3D Printing - whether to buy, what to buy and how to use it?

[Boyblunder]

Wish I had thought of Mick's idea of using water in the ultrasonic cleaner and floating a bag or pot of IPA in it. If I had known that I wouldn't have melted the hinges of John B's US cleaner and had to throw it away..... Anyway on a more positive note I have found this puffer is very useful for starting the drying process of prints, it was from Eileen's I think. Not as good as the compressor in the garage set to 10 psi but safer for tiny things. Follow up with an old hairdryer.

 

[mickoo]

Wish I had thought of Mick's idea of using water in the ultrasonic cleaner and floating a bag or pot of IPA in it. If I had known that I wouldn't have melted the hinges of John B's US cleaner and had to throw it away..... Anyway on a more positive note I have found this puffer is very useful for starting the drying process of prints, it was from Eileen's I think. Not as good as the compressor in the garage set to 10 psi but safer for tiny things. Follow up with an old hairdryer.

View attachment 175384

Robin, I can't take credit for that little US cleaner tip as I read it on here some time ago. It wasn't directly linked to IPA, but to using plain water in the cleaner with a smaller pot holding the part and a cleaning solution to save; especially if you have a big tank like mine.

I just made the jump from US chemical cleaner for brass to IPA for resin.

 

[simond]

A question for those with more scrap making experience than I…. I set the printer off before going to work, I guess this happened after about 30 minutes to an hour.

Any ideas what went wrong here?






it’s curious, it appears that the prints proceeded well up to a given layer, and then somehow split away. This only affected these four parts, not the two tank bodies for which they were to be the ends.

the only factor I’m aware of is that there were four other parts (which also printed fine) the top (or bottom, depending on how you look at it) of which may have coincided with this glitch.

ideas to avoid a repeat very welcome!

cheers
Simon

 

[simond]

On a slightly more optimistic note, I discovered that the FNG resin can be turned happily on my Unimat.

“Why?” I hear cries…

well, following Mick’s earlier advice, I created sacrificial beads around the edge of what I want to be a completely flat joint plane between the tanks and the ends, and I can then chuck the tanks, and turn the sacrificial bit off.



the right-hand part shows the sacrificial bead from the support end, the left is obviously the as-printed end.

 

[Rob R]

Could you post a screenshot of the sliced file arranged on the build plate please?

 

[simond]

And the turning works, this is one of the tanks from the post above, with an older end.



unfortunately the end isn’t so good at the bottom



but we’re clearly getting there. If I can get the ends to print cleanly with their sacrificial beads around the rim, I can sand them off and hopefully get the really nice fit all round that I’ve partially achieved so far.

sliced file images to follow

cheers
Simon

 

[simond]

Rob

as requested





it appears to be around layer 230-240 which is the top of the four cylindrical items (they are the spigots to align the ends with the tank) and coincidentally pretty much the top of the little batch of loco lamps at the rear right too.

I wonder if it was a mistake to print the spigots horizontally. The support surface is horribly rough, but it is inside the tank so does not matter, but perhaps the sudden change in adhesion to the FEP caused the glitch.

atb
Simon

 

[John Baker]

The printing issues with the tank ends are likely to be support issues. I tend to over-support my models, but I'd have supports covering the middle surface of the tank end, as well as just around the edge. The lifting forces are enough to de-laminate the layers if there aren't enough supports attached.
Love the idea of turning the ends to create a flat surface - trying to get a perfect surface where the supports are placed is very much a dark art, if not impossible!

 

[Rob R]

Simon,
I think you have pretty much hit it on the head - not a mistake, just another school day.
There is quite a large flat area there with the 4 spigots which is very likely to upset the FEP, ok if you were just printing them but obviously problematic with this print selection.
I would also agree with John, beef the supports up, large not medium for parts this size. You have lots of non-decorative surfaces to stick supports on, it would be rude not to use them
**As you have some supports missing from that print please filter your resin before the next print - that is a school day you don't want! **
Did you get a bigger bin?

 

[mickoo]

Dont print the flat discs with angled parts, as you suggest....it is the sudden rapid change in peel forces that have caused the failure in other parts I suspect.

 

[simond]

Thanks all.

