UV light failing?

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philipy
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UV light failing?

Post by philipy » Sun Jan 09, 2022 10:46 am

A couple of years back when I first got my resin printer, I bought a small and cheap UV light to cure the prints. It's been fine until recently, when I found that even leaving prints under it overnight, they are still sticky in the morning. I thought perhaps it was the resin getting old, but I opened a brand new bottle yesterday and found the same thing this morning, so I'm thinking perhaps the light is past it. I know that back in the day, when I was responsible for getting UV flying insect killers installed, the manufacturers used to say that the UV tubes need to be replaced every 12 months, so I'm wondering if the same thing might apply here ( although of course my UV light isn't on 24/7).
Anyone got any thoughts or experience?
Philip

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Re: UV light failing?

Post by Peter Butler » Sun Jan 09, 2022 11:41 am

Philip, I know nothing about this problem but it aroused my interest so I searched Google for an answer....

https://www.americanaquariumproducts.co ... oting.html

It seems to be related to a variety of bulbs/lamps etc. and not only American (as in the title). There are several other links shown there too. Hope this helps.
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Re: UV light failing?

Post by philipy » Sun Jan 09, 2022 11:54 am

Thanks Peter.
That seems to confirm what I had remembered from days gone by, that the bulbs are only good for 6-12 months of continuous use. Obviously sterilising aquarium water is more critical than curing a resin print and as I said mine isn't on 24/7, but then again it was only a cheap unit from Amazon/ebay ( can't remember which now), so may not have been top quality to start with.
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Re: UV light failing?

Post by GTB » Sun Jan 09, 2022 12:17 pm

philipy wrote: Sun Jan 09, 2022 10:46 am I know that back in the day, when I was responsible for getting UV flying insect killers installed, the manufacturers used to say that the UV tubes need to be replaced every 12 months, so I'm wondering if the same thing might apply here ( although of course my UV light isn't on 24/7).
Anyone got any thoughts or experience?
There are different designs, but the cheapest/simplest UV light is basically just a fluoro tube without the phosphor coating. White LEDs are actually UV-LEDs with a white phosphor, so I guess there are also UV-LED bulbs around now.

The output of any light bulb reduces as they age. Can't remember the numbers for fluoros, but there were thousands of the things in the place where I worked and when the sparkies went through and replaced the dead and flickering ones, the difference in output between old and new tubes was very obvious.

If I recall correctly, fluoro tubes deteriorate faster if turned on and off frequently, than if they are left on for extended periods.

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Re: UV light failing?

Post by GTB » Mon Jan 10, 2022 12:05 pm

Peter's post jogged loose a memory of something else that may be relevant to the problem.......

UV lamps have fairly narrow wavelength ranges and with resin printers being sold for consumer use, they probably use a less dangerous UV band than that needed to disinfect water.

It would be worth checking what wavelength of UV light your acrylic resin requires and check that the lamp works at that wavelength.

If this lamp worked before it was probably near enough, but that may not be the case with another type.

Graeme

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Re: UV light failing?

Post by philipy » Mon Jan 10, 2022 1:36 pm

GTB wrote: Mon Jan 10, 2022 12:05 pm Peter's post jogged loose a memory of something else that may be relevant to the problem.......

UV lamps have fairly narrow wavelength ranges and with resin printers being sold for consumer use, they probably use a less dangerous UV band than that needed to disinfect water.

It would be worth checking what wavelength of UV light your acrylic resin requires and check that the lamp works at that wavelength.

If this lamp worked before it was probably near enough, but that may not be the case with another type.

Graeme
Thanks Graeme. Yes, the standard wavelength for printer resin is 405nm. 405 and 365nm are commonly available in small units, which is what I bought, but I can't now remember which. However it has been working until recently so I assume (!) that it was 405nm to begin with athough I suspect that it is now just a pretty purple light.
Anyway, Mr Amazon is currently somewhere between Northampton and here with a new unit which is sold by the Sunlu resin brand for resin curing, so hopefully that will solve the problem ( or show me that the problem is actually with the resin not he UV!).
Philip

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Re: UV light failing?

Post by philipy » Wed Jan 26, 2022 6:10 am

I think I may have accidentally found the answer to my sticky problem, which might be worth other folk bearing in mind, just in case.

