Fan vibration testing for 2600, 533 and 183 cooled cameras.

Kevin_A

The 2600 and even the 6200 series cameras differ fron the 533 and 183 cameras wheras the 2 cameras with the larger 50mm fans have a thru bolt which uses a nut to hold the fan, wheras the 533 and 183 have no room for such so the 40mm fans just use stardard fan mounting self threading screws.

w7ay

Kevin_A

Yeah, this is what I am thinking of:

From Sunon's specs sheet, the mounting holes are 4.3 +/- 0.3 mm in diameter.

So, one of my schemes is to insert 4.5mm OD 2.5mm ID o-rings into the fan holes. With 5.5/2.5 o-rings outside.

The above figure shows drilling the hole to 5mm to a depth of about 1mm, and use the larger o-rings in the interior locations. This will give more silicone material between the M3 screw and the fan body.

Another scheme (already have a 8mm countersink drill with 4.2mm inner bore) to counterbore the fan so I can insert a 8mm OD/3mm ID o-ring into the counterbored area. This gives the most silicone in between the M3 screw and the fan body.

Once all parts are on hand, I will start working on it, starting with the existing ZWO scheme using a vibration analyzer app. Then each of the above in sucession to see if/how the vibration changes.

I also have the sorbathane fan gasket from Mouser on hand, and also some sorbathane Duro 30 washers (1/8" hole) from Isolate-It, but I don't think I will need them once I can isolate the M3 screw from the fan body. We'll see.

The o-rings I bought are cheap Amazon stuff. Red, and each one claims Duro 50. And will remain soft down to ridiculously low temperatures (perhaps not ridiculously low by Canadian standards, but temperatures that I will not venture outdoors :-).

My dealings with isolation post has been negative, only allowing a bad fan to shake more. I

That is a shame, since the Noctua mounting spikes seem the easiest way.

I am still testing out sorbathane but the version I have is too soft.

I take it Duro 30-ish?

I must be stupid but how do you directly quote someone from another link and quote included in this discussion using an ipad…

Donno... I use macOS to browse the web :-).

Chen

Kevin_A

w7ay my sorbothane is duro 30-40, I cannot remember.

Kevin_A

w7ay no, I mean I tried to link part of a comment you made under AM5 and quote you in this discussion so that you are tagged and responded to it

Kevin_A

w7ay Another scheme (already have a 8mm countersink drill with 4.2mm inner bore) to counterbore the fan so I can insert a 8mm OD/3mm ID o-ring into the counterbored area. This gives the most silicone in between the M3 screw and the fan body.

Just make sure the o-ring does not get in the path of the fan blade. I used a big washer and compressing it distorted it a bit and my fan blades actually hit it making the card in the spokes sound.

w7ay

Kevin_A My dealings with isolation post has been negative, only allowing a bad fan to shake more.

Is the shaking caused by unbalanced fan blades?

Sunon puts a dab or two of glue-like material on their fan blades to balance the blades during QA. Be sure not to scrape them or wash them away :-). From their drawing:

Chen

Kevin_A

w7ay i think it just has to do with the increased rpm and thus more chance of slight imbalances showing up. These fans were never intended to be 100% perfectly balanced

w7ay

Kevin_A I mean I tried to link part of a comment you made under AM5 and quote you in this discussion so that you are tagged and responded to it

I usually just cut and paste, and then place a right arrow (>) at the start of the paragraph.

I guess you can use the double-quote icon at bottom of the reply window too, but it is faster to just type a right arrow :-).

Chen

w7ay

@"Kevin_A" et al

Resurrecting an old thread.

Last week, I managed to chip the fan blades of my ASI2600MC (while making tilt adustments, I had stuck a 2mm hex wrench accidentally into the fan opening while the fan was running :-).

You can see the chipped fan blade (at about 10 o'clock), together with some other scratches:

As expected, the camera vibrated much more than normal (a ZWO camera is never vibration free).

So, I took the opportunity (before replacing the fan) to try testing the fan isolation idea I had earlier.

https://bbs.zwoastro.com/d/16690-fan-vibration-testing-for-2600-533-and-183-cooled-cameras/6

Thr o-rings kept the screw in place when mounting, so I did not install the nut next to the fan grille. And, I only used 1 oring on the right side of that drawing (although I think 2 may actually be better to ensure the lock nut does not touch the fan body).

