .

( ... that compressor closet looks like a good place for snakes )
1 member likes this
by Magnetoman
As an aside, the manual for my blasting cabinet says it uses 9.5 cfm @ 90 psi, but my measurements found the gun that came with it limits the actual flow to less than 3 cfm, which is less than a third of the value given in the manual. This shows, once again, there's no substitute for instrumentation (in this case, an air flow gauge) if you want to actually know what's what, rather than be at the mercy of whatever you're told. As a further aside, I didn't find similar flow measurements anywhere on the web so keep that in mind when reading about blasting cabinet "upgrades" elsewhere. I'm always skeptical of claimed improvements absent actual measurements of those "improvements."

Several times earlier in this thread I mentioned measurements made at 55 psi. However, I found significantly better (faster) results with Al oxide when I used 80 psi. There will be more on pressure and media later in this thread.

The following items were used for the above blasting cabinet and modifications.

blasting cabinet
plywood base
(4) locking wheels
quick connect
pressure regulator/moisture separator capable of flowing at least 10 cfm
120 psi pressure gauge
miscellaneous pipe fittings
⅜" ID high pressure tubing
⅜" air hose barb
6 cfm replacement gun
bottom feeder assembly for media (complete with hose)
guillotine-type air inlet valve
hose to connect outlet of cabinet to inlet of cyclone separator
cyclone separator
5-gallon bucket
plywood stiffener for underside of bucket lid
shop vacuum with adaptor for cyclone separator outlet

Everything on the above list that I didn't already have came from Amazon, eBay, Lowes, McMaster-Carr, or Harbor Freight, and the items I did have (e.g pressure regulator) also could be found at those sources.

[to be continued]
1 member likes this
by Magnetoman
Originally Posted by BSA_WM20
Aluminium oxide grown at room temperature is full of "pores" ...
When you anodize aluminium you force the oxide layer to grow 2 to 4 times thicker than it normally would
That's not correct. The natural oxide that slowly forms on a polished Al case or mudguard is very uniform, in contrast with electrolytically grown (anodized) oxides, which are "forced" to grow more than 10,000× faster and are more than 1000× thicker. Even then, there are several anodization processes that each produce oxides of different densities.

It's worth noting that although we may call it aluminum (or aluminium), everything we deal with is an alloy whose principle component is Al, but which also includes Cu, Zn, Si, etc. in amounts that depend on the specific alloy. Hence, more than just Al2O3 forms. In any case, it's the slowly-forming natural oxide that develops over the course of months (faster, if you live on an ocean beach) that concerns us.

On the compressor front, I've treated it to fresh synthetic lubricant and a replacement air filter in addition to the bespoke drain valve, so it's now ready for my maintenance guy to ignore it for another 30 years. However, I did tape a note to it with the date of the latest oil change and that it should be replaced annually, so that note should at least make him feel somewhat guilty starting ~18 months from now...
1 member likes this
by HughdeMann
I use a tumbler to clean brass for reloading. I have found that going to the local pet shop, and asking for reptile media gets what I think are ground walnut shells, and is much cheaper than "tumbler media". Also drop a dryer sheet into the bowl with your parts. It will collect most of the dust like waste and make the media last longer.
1 member likes this
by kommando
I worked in a company that used a bank of 20 odd vibratory drums running day and night cleaning several million plain bushes a week. The process to make the bimetallic bearing materials left oxide on the steel back of the bush plus machining of internal grooves and holes needed deburring.

1. The size of the media in relation to the part being cleaned is critical, the media must be small enough to easily pass through the smallest hole and not get stuck. There was a range of media and each bush had the size to use in the process sheet.

2. You are not going to clean any threaded item fully until you use media that can get into the root of the thread. Some blasting media either at 100% or mixed in with the current media would work. This will possibly permanently add blasting media to your green pyramids so not without risk.

3. All the vibratory machines used a hot detergent water solution mixed in with the media to improve cleaning time and reduce abrasive decay of the base part. The solution also made it easier to keep the bowls clean.

4. The complete contents were tipped over into a cage with a grid sized so the media fell through leaving the bushes inside the cage, vibration and more washing fluid helped. Grid sizes were in the process sheets.

5. The cleaned parts were then immediately oiled and then sent for inspection and final packing.
1 member likes this
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