I have been working on this project off and on for a few years now. I hope to learn a lot out of this. Not super keen with all of the terminology out there so simple is best I started out a couple of years ago with Sketch Up and free cad then got my Prusa MK2 3d printer for prototyping the part. I’ve since acquired an Xcarve for my wood working projects. I enjoy the automated production machines. Anyways, so this part can be inserted into bottle. The smaller diameter hole is for air and the other is for fluid. Tubing can or will be inserted and removed at times into this smaller diameter opening and will have to be absolutely leak free or the purpose for the whole project will be lost. If the bottle is turned upside down for an extended period of time, the fluid absolutely cannot enter the air hole. The tubing may come into slight contact with the inside of a bottle which will exert a lateral force, but should be minimal.
So, I am looking at 3 or so o-rings to provide a rod seal between the part and the tubing that will be inserted into the part. The OD of the inserted tube will be 3mm with thin walls. I have plugged numbers in Apple Rubbers calculator and designed the o-ring grooves according to their range of acceptable stretch, squeeze and volume fill. I would like to hear what is a good number to look for if possible.The bore for the rod is currently sized at 3.1mm.
I’m not sure what all info someone would need to help me make a decision on what would the best sized o-ring for my application. This part could be used in a food safe environment as well and I’d prefer if orings didn’t slip into someone’s mouth! . I am looking at a silicone o-ring with about a 1mm c/s on the Apple Rubber site. I could get the numbers from there if needed. Space in the design is limited, so wall thicknesses have to be taken into account. Btw, what is a good wall thickness for injection molded Polypropylene? Anyone recommend a different material? Just needs to be food safe and not affect taste.
I really appreciate anyone’s help with this and will try to provide as much info as I can. Are orings the best solution? Is there a better type seal to consider? I have thought about having stainless tubing, with appropriate sized wall thickness, milled for orings and make a piston type seal. This would simplify the injection molded part by turning the air hole into a smooth bore, cutting costs. Any suggestions going the piston seal route?
Another was a stepped grommet.
So many question! Thanks for anyone willing to try to help! I have a screen shot of the part so far.
So, I am looking at 3 or so o-rings to provide a rod seal between the part and the tubing that will be inserted into the part. The OD of the inserted tube will be 3mm with thin walls. I have plugged numbers in Apple Rubbers calculator and designed the o-ring grooves according to their range of acceptable stretch, squeeze and volume fill. I would like to hear what is a good number to look for if possible.The bore for the rod is currently sized at 3.1mm.
I’m not sure what all info someone would need to help me make a decision on what would the best sized o-ring for my application. This part could be used in a food safe environment as well and I’d prefer if orings didn’t slip into someone’s mouth! . I am looking at a silicone o-ring with about a 1mm c/s on the Apple Rubber site. I could get the numbers from there if needed. Space in the design is limited, so wall thicknesses have to be taken into account. Btw, what is a good wall thickness for injection molded Polypropylene? Anyone recommend a different material? Just needs to be food safe and not affect taste.
I really appreciate anyone’s help with this and will try to provide as much info as I can. Are orings the best solution? Is there a better type seal to consider? I have thought about having stainless tubing, with appropriate sized wall thickness, milled for orings and make a piston type seal. This would simplify the injection molded part by turning the air hole into a smooth bore, cutting costs. Any suggestions going the piston seal route?
Another was a stepped grommet.
So many question! Thanks for anyone willing to try to help! I have a screen shot of the part so far.
Last edited:
