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Brews & Views Bulletin Board Service * Brews and Views Archive 2005 * Archive through March 25, 2005 * Test of homemade magnetic stirrer < Previous Next >

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Fredrik
Senior Member
Username: Fredrik

Post Number: 2045
Registered: 03-2003
Posted on Wednesday, March 23, 2005 - 06:32 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I finally got a my order ot labstuff yeasterday, including the stirbars so I coult test my stirrer. As some may remember, someone else posted a link to another guy who build his own stirrers, I got inspired and tried to do the same.

It works pretty good, magnets are strong and good. However I need to finetune a few things to make it perfect. The magnets are slightly out of balance, so the center of mass of the stirrbar is oscillating a few mm, it still works but it makes it unstable at highers speeds. This is easily fixed though. I just have to reglue them with higher precision.

Also the 12V fan I used are almost too big, only at the lowest possible rpm does it run, this is at the motor treshold to rotate. So I need to tweak this for stability, worst case just put a low speed fan in there.



Anyway, it works! :-) Got a nice vortex.

Once I've got it tuned in, I'll do some of the biomass experiments I've been waiting to do.

/Fredrik
 

Belly Buster Bob
Senior Member
Username: Canman

Post Number: 2235
Registered: 02-2003
Posted on Wednesday, March 23, 2005 - 11:03 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

biomass experiments???? try using it to stir stuff.

looks great Fredrik
Bellybuster Bob
www.bellybuster.netfirms.com
 

Paul Erbe
Junior Member
Username: Perbe

Post Number: 67
Registered: 05-2001
Posted on Wednesday, March 23, 2005 - 02:14 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

COuld you repost the link, that looks like a fun project.
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer."
-Abraham Lincoln
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 2047
Registered: 03-2003
Posted on Wednesday, March 23, 2005 - 02:19 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Here is the other thread

http://hbd.org/discus/messages/1/28718.html

/Fredrik
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 2048
Registered: 03-2003
Posted on Wednesday, March 23, 2005 - 02:25 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

The stirbar are only some 2$ each. I got them from a lab supplier.

Their chepeast/smallest magnetic stirrer are around 175$. I don't think I spent more than some 20$ maximum on this one. I had some plywood and stuff laying around. I only had to buy the fan and magnets.

/Fredrik
 

Paul Erbe
Junior Member
Username: Perbe

Post Number: 68
Registered: 05-2001
Posted on Wednesday, March 23, 2005 - 02:39 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Danka
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer."
-Abraham Lincoln
 

Andrew Pearce
Intermediate Member
Username: Live4beer

Post Number: 325
Registered: 02-2003
Posted on Wednesday, March 23, 2005 - 03:22 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I object to Fredrik's shameless self-promotion of his stirrer-thingie. It's obvious he is only going to turn around and have it mass produced by the Chinese and sell it at high-profit margins to unsuspecting but notoriously cheap homebrewers.

[sigh]...I still remember the days back when this board was about brewing beer.
 

Joseph Listan
Advanced Member
Username: Poonstab

Post Number: 597
Registered: 03-2003
Posted on Wednesday, March 23, 2005 - 04:17 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

How is this thread NOT about brewing beer?

...

I wonder if a bar magnet would work better than two "dots"?
 

Catt22
Junior Member
Username: Catt22

Post Number: 27
Registered: 12-2000
Posted on Thursday, March 24, 2005 - 04:32 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I just built one of these with a 120 volt muffin fan using a dimmer switch for speed control. Made up an experimental starter last night to test it out. It appears to be working very well with a lot of yeast in suspension. I have never used a stir plate before, but now I am hooked. I will have a better idea when I cool it down tomorrow and see how much yeast settles out. This project looks like it might pay for itself by using a lot less DME with fewer steps.
 

J. Steinhauer
Advanced Member
Username: Jstein6870

Post Number: 641
Registered: 03-2002
Posted on Thursday, March 24, 2005 - 04:42 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Fredrik, I'm interested in the data. That will determine, if I think the stirrer is worth it. I look forward to seeing you results.
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 2052
Registered: 03-2003
Posted on Thursday, March 24, 2005 - 07:34 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Steinhauer, I'll be sure to post it whenever I get around to testing it. It will probably a series of different test.

