The Long Road - Part 3b - Testing Longer Drying Times and Cover Insulation

3D Printing + The Long Road

I used my printed drying cover to heat two spools over a longer period of time, and the results weren't impressive, so I decided to try to improve it. 1. By printing it with thicker walls, and 2. by adding some heat reflecting material. Those two steps did the job!

Timestamps

Please ignore the timestamps and the temperatures mentioned in the images. My el-cheapo IR camera keeps messing up the timestamps, and the reported temperatures are even worse. Still, it shows which areas are hotter than others, and I have a Bosch laser temperature meter to actually measure stuff.

Original design, without insulation

At 00 hrs

At 03 hrs

At 05 hrs

There's a minor increase of temperatures on the top spool, but it's marginal stuff.

At 06 hrs

At this point I flipped the spools, ie. I left the same spool on top, but flipped the spools themselves.

At 09 hrs

Pretty much the same...

So, now I'm tempted. Should I print another version with thicker walls? Or go for insulation first?

Improved design, without insulation

I created a newer version, with slightly thicker walls, a wider neck, and a little lower. This improved the vertical heat spread quite a bit, but I'm doubtful if drying multiple rolls at the same time is a good idea.

I also added some 'fins' to make it easier to center the roll, and I smoothed most of the sharp corners.

(Click image to enlarge)

Improved design, with insulation

All I added was a 0.2 glass fiber backed alu foil / heatshield. This had quite the impact!

The newer design (with thicker walls) in combination with the reflecting foil resulted in a much higher temperature. Measured after an hour it was 80+ at the bottom, around 78 just above, then slowly decreasing up to 75 at the top - a full ten degrees more!

The printer's interior felt a lot cooler as well.

I haven't tried stacking multiple rolls / covers yet, but I suspect that it would make drying more than one roll actually feasible, as it will probably still reach 65 to 70 C at the top of a set of stacked rolls.

(Click any image to enlarge)

Conclusions

Older design

1. The size of the spool has more impact than expected. A lot of warm air appeared to bypass the top of the spool.

2. Yes, you need to flip your spools halfway anyway, but also notice that - when using two spools - the top spool doesn't properly dry. In other words: put the wettest spool at the top, and assume it isn't well dried at all. You might be able to put a roll of ABS on the bottom and a roll of PETG on the top, but check the temperatures before doing so.

3. After a certain point (roughly 3 to 4 hours) time had little impact on the (vertical) spread of the temperatures. Too much heat escaped through the walls of the cover, and the (side) panels of the printer.

Newer design

When combined with some heat insulation / heat reflecting foil, the newer version is at least 10% to 15% more efficient than the older version, more so compared to any circular designs (that don't redirect the maximal amount of heat to the roll) or a cardboard box (though a carboard box with a heat shield layer should work pretty damned well).

But... should you?

One final question remains: is it worth it to print this improved, insultaed drying cover? The answer to that is a little mixed...

1. No. Use a non-insulated cardboard box if you only incidentally want to dry a roll in your printer. It works pretty damned well.

2. No if you have an external dryer, and you're happy with that.

3. Yes, if you plan to dry stuff in your printer on a regular basis, if you care about maximal efficiency (power consumption), if you don't want to heat up the area around your printer that much, if you want to have predictable drying times, and if you like to have a solution that's a little more sturdy than a cardboard box.

4. Yes, if you have an external dryer. This may sound funny, but to run an Ams-HT you have to keep the printer on anyway. So, why not dry another roll at the same time inside the printer? In which case the newer design with insulation helps to reduce energy usage and heat loss.

How about other designs?

I studied a few popular designs, and (you may disagree 😁) have my reservations about some of the claims...

1. Designs claiming to create a 'vortex'... The air is moving way too slow to have any impact.

2. Designs using the 'printer cooling fan'... You're actually increasing the volume of air moved and heated, lowering the temperature in general, and wasting a lot of energy. This *may* improve the drying of lower temperature filaments (PLA) but even that is questionable. You might be better of with the Ams-2 Pro, or with a simple 40C external dryer.

3. Designs with an attached fan... Reducing the number of ventilation holes, and adding a little 30 or 40 mm fan will improve air recirculation inside the drying cover. (The fan needs to circulate only the air inside the drying cover, as otherwise you're loosing a lot of heat.)

If you have an easy way to provide power to such a fan this might actually improve the drying a bit. The key element however is this: it takes time for water molecules to leave the filament, and blowing air does not improve that. Blowing air only helps to spread the air (and heat) more evenly.