8 replies to this topic

[KTAZ]

Yep, interestingly enough, it does!

 

Just had it out for the first clear evening in weeks (AZ monsoon season, ugh) to do a quick visual star test for collimation. Sure enough, it needs to be tweaked a bit after shipping.

 

However, when turning the focus knob counterclockwise, I get an audible metallic "singing" coming from the mirror sled. Focus is smooth, but the CCW movement is just slightly stiffer. I don't expect that this is any issue at all; the Edge units do have tighter tolerances between the mirror and the baffle, so I expect it will "shut up" once enough lube distributes along the baffle tube.

 

I just found it interesting and though I'd ask if anybody else experienced this.

[dpippel]

Since the focuser is pushing against the weight of the mirror when you turn it CCW, it's normal for it to feel "stiffer" in that direction. One thing that I did when first got my C9.25 Edge was run the focuser all the way through its travel in both directions about two dozen times to try and distribute the grease as evenly as possible on the baffle tube. It helped quite a bit, but I ended up getting a Feather Touch for it anyway, which made things even better.

 

EDIT: I don't know what to tell you about the "singing." That's a first for me!

Edited by dpippel, 06 August 2022 - 10:42 AM.

[Notdarkenough]

The focuser grease has 2 tips from the Celestron Help Desk: run the focuser from stop to stop a few times on arrival, and point the OTA towards the sky to ensure any warmed-and-thinner focuser grease leaks out of a vent instead of flowing down on the inside of the corrector plate. I have my EdgeHD 8" outside all year and I haven't seen any grease leaking personally, but you do have hotter summers than I do in Northern Utah.

[KTAZ]

Yep...already did that several times. Was just curious if any others have heard the "song" on a new Edge unit.

 

I'll install the CFM shortly and the calibration routines will run it through several more cycles.

Edited by KTAZ, 06 August 2022 - 12:08 PM.

[carolinaskies]

SCT focusers are planetary gear sets riding on bearings, the source for the 'singing' may be gear mesh or bearing.

Focusers are pretty simple to remove and inspect if the noise doesn't reduce after a few weeks/months usage.  

Causes include lack of proper lubrication, incorrect gear seating, bad bearing.  

If one direction remains extremely stiff after repeated use then something is binding and you should remove the focuser for inspection.  

[12BH7]

Contact the seller and keep them informed of everything that is going on. Worst case scenario is you may have to return it for servicing.

 

If that noise didn't clear after one or two runs up and down the focus tract then it's not greased somewhere inside. And opening it up will invalidate any warrantee you may have.

[KTAZ]

Contact the seller and keep them informed of everything that is going on. Worst case scenario is you may have to return it for servicing.

 

If that noise didn't clear after one or two runs up and down the focus tract then it's not greased somewhere inside. And opening it up will invalidate any warrantee you may have.

It's brand new. I'm relatively certain that it will go away, and if anything I am happy with the extremely little focus shift that I see at high power. I think it's just a nice, tight, fit on the baffle. There is no undue resistance in the focuser knob.

 

It was really just a curiosity and it sounds like nobody else has "heard the music".

[12BH7]

It's brand new. I'm relatively certain that it will go away, and if anything I am happy with the extremely little focus shift that I see at high power. I think it's just a nice, tight, fit on the baffle. There is no undue resistance in the focuser knob.

 

It was really just a curiosity and it sounds like nobody else has "heard the music".

I've had a number of SCT's and know a lot of people with SCT's, and none of them make a noise on focus. Sumpin ain't right.

[KTAZ]

I've had a number of SCT's and know a lot of people with SCT's, and none of them make a noise on focus. Sumpin ain't right.

You know...as an afterthought, I really should have done a recording. I already installed my focus motor, so can't do that now.

 

Hard to explain, but it just doesn't come across as the "Sumpin ain't right" type of sