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JDW

Macintosh SE Squirrel Cage Fan to 60mm Boxer Fan Upgrades

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I've been working on a new video focused on SE and SE/30 fan upgrades over the last month and a half.  I don't have any machines with the old squirrel cage fan, but I am aware many SE owners are.  I want to add info in my video for those folks.  I've searched this forum for "squirrel cage" and read through a lot of posts, but no one has provided a step-by-step upgrade with photos.  Uniserver said that in his opinion it was the best fan because it moves a lot of air and is quiet, although he admits that it's noisy when dirty; and the reality is fans get dirty faster than you think.  The boxer fans in contrast remain about the same in volume even with a bit of crud on them.  Plus, the boxer fans are sold today whereas the squirrel cage fan is not.  Anyway, I want to confirm with those of you who have done this squirrel-to-boxer fan upgrade how you did it.  Specifically, if all you have is an older SE analog board with the squirrel cage fan, removing that fan means you have no metal bracket for mounting a replacement 60mm fan.  (Newer analog boards had 60mm boxer fans.)  I did find the following post:

 

But "Velcro"?  Really?  Seems like it would wobble around after a while.  In any case, I'd love to see a photo of that.

 

Another post I found was this:

 

 

But that is only for a 50x20mm fan, which I personally would not use because it's too small.  Even most 60mm fans are rather small in terms of their airflow.  Anything smaller would either not move much air at all or need to ramp up the rpms and be noisy to move sufficient air.

 

If anyone knows of someone who created a 3D printable bracket, that would perhaps be the ideal solution.  It might a bit more sound damping too as compared to the stock metal bracket, but one would need to print and test such a plastic bracket to know for certain.

 

Any thoughts, suggestions and photos you are willing to share would be appreciated.  Thank you.

 

 

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I thought the biggest issue was the video board on the back of the CRT for squirrel cage units?  Specifically they are horizontally oriented and don't leave enough space for a 60mm fan?  I have an SE with the squirrel cage fan but have no intentions of changing it.  It moves a fair bit of air and I don't find it an louder than the Elina in my SE/30.

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On 1/19/2020 at 4:02 AM, JDW said:

But "Velcro"?  Really?  Seems like it would wobble around after a while.  In any case, I'd love to see a photo of that.

Well, Larry Pina suggested using cable ties or double-stick mounting tape to add a fan to a 128k-Mac Plus .... :)  I’d guess heavy duty Velcro would work just fine! 

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When it comes to moving air, uniserver is spot on. You likely won't find anything but squirrel cages in an HVAC unit, certainly not in dust collector units. Window box AC units have severe space restraints calling for a wide/high heat transfer coil and a more suitable, if less efficient and noisier fan setup. A dead squirrel cage is the only reason to install the squirrelier type. Just checked, the exhaust grid/opening is the same. Exit of squirrel cage widens to slow down exiting airflow and dampen noise apparently. Seemed a strange setup, but adn't thought of that before, it makes perfect sense.

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@JDW I'd be happy to donate a custom made clear SE fan that was offered with the clear case project.  I bought the molds for these and they are clear (well slightly frosted) with LEDs.  They put out 24 CFM which beats Noctua on performance, though slightly louder.  If you are interested, please PM me your address and I'll have one set your way. 

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I finally found the type of fan in the SE, it's not a Squirrel Cage/Centrifugal Fan at all, but a Cross-Flow Fan/Tangential Blower which brings up a question:

 

When did the SE begin to be equipped with axial cooling fans interchangeable with the SE/30?

 

If the changeover was made before the SE started shipping with the SE/30 Chassis it's probably no big deal. But if fan type was changed at the same time as the switch to the "SE/30 Chassis" for the SE it may not a great idea to change fan types unless absolutely necessary. The two PCB/PDS/Chassis design combos have different requirements. The vertical PDS slot design and open chassis of the SE/30 likely requires a lower pressure coefficient for proper airflow easily met by its axial design cooling fan. Dunno, but might be worth looking into as the SE might need a "stronger fan" than the SE/30?

 

Cross-Flow:

Myson%2520FCP1202026%2520c.jpg&f=1&nofb=

 

Squirrel Cage:

180cfm-blower.png

 

Who knows? :blink:

 

 

Edited by Trash80toHP_Mini
spelling ::)

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35 minutes ago, Trash80toHP_Mini said:

I finally found the type of fan in the SE, it's not a Squirrel Cage/Centrifugal Fan at all, but a Cross-Flow Fan/Tangential Blower which brings up a question:

 

When did the SE begin to be equipped with axial cooling fans interchangeable with the SE/30?

 

If the changeover was made before the SE started shipping with the SE/30 Chassis it's probably no big deal. But if fan type was changed at the same time as the switch to the "SE/30 Chassis" for the SE it may not a great idea to change fan types unless absolutely necessary. The two PCB/PDS/Chassis design combos have different requirements. The vertical PDS slot design and open chassis of the SE/30 likely requires a lower pressure coefficient for proper airflow easily met by its axial design cooling fan. Dunno, but might be worth looking into as the SE might need a "stronger fan" than the SE/30?