I’m sure John recognises these parts, he kindly printed & sent me versions 1 & 2 so very long ago. Version 2 were very good, but the idea of trying to get the ends to fit just that bit better got me going, so I had to try again…. Mick’s advice about having flat surfaces that can be sanded down was also taken to heart, as you can see!

Rob, I don’t think any of the supports were lost in the tank (but you never know) but I habitually do a tank clean (15s with all the screen on) and filter the goo as it goes back in the tank. Initially, I hadn’t realised the potential impact, but I’ve worked it out!

I’ll have another go, and just do the ends, not pack the build plate.

more soon!
Simon

 

[Rob R]

Thanks all.

I’m sure John recognises these parts, he kindly printed & sent me versions 1 & 2 so very long ago. Version 2 were very good, but the idea of trying to get the ends to fit just that bit better got me going, so I had to try again…. Mick’s advice about having flat surfaces that can be sanded down was also taken to heart, as you can see!

Rob, I don’t think any of the supports were lost in the tank (but you never know) but I habitually do a tank clean (15s with all the screen on) and filter the goo as it goes back in the tank. Initially, I hadn’t realised the potential impact, but I’ve worked it out!

I’ll have another go, and just do the ends, not pack the build plate.

more soon!
Simon

That's the problem, you can never be sure the missing bits haven't been printed and not broken off and lurking in the vat. It is a bit easier with the transclucent resins bit you can never be 100%.
The last stray I had cost me a new screen...

 

[simond]

There’s nothing even slightly translucent about FNG!

thanks for the warning
Simon

 

[mickoo]

That's the problem, you can never be sure the missing bits haven't been printed and not broken off and lurking in the vat. It is a bit easier with the transclucent resins bit you can never be 100%.
The last stray I had cost me a new screen...

It'd have to be quite a big bit as the Saturn 2 comes with a tempered hardened screen cover, I've got three dings from debris in my current FEP that would have almost certainly cracked an older unprotected screen.

However, good house keeping is always a prudent move.

 

[Rob R]

It'd have to be quite a big bit as the Saturn 2 comes with a tempered hardened screen cover, I've got three dings from debris in my current FEP that would have almost certainly cracked an older unprotected screen.

However, good house keeping is always a prudent move.

My FEP got holed just a few mm from the edge right next to where the power lead feeds the screen. Resin made a bee line for the ribbon cable and wicked into the screen. Didnt kill it, just left a few dead lines right across the screen.
On the plus side the screen is fairly easy to replace.

 

[Arun Sharma]

As Mickoo says, the Saturn series of printers not only have toughened screens, they have large build platforms. Apart from some very large battleship parts for HMS Vanguard which might need to be done on an industrial FDM printer, the large Saturn S build surface allows the side of a 30ft bus to be printed in 7mm scale to a quality indistinguisable from that of a commercial SLA print. The phrase 'Economies of Scale' takes on a whole new meaning!

 

[simond]

A general question, does anyone know if there’s an optimum post-print UV curing time?

my experience so far is that prints come off the plate a little soft, “green”, and are much crisper, harder and presumably more brittle after curing.

but is it possible to overcook things?

and if so, how do you know when to stop?

cheers
Simon

 

[Rob R]

A general question, does anyone know if there’s an optimum post-print UV curing time?

my experience so far is that prints come off the plate a little soft, “green”, and are much crisper, harder and presumably more brittle after curing.

but is it possible to overcook things?

and if so, how do you know when to stop?

cheers
Simon

Trial and error. Hopefully not too much of the latter.
Curing is an exothermic process, the first wagon I did had 5 minutes in the Elegoo Mercury and was almost too hot to handle as well as warping all over.
Put everything in a jam jar of corporation pop and give it short bursts of 30 -60 seconds for 2 to 3 minutes. If we ever get any sunlight back you can then put the bits on a window ledge to dry off and finish curing in natural uv
For grey resins, if it looks matt it's probably not far off done.
Have fun.

 

[mickoo]

For FNG I stick everything in the Form UV chamber with the heater off for 30 mins, probably way over done but if it's going to fail then better to fail in the UV chamber than on the model months later.

I've heard 2-3 mins is normal but mine still feel slightly 'green' hence the long cook.

 

[simond]

Thanks guys, my guesstimate of 7 minutes isn’t daft then.

I’m using FNG, and in general quite thin sections, so cooking from the inside out hadn’t been an issue so far.