I have several tests planned. I aim to try to isolate the effects of stirring itself (trying to isolate it from aeration) on viability, yeast count, and try to see if there is any size difference in the microscope.

I will also investigage the effect of stirring on attenuation and eventually.

/Fredrik
 

Richard Nye
Advanced Member
Username: Yeasty_boy

Post Number: 622
Registered: 01-2004
Posted on Thursday, March 24, 2005 - 10:26 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Cat22 - I really don't think there is much of a payback with stir plates. I've been using one for about a year and I do get a lot more yeast than without it, but my starters haven't gotten any smaller, I just pitch more yeast. I also use the stir plate to aerate the yeast prior to pitching. After chilling and decanting, I warm up slowly, add a pint of wort, then stir quickly for a hour or so. It gives the yeast a good load of food and oxygen before they get pitched. Always fast starts and good attenuation.

Stir plates are great!
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 2053
Registered: 03-2003
Posted on Thursday, March 24, 2005 - 10:49 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I have had more than good enough results without a stirplate. I honestly don't need one to brew beer. I need one to make experiments, that in the extension will help me to understand the yeast better, which in the end hopefully might help me control fermentation for beer quality even better. It's quite possible that I might use it for starter once I have one, but that certainly wasn't why I wanted one.

There are even in my mind some potential fears with the stirplate, depending on how it's used. I hope to get some more info on them too.

/Fredrik
 

John McElver
Member
Username: Johnmc

Post Number: 181
Registered: 02-2004
Posted on Thursday, March 24, 2005 - 01:59 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

If it'll stir water, it'll stir yeast.

Fredrik, I'd drill some holes near the top, on the sides, to vent heat from the motor, as you'll be running it for day or two. That way, most of the motor heat will go out the holes instead of warming the yeast, at least I'd hope so.
 

Ken Anderson
Advanced Member
Username: Ken75

Post Number: 794
Registered: 11-2002
Posted on Thursday, March 24, 2005 - 02:03 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Fredrik, why don't you try to corroborate the Maribeth Raines data?
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 2054
Registered: 03-2003
Posted on Thursday, March 24, 2005 - 03:16 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

John, some of the minor issues I had in mind has nothing to do with the motor or heat. The fan I'm using is designed to run 24/7 at full speed. I will be running it at the lowest possible speed, also the box has hole on the back. I am quite confident with that. I was thinking of how increasing the biomass yield on a given set of limiting nutritiens affect the health of the yeast and stuff like that. I have seen other reports that unless you add nutritions to balance the increased yield, there is a tiny drop in viability. In any case it's easily fixed.

Her data is really nice Ken and I think some test will overlap, but I want to know some more things not evident from her data. I am not just looking to maximize the yeast count. I am mainly curious on the order impact the stirring alone has, provided there is no continous aeration.

/Fredrik
 

Vance Barnes
Senior Member
Username: Vancebarnes

Post Number: 1522
Registered: 03-2003
Posted on Thursday, March 24, 2005 - 04:28 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Some of us brew beer, some stir yeast.
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 2789
Registered: 01-2002
Posted on Thursday, March 24, 2005 - 05:12 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I suspect that the influence of oxygen is obscured by the fact that continuous stirring also tends to cause agitation that aerates the liquid.
 

Paul Erbe
Junior Member
Username: Perbe

Post Number: 75
Registered: 05-2001
Posted on Thursday, March 24, 2005 - 06:52 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Hmmm, I dont believe I have ever aereated a starter. I do boil my starters for about 10 minutes which must make the starter pretty low in oxygen. Doesn't the vortex draw in oxygen until the starter begins to offgas CO2.
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer."
-Abraham Lincoln
 

Paul Erbe
Junior Member
Username: Perbe

Post Number: 76
Registered: 05-2001
Posted on Thursday, March 24, 2005 - 06:59 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

PArts express has a buyout deal on a fan like Cat22 suggests. Seems easier to build than my other option of a 12v fan, power supply etc...

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=259-150
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer."
-Abraham Lincoln