Over on my threads about the contractors loco, I started by using grey resin, just because that was the bottle I happened to have opened already. Most of the early prints had a degree of stickiness which eventually disappeared and there were some small surface blobs of whitish material, which I thought might be associated with the grey pigment in the resin. Later on, I changed to black resin to do the wheels and the various underframe bits, just because any worn paintwork in the future would chip to show black underneath. These black prints also came out slightly sticky and also with some glossy surface areas. However by the time I got to the roof sheets the stickyness had got ridiculous and even after a full 24 hours under a UV light they were still as sticky as though they were fresh from the printer and had never been washed at all.

Since I also had the problems with the roof sheets losing their detail, which I've gone into on another thread, I decided to go back to square one. I cleaned everything meticulously, including washing out and refilling my IPA wash pot, and reset the printer's leveling and zero. Two things happened (1) the prints failed even worse than before ( different story to which I don't yet have an answer), and (2) when I washed the fresh grey prints in new IPA, black stringy bits appeared from nowhere and stuck like YKW-to-a-blanket, on the print surfaces.
Eventually it dawned on me that these were traces of black resin which had stayed trapped on the edges of the plastic mesh of the wash basket and were now being released and reacting with the grey resin in the fresh IPA. If that's the case then I think my earlier sticky problems were also to do with the inadvertant mixing of the two resins in the wash pot.

For info, the resins I have always used are Anycubic brand, with one exception...the Black, which is, "Monoprice Rapid UV 3D Printer Resin - 500ml - Black Compatible With All UV Resin Printers DLP, Laser, or LCD ". I only got it because having seen the results that Jerry Irwin got with his FR couplings, I asked him which resin he used and this is what he told me. I'm guessing now that the chemistry of the Anycubic resins is not compatible with this other one, and even trace amounts cause a reaction.

I think in future I'll stick to one brand.
Philip

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Re: UV light failing?

Post by ge_rik » Wed Jan 26, 2022 7:53 am

Interesting and useful info, Philip. Thanks.

I've only ever used AnyCubic resin so not had that sort of issue as yet.

The only problem I've had is some prints sticking to the base of the tank. I've not yet found a solution to this but it looks like spraying the base with PTFE spray helps. Just awaiting delivery of a spray.

Has anyone else had this problem?

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Re: UV light failing?

Post by philipy » Wed Jan 26, 2022 8:42 am

Funnily enough, thats the other problem that I mentioned in my earlier post. :)
I have had it in the past but not for a long time until yesterday! It occurred yesterday after I relevelled and rezero'd the plate. I suspect that the zero isn't quite right and the first layer is a minute fraction below the plate. Close enough to stick for a few layers but then when the weight starts to build up it detaches from the plate and sits on the bottom then every time the plate lowers it simply tries to refuse the lowest layer ie the same layer each time, and sticks hard.

Just my theory, but it makes sense to me. :roll:
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Re: UV light failing?

Post by GTB » Wed Jan 26, 2022 11:18 am

philipy wrote: Wed Jan 26, 2022 6:10 am For info, the resins I have always used are Anycubic brand, with one exception...the Black, which is, "Monoprice Rapid UV 3D Printer Resin - 500ml - Black Compatible With All UV Resin Printers DLP, Laser, or LCD ". I only got it because having seen the results that Jerry Irwin got with his FR couplings, I asked him which resin he used and this is what he told me. I'm guessing now that the chemistry of the Anycubic resins is not compatible with this other one, and even trace amounts cause a reaction.

I think in future I'll stick to one brand.
Like the old Mortein ad used in Aust. says 'When you're on a good thing, stick to it'. ;)

Anycubic list six different resins and don't make the SDS easily available, so it's difficult to work out what they are..... The one SDS I found suggests Anycubic use a different acrylic resin to the one in Monoprice Rapid UV resin.

The description 'Compatible with all UV resin printers, DLP, laser, or LCD' most likely just means they are all formulated to polymerise at the same UV wavelength and the power level of the average consumer grade printer.

Things that could go wrong chemically.......

- Something in one of the resins may inhibit the polymerisation reaction of the other. Think of the way some modelling clays can inhibit silicone rubber from curing.

- The solvents in the resins may not be fully miscible. Think mixing enamel paint and acrylic paint.

- One of the resin formulations may not fully dissolve in IPA, leaving residues on surfaces after cleaning.

You may need a better cleaning solvent, but it should be listed in the manufacturers instructions, assuming you get any.

I assume you are using IPA to refer to Iso-Propyl Alcohol, as Indian Pale Ale is an even weaker solvent than iso-propanol........

Graeme

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Re: UV light failing?

