I am a flavorist and needed a way to reduce the steep time on flavors I was mixing and developing. I built this stirrer to do that job for under $20.

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Step 1:

Overview

I am a flavorist in the the greatest thing to ever come along to help people stop smoking. Vaping. The flavors people vape are made from Propylene Glycol, not to be confused with ethylene glycol or anti freeze, and Vegetable Glycerin. Both pharmaceutical grade products found in cough syrups and elixirs. These provide the base for flavor FDA approved flavor concentrates to produce the water vapor inhaled by the user. Because these elements are viscus and do not produce the final flavorful vapor until they have time to meld chemically. This process can take up to as long as six weeks if just left to develop naturally. Vigorous shaking shaking over time, with or without heating, can cut steep time to from 24 hours to a couple weeks. However, if a mixture is stirred continuously for 3 to 8 hours, the mixture will meld completely and if it is heated with a 100 watt light bulb, even that time is reduced.

That is the reason I built this stirrer. I will stir batches from 3ml (milliliter) to 100ml with ease. I make smaller batches, so it is ideal for me. Changing the size of the cooling fan can increase it’s stirring capabilities. If your requirement are less demanding, you can make a single unit stirrer by using a smaller project box and installing single controls.

2. What You Will Need

The part to build the single stirrer unit cost less than $20 and can be reduced if you have an old 12 volt adaptor that may have been use to power or charge a tool or toy. Otherwise, making use of eBay, DigiKey, et al will bring the cost to a very reasonable amount. Building the dual stirrer will cost more, but not quite double it. To control cost, be sure to buy from vendors that offer “Free Shipping”. The hardest part of this project, is waiting on the parts to arrive.

I am going to provide the parts list for the dual stirrer unit.

PARTS LIST

1 ea Project Box 200mm x 120mm x 75mm (7 7/8" x 4 3/4" x 2 15/16")

2 ea 60 or 80 cfm computer cooling fans

2 ea Fan speed controls

8ea 12mm x 3mm (round) refrigerator magnets

1 ea terminal strip

1 ea 2mm power connector (female)

2 ea dpst toggle switches

2 ea Green LEDs (5mm) and 2 ea 560 ohm 1/2 watt resistors

1 ea blue panel mount LED (Digikey) 0ptional

20g stranded hookup wire

6 ea rubber feet

2 ea 560 ohm 1/2 watt resistors

12v 1A ac adapter with 2mm male plug (center positive)

Stirrer Bar set

TOOLS & HARDWARE

drill motor

drill set (minimum a 1/4" & a ½" drill)

hot glue gun and glue sticks

soldering iron

thin rosin core solder

soldering flux

clear fingernail polish

8 ea 8-32 x 1 ½" flat head machine screws, nuts, star lock washers, & flat washers.

4ea 8-32 x 3/4" pan head or round head machine screws.

28ea 8-32 hex nuts

12 ea #8 flat washers

4 ea #8 star lock waskers

NICE TO HAVE

shrink tubing

heat gun

When buying things like the CPU cooling fan and the Fan Speed Control,do not buy the first one you see. Continue down the page until you find the best price and Free Shipping. You will find the same piece for $2.14 and $35.00, Keep looking. Also, don’t get frustrated waiting for your purchases to arrive. Some of these things may take 3 weeks, or more, to arrive.

https://www.instructables.com/files/deriv/F1H/JV1V/...

Figure 1 is the fan speed controller. There are different types out there, but, this one works for this project. Figure 2 is the terminal block, It comes with more terminals and you cut off with more terminals and you cut off what you need. Figure 3 is the 2mm power connector. It requires a 7mm or .270" hole for mounting, .270" is a letter drill I (.272") or a 7mm metric drill.

Assembly

With a 1/4" drill, drill two rows of 4 holes each at both ends of the b

ottom of the project box, as seen in the example below.

Using the fan as a pattern, mark the eight holes for mounting the fans and counter sink them on the top side of the top

Layout the holes pattern and drill all holes, including an I letter drill (.272" or 7mm) hole in the lower left corner of the back, 3/4”

3) Layout the holes pattern and drill all holes, including an I letter drill (.272" or 7mm) hole in the lower left corner of the back, 3/4” up from the bottom and 1" over from the left side

4) Using your favorite graphic or label design program, make the decals for the front of the stirrer. I printed mine on plain paper and doped them with clear fingernail polish. After I had them in place, I put another coat of the polish on them to seal the edges and put a final coat on the rest of the decal. An alternate method is to buy wet slip decal paper for your specific type of printer and print your decals on that. I would still seal them with either a decal sealer (from your local hobby shop) or a coat of clear fingernail polish. Put these aside until you are ready to mount all the components. I didn’t and as you may have noticed, I tore one on the left side.

5) On each of the components, solder wires to the terminals that are going to be used in the wiring phase. I recommend putting shrink tubing over each solder junction. Cut the connector off of the end of the fan speed controller and cut the yellow wire off of the fan as close to the fan as you can. This is the tach connection and will not be used.

6) Mount all of the hardware and hot glue the terminal block to the bottom of the project box and hot glue the LEDs in place on the back of the front panel (this is not my favorite part of the job)

Before mounting the fans, hot glue the magnets to the fan hub on the back side of the fan. Start by gluing 2 magnets together with a thin bead of glue along the seam. Now glue the pairs of magnets in place on the fans hubs.

With the magnets in place start mounting the fans by putting the 8-32 x 1 1/2 flathead screws through the hole in the top, from the top, and secure with a flat washer, a lock washer, and 2 hex nuts on each screw (2 nuts provides the space for the magnet to clear the top). Slip the fans over the mounting screws and secure with an 8- 32 hex nut. If your mounting holes are a little off, you may have to loosen the pair of nuts at the top slightly and gently tap the fan in place by tapping om each corner of the fan frame.

7) Wire in accordance with the Block Diagram (Figure 5):

8) When wiring and testing are complete top to the box and put the rubber feet on the bottom.

The LEDs have a long lead & a short lead. The long lead is the positive lead and connects to the Pos + power source.

Figure 5 Block Diagram

The LEDs have a long lead & a short lead. The long lead is the positive lead and connects to the Pos + power source.

Figure 5 Block Diagram

I hope you enjoy your stirrer as much as I enjoy mine. Feel free to add your own touches to the design. I added a flat, panel mount, blue LED on the top deck to indicate power is applied to the unit and I have the parts to add a timer (i.e., hour meter) to time the stir time on a mix. When in use, use the smallest beaker you can to mix in without splashing the liquid out and the largest magnet bar that will fit in the beaker. Small beakers are available on eBay and they are low priced. I bought four 20ml glass beakers for under $5.