DIY - Dosing Basket Funnel

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MB
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#1: Post by MB »

I wanted to make a nice dosing funnel without going to too much trouble. The nice thing about this method is that you can make it exactly the size you want, it can be done with scissors, and it is stable on top of the basket. Here is what I came up with.





It's made from aluminum flashing available from the hardware store. I glued it with JB Weld, and attached little pieces of Sugru I had on hand. (Alternatively you could use those self-adhesive cabinet bumper pads, or silicone caulk mixed with a drop or two of acrylic paint and formed into little balls with wet fingers or something similar.)

I made a paper pattern, cut it out, taped it to the aluminum flashing and cut it out with cheap dollar-store scissors. The pattern dimensions are determined with the Excel formulas below and then created in Word with the drawing tools. (For some reason if I draw it in Excel, the dimensions don't print correctly. It prints elongated.)

To get the dimensions for the circles copy the following into Excel starting in the top left cell (bolded items go in the first column):

Funnel
80.00 Upper Opening Diameter
48.50 Lower Opening Diameter
25.53 Vertical Height
Material Layout (2 centered circles w/ so many degrees marked)
152.38 OD
92.38 ID
189.00 Degrees Used (Layout with more for overlap)

And copy the following into cells A6, A7, and A8 respectively (replacing 152.38, 92.38 and 189.00)
=(SQRT((((A2-A3)/2)^2)+(A4^2)))*2/(1-(+A3/A2))
=((SQRT((((A2-A3)/2)^2)+(A4^2)))*2/(1-(+A3/A2)))-((SQRT((((A2-A3)/2)^2)+(A4^2)))*2)
=((A2*PI())/(((SQRT((((A2-A3)/2)^2)+(A4^2)))*2/(1-(+A3/A2)))*PI()))*360

To use the spreadsheet, you just fill in the first three numbers (how big you want the top opening, bottom opening, and how tall you want it to be.) The example is in millimeters, although you could use any measurements. The last three numbers give you the information to create the pattern.

I draw two circles in Word, double clicking them to size properly to the OD and ID specified on the Excel spreadsheet, and center the smaller one on top of the larger one. (Actually, instead of plain circles, I use the Flowchart circles with the plus sign in the middle to show the centers.) Then I make a vertical straight line a little larger than the radius of the larger circle. Next, I right click it so I can bring up the Format AutoShape dialogue box to rotate it the number of degrees specified on the Excel spreadsheet. Then this line (shown dashed in the picture below) is placed with one end on the center of the circles, so that it corresponds to the degrees around the circle that need to be used for the funnel body. (If you aren't using the flowchart circles, you will need an additional vertical line from the center to the top of the circle to represent the zero degrees line.) Finally, to make a little overlap for gluing, draw an additional line (shown in green below) from the center of the circle to the edge. Make it about 3/4" past the measured degree line for the overlap. This is the line that actually gets cut. It's important to remember to leave the overlap and not to cut the wrong line, so I make the uncut line dashed or mark it somehow. You still need it, so you can mark the aluminum flashing to get the proper overlap and line up the cut edge on it squarely for gluing. If you are doing a larger funnel, you can usually fit the pattern part on the printable area of the page and let the unused portion of the circle run off the edge. Here is an example of what it will look like (with a little shading enhancement for illustration).



I print and cut out one copy of the pattern and tape it together with the overlap. Then check it for size on the portafilter basket. I like mine to fit just inside, but not so much that it would stick into the grounds too much. If it's good, you can untape it and then tape it flat on top of the aluminum flashing with clear/transparent tape. Cutting out the pattern on the aluminum flashing is pretty easy with scissors. I wouldn't recommend using your good scissors though. A little fine sand paper can round off the sharp edges and corners.

I used some JB Weld I had on hand to glue the overlapped ends together and held it with a clamp overnight. I suppose superglue would work too. For alignment, you can place a piece of masking or other thick tape next to the overlap line and then push the cut end up against the tape.