Post by ge_rik » Wed Jan 26, 2022 12:23 pm

philipy wrote: Wed Jan 26, 2022 8:42 am Funnily enough, thats the other problem that I mentioned in my earlier post. :)
I have had it in the past but not for a long time until yesterday! It occurred yesterday after I relevelled and rezero'd the plate. I suspect that the zero isn't quite right and the first layer is a minute fraction below the plate. Close enough to stick for a few layers but then when the weight starts to build up it detaches from the plate and sits on the bottom then every time the plate lowers it simply tries to refuse the lowest layer ie the same layer each time, and sticks hard.

Just my theory, but it makes sense to me. :roll:
The odd thing is that I printed four items of similar size and shape. The four items were in a row, side by side. Two stuck to the base and two didn't. What makes it slightly baffling is that they alternated; stuck, not stuck, stuck, not stuck .... :dontknow:

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Re: UV light failing?

Post by philipy » Wed Jan 26, 2022 12:48 pm

ge_rik wrote: Wed Jan 26, 2022 12:23 pm
The odd thing is that I printed four items of similar size and shape. The four items were in a row, side by side. Two stuck to the base and two didn't. What makes it slightly baffling is that they alternated; stuck, not stuck, stuck, not stuck .... :dontknow:
I've had that, to the point that I no longer try to do it. Even if I want four identical items I always print them individually. I've tried grouping them together in sketchup and then stl the whole lot as one and then put them into Chitubox as one. I've taken one from SU and put it into Chitubox and multiplied it, I've made sure to click the 'put on plate' button but usually it is only the original one that prints and not the clones. No idea why, but I think it must be something that the slicer misses somehow, or a minute difference in the base z height.
Philip

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Re: UV light failing?

Post by Mamod sterling » Fri Sep 23, 2022 8:27 pm

Folks,

Digging up this old thread, but probably worth it.

I do quite a lot of 'resin' printing, and found the best all rounder resin, is Siraya tech fast.

- minimal warpage
- a good easy resin to wash off (some resins stay sticky even after a good IPA 99% wash).
- good mechanical properties.
- lots of online support for settings.

at some point I may be able to put a hard knocks guide to printing up.

Image

Image

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Re: UV light failing?

Post by -steves- » Sat Sep 24, 2022 10:24 am

I use every brand of resin going, whatever is on offer at the time, I even mix them, including colours and brands when one is getting low in the vat. I have never had any issues doing this and must have gone through at least a dozen or more bottles. Some of the prints are a marbled effect as the colours mix :D

I do use the Wash and Dry from AnyCubic. The only issue is don't leave the wash tub in any sort of sunlight as the resin it washes off starts to set and go very very sticky inside the wash post. It is the a complete nightmare to wash the basket and tub.
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Re: UV light failing?

Post by philipy » Sat Sep 24, 2022 10:52 am

That's interesting Steve. I have wondered about mixing resins but having had that duff new bottle of Anycubic grey months ago which has never cured properly even after laying around on the window sill for 6 months, I've never been brave enough to try mixing as well.

Leaving part used IPA in a pot is a recipe for a slimey gooey mess, so I see no reason why your fancy machine would be any different :roll:

On a not unrelated subject, last week I needed a new bottle of Anycubic Standard Translucent green and accidentally bought a bottle of their Tough Translucent green. It seems to be fine and does have a small degree of flexibility and seems to be less brittle. Again it's something I've thought about but never actually shelled out for previously! Having had an unfortunate experience with the grey and black being difficult to wash out, I've been operating on the "if it ain't broke don't fix it" principle and stuck to green.
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Re: UV light failing?

Post by Mamod sterling » Thu Sep 29, 2022 12:56 pm

-steves- wrote: Sat Sep 24, 2022 10:24 am I use every brand of resin going, whatever is on offer at the time, I even mix them, including colours and brands when one is getting low in the vat. I have never had any issues doing this and must have gone through at least a dozen or more bottles. Some of the prints are a marbled effect as the colours mix :D

I do use the Wash and Dry from AnyCubic. The only issue is don't leave the wash tub in any sort of sunlight as the resin it washes off starts to set and go very very sticky inside the wash post. It is the a complete nightmare to wash the basket and tub.
With the washing station I've ended up with two wash tanks, one for IPA and one for water.

I used to fall into the trap of leaving prints in the IPA for excessive lengths of time, but in reality, should only put the parts in IPA for long enough to be fully cleaned, and then get it into the water tank to stop the IPA attacking the parts.

The water tank will eventually (subject to me printing a turntable to sit ono its rotor arm), be used for under water curing.

Thanks,
Paul.
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Mamod Brunel - ongoing modification
IPE Jane - rebuilt from 45mm to 32mm gauge, 'globetrotter'

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