Multi-Positional Transfer Pump (Suijin V0.36)

About Me

Howdy folks! My name is Murphy, and I'm currently pursuing my Bachelor's in Computer Science. I also work as an HVAC Service Technician, and have often found myself in need of a water transfer pump while at work to remove water from drain pans in attics. Of course, I could buy one, but learning to design one has been far more rewarding; if not ridiculously challenging given my lack of mechanical engineering education.

The Design Process

I started my first prototype last summer, and am utilizing many of the parts from that original design in this iteration. Unfortunately, I didn't have a clue as to which motor would work best at the time, and bought a motor with a threaded shaft instead of one with a flat side. (Step 2 is dedicated to making the threaded shaft usable!)

The motor is also DC as I had intended the pump to be battery operated, but have since decided that I typically have access to 120VAC power at work, and so I snagged a 120VAC -> 24VDC transformer for cheaper than the cost of a new motor. (I regret this decision a little as a stronger motor would have been nice, but that's what prototypes are for, right?)

For the 3D printed parts, I utilized FreeCAD to design everything as it's what I'm most familiar with due to its open-source nature. (*takes shelter from incoming rocks thrown from off camera-right*)

I'm slicing up some GCODE with UltiMaker Cura, and printing it all out with an Anycubic Kobra 2 Neo underneath a cardboard enclosure. (Not recommended, this is a fire hazard for sure. I'll explain more in Step 1.)

Plan Ahead Before Purchasing

Many of these materials I had on hand already due to either my current line of work, or from previous projects. My total cost for this version of Suijin is a little over $100 USD not including previously purchased parts, but that would have easily doubled or more if I'd purchased it all at once. (The electrical housing was designed to fit the exact electrical components listed below, and I would not recommend purchasing alternatives unless you're comfortable modifying the 3D files.)

Regarding the tools, take my suggestions with a grain of salt. None of them were picked based on brand preference, but simply as points of reference. The only exception to this would be the soldering station listed, I personally own and use that one with great success with threaded heat inserts and highly recommend it.

Bill of Materials (Tax not included)

COMPONENTS

1. DC Motor (12-24v) | $25.09 | https://a.co/d/bv1lb9M
2. DC Motor Governor (9-60v) | $9.99 | https://a.co/d/eUOgF4A
3. DC Amp/Voltage Meter (5-100v) | $21.59 | https://a.co/d/0IG4yQY
4. 24v DC Power Supply (120VAC) | $19.99 | https://a.co/d/dk25vTf
5. 12v DC Rocker Switch | $7.99 | https://a.co/d/59jWZMc
6. 250v AC Rocker Switch | $9.99 | https://a.co/d/5gBeHzl
7. 125v PC Power Cord | $8.40 | https://a.co/d/gnQHR15
8. 750PCS M3 Assortment | $9.99 | https://a.co/d/1xAD8jt
9. M3 Threaded Inserts | $9.49 | https://a.co/d/i2LDnZC
10. 1kg ABS (Orange) | $19.79 | https://a.co/d/2QFaH2U
11. 1kg ABS (Blue) | $19.79 | https://a.co/d/6WwO2l0
12. 1kg 95A TPU (Black) | $22.99 | https://a.co/d/eyaJKWA
13. (2) 3/4 Barb Adapter (PVC) | $9.65 | https://a.co/d/iaXMne4
14. 2-Pack 3/4->3/8 Brass w/clamps | $9.66 | https://a.co/d/1xTFEVf
15. 4-Pack Teflon Tape | $3.59 | https://a.co/d/5Jv5jPk
16. 10ft 3/4 Vinyl Tubing w/clamps | $14.99 | https://a.co/d/3IB3lR8
17. 10ft 3/8 Vinyl Tubing w/clamps | $14.99 | https://a.co/d/3XSGI2d
18. Wire Push Connectors | $4.99 | https://a.co/d/eAwvVf3

TOOLS

1. Klein Precision Screwdriver Set | $29.97 | https://a.co/d/cjnk8Vn
2. 10in. Channel Lock Wrench | $9.98 | https://a.co/d/5cda3ei
3. 1/4-5/16 Reversible Bit | $12.99 | https://a.co/d/8qZITQD
4. Exacto/Razor Knife | $4.99 | https://a.co/d/0HrwkZr
5. Cordless Dremel Sanding Tool | $27.01 | https://a.co/d/4c2T2jr
6. Power Drill | $59.00 | https://a.co/d/hmuhr81
7. Soldering Iron w/Temp Control | $29.99 | https://a.co/d/5sFUdIF
8. 1/8 Metal Drill Bit | $8.64 | https://a.co/d/dobXHBd
9. Needle Nose Pliers | $5.99 | https://a.co/d/9q57lae
10. Sanding Cloth | $6.99 | https://a.co/d/4RXVzxj
11. Microfiber Cloth | $3.98 | https://a.co/d/6b9sjSY
12. 100% Acetone | $8.99 | https://a.co/d/cP4apZ3
13. Terminal Kit w/ Crimper | $17.99 | https://a.co/d/iXTRw1R
14. 3D Printer | $169.00 | Anycubic Kobra 3

Material Selection

Alright folks, this here was hands down the most difficult series of prints that I've pulled off with my printer, and I wouldn't recommend going about it in the same manner that I did.