To apply the Sugru, I covered the basket with plastic Saran wrap, placed it on the inverted funnel, and applied the Sugru bits as shown in the photo, so they would grab the basket edges, but still release it easily. I let that cure overnight in place. Next morning it was ready to go. Sugru is a little pricey, and I had one packet left over from another project so that's what I used. It's really great stuff for this application. [EDIT: I realized those little self-adhesive cabinet bumper pads would be easy to obtain and use.] I imagine there are other products such as RTV gasket maker (not flowable) that, if hardened up a bit, could do the job (maybe kind of messy). I have used 100% silicone caulk mixed with a tiny amount of acrylic paint to make molds before. If you mix it up and dump a glob in soapy water it's pretty easy to handle and shape, plus it sets up quickly. As long as it adheres to the funnel, it would be easy to obtain and use. If it didn't adhere well, a little dot of straight silicone to connect the two would probably do the job.

I plan to make a larger funnel that will fit under a Voodoodaddy modded Pharos to catch the grounds directly into the portafilter basket.
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MB (original poster)
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#2: Post by MB (original poster) »

I realized this morning that there is an simple solution to replace the Sugru, and it's readily available at the hardware store, so I edited the above post. Those little self-adhesive cabinet bumpers are cheap, easy to attach and the edge has a good contact angle to the basket rim. I wanted to see if it would easily conform to the rounded surface, and the answer is yes.



Another solution that looks good would be to use 4 Sorbothane hemispheres, 1/2" size, which I found on e-bay for under $7 shipped.
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drgary
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#3: Post by drgary »

Very nice. Thank you for posting this.
Gary
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What I WOULD do for a good cup of coffee!

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weebit_nutty
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#4: Post by weebit_nutty »

Hi guys..

Here's an alternate DIY dosing funnel you can make in about 10 minutes using InstaMorph moldable plastic. BTW, it actually it took me 20 minutes to make for this tutorial.

Anyway if you mess up you can always start over.. :D

Most of pics are self explanatory.

1. Get this product.


2. Use about a table spoon. Put in bowl and pour in boiled water.


3. Mold into a ball and then a long noodle.


4. Grab a funnel and wrap the soft bead it around the funnel roughly at the diameter of the intended basket. Flatten it out. Cool with cold water.
EDIT: Alternatively if you have two funnels that nest together closely, you could probably use both and squish them together for best results. I haven't tried this but I'm perfectly happy with just doing it by hand. It feels like silly putty when soft and very easy to work.. I gently rolled it on the table as it cooled to smooth it out.

5. Grab a pair of scissors and trim the top edge. Then soften the lower edge in the hot water.


6. Place on basket and squish the moldable plastic along the inside. Cool with cold water.


7. Trim lower lip of funnel and check fitment.


All Done!
You're not always right, but when you're right, you're right, right?

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MB (original poster)
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#5: Post by MB (original poster) »

Hey Scott - That's pretty cool. Looks like a fun product. Do I understand right that it can be completely reworked into another object just by putting it in hot water again?
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weebit_nutty
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#6: Post by weebit_nutty »

yup.. that's the beauty of it.. it melts at around 150F. In fact the ball of it in the photo was repurposed from a previous object I made (a button guard for my MyPressi, which I hardly use). I just took the photo of the new pellets for the demonstration.

also, you can buy color pellets if you want to change the color to something a little nicer than the standard off white color.. This material is nontoxic and like many folks, I bought it to make vampire teeth for Halloween.. But I've found far more uses for it since. It's as versatile as sugru (which I love btw) for DIY applications.
You're not always right, but when you're right, you're right, right?

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achipman
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#7: Post by achipman »

That stuff looks really cool... But doesn't it melt in the hot PF?
"Another coffee thing??? I can't keep up with you... next you'll be growing coffee in our back yard." - My wife

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weebit_nutty
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#8: Post by weebit_nutty replying to achipman »


As I said, "around 150F".
You're not always right, but when you're right, you're right, right?

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achipman
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#9: Post by achipman »

I guess I've never checked the exact temperature of my PF... I thought it would be closer to the 200 mark judging by the readiness with which it can burn my hand if I'm not paying attention.
"Another coffee thing??? I can't keep up with you... next you'll be growing coffee in our back yard." - My wife

DanoM
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#10: Post by DanoM »

I just received my formable plastic: InstaMorph

First test was to melt a bit and then form it a little. Looks and reminds me of HDPE plastic: milk jugs and cutting boards. Probably a little less stiff than normal HDPE, but easier to work at lower temps.

I'm sure it will go to good use around here, and the ease of reheating and reshaping is a nice touch. It doesn't melt instantly. The instructions say 140F water for 2 minutes will soften the beads, but perhaps a little hotter would be better to get a full meld of the plastic.

This would probably hold up to the PF heat for a dosing session.
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