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Message started by Gary_in_NJ on 12/27/21 at 18:59:41

Title: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 18:59:41

In another thread on polishing aluminum parts I mentioned that I built my own Vapor Blasting cabinet to clean and restore metal parts. Vapor blasting is different than sand blasting and soda blasting in that it uses water as part of the media. The water washes the part, but more importantly it cushions the glass beads, and therefore it peens the part leaving a finished look not unlike new OEM parts.

This design is not mine, it’s common on YouTube. What is hard to find is a coherent how-to with details. So this is my interpretation of the design with implementation details.

The parts list below will put a vapor blasting cabinet in your garage/shop for $400 to $500 depending on how you configure it. This price range assumes you already have an air compressor. And not just any air compressor. You will want (ok need) a unit that can deliver 15psi or more. Typically 5hp two-stage compressors will deliver good CFM. My compressor is 3.2HP and can refill at 13CFM (measured) - and I’m delivering 15CFM to the blasting nozzle. As a result I can blast for 6 minutes and then have to wait 6 minutes for the compressor to recover and cool. This is wearing out my single-stage pump and when it goes (and it will) I’m going to replace it with a two-stage pump.

You will also need a shop vacuum to keep the cabinet work area clear.

So here is the parts list:

Harbor Freight Blasting Cabinet
Harbor Freight 2000 LED Lumen Work Light (at least 1)
6 gallon bucket (Amazon)
Stainless Steel Sewage Pump - 1.5hp 4300gph (eBay)
Vapor Blasting Gun (Amazon) – see details below
REQUIRED In-Line Check Valve for air line (prevents slurry from back feeding into your compressor)
10’ of 5/8 ID Hose for Slurry agitation and delivery
1/2 air hose
5/8” barb to barb bulkhead fitting
1/2 NPT Bulkhead fitting
3/4  NPT to 5/8 barb (x2)
1-1/2 PVC Tee
1-1/2 Female Threaded Bushing
1-1/2 x 3/4 PVC Threaded Bushing (x2)
1-1/2 PVC elbow and threaded fitting for air inlet.
Glass Bead Media - I’m using 170-325 Mesh (Amazon)
Silicone Caulking (3-4 tubes)
Zip Ties
Optional - Dragway Tools Pneumatic Foot Switch (Amazon)
Optional – Cabinet mounted air regulator
Optional – Powered Switch (min 14/3 wire)
Optional – Power Strip (for lighting and vacuum)
Optional – Threaded Union with o-ring (used as disconnect at pump/delivery hose). This will require 2 additional 3/4  NPT to 5/8 barbs
Optional – 90 degree adaptor for shop vacuum hose (strain relief)
Must Haves – 1) Air Compressor. As a minimum size it should have 3HP and 60 gallons capacity and be able to deliver 10 CFM. A 5HP/15CFM (or more) is ideal. 2) A shop vacuum is required to vent the cabinet.
Installation Dependent – 1/2NPT to 1/2 Barb Fittings, quality hose clamps and any fittings to get air to the gun.

Build and/or Modification Notes
Cabinet
Caulk everything – three times. Leaks suck. I have one that I’ll address when my current project is done and I can really clean the cabinet. Throw away the trap door and blasting gun that comes with the cabinet, you won’t be using them. Block the top of the “chimney” to convert it from an air inlet to a vacuum outlet (I’ll post a photo). You’ll have to cut a 2-1/2” hole in the large blocking plate and use regular JB Weld to affix/seal it in place (you can also drill the 4 mounting holes and use fasteners as well). Cut a 1.9” hole in the small blocking plate to convert into an air inlet and adapt a 1-1/2” PVC elbow to that plate (I’ll post a photo). You will want to add additional lighting because the included light bar is not adequate (it’s not even good). Just one LED unit sitting on top of the glass works, but two installed in the cabinet is ideal. Use rubber grommets to pass the power plug through the back of the cabinet and seal with caulking.

Bucket – A 6-gallon bucket comes right to the top of the hopper outlet. You can use a 5-gallon bucket, but there will be splashing. It’s worth the $15 – especially when the slurry turns gross. You will be consuming water (through the vacuum). When the water drops below the top of the pump it will stop working, so check the water height often. The larger bucket gives you more blasting time. BTW, water and media can be added right inside the cabinet - it all goes into the bucket.

Pump – The pump will come with a 1-1/2 threaded elbow. To that you will attach a 1-1/2 PVC Tee with the female threaded bushing, the two 3/4 bushings and the 3/4 NPT to 5/8 barbs. The vertical outlet will deliver slurry to the cabinet. The horizontal outlet will wrap around the pump towards the bottom and be used as an agitation line. Zip-tie this line to the bottom of the pump. Place the threaded union near the pump so when you disconnect the pump for maintenance the slurry drains back into the bucket rather than your shop floor. I think the powered switch is a good feature because it allows you fast access to turn the slurry pump on/off. I’ve seen people install a solenoid, it’s overkill. There is a float cut-off switch. Zip tie this to the pump so the pump is always in the run position (wire facing down).  

Vapor Blasting Gun – The guns are all the same, however the nozzles are not. You want to get a gun with a boron nozzle. The nozzle size will depend on your air compressor. You will need to deliver maximum CFM to the gun, so you will need to use 1/2 air hose. If your compressor is in the 10-15 CFM range, use a 8mm nozzle. If you can deliver 16+CFM you can go larger to a 10mm nozzle…but the $30 gun won’t really deliver any more. If your compressor is very capable consider a better nozzle. The $30 blast nozzle works, but it’s not great. (the HTMR blast nozzle is great, but it’s over $200).

Pneumatic Foot Switch – this is sold as a 3/8NPT switch. It’s actually a 1/2NPT switch, but you have to disassemble it to remove the 3/8 to 1/2 NPT Bushing installed in each end. This is the same switch sold by Eastwood, but without the junk sandblasting nozzle…and it’s $25 less (and it’s red). The foot switch isn’t required. You can install a ball valve in the cabinet and turn the air on/off with that. But the foot switch is very convenient and makes resting and examining the part easier.

Check Valve – I installed mine inside the cabinet, directly to the bulkhead fitting. Attach a 1/2NPT to 1/2 Barb fitting to that. If you elect not to use a bulkhead fitting (both water and air lines can be run through the bottom opening) then attach the check valve directly to the gun.

Glass Bead Media – you need less than you think. Try 1 solo cup to about 5 gallons of water. Adjust as necessary (based on your CFM). Blast at a working (not static) pressure between 50-60psi. You can go higher, but you will break the glass above 70psi and it will become less effective. If your compressor is on the low delivery side, blast at 50psi.

If you use the vapor blaster to clean dirty parts, you’ll be changing media/slurry often. You will get maximum life from the media if you clean grease and dried gunk from the part before blasting. If you want to clean, run a second bucket with an aluminum oxide /glass media mix, and then swap out buckets. You’ll want to hose out the cabinet between buckets otherwise you’ll get aluminum oxide in the polishing bucket.

Other things – I used 90 degree fittings at the bulkhead fittings (outside the cabinet) and regulator for strain relief. The down side to having fittings in the airline is that they have an I.D. of 3/8, so you’ll be sacrificing delivered CFM to the gun. You can definitely build with minimal fitting to increase CFM.

I think the 90 degree vacuum hose fitting for strain relief is important too. I attached mine to an extension and attached that to the cabinet leg so the hose doesn’t pull on the JB Welded adaptor.  Depending on your height, you may need to raise the cabinet (and bucket by the same amount). I’m 6’1”, and I found it easier to lower me – with a 30” high stool. You have to be comfortable at the cabinet. You’ll be working there for a good period of time, and you have to keep the foot switch engaged.

Photos follow. Feel free to ask questions.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:00:43

Pump, foot switch and blasting gun.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:01:40

Chimney. This gets converted from an inlet to an outlet.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:03:02

Make a tray. I used aluminum. I have a hand seamer and bending brake to form parts.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:04:33

Attach to the top of the chimney and seal it with caulk. This will cause the vapor in the cabinet to stay low.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:06:16

Convert the Harbor Freight supplied air block into an air outlet by adding a hole and JB Welding the outlet pipe to it.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:07:44

Make a 1.9” hole in the smaller Harbor Freight air block plate to convert it into an inlet. I modified a PVC fitting.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:08:17

Air inlet in place.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:09:20

Air outlet with 90 degree hose fitting. This is supported with a hose clamp at the leg.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:11:05

Pump, PVC fittings, barbs. This is shown in a 5 gallon bucket (trial fitting). Note the float switch (blue) is zip tied.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:12:16

Foot switch with 3/8 NPT fitting and adaptor removed (shown at bottom)

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:13:09

Air regulator and power switch added to cabinet.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:13:53

5 gallon bucket is too small.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:15:54

6 gallon bucket is perfect. The second bucket on the left has a mix of 100-170 mesh and Al-Ox for cleaning. The seat makes it easy to sit at the cabinet for long stretches. The lights just sit on the glass above.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:18:05

Ready to blast. The air hose is the straight section of the gun, slurry comes from the angle. I used tube/zip-tie stand-offs to attach the air and slurry lines.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:19:11

Before blasting

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:19:51

After blasting, before restoring the paint

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:20:28

Restored

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:21:02

Before

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:21:24

After

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:22:33

Every part of this engine went through the vapor blaster. I’m restoring an ‘81 CB900C.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:23:04

Right side

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by Gary_in_NJ on 12/27/21 at 19:23:41

Before.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by ohiomoto on 12/28/21 at 16:53:18

Super cool Gary. Thanks for the detailed post.

Title: Re: Building a Budget Vapor Blasting Cabinet
Post by DragBikeMike on 12/31/21 at 14:57:36

That is a real nice setup Gary.  Your parts come out beautiful.  I appreciate the effort you went through to put this post together.  That CB engine is lookin sweet.  Excellent.

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