I selected ABS plastic because I was worried about potential heat dissipation from the transformer, as well as from friction in the self-priming version of the impeller housing. What I was not prepared for was the difficulty that comes with printing ABS without an enclosure. Even with my printer at maximum temperature on the heat bed with glue sticks, I was having issues with the print lifting off the build plate within a couple of hours, creating deformation curves in the final prints.

It was this difficulty that drove me into a fit of insanity and motivated me to build my cardboard enclosure. (I also slept in a recliner next to it while the longer prints went overnight, because I was paranoid about burning my house down.)

ANYWAY, if you think you'll have similar difficulties because your printer doesn't have an enclosure, then I would recommend trading the ABS for perhaps a PLA+ that would be easier to print and may offer some heat resistance. The TPU is non-negotiable, as you'll need it for the gaskets and flexible impeller. Fortunately, TPU is much easier to print with, just a tricky devil to get off the build plate once it's done. (I found freezing the build plate forces the TPU to contract and pop off the plate.)

Check the data below to reference some of my printer settings for ABS and TPU, as well as time and plastic estimates. (I HIGHLY recommend saving yourself some time and utilizing a 0.6 nozzle for your prints. It is not fun waiting 15 hours for your motor housing to finish printing.)

Printer Settings [ABS]

1. Layer Height: 0.4
2. Line Width: 0.6
3. Wall Thickness: 0.6
4. Wall Line Count: 1
5. Top/Bottom Layers: 2
6. Top/Bottom Thickness: 0.32
7. Top/Bottom Pattern: Lines
8. Infill Density: 100%
9. Infill Pattern: Lines
10. Connect Infill Lines: True
11. Printing Temperature: 260°C
12. Build Plate Temperature: 110°C
13. Top/Bottom Speed: 50
14. Top/Bottom Travel: 50
15. Regular Print Speed: 75
16. Regular Travel: 75
17. Retraction: True
18. Retraction At Layer Change: True
19. Retraction Distance: 3
20. Retraction Speed: 15
21. Combing Mode: False
22. Print Cooling: False
23. Generate Support: True
24. Support Structure: Normal
25. Min Z Seam Distance: 0.44
26. Support Placement: Everywhere
27. Overhang Angle: 45°
28. Pattern: Zig Zag
29. Support Brim: False
30. Top/Bottom Distance: 0.44
31. X/Y Distance: 0.48
32. Distance Priority: X/Y Overrides Z
33. Build Plate Adhesion: None

Printer Settings [TPU]

1. Layer Height: 0.4
2. Line Width: 0.6
3. Wall Thickness: 0.6
4. Wall Line Count: 1
5. Top/Bottom Layers: 3
6. Top/Bottom Thickness: 0.4
7. Top/Bottom Pattern: Lines
8. Infill Density (Gaskets): 100%
9. Infill Density (Impeller) 25%
10. Infill Pattern: Cubic
11. Connect Infill Lines: True
12. Printing Temperature: 210°C
13. Initial Printing Temperature: 215°C
14. Build Plate Temperature: 70°C
15. Initial Build Plate Temperature: 75°C
16. Flow: 110%
17. Top/Bottom Speed: 25
18. Top/Bottom Travel: 30
19. Regular Print Speed: 40
20. Regular Travel: 40
21. Outer Wall Speed: 30
22. Top Surface Wall Speed: 30
23. Z Hop Speed: 1
24. Retraction: True
25. Retraction At Layer Change: True
26. Retraction Distance: 3
27. Retraction Speed: 40
28. Combing Mode: Within Infill
29. Max Comb Distance With No Retract: 30
30. Print Cooling: True
31. Fan Speed: 75
32. Generate Support: False
33. Build Plate Adhesion: None
34. Special Modes - Print Sequence: One at a Time

