Dry box confusion  

RE:

I think it depends on where you live and your house conditions.

I do the same as you and never had a problem.

If you notice better results from a fresh dried spool vs one that’s been left out for months then perhaps a dry box is something to look into.. but if you don’t notice a difference then I wouldn’t bother.

RE: Dry box confusion

Hi Cynan,

Thanks for the reply. I have just been printing with a part used reel of PETG which I bought from Rigidink around six years ago  and stored as I described with no obvious problems so had decided to carry on as before. Given the addition of the MMU3 I thought it was worth asking particularly as the need for a dry box would force a significant change in the layout of my office.

B

RE: Dry box confusion

To add to what Cynan said, much depends on your living conditions and how well your print room is controlled.  I live in a dry climate most of the time but we do get high (for us) humidity from time to time. 

Like you, I am going to be using an MMU and will want to leave my filament in the printer.  For my purpose, I am building a large dry box that can hold at least 5 spools.  Even large (>2kg) spools and feed them from there.  The buffers for the MMU will be in the dry box and I am still debating putting the MMU in the dry box as well.  May in the future.

I will be using Activated Alumina for the desiccant.  I tried silica desiccant and found that this is working much better after a suggestion on one of these forums.  It is also easier to dry than silica.  There was a nice dry box I saw that can be printed or purchased from AliExpress.  There is also the idea of individual dry boxes for each spool I have seen, where the buffer is in the box.

I am under the belief that if my filament is dry, I want to keep it dry.

RE: Dry box confusion

All noted. Thanks.
B

RE: Dry box confusion

That table on Prusa site is a general guideline, and I guess they did it while working in air conditioned rooms, thus only certain materials will be affected (especially nylon).

If  you live in dry areas such that humidity is under 40% most of the year then you probably do not need a drybox.

For the experiment you could ask someone to dry the spool for you and you could try to print it before/after drying and compare print quality and decide yourself if you need it.

Usually smaller layer heights will make filament issues more visible ( for example 0.1mm).

Wet filament results in hearing popping and hissing when printing, and little zits and blobs on the walls. There are more details in that matter and I suggest to look around the internet and trying to grasp the idea if you have those issues and if you want to get rid of them, or not 🙂

RE: Dry box confusion

If  you live in dry areas such that humidity is under 40% most of the year then you probably do not need a drybox.

I live in a dry area and at work, I saw the disaster of not having dry nylon filament.  They tried to do an overnight print and the filament ended up destroying the print head due to problems.  Right now, with the rain we have had, our humidity is over 50% at 22 degrees.  This is in a climate controlled building but the humidity in the building was usually under 40% in summer and under 10% in winter.  Static was terrible.

I want to add to my comment about my dry box needs.  It is also to keep dust and debris away from my filament in my shop.  In dry locations, dust can be a big issue.

There are instructions for drying filament in an oven or even using your printer build plate to dry filament for a test.

Relative humidity is confusing as well.  It is dependent on temperature.  Colder temperature, higher humidity, warmer temperature, same water vapour in the air and you have a lower humidity.  So, 30% RH at 30 degrees means there is more water vapour in the air than 30%RH at 22 degrees. 

RE: Dry box confusion

I don’t think it’s that’s simple. My office where my printer is, is currently 19C and 65% humidity.

PETG is printing fine on a spool that’s been sat there for the past couple of months.

The best way to find out is to simply test it where you are.

RE: Dry box confusion

An interesting data point for humidity and temperature as well as exposure.  One of the first things I was told when I got my printer and was having issues with printing PETG was humidity and "dry" filament.  I spent days trying to find out more about RH and filament and found that there is no "correct" answer.  All the so called experts pointed to ~30% RH, without any temperature reference, including nylon.  FWIW, my issues when I started, turned out to be a bad thermistor in my print head that wasn't regulating the temperature properly and eventually melted my print head.

Where I live, if I am at 65%, it has been raining for a week.  Even today, we are less than 50% after a day of rain.

You make a good point that there is much more to this than humidity.  I will keep my filament in dry boxes to eliminate the risk.  The cost of the Activated Alumina and stainless steel containers is low compared to the cost and time to dry filament.  I can grab any filament and load it when I need it and not worry about moisture.  I also use my dry boxes to keep filament clean from dust and other debris in my shop.

