@axellarcos_458491 its struggling a little at really fine grinds but a lot easier than the piston method in use. Some air is escaping at the rim so might be i need to tweak tolerances or seal it. I was thinking a conical bellow with TPU printed on a PLA top and bottom would be worth a try if/when I get time. Many thanks for posting the design , wanted to test single dosing before going the whole hog!
oh and its not the volume i think - its the seal and or simply air flow through the grinder on fine settings. My internal setting is on 1 , when i grind on the external setting at 10 it works fine, at 5 it struggles.
@Chris_59574 I could potentially increase the rigidity around the rim to avoid it moving around and causing a break in the seal. But having an air tight seal could also be a problem because it could pull air in through the hole where grinds come out and potentially suck grind back in. Maybe a one way valve at the top of the bellows would solve that? I'm not sure how to design that though
@axellarcos_458491 given its pushing grounds into the open air doubt backflow is much of an issue as the grounds should fall well below the indraft but could use a couple of TPU flaps slanted together in the top. I was thinking of printing TPU between rigid PLA collars in one print with filament change and could get a lidded bellows style but simply thicker TPU collars would be a lot easier print! Good thinking :). Am flat out at the moment but will have a play over the break period. Its only a issue with much finer grinds at all though and its completing with budget single dose grinders happily enough it seems
@Chris_59574 I'm currently printing a new version with a thicker collar around the lip that goes into the funnel. This is mostly for stability but it could also help with getting a better seal. I'll let you know once I've tested it and will upload as soon as I know it works good. (edited)
@Chris_59574 I uploaded a new version with a thicker lip and longer inner lip. That should give it a bit more stability when pushing down. Give it a try and let me know how it works out.
I did use the parameters as described in the details section using my MK3s+. My printer wasn't getting good results when printing faster, so I had to slow it down.
The result is strong, very flexible and hasn't torn on me in a few months of use.
@Chris_59574 I printed the first one at 78% and it was loose as you describe. After measuring the bellows model and the single-doser for the Smart Grinder I determined it needs to be printed at 80% and after doing so it was much better.
Printed at 78% to go with a sage smart grinder conversion: https://www.printables.com/model/309061-sage-breville-the-smart-grinder-pro-single-dose-ho
@Chris_59574 I'm glad it worked out for you! Let me know if it moves enough air to push out all the grounds?
@axellarcos_458491 its struggling a little at really fine grinds but a lot easier than the piston method in use. Some air is escaping at the rim so might be i need to tweak tolerances or seal it. I was thinking a conical bellow with TPU printed on a PLA top and bottom would be worth a try if/when I get time. Many thanks for posting the design , wanted to test single dosing before going the whole hog!
oh and its not the volume i think - its the seal and or simply air flow through the grinder on fine settings. My internal setting is on 1 , when i grind on the external setting at 10 it works fine, at 5 it struggles.
@Chris_59574 I could potentially increase the rigidity around the rim to avoid it moving around and causing a break in the seal. But having an air tight seal could also be a problem because it could pull air in through the hole where grinds come out and potentially suck grind back in. Maybe a one way valve at the top of the bellows would solve that? I'm not sure how to design that though
@axellarcos_458491 given its pushing grounds into the open air doubt backflow is much of an issue as the grounds should fall well below the indraft but could use a couple of TPU flaps slanted together in the top. I was thinking of printing TPU between rigid PLA collars in one print with filament change and could get a lidded bellows style but simply thicker TPU collars would be a lot easier print! Good thinking :). Am flat out at the moment but will have a play over the break period. Its only a issue with much finer grinds at all though and its completing with budget single dose grinders happily enough it seems
@Chris_59574 I'm currently printing a new version with a thicker collar around the lip that goes into the funnel. This is mostly for stability but it could also help with getting a better seal. I'll let you know once I've tested it and will upload as soon as I know it works good. (edited)
@Chris_59574 I uploaded a new version with a thicker lip and longer inner lip. That should give it a bit more stability when pushing down. Give it a try and let me know how it works out.
@axellarcos_458491 many thanks - my first one just split so running it off today
@Chris_59574 yes that works really nicely on t he smart pro at 80%
@Chris_59574 Hi ! Thanks for sharing !
Can I know the shore hardness of the TPU used to print this part?
Thanks :)
@Titi_1774416 I used this filament: OVERTURE TPU Filament 1.75mm Flexible TPU Roll, 95A Soft 3D Printer Filament
@axellarcos_458491 Great, thanks !
And did you respect all the printing parameters in the details section?
Is the bellows flexible enough ?
@Titi_1774416 No problem.
I did use the parameters as described in the details section using my MK3s+. My printer wasn't getting good results when printing faster, so I had to slow it down.
The result is strong, very flexible and hasn't torn on me in a few months of use.
@Titi_1774416 very old TPU ! Let me see if i can find it on the roll
@axellarcos_458491 Thanks !!!
@Chris_59574 I printed the first one at 78% and it was loose as you describe. After measuring the bellows model and the single-doser for the Smart Grinder I determined it needs to be printed at 80% and after doing so it was much better.