I had reused the original M3 bolt, lock nuts and washer, and only left out ZWO's o-rings (no specs on the Duro number in ZWO's documentation, so I don't trust them).

Well, the vibration came down substantially, and even the noise appears to be completely smooth now.

Notice that this is how ZWO wants you to install their fan.

Among other poor design choices, notice that the lock nut at the end of each M3x22 screw is coupling the fan vibration directly to the body of the camera! (What happened to critical thinking classes at university, ZWO?)

I will of course replace the fan with a new one now that I have the chance to test it with a real life case (and use two o-rings at the end, instead of 1). I should have thought about purposely unbalaning the fan blades (RTV would work well for that purpose) to test vibration.

So, if you have a problem with fan vibrations from ZWO's camera, give this a try. Make sure that you buy 50A DURO o-rings. The 70A DURO ones will couple a lot of vibration through.

Chen

Tech@ZWO

w7ay Thank you for your sharing, we noted this problem, and have changed the assembly method of the fan in the last year, the new assembly method has a great improvement for the vibration issues.

Also, we also found the dust on the fan blade, bug in the fan chamber, broken fan or the unlevel screw installation cause the vibration.

w7ay

Tech@ZWO we noted this problem, and have changed the assembly method of the fan in the last year, the new assembly method has a great improvement for the vibration issues.

Can the customers who bought the faulty vibration-prone cameras, and not able to do any modifications themselves, be able to ask for an RMA to get their cameras updated by ZWO?

Chen

Tech@ZWO

w7ay Of course, if the customer has the vibration problem, he/she can directly contact the seller for after-sales service, we will provide the parts to upgrade it.

Kevin_A

Tech@ZWO do you have a revised diagram of your new assembly process with parts notation for those who wish to do the change themselves?

w7ay

Tech@ZWO Of course, if the customer has the vibration problem, he/she can directly contact the seller for after-sales service, we will provide the parts to upgrade it.

That was not my question.

Permit me to ask again. Can a user who has no skills to do it themselves, obtain an RMA from ZWO to return the camera, so that ZWO will fix the defective camera for them?

All of your past cameras vibrate because the metal bolts directly touch both the body of the fan and the body of the camera. It will eventually become a problem when the user decides one day to use them with a long focal length OTA, especially when the camera extends more than 30cm from the declination saddle that holds the OTA.

Chen

w7ay

Kevin_A do you have a revised diagram of your new assembly process with parts notation for those who wish to do the change themselves?

I have a very recent ASI6200MM (just took it out of the box today, even though I had bought and received the camera perhaps two or three weeks ago).

This is what the fan mounting now looks like

Appears to be:

Camera back plate
Fan Grille
Washer
O-ring
Fan body
O-ring
Washer
lock nut.

So, the lock nut is no longer directly touching the fan body (what we have been telling ZWO on this thread since a year ago, now).

I don't know what mechanism is used to keep the screw itself from touching the plastic fan body. My solution above was to drill a 5mm hole to seat the 5.5mm OD o-ring to center the M3 bolt.

There is apparently some metal sleeve (the shiny metal that you can see through the slotted fan body) that was not there before.

The vibration is smoother now. Not gone, but much smoother than their original configuration; probably good enough for most people. There is also no large peaks in the vibration spectrum (Vibration Analysis app for iOS):

Chen

Tech@ZWO

Kevin_A
This is the picture of the new assembly way.

A bit longer screws and one more set of the rubber O-rings.

Tech@ZWO

w7ay This is of course.

w7ay

Tech@ZWO

The ASI585MC "Pro" that I bought about a month has the mounting bolts directly threaded into the fan body.

What this means is that the bolt directly touches both the fan body and the camera back plate. That directly couples the vibration from the fan to the camera body, and in turn, to the OTA. This was the problem with the ASI2600/6200 fan.

Will you also be offering a kit to isolate the fan vibration away from the ASI585's body?

Chen

cc: @Kevin_A

Hara

Tech@ZWO

This doesn't work with 294, there is not enough room for those nuts between fan and cooler blades. I had to reverse it and also use conical bolt heads which sunk into fan holes partly, and nuts are outside the camera case. Otherwise my solution is similar than w7way:s.