Harbor Freight Sand Blaster Modifications

These are my various modifications to the Harbor Freight Sand Blasting Cabinet (SKUs 68893, 93608, 62144, 39170). My goal was to make as many of the modifications as possible to be 3D printed parts.

Note that in addition to the .STL files, the Fusion 360 file containing all these parts is also provided.

Some parts need to be rotated after importing into the slicer. Several parts require supports and/or brims. If a file requires any special print settings, it's mentioned in parenthesis.

File description

• Cabinet_Air_Inlet_Plug.stl is for blocking off the 13mm port on the front right side of the cabinet. Attach with CA glue.
• Cabinet_Baffle_Box_Top.stl blocks off the top of what HF calls the inlet, but actually gets used for the vacuum. Blocking off the top of the baffle causes the vacuum to draw from near the top of the grate. Dust will be picked up but the heavier media will not get sucked into the vacuum. This plate would be better with an angled top so that media does not accumulate on top of it. I use the air nozzle inside the cabinet to clean it off. (rotate 180 degrees in the Y axis)
• Cabinet_Foot.stl allows the cabinet to be screwed down to a sheet of plywood or other base. Each foot uses four #8 sheet metal screws and two #8 machine screws.
• Cabinet_Inlet_Baffle.stl gets attached inside the cabinet, using three of the screws that hold what HF calls the vacuum port. If you remove the vacuum port, the original screws can be used to mount the baffle. If you choose to keep the port, you'll need slightly longer M4 screws. (rotate 45 degrees in Z axis, enable supports)
• Cabinet_Light_Bar_Plug.stl is for plugging the two holes near the top left on the back of the cabinet. The original HF light is useless, and is generally replaced with LED lights or halogen bulbs. You'll need two of these. Attached with CA glue. (brim recommended, not always needed)
• Cabinet_Side_Block_Off_Plate.stl blocks off where the HF light switch box was. I used 24V LED lighting in my cabinet and ran the 24V leads through some 1/2" split loom into this plate. Apply sealant around the leads inside the cabinet where they come through the plate. Re-use the screws that held the HF box on. (supports optional)
• 'Chute_Drain_Cap.stl is part of the chute assembly. See the chute assembly section. (rotate 180 degrees in Y axis)
• Chute_Drain_Pipe.stl is part of the chute assembly. See the chute assembly section. (brim recommended, 0.16mm or smaller layer height if available)
• Chute_Hopper.stl is part of the chute assembly. See the chute assembly section. (supports not required, but screw holes will be better if enabled)
• Chute_Hose_Barb_External.stl is part of the chute assembly. See the chute assembly section. (rotate 180 degrees in Y axis, supports required)
• Chute_Hose_Barb_Internal.stl is part of the chute assembly. See the chute assembly section. (rotate 180 degrees in Y axis, supports required)
• Chute_Metering_Body.stl is part of the chute assembly. See the chute assembly section. (rotate 180 degrees in Y axis)
• Chute_Metering_Cover.stl is part of the chute assembly. See the chute assembly section.
• Chute_PVC_Coupler.stl is part of the chute assembly. See the chute assembly section. (brim required)
• Vacuum_Adapter_2.50_To_1.875.stl allows the smaller 1 7/8" Rigid vacuum hose to be connected to the above vacuum adapter. I replaced my larger vacuum with a smaller one and didn't realize the hoses were different sizes. Since I already had the 2.5" adapter glued in to the PVC tee, I created another adapter. (brim recommended)
• Vacuum_Adapter_PVC_Tee_To_2.50.stl adapts a Rigid 2.50" vacuum hose to the waste gate. See the waste gate assembly section. (brim recommended)
• Victor_Bared_Nozzle_Adapter.stl allows using the original HF ceramic nozzle in the vapor blast gun designed by Victor Bared. Probably the best blast gun to use is from The Tacoma Company. (rotate 90 degrees in Y axis, brim required)
• Waste_Gate_Bottom.stl is part of the waste gate assembly. See the waste gate assembly section. (rotate 180 degrees in Y axis)
• Waste_Gate_Cover.stl is part of the waste gate assembly. See the waste gate assembly section.
• Waste_Gate_Plate.stl is part of the waste gate assembly. See the waste gate assembly section.

Sealant

For gluing the parts together, use either RTV or silicone caulk. For joining the printed parts to the PVC pipe, only a very thin film of either on the inside of the PVC joint is necessary. The parts are a snug fit by design, and excess sealant will get push up into the joint. This isn't an issue with the vacuum port, but can disrupt the smooth flow of media in the chute and metering valve assembly.