Important Notes

1. Don't think you can slack off on the 100% infill. You'll get waterlogged components, and heat inserts wiggling around on you because the infill is weak. While it seems counterintuitive, you'll actually save plastic by just printing it 100% the first time. More walls won't save you!
2. Print ALL of your ABS at once, don't switch back and forth between it and TPU unless you want the most flexible, heat resistant clog you've ever had to cold pull out of an extruder gear. (I lost my first ever print head to this.)
3. Make sure your initial ABS extrusion is at a minimum of 250°C. My printer defaults to 215°C for extrusions, and that left me with some clogged tips that had to be swapped out when switching to or from ABS.
4. If you're using Cura as your slicer, I recommend selecting the Special Mode: Print Sequence: One at a Time when printing your TPU. This will save you a lot of string cleanup from the printhead switching between prints in a single layer. You could also just print one at a time manually if you don't have access to these slicer settings.
5. Place support blockers on the gasket slot for impeller housing v0.36, and on the slotted section of the inlet and outlet ports of impeller housing v0.33. You don't want to be trying to dig supports out of these regions, it's not easy.

Print Data

1. Motor Housing: 8hr 46min | 685g | ABS
2. Motor Housing Lid: 5hr 59min | 468g | ABS
3. Motor Stop: 12min | 12g | ABS
4. Impeller Housing (v0.33): 2hr | 109g | ABS
5. Impeller Housing (V0.36): 1hr 27min | 104g | ABS
6. Impeller Housing Cap (v0.33): 20min | 21g | ABS
7. Handle + Handle Base: 56min | 59g | ABS
8. Impeller Housing Gaskets (v0.33): 2hr 10min | 75g | TPU
9. Impeller Housing Gasket (v0.36): 1hr 29min | 52g | TPU
10. Impeller (4 Blade): 16min | 7g | TPU
11. Impeller (6 Blade): 20min | 9g | TPU

This motor is decent, with a 24v output of 1/20hp at 7,000RPMs and a max DC amperage of 4.9. If it just had a flat side on the shaft, I could recommend it with conviction. That said, these threads were not an easy problem to overcome, and if you want to truly build Suijin in its current form, you'll have to overcome the same problem.

Fortunately for you, I already know how to do it!

You'll need your 1/8 metal drill bit and drill at this part, so probably get some safety gear as well. (If you're into that kind of thing.) I also recommend finding a way to secure the motor before drilling the hole, as you don't want to go drilling holes in your leg. I found some success standing on it with a steel toe boot, but I don't recommend this unless you're experienced in redneckery. A vice is probably a better idea, with some channel locks to hold the shaft still.

Mark your motor shaft 25mm from the base of the shaft, or 13mm from the tip. Then drill your hole and you're good to go! It never hurts to measure twice...

Now that you've gotten your parts printed and your shaft prepared, you're ready to start preparing the printed parts! For this stage the name of the game is smooth.

1. Break loose your supports with a razor blade or exacto knife with great caution.
2. Sand the impeller housings down with the dremel tool first, working in circular motions against the grain of the layer lines until you can't see them. Take care not to dremel the overall shape out of the impeller housing, especially for v0.33.
3. Sand the impeller housings down with the sanding cloth until the roughness is mostly gone. It should be almost ready to use, albeit a little dusty. (A dust mask for this part probably isn't a bad idea.)
4. Dab some 100% acetone onto a microfiber cloth and smooth the interior surface of the impeller housings' impeller cavities with the cloth. Once the cloth starts to stick, you need more acetone. Repeat the process until layer lines are gone and the plastic is shiny and very smooth to the touch.
5. Set (2) heat inserts into the back of the motor housing lid where the high voltage switch goes.
6. Set (2) heat inserts into the side of the motor housing lid where the handle will go.
7. Set (4) heat inserts into the handle base. (This is tricky but possible with love. I'm sorry.)
8. Set (17) heat inserts into the motor housing in all of the 4mm diameter holes that you see. (The edges are also tricky, but if you did that handle base first then you've got this!)
9. Set (8) heat inserts into impeller housing v0.33

Now with all of our pieces gathered and prepared, we can finally begin assembling Suijin! It's got some quirks, being a prototype and all. Stick with the following instructions though, and you should make it through!