 

Cross-Flow:

Myson%2520FCP1202026%2520c.jpg&f=1&nofb=

 

Squirrel Cage:

180cfm-blower.png

 

Who knows? :blink:

 

 

Maybe we can make a souped up version of the Tangential blower to make it like a wind tunnel machine :)

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The "squirrel cage", also termed the "rat cage" by some, was phased out in early 1988. The noise wasn't the principal complaint, however. Many felt the fan was responsible for screen interference; this could have also been the result of the horizontal-facing video board (which isn't recommended for the newer fan, either). I have also witnessed this firsthand in SEs, long before the capacitors became the chief concern among SE analog board problems.

 

All SE/30s left the factory with a blade fan, but it is theoretically possible to put the old analog and video board combination inside an SE/30.

 

As I recall, Apple offered a fan replacement program for some time for SE owners. It must not have been all that popular, however, as I don't see many 1987 SEs with the newer fans.

 

Apple used two blade fans in North American SE models. There's a DC Pico Ace 25 and an Elina-Fan. The Elina seems to be the slightest bit quieter. Of course, the real noise factor can be a hard drive. Both the MiniScribe and older Quantum 3.5" drive, usually installed in an SE with a factory hard drive, were notoriously noisy drives. (However, perhaps to compensate, the SE has a speaker which projects better than any compact Mac as a result of placement and front bezel design).

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Phase out of the "Squirrel Cage" having been in early 1988 is interesting as the SE/30 wasn't announced until a few days into 1989. My original 1987 SE had the crossflow fan as does the SE I have now. Also interesting is that the vents on the back of my SE and SE/30 cases are identical with about two-thirds of the opening covered by part of the crossflow unit's minimalist shrouding. I guess they must have been covering all bases?

 

A small portion of the axial fan's entry arc is blocked by the flyback's "cage" in the SE/30. I'm wondering about effective areas involved in the airflow between types. I'm also wondering as to why the replacement fan was two-bladed in the SE, that's very curious? Turbulence induced by the sharp transition from round fan exit to rectangular vent grating definitely induces pressure loss in the axial design's airflow. A Printed replacement housing for the axial fan with a smooth transition might have a measurable, positive effect on cooling the machines, but I wonder if sound would be reduced or let more pass through the vents? Turbulence in the housing might have a muffling effect, dunno?

 

It would be great if someone modeled a replacement housing with "Squirrel Cage" mounting points for 3D printing with a far more more efficient, smooth exit transition than the stock sheet metal box. Making it compatible with replacing the SE/30 unit with a far better modern axial fan design and much improved ducting as well would be ideal.

 

Technically, in terms of lower decibels and better pressure co-efficients the crossflow design should have been superior, but perceptions count.

 

On 1/26/2020 at 12:13 AM, maceffects said:

Maybe we can make a souped up version of the Tangential blower to make it like a wind tunnel machine

:lol: That's easily done, print a clear housing for bolting the (round) entry up to the back of the SE/30's vents with the snail drum housing blasting across the info plate with flame colored streamers. :rambo:

 

s-l1600.jpg

Edited by Trash80toHP_Mini

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The drop dead simple and BEST solution to adding a 60x25mm boxer fan to an older analog board with a squirrel cage fan would be to 3D print a copy of the metal bracket that is included on analog boards that have the boxer fans.  It certainly would be a lot better than tape or velcro or even a wire tie, and with it being plastic, I can only guess there would be a tad more vibration damping of the boxer fan as compared with the official metal bracket.  I've found all manner of 3D CAD files for other vintage Mac things, but I've not come across a boxer fan mount.  Have any of you seen such a 3D file anywhere?

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Yep, beat you to it, buddy! :lol:

On 1/27/2020 at 5:54 PM, Trash80toHP_Mini said:

It would be great if someone modeled a replacement housing with "Squirrel Cage" mounting points for 3D printing with a far more more efficient, smooth exit transition than the stock sheet metal box. Making it compatible with replacing the SE/30 unit with a far better modern axial fan design and much improved ducting as well would be ideal.

Seriously though, smoothing that circular to rectangular transition will help cooling tremendously. Check out like HVAC ductwork at any Big Box Home Improvement store and you'll see what I mean. Any air moving system is optimized for as little pressure loss in every transition as possible.

 

The metal box in the SE/30 gives you about 21mm to smooth the transition. Switching to a modern, thinner profile, silent design that moves more air than the stock SE/30 fan (or the two bladed SE fan) is definitely the way to go. Any possible (but not likely) muffling effects that might be afforded by that overly nasty, pressure loss inducing metal box transition would be nullified and cooling much enhanced by improved ducting done over the added length afforded by a modern fan.

 

A single, printable 3D design using said modern fan with smoother cross sectional transition over a longer than the 21mm depth of the metal box that has mounting point provisions for both SE fan types and the SE/30 fan would be a real feather in someone's cap.

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