Apply an amount just large enough to smear around the inside of the joint, leaving a thin coat. After joining the parts, any excess sealant can be allowed to dry and then wiped or rolled off. The goal is not so much to permanently join the two parts (like when gluing PVC to PVC), but to prevent media from leaking out.

Painting PVC Parts

Before assembling, you may wish to paint the PVC tees black, red, or whatever to match everything else. Rough up the outside surface of the tee with 220 or 320 grit sand paper, wash in soap and water, dry thoroughly, and use something like Rust-Oleum 2X Ultra Cover Gloss Black Spray Paint and Primer In One spray paint. Apply two or three light coats of paint and allow to dry overnight.

Chute Assembly

The Harbor Freight media chute and door are leaky, require modification, and are sub-optimal for feeding media. The chute assembly replaces it, and adds a metering valve and a screw-on cap for draining media. Unlike the HF door, this doesn't have a flat bottom for media to accumulate on, resulting in better media feeding.

The only additional components required are (2) 1" PVC tees, a 1" #8 machine screw, two #6 washers, and a #8 Nylock nut. Although #8 washers are normally used with #8 screws, #6 washers have nicer fit on the #8 screw, and are slightly smaller in diameter. Either can be used, but the #6 looks nicer.

Decide which hose barb is to be used. If using Flexzilla 5/8" water hose, either can be used. The internal barbs will be slightly less restrictive to the media flow than the external barb, but will only work with a hose that has a 22mm outside diameter. The external barb will work with any 5/8" internal diameter hose. A hose clamp can be used but is not necessary, as there is no positive pressure on the hose.

To assemble the metering valve, attach the metering cover to the metering body with the #8 machine screw. Place a washer under the head of the screw and another on the nut. Tighten the nut only far enough where the metering cover has some resistance when rotating it.

Ensure that the drain plug cap screws easily on and off the drain plug pipe. When printed at 0.2mm or finer, the cap should turn fairly easily. Running the cap on and off the pipe 4 or 5 times will generally make sure it won't bind up. Once media has been put in the cabinet, it's a good idea to clean the threads any time the cap is removed. Media is abrasive and can chew up the threads.

The PVC tee has 3 legs. Orient the tee so that the two inline holes are vertical and the middle leg points to the right. Leg 1 will be the top hole, leg 2 will be the middle hole, and leg 3 will be the bottom hole.

Apply sealant on the inside of leg 3 of one of the PVC tees and insert the drain plug pipe until fully seated. Apply sealant to the inside of leg 2 and insert the PVC coupler until fully seated. THIN is the key word. The connections are snug and will push any excess sealant into the joint, potentially preventing the smooth flow of the media.

Using the second PVC tee, apply sealant to leg 2 and insert the metering body until fully seated. Apply sealant to leg 3 and insert either the internal or external hose barb until fully seated. Lastly, apply sealant to leg 1 and insert the PVC coupler attached to the first tee. I prefer to rotate the PVC tee with the metering valve so that it is positioned at about a 45 degree angle towards the front of the cabinet. Remember to consider whether the assembly will point to the left or right when angling the metering valve.

Attach the printed chute using the original chute screws and nuts. After positioning the chute on the sheet metal, insert the 4 screws and then use a piece of tape to hold each one in place. Reach in through the side door to start the nuts on the screws. Set a 7mm open end wrench on a nut, then rest the wrench handle on the back of the cabinet for the right side screws and the front of the cabinet for the left side screws. Remove that screw's piece of tape, then tighten. Repeat for the 3 remaining screws. Apply a thin bead of sealant between the lip of the chute and the outside of the cabinet.

Apply sealant to leg 1 of the first PVC tee, orient the assembly so the hose barb points in the desired direction, then press on to the pipe portion of the chute. Allow sealant to set for whatever time is recommended by the sealant manufacturer.

A photograph is included in the files to show how a completed assembly should look.

Waste Gate Assembly

This is my spin on the waste gate as offered by The Tacoma Company.

The waste gate controls how much vacuum is applied to the cabinet. Too much vacuum results in sucking media into the vacuum. Too little results in excess dust in the cabinet. The ideal level of vacuum removes the majority of the dust and none of the media. Adjusting the opening on the waste gate allows the level of vacuum to be controlled. Less powerful shop vacs are a good choice. A single waste gate may not provide enough bypass, so a second one may need to be placed at the shop vac.

In addition to the printed parts, you will need one 1" #8 machine screw, a #8 Nylock nut, six #8 washers, four 3/4" #8 sheet metal screws, and a 2"sanitary PVC tee (such as this one). Do not use a straight PVC tee as these provide poor airflow compared to the sanitary tee. The sanitary tee has a sweep in the middle leg, providing smoother airflow.