1. Start by cutting the fork side off of (3) of the given wires that come with the 120VAC switches. Strip these ends and wire them into the line, neutral, and ground terminals of the transformer. (I used thermostat wire, but you should have no problem with the given wires.)
2. Fold the wires over the top of the transformer and push the transformer into the slot at the bottom of the motor housing, so that your (3) spade connectors are sticking out towards the opening at the back of the housing.
3. Use (1) M3*6 screw to secure the transformer to the bottom of the motor housing.
4. Place the motor into the motor bed, pushing the front screws into their designated holes at the back of the front wall of the motor housing. You should also be pushing the shaft through the center hole in this motion.
5. Connect the motor stop at the back of the motor, and screw it into the two heat inserts with (2) M3*6 screws.
6. Push your motor governor and DC voltage/amp meter through their slots in the lid, and then twist in the rocker switch. I didn't include the switch cover on mine, but you could if you want to feel cool every time you turn it on. Then place your 120VAC switch into the slot at the back of the lid, with the switch oriented higher than the plug section of it. Screw this in with (2) M3*6 screws.
7. Connect your three spades from the transformer to the line, neutral, and ground terminals on the back of the 120VAC switch.
8. Connect a wire from the V+ on the transformer to one side of the DC rocker switch at the top of the lid. Use some of the given wires with the 120VAC switches, unless you have your own. Anything 16-20ga should do. Connect another wire from the V- on the transformer to the negative junction which would be one of the push in connectors listed in the BoM.
9. Run another wire from the other side of the DC switch to the V+ side of the motor governor, feeding this wire through the amp clamp from the voltage monitor. You'll also want to tie the red and yellow from the voltage monitor together into a crimped fork connector, and connect that to the leaving side of the DC switch. (The same side the output wire going to the governor is connected to.)
10. Run a wire from V- of the transformer to the negative junction.
11. Twist the negative wire from the voltage monitor around another wire and connect them to the negative junction together into a single port. (The wire on the voltage monitor is tiny and hard to feed in alone.) Trim the 2nd wire and connect the other side to the V- side of the motor governor.
12. Connect your motor positive to the output negative on the motor governor, and the motor negative to the output positive on the governor. (We want a reversed spin from the motor default, as that's how I designed the impeller housings before I realized it was backwards.)

Wow that's a whopper to read through, sorry I didn't make an instructional video for this, but I think the diagram will help you make sense of the above steps. At this point you should be ready to connect your lid to your motor housing and secure it in place.

1. First, you'll need to take that negative junction and shove it up in the space next to the motor governor wire terminals. (Only one side of the lid has the extra slot on it, so if it isn't next to your governor terminals then your governor is backwards.)
2. Now slot the bottom of the back of the lid onto the grooves at the bottom-rear of the motor housing. Once the grooves fit into place, smush all those wires in there and them mash the top front of the lid down onto the front of the motor housing.
3. Screw the lid to the motor housing by using (10) M3*16 screws. This is a pretty tight fit, so I recommend you slowly work the screws in going around, instead of just screwing them in all the way one at a time. If you apply too much stress on those heat inserts, they'll pop right out. Once you've got it connected for the first time it gets easier.
4. Screw the handle base onto the side of the lid. (The handle base is reversible so just pick how you want it. I prefer it with the handle facing outward to make it easier to hold while in the vertical pumping position.)
5. Screw the handle onto the handle base. This might be easier done before screwing it to the lid, I'll let you decide.
6. Now you've got to pick which impeller housing you want, and then slide the appropriate gasket over the shaft. (I had plans to unify these gaskets so you only need one for either impeller housing but ran out of time for the contest.)
7. Gasket in place, slide your impeller of choice onto the shaft, lining up the hole in the impeller with the hole you drilled in the shaft. Place a washer onto (1) M3*20 screw and then feed it into the hole. On the other side place another washer and a nut, then secure the nut while you tighten the screw.
8. Impeller in place, go ahead and slide your impeller housing of choice over the impeller and then secure it to the housing with (4) M3*16 screws.
9. If you chose the vertical pumping impeller housing then you're done! If you chose the self-priming impeller housing, then drop some vegetable oil into that impeller cavity and run the pump dry and face up without the lid on for 5 seconds. (It's gonna sling oil everywhere, watch out!) You're doing this to lube up the impeller so it doesn't bind in the initial priming process.
10. Secure the v0.33 cap gasket and cap to the impeller housing.

Now that you've got your pump build, it's time to test it out! While most people recommend not dry running a pump, I recommend you do that with this to break in the impeller. Let it run and watch the amps on the amp meter, sometimes it'll slow down or bind up after a few seconds. If it does, just stop it for a moment at the governor until the amperage drops and voltage rises, and then repeat.

I did this process for about 3-5 minutes and got a nicely worked in impeller that only pulled 0.6ADC dry running.

Congratulations friend, you made yourself a transfer pump! I haven't completed any extensive testing on the pumps regarding exact flow rates or lift, but from my 5-gallon bucket tests I estimate the submersible head with the 6-blade impeller has approximately a 2.5GPM flow, whereas the self-priming head with the 4-blade impeller has closer to a 1GPM flow.

If nothing else, I'm excited to design version 0.4x using AutoDesk software! I have a boatload of improvement ideas to work on, and I look forward to any tips or information that you fine folks in the community can provide to help get my pump to version 1.0!

-Murph