Thread: Bell mouth 3D printing models

Peters files are here
Printables

Thread that link comes from is here.
3D Printed Dust Collection Parts.

Spurred on by this thread I just knocked up the OPEN SCAD file to generate BMHs.

Screen Shot 2022-08-03 at 7.14.39 pm.png Screen Shot 2022-08-03 at 7.15.23 pm.png

Code suits any length, pipe radius, and wall thickness and tightness of taper fit of pipe ID.
This means they can be made to go over duct or flex.

Radius of curvature of lip is directly tied to the pipe radius.
This keeps the BMH compact which is generally less obtrusive around machinery.

Next step is to offer a threaded flex connection.
If anyone wants the prototype STL files for the 100 and 150 mm pipe send me a PM as the forums can't handle these files.
There's no guarantee they will actually fit your pipe - you may have to tickle the printer scale up or down to get a tight fit.


For anyone interested in SCAD this is the code
$fn = 100;
piperadius= 80.125; // ID radius of pipe atteched to hood
idradiuspipe=piperadius; // Redundant maybe for some future thingo
wallt=3; // wWallthickness
rcurvebmh=idradiuspipe/2; // Radius of curvature of BMH lip
pipelength=50; // Length of pipe behind hood
taper=0.15; // Extent of taper of pipe
rotate_extrude(convexity = 20){
translate([idradiuspipe*1.5, 0, 0])
difference(){ // forms BMH lip
circle(r = rcurvebmh);
circle(r = (rcurvebmh-wallt));
translate([-rcurvebmh, 0, 0])
square([rcurvebmh*2,rcurvebmh*2]);
translate ([0, -rcurvebmh*2, 0])
square([2*rcurvebmh,2*rcurvebmh]);
}
}
difference (){ // generate pipe behind the BMH lip
cylinder(h=pipelength, r=idradiuspipe+wallt);
cylinder(h=pipelength, r1=idradiuspipe-taper, r2=idradiuspipe+taper);
}

Bob I don't have a printer or know how to use one but wonder if the file can be modified to make the flange bigger for mounting to machine cabinets. Or would a different file have to be created? I suppose one could drill the holes or have the printer make them. It could be useful to others, me only if I could find someone with a printer.

Pete

Originally Posted by QC Inspector

Bob I don't have a printer or know how to use one but wonder if the file can be modified to make the flange bigger for mounting to machine cabinets. Or would a different file have to be created? I suppose one could drill the holes or have the printer make them. It could be useful to others, me only if I could find someone with a printer.

Pete

Yep - no probs - all sorts of mods are up for consideration.

I assume you mean like this.
I have exaggerated the flange width a bit.
Can add holes and appropriate cutaways as required to suit ports in corners etc.
Screen Shot 2022-08-04 at 5.57.02 am.png

Cutaways are easy to program but can of course also be cut with a BS
Screen Shot 2022-08-04 at 6.15.25 am.png Screen Shot 2022-08-04 at 6.28.00 am.png

I think those are pretty cool and the type of thing I was asking about.
How hard would it be to make the mounting flange set back the thickness of the sheet metal in a cabinet, say 1mm, to have a smooth transition into the bell mouth? I realize it wouldn't amount to a lot of increased efficiency given the other things in a machine but if one is doing it, might as well go all the way.

Maybe I should get a printer.

Pete

Like this?
Screen Shot 2022-08-04 at 6.53.46 am.png

Originally Posted by QC Inspector

Maybe I should get a printer.

If you decide to get one make sure the bed is big enough to print these hoods in one piece.

For a 150 mm BHM to fit over a 150mm pipe the ID of the flange needs to be 160mm, this means a BMH of 160 + 80 in diameter, Then add 20 mm for a flange and you are looking at 280 mm. A 300mm printer be d would be a minimum size to get, 400mm would be better.

That's it exactly Bob. Thanks. I didn't mean for you to spend your time making bell mouth port drawing files when you could have actually done some of the things you need.

The biggest obstacle for me is I don't find working in Cad to be enjoyable or instinctive. I've thought about going to one of those makers space places that have the CNC and 3D printers among other things but the cost per hour makes anything you create very expensive.

Pete

Originally Posted by QC Inspector

That's it exactly Bob. Thanks. I didn't mean for you to spend your time making bell mouth port drawing files when you could have actually done some of the things you need.

Some things that appear difficult can be just two more lines of simple code, and of course VV!

The biggest obstacle for me is I don't find working in Cad to be enjoyable or instinctive. I've thought about going to one of those makers space places that have the CNC and 3D printers among other things but the cost per hour makes anything you create very expensive.

Over the years I've tried a few different CAD packages (FreeCad, Fusion360/Auto CAD Tinker CAD and a few others) but eventually tried OPEN SCAD and found suits my maths background and experience with programmer. It's not quite as fancy or as WYSIWYG as the others but for old school programmers, once you get the hang of it, its very fast and surprisingly flexible.

A few weeks ago SWMBO had a go at me for losing the inner part of our 40+ year old Tupperware Crisp-it Lettuce keeper.
We actually have 3 of these lettuce keepers and no inserts for any off them,

Whenever we lose anything it's always my fault so hoping to fob her off I said I would 3D print one for her.
A few days later while doing a bunch of other stuff I programmed the gizmo in about ~15 minutes.
Printing took a couple of hours, only because I wasn't in a hurry and couldn't be bothered to optimise the printing speed.

It's printed in PETG material so should be food safe.
Crispot1.jpgCrispit2.jpg

This option should have been easy but to make it work took me about an hour - had to redefine a bunch of variables.
It's to enable a BMH to be installed right into a corner of a machine cabinet.
The vertical corner flaps seal the gap that opens up on the edge of the BMH from making any cutaways so close to the BMH lip.

Screen Shot 2022-08-05 at 5.32.35 pm.pngScreen Shot 2022-08-05 at 5.32.48 pm.png

I'm printing one of these at the moment. Thanks Bob