Thread: 3d Printed Bellmouth

Did a few of these myself - not quite as beefy as yours. I like the extra curve on the mouth.

Interested to see how you get on without supports.

6inch BMH printed.jpg. 6inch BMH.jpg

Good effort BM.

FWIW I reckon the backward curving very outer lip is not worth worrying about as it adds very little additional flow and can get in the way of getting the hood close to the dust source (closer is better, especially for chips). You might also find you can then print the hood in fewer pieces.

How long to print, and how many $$ worth of filament do you reckon it costs?

Originally Posted by BobL

Good effort BM.

FWIW I reckon the backward curving very outer lip is not worth worrying about as it adds very little additional flow and can get in the way of getting the hood close to the dust source (closer is better, especially for chips). You might also find you can then print the hood in fewer pieces.

How long to print, and how many $$ worth of filament do you reckon it costs?

Thanks Bob, I figured the curve would give me a lot stronger structure in what is a pretty light part (and it looks good after all!) - I take your point about chips - will be designing specific parts (eventually) for places where that is an issue - hopefully not something I'll see on the sander.

Printing time is trivial for "print guys" - you just set and forget, four (or six times) and let the printer get on with it while you do something else, but total print time was about 30 hours over two days.

Total filament used is around 450gms. I use top shelf PLA (because either I'm mad, or I am willing to pay more for an easy result) - about $40.00 per kilo.

So this cost about - $18.00.

I had intended to flop them out in fibreglass, but the cost would have been at least four times that!

Originally Posted by Bernmc

Did a few of these myself - not quite as beefy as yours. I like the extra curve on the mouth.

Originally Posted by Bernmc

Interested to see how you get on without supports.
​. ​

Thanks, no supports is a doddle as it turns out (@ 6 pieces) and gives perfect prints "on side". They are pretty light though - two perimeters and 15% infill, so the curve does add a lot of stability when printing and rigidity after gluing.

Cheers,

P

ye gods - half a kilo of filament?! That's a monster print.

Originally Posted by Bernmc

ye gods - half a kilo of filament?! That's a monster print.

That's TOTAL of course! Doesn't take long to go through a kilo of filament in this household... OK it takes a week, but you know what I'm saying!

Originally Posted by bitingmidge

Thanks Bob, I figured the curve would give me a lot stronger structure in what is a pretty light part (and it looks good after all!) - I take your point about chips - will be designing specific parts (eventually) for places where that is an issue - hopefully not something I'll see on the sander.

For disc sander I found the following setup extracts better than a BMH although not all sanders have enough space around them to do this.
It works surpriinbingly well even with 4" ducting because the sawdust collection is within cm of the dust production of dust and follows the direction of rotation of the disc.
discport.jpg

Printing time is trivial for "print guys" - you just set and forget, four (or six times) and let the printer get on with it while you do something else, but total print time was about 30 hours over two days.

Set and forget is good but overall I guessed it was going to take a while. I was thinking more of someone like me who gets orders for half a dozen BMHs at a time. I can make these out of PVC in pottering mode in about an hour.

Total filament used is around 450gms. I use top shelf PLA (because either I'm mad, or I am willing to pay more for an easy result) - about $40.00 per kilo. So this cost about - $18.00.

I got my son (he has 3, 3D printers) to look into this a couple of years back and I seem to recall he said something like $15. Again I was thinking of my situation. The PVC I use for the ones I make are <$1 a piece.

I had intended to flop them out in fibreglass, but the cost would have been at least four times that!

Ouch!

Don't get me wrong I still think 3D printing is worth pursuing, someone has to lead the way.

Originally Posted by BobL

Don't get me wrong I still think 3D printing is worth pursuing, someone has to lead the way.

It's definitely not the best method of production of something of this size - great for prototyping or for a 3d printing hobbyist, and hopefully you'll see a few more fittings over coming months, but if you were to pay commercial rates... ouch! ( I think officeworks are charging something like $12 per hour. You could buy a basic printer for the cost of having one of these printed there!)

While I'm happy to fiddle, there's no suggestion that performance in real life is any better than your $1 pvc. Actually there's plenty to suggest it, but it's a bit like so many other things today, will that last 0.2% improvement really make a difference to your life? Nah... but it does look good!

That's an impressive fitting. You certainly have a flair for design.

I don't see any locating features like Bernmc has. How do you keep things aligned during glue up? What adhesive are you using?

Originally Posted by dmorse

That's an impressive fitting. You certainly have a flair for design.

I don't see any locating features like Bernmc has. How do you keep things aligned during glue up? What adhesive are you using?

Thanks Dave, I didn't even need any locating pins - the print is very true. I just gave the mating edges a quick sand with 240 grit, and used a little thickened CA glue. Since they are perfect mating surfaces, I didn't even bother with tape or clamps, just held them together in place for a few minutes (our ambient temperature is 27°C so it goes off pretty quickly).

As the glue starts to cure, there's a teeny window of opportunity to massage them into place if they've slipped a tiny bit. In reality it's a lot easier than one would think.