RE: Dry box confusion

Unfortunately, in my experience, even filament stored at a low humidity (my dry cabinet is between 5% and 10%) will take a very LONG time to dry if it is wet. With Nylon, we are talking more than 3 months. If the filament is dried fully in a heated filament drier first, then stored at a dry humidity, it will stay dry.  I have tested activated alumina in a sealed bag with a calibrated hygrometer, and the humidity will drop to the 8% - 12% range.  But also note, few containers are 100% moisture tight, so over time, the desiccant does need to be dried and replaced. 

RE: Dry box confusion

Fully agree with what you say.  I take my filament from the shipped bag, when I open it, weigh it and put it in the dry box.   The process is to keep it dry in the first place.  In the last two days, a couple of sudden print jobs with different colours of PETG, and they were ready to go.  🙂

I have multiple containers of Activated Alumina that can be dried in rotation.  They are all stainless steel containers so they can go into the oven for drying.  I tried silica desiccant and found that the colour change didn't start to happen till the RH was over 20% and the process to dry it was a real problem, since I had to be really careful about the temperature and it took a very long time to dry.  Activated Alumina will also absorb more moisture than silica for the same mass which is an added benefit.  Worth the extra cost in my books.

Most plastic will leach moisture, and special processes are in place to ensure items that have to remain dry are repackaged over and over as necessary.  There is a military specification for storage of equipment.  In most cases, we don't notice it but over time, it occurs.  Also, we open the containers to grab or change filament which will allow moisture ingress.

It all comes down to what you want to do and what you want to spend.  I work with my situation and learned that keeping filament dry is much better than having to dry overnight when I need it.  My RH is usually less than 25% in the summer and maybe 35% in the winter so I was not thinking about a dry box when I first got the printer.  After warnings about damp filament and that being the first thing most people say to check, I started to look at moisture.  Many YouTube videos later, came to my conclusion to go with dry boxes.  After a comment on one of these boards about activated alumina, and doing some background checking on it, that was the direction I went.  I also have dust as a major headache.

I believe it was CNC Kitchen did a review of drying filament and showed that it takes a very long time to use just desiccant.  You need the heat and the air flow to cut the time down.  Even vacuum drying wasn't as good compared to good old heat and air flow.  Which all take time away from printing.  I have also read/watched about people that started a long print job with dry filament but due to time and conditions, by the later part of the process, the filament was becoming an issue due to moisture absorption.   Which will be worse with some filaments than others.

As the OP stated their going to start using an MMU and how that will change their printing process (same with me) then the answer changes.   I have seen the nightmare of a wet filament (nylon) and what can happen when it goes bad (at work).    As stated, the OP's office is at 65% RH at 19 degrees and didn't have any issues with an open roll of PETG after a few months.  Now, if the OP wants to change or mix materials with the MMU, they may need to use a dry box or collection of dry boxes.

I am going to see how my dry box arrangement works and if I have issues, then may move the MMU into the dry box.    I may also put a can of activated alumina in the printer box as good measure.  It is all testing and my personal needs.  There is no yes/no answer to the OP's original question.  Peoples knowledge is shared on these forums and that is why many of us are here.

If I was going to purchase a dry box, I would look at the "Blurolls Prusa Drybox Enclosure Kit PC Cover Filament Box Panel Aluminum Rod Fitting 608zz Bearing for Prusa I3 Voron 3D Printer" that is available on AliExpress.  Nice an neat and can hold 6 rolls with fittings for tubing.  it didn't fit my needs as I have some 2kg rolls and looking at some larger rolls.  The other option is to use cereal storage bins that hold one roll of filament.  There are so many different options for "cheap" dry boxes shown online.

RE: Dry box confusion

This is a bit more pricy at $200 and shipping, but it's one of the cheapest ultra-dry cabinet.  

https://www.gotopac.com/statpro-xustefd3d25qp-cm.html

These come in a shapes and sizes, but this one is for filament and claims under 15% humidity, which usually costs $800+.  Don't fall for the camera or musical instrament storage ones because they typically can't get lower than 35% - 40%.  And they use very little power, under 10W.  

RE: Dry box confusion

Looks good.  Stylish.  No fighting with desiccant.  Too small for my usage but interesting.  I may look for a company that sells an electronic desiccator in the future.