I have tested my new 40/40/10mm vent for ormerod

First of all - its super quiet! Its like "OMG I cant believe something can be this quiet after that original fan while Rihanna sings where have you been all my life" quiet!

The vent in question is THIS ONE



Fan Dimension: 40 x 40 x 10mm
Sound level: 19 db(A)
Fan Bearing: Hydro bearing
Air Flow: 6,9 CFM
Fan Speed: 4.500 RPM ± 10%

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First test; checking the temperatures while heating from 0C (cold):

• 0 - 100C - overshoots to 105, drops to 96, and gets back to a steady 100C.
• 0 - 155C - overshoot of max. +1.5C, drop to aprox. 152, and gets back to a steady 155C. (seems that the overshoot and drop are more or less the same above 150C)
• 0 - 185C - overshoot of max. +1.5C, drop to aprox. 181, and gets back to a steady 185C.

When the temperature eventually sets to desired temperature, it holds it constantly at +/-0.1C.

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Second test; checking the temperature by lowering and raising the temp at high temps from 185 to 220:

• if lowering by 5C the drop is -3C from the desired temp;
• if lowering by 10C the drop is arround -6C from the desired temp;
• if lowering by 20C the drop is arround -8C from the desired temp;

• if raising by 5C it overshoots by +2.5/3C, then drops -0.5C from the desired temp before reaching the desired temp;
• if raising by 10C it overshoots by +5/6C, then drops -1.5C from the desired temp before reaching the desired temp;
• if raising by 20C it overshoots by +3C, then drops -1/1.5C from the desiret temp before reaching the desired temp.

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Cooling of the hot end varies, and goes from -1.5C per second when the hot end stops heating, all the way down to -0.5C/-0.2C per second when it falls under 80C.

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What I find positive about this fan:

• When it gets to wanted temperature it holds it by +/-0.1C
• Extremely quiet

What might be negative:

• Layer temp change could be an issue. From 200C to 190C goes first to 183.6C then up, altough I didnt pay much notice to this with the original vent, maybe its the same so its not an issue, dont know.

What does not bother me that much:

• The best would be to set the hot end temp manualy before uploading/choosing the file for print, and to wait for the temp to set. This shouldnt be a problem if printing all with same hot end temperature.

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And if you ask me why I did all of this - I dont really know, just wanted to see how everything reacts with this smaller vent. Also to check that the operating temp will be constant under pressure and that this vent wont melt or something like that And I had a lot of fun

For now everything seems ok, however, I havent printed anything yet with this vent cause Ive been playing with the temperatures for 2 days, so I will update this post later on.

Cheers,
Antonio

Edited 2 time(s). Last edit at 07/15/2014 03:07PM by Sardi.

The fan has little if any effect on the hotend temperature or its stability. The extent of the overshoots/undershoots are controlled by the firmware PID variables (and can be adjusted with G commands in DC42's firmware). To check that the fan is adequate you should measure the temperature of the cool block (the block above the hotend that is bolted to the heatsink) after the hotend has been at a steady 230 deg C for 15 minutes or more. After I replaced my fan with a quieter fan that pushed a lot less air than the original, the cool block remained cool enough to hold a finger against (I recorded the actual temperature quite a while ago in a post here) From memory I think it was 55 deg C or thereabouts.

Dave
(#106)

Unfortunately, the only thing I can check the aluminium cool block is my finger. But does it have to be 235C? I never go that high up while printing.

Nevermind, I just held my finger on the block for about 10 seconds, so I guess its ok

It doesn't require very much from the fan to cool the hotend, especially since air resistance is reduced by just having half the fan duct. Lots of air can be useful though if you are using it to cool the print.

I suggested 230 deg C to ensure things won't go pear-shaped if you ever print ABS. If you are quite certain that you will only ever use PLA, then no, you don't have to test with a temperature that high.

The finger test is a perfectly adequate test (if you don't mind the risk of getting burned if the fan is inadequate). Few people could hold their finger against anything hotter than about 70 deg C for any length of time.

Dave
(#106)

I am planning to replace my Ormerod hotend fan also (the original that came with the kit is much too loud - causes me tinnitus).

Are there any specifics about the original Ormerod fan: what kind of RPM:s or m^3/h -ratios should be sufficient? I plan to do more ABS later (just PLA for now).

For example, would this be suffucient (or do we need more airflow?):
[www.fractal-design.com]

This post has the fan data: [forums.reprap.org]

Ian
RepRapPro tech support