Cooling a Mewlon.......

[Kunama]

Another little DIY project from Kunama Industries Inc.

A little bit of active cooling for Phil's M300 (he thinks this will make it as good as my "Guinevere" ;) )

Spent an hour installing the 6 fans Phil sourced from the USofA.....
Using a 3mm-35mm Step drill, I made a few 35mm holes in the backing plate of the Mewlon.

These 25mm fans can push more than 18 cubic feet of cooling air onto the back of the primary mirror every minute. Should help the views :D

[issdaol]

Nice Job Matt :-)

Secretly though ......I was looking for either a flying saucer or to convert the M300 into a Hair Dryer :lol:

[glend]

Drilling holes in a TAK? There goes the investment value! Seriously, isn't it an open tube, does it really need that much ventilation? Where does the air exit, out the front?

[Kunama]

The only real investment value in telescopes is getting those magnificent views. These fans will probably add an hour of viewing at ambient to each observing session, that sounds like a pretty good investment to me......

(but to address your concern, this backing plate is Phil's spare one, the original is safely tucked away ..... )

Yes the air exits out the front.

[glend]

An old trick used on newts is to put a rim of weather stripping around the inside of the tube just above the surface of the mirror - this diverts the airflow from rear mounted pusher fans over the surface of the mirror, ie boundary air flow. Can also be used as a quick way to remove any mirror fogging.

[Atmos]

Considering that the Mewlon-250 has fans I would have thought that the Mewlow-300 did, unless that is only the brand new ones :P
Little bit of Kunama Industries Inc. in Phil's observatory.

[issdaol]

Tak kindly supplied me with a brand new Mewlon 300 backplate from their new warranty spares......its not usually a separate order-able item so IMO they are to be commended for their flexibility in supplying it.

The original backplate is stashed away in spotless as new condition with the original model and serial number identification plate attached.

So there is no loss of value/investment in the scope as an original fit out :)

Open tubes also have issues with cooling and currents during acclimation which any open tube owner will recognise.

The Mewlon 300 Mirror and Mirror Cell are heavily over engineered by Tak and the mirror is reasonably thick so increasing Airflow to the rear of the mirror will significantly improve cool down time.

Air is drawn into the tube through the fans which are fitted with filters to remove incoming particulates and is blown directly against the rear of the mirror and mirror cell and vented out the front of the tube.

The Mewlon 300 puts up outstanding views when the mirrors are properly acclimated but it still takes time.

As Matt suggests I should gain a minimum of 1 hour or viewing time but with the mirrors being at optimised acclimation instead of half way there.

IMO money well spent on getting more time with better views :D

[issdaol]

Only the newest CRS versions of the M250 and M300 have cooling.

Tak only have 3 fans which should work but I want extra airflow cause I like big hair driers :lol:

[LewisM]

Shame Phil's eyesight won't! :poke:

[LewisM]

Looks like a Tak drone :P:lol:

[issdaol]

Watch Out !! :ship2:

[LewisM]

See, this is where I love true craftsmen like Matt. A lot of lazy-butt fiddlers would have just whacked the fans in there, wires wherever held together with electrickem tape, and not even bother having the fan screws line up perfectly.

Do the job once, and do it right. Don't make shoddy sheet.

Kudos, as usual to Matt and for Phil seeking out a craftsman.

[AnakChan]

Great job Matt! Phil, lucky that Tak was dishing out breakfix spares. The 300CRS has only 3 fans but this mod has 6.

Out of curiosity though I thought the 300 had side venting for cooling? Or is the side window for some other purpose? I also thought the 300 was like the 250 with a removable back to expedite cooling? Or keeping it closed but cooling via fans is more appropriate?

[Kunama]

Hello Sean,
Yes there are side vents and the backing plate is removable though once viewing I think it is better to close the sides to prevent any reflections or light from iPad screens etc reflecting off internal tube surfaces.

I think the end plan is to also include a pot to vary the fan speed to keep the scope as near to ambient as possible.

It could also turn out to be an unnecessary modification :shrug: that's why it's good to practice on Phil's scope ;);) at the moment I am removing the filter screens to test the change in airflow.....
(maybe someone will volunteer their refractor for me to cut into to test active cooling in one..... :D )

[LewisM]

Phil's TOA150 should be a prime candidate for cooling experiments...

[Atmos]

Ageee, it's always sitting around not being used, just begging to be experimented with!

[thebonz]

My cooling device is made from plywood that has 4 fans mounted that plugs into a variable output voltage adjustment. It definitely helps. Not as refined as a genuine Tak back but it still works.
John

[Kunama]

That's the main thing John :thumbsup:

[LewisM]

I'll leave the full report to Phil, but it works :)

Noisier than expected, but it def. works.

[issdaol]

Went out and fitted the replacement Mewlon 300 Back Plate with the TEMPEST fans to the OTA.

This was very quick because the backplate was exactly the same as the original, so all that was required was to remove the retaining ring, take off the original plate and position the new cooling plate in its place.

Made sure that the fans were all signed up roughly centre to the gaps in the mirror cell and tightened up the retaining ring.

All done in one or 2 minutes :D

Powering was just a matter of plugging in the external 12v cigarette lighter plug lead into the jack Matt mounted in the plate.

All the fans powered up fine and were a little bit noisier than expected but when one remembers I now have 6 fans installed into a aluminium backplate its nor that bad.

Let the fans run for an hour and there was definitely good airflow.....as we could feel slightly warm air being pushed out of the front of the OTA so they were doing their job (the hairdryer effect :lol: )

Based on my usual experience, running the fans effectively reduced acclimation time and gave me back an hour extra of viewing.

Im planning on making a small control box with a potentiometer so I can run the fans while viewing at reduced speed and have a on/off switch rather than just the plug :)

Added some pics of the build and final product:

[LewisM]

Yes, it was nice to warm my hands at the open end of your Mewlon :) (I am kinda half joking!)

[issdaol]

I should mention that the final finish by Matt was excellent ....very happy with the installation of the Fans, Power Jack and Fan Covers :thumbsup:

Although I did find one partial fingerprint after careful forensic analysis and some particles of dust.

So he could have perhaps done a better job still .... :lol:

[LewisM]

Clean it with Methyl Ethyl Ketone...it'll get that fingerprint right off.

And I brought my Tak green paint with me when you need to redo it ;)

[Kunama]

At the rate you were paying me I thought I would do the convict trick of pressing my thumbprint into it......... :mad2:

[LewisM]

Reminds me of a Bruce Springstein song....

[issdaol]

I thought you liked stale bread and water.....!!! :P

[issdaol]

I prefer the sweet smell of DIBK......:lol:

[LewisM]

Lutefisk and aquavit

[LewisM]

More time to dissolve the paint... :)

[MortonH]

Should have the added bonus of keeping bugs out. :P

[Atmos]

Planning on doing something similar with my Mewlon 250 at the moment and I was wondering if there was any benefit to getting the Tempest fans over four ordinary fans from Jaycar?

[LewisM]

Not sure Colin but I replaced an ADA fan in something else just the other day with a $16 jaycar one. Interestingly the generic replacement runs with noticeably less vibration or sound.

Not sure which brand/rebrand Tempest uses.

[multiweb]

:eyepop: drilling a tak. Sacrilege!

[Atmos]

I've already got four small fans and I wouldn't think that it would make much difference but I am uneducated in these matters.
I'm also not going to be drilling into my Tank Marc, getting Meru to 3D print me a new backplate with holes a ready hehe