Cheers,

P

Originally Posted by bitingmidge

Thanks Dave, I didn't even need any locating pins - the print is very true. I just gave the mating edges a quick sand with 240 grit, and used a little thickened CA glue. Since they are perfect mating surfaces, I didn't even bother with tape or clamps, just held them together in place for a few minutes (our ambient temperature is 27°C so it goes off pretty quickly).

As the glue starts to cure, there's a teeny window of opportunity to massage them into place if they've slipped a tiny bit. In reality it's a lot easier than one would think.

Cheers,

P

Good to know. I wouldn't have expected the angled surface to be smooth enough for good bonding with CA. Time for a few tests.

What layer height are you using?

Originally Posted by dmorse

Good to know. I wouldn't have expected the angled surface to be smooth enough for good bonding with CA. Time for a few tests.

What layer height are you using?

Remember THICKENED CA not the runny stuff - it has minor gap filling properties, so it is pretty handy. A light sand may not be necessary, but it works for me.

I'm using .20 mm layer height and a .4mm nozzle - on Prusa Slicer set to 20mm "Quality", two perimeters and 15% infill, the mating surfaces are 7mm wide which gives plenty of glueing area, and not much plastic between the outer skins.

I know there are faster/ stronger/ more efficient ways of doing this - but I wanted a smooth(ish) finish, and there's only a couple of hours printing difference. If a print is going to run all day, an hour or two doesn't mean anything to me if the end result is a nicer finish.

Cheers,
P

Originally Posted by bitingmidge

Remember THICKENED CA not the runny stuff - it has minor gap filling properties, so it is pretty handy. A light sand may not be necessary, but it works for me.

I'm using .20 mm layer height and a .4mm nozzle - on Prusa Slicer set to 20mm "Quality", two perimeters and 15% infill, the mating surfaces are 7mm wide which gives plenty of glueing area, and not much plastic between the outer skins.

I know there are faster/ stronger/ more efficient ways of doing this - but I wanted a smooth(ish) finish, and there's only a couple of hours printing difference. If a print is going to run all day, an hour or two doesn't mean anything to me if the end result is a nicer finish.

Cheers,
P

CA glue is the recommended and preferred glue for PLA and you likely have a solid joint, alignment tabs etc may make it easier but 7mm is pretty wide anyway for the edge glue.

The pain of glueing PLA is one of the reasons i nearly exclusively print that require joining in ABS.

Not sure if you know that you can buy PLA/ABS and now PETG in bulk spools direct from a manufacturer
here's the page for the PLA Aurarum PLA bulk spool 2-5kg (ch FDM / SLA / DLP 3D printing resin / filament

I buy my ABS from them in 5kg spools now mainly for the convenience of not constantly changing spools.

Originally Posted by Aussiephil

Not sure if you know that you can buy PLA/ABS and now PETG in bulk spools direct from a manufacturer
here's the page for the PLA Aurarum PLA bulk spool 2-5kg (ch FDM / SLA / DLP 3D printing resin / filament.

Thanks for that - I have been waiting for my stock to dwindle a bit to give Aurarum a crack, but haven't had any feedback on the product so have been a bit tentative, having seen what "cheap" filament can produce! Obviously if you are buying in bulk it must be OK!

I've been using Prusament and Filament-PM from Czechia because it costs about the same delivered as the other premium brands (as long as you find the freight "sweet spot") and it's been printing flawlessly, but I like the thought of buying locally.

Haven't thought about ABS (nor what I might use it for) but I suppose I really should grow up one day!)

Cheers,

P

Originally Posted by bitingmidge

Thanks for that - I have been waiting for my stock to dwindle a bit to give Aurarum a crack, but haven't had any feedback on the product so have been a bit tentative, having seen what "cheap" filament can produce! Obviously if you are buying in bulk it must be OK!

I've been using Prusament and Filament-PM from Czechia because it costs about the same delivered as the other premium brands (as long as you find the freight "sweet spot") and it's been printing flawlessly, but I like the thought of buying locally.

Haven't thought about ABS (nor what I might use it for) but I suppose I really should grow up one day!)

Cheers,

P

I haven't used their PLA at all as any PLA i have is eSun for use with the very large Delta i have that hasn't been used for a number of years now, just repaired all the carriages on it last couple months.

I'd buy a couple of 1kg rolls of PLA to test out expecting to do some tuning for temperatures used at least.

My experience as far as the ABS goes has been positive
I used probably close to 100Kg of the Auramum natural ABS in 12 months printing around 9k C9 shape led covers for xmas lights and maybe got one bad roll where size wasn't consistent and they replaced that on the next order. i refuse to buy the clear from them as it doesn't behave well but all colours i've tried have seemed fine.

Size consistency has been good enough over the years i never measure it unless it feels thinner, meaning a nearly never change my slicer settings i'm into my 4th 5kg roll since the middle of the year so haven't printed a lot this year

ABS though does really demand a heated enclosure and my Flash forge pro is now sealed enough that just via the print bed i maintain around 45c in the chamber.

Glueing ABS is done with acetone/abs mix and the resultant joint is just pure abs once the acetone evaporates.

My large Delta printer could print those bell mouths as a single unit as it has around 500mm effective print diameter on the 600mm round plate