To assemble the waste gate, attach the waste gate cover to the waste gate bottom with the #8 machine screw. Place a washer under the head of the screw and another on the nut. Tighten the nut only far enough where the waste gate cover has some resistance when rotating it.

The waste gate plate gets attached to the back of the cabinet, covering the hole that HF calls the vacuum port. The plate has a 2mm raised ridge to help with alignment. Use painters tape to mount the plate to the back, then pre-drill the holes for the four #8 sheet metal screws with a 7/16" drill bit. After drilling the holes, apply a small bead of RTV or silicone caulk around the outside edge of the alignment ring and the four screw holes, then screw it down. Use #8 flat washers under the screws, and don't over-tighten. Make sure the plate is fully seated and isn't sitting up on the alignment ring. Obviously you'll need to remove the HF rubber gasket first.

The sanitary tee has 3 legs. Orient the tee so that the two inline holes are vertical, the middle leg points to the left, and the curve of the middle leg goes from left to down. The vacuum will attach to the bottom (leg 1), the waste gate bottom and cover will be inserted into the top (leg 2), and the middle leg (leg 3) will attach to the waste gate plate.

1. If using the vacuum adapter, apply sealant to the inside of leg 1 and press the adapter in firmly.
2. Apply sealant to the inside of leg 2, and insert the waste gate bottom and cover assembly. The waste gate cover will prevent it from going too far in. This is a snug fit, so be sure the waste gate is inserted in fully.
3. Finally, apply sealant to the inside of leg 3 and press it onto the mounting plate. This is a tight fit, so be sure it's aligned vertically. Once it goes on, it's very difficult to remove.

Cabinet Foot

The cabinet foot allows the cabinet to be attached to a sheet of plywood. I created a V-shaped rolling base by mounting a piece of 3/4" plywood on top of 2x4's with casters. It's right at the border line of being too tall, but it's usable. It's tall enough that a 5 gallon bucket can be placed under the plug for draining the media.

There were two primary reasons I wanted the base attached to the cabinet. The first was so the cabinet wouldn't just slide off. The second is that I can use the forks on my tractor to lift the cabinet by the metal shelf, and the base won't fall off.

This was one of the first 3D prints for the cabinet I designed, and at the time I was using OpenSCAD. I've since switched to Fusion 360 for all the subsequent parts. The OpenSCAD source file is included in the uploaded files.

Victor Bared Blast Gun

I went with this blast gun for a couple reasons. One is that I like how the air and media hoses feed into it better than the HF gun. I'm also planning on converting the cabinet to a vapor blast cabinet, and the HF gun won't work for that. Victor's design has several sizes of printable tips that are the equivalent of the ceramic nozzle in the HF gun, and I don't think they'll last very long with dry media.

What I did was create an adapter that will hold the ceramic nozzle in the correct position for media to feed into it. It's somewhat stubby, and an extended ceramic nozzle like The Tacoma Company sells might be a better choice. Overall, I'd suspect their nozzle is a better choice, but I don't have one (at least not yet).

I have very little time on the Victor's blast gun with the ceramic nozzle, so I can't say if this is the way to go or not. But if we don't try it, we'll never know :)

Printing Notes

Most of these parts are 3mm or less in thickness, so I usually set the walls to 6 or higher, effectively making it 100% infill. Resolution can be pretty much anything, although I typically use 0.16mm Optimal on the X1C.

I used Prusament Jet Black PETG and Prusament Lipstick Red PETG for these parts. The red is surprisingly close to the cabinet color.

There are two parts that have structural considerations. These are the vacuum adapter and the waste gate plate.

The vacuum hose hangs from the vacuum adapter, which puts the load perpendicular to the layer lines. Ideally, the part should be printed so the layer lines are parallel to the load, but that requires a lot of support and generally results in a part that isn't very round (e.g., lacks concentricity). The hose isn't all that heavy, but a sudden side load may snap the part. This could be prevented by using a zip tie to attach the hose to the cabinet leg so it can't move.

The waste gate mounting plate has the stub for the PVC tee to hang from, which bears the weight of the waste gate, tee, vacuum adapter, and the hose. I printed the part by rotating it to a 45 degree angle on the plate, with the tee stub pointing down. This worked really well on a Bambu Carbon X1C, resulting in a very strong part that had a nice finish to it. This may not work on all printers, but it's worth a try. Enable supports, set Type to normal(auto), Style to Default, Threshold angle to 35, and Remove small overhangs to checked. On build plate only doesn't matter. Uncheck Reduce infill retraction in the Others tab. Set Wall generator to Arachne in the Quality tab.

Print Settings

Printer Brand:

Bambulabs

Printer:

Bambu X1C

Rafts:

Doesn't Matter

Supports:

Yes

Infill:

100%

Filament: Prusament PETG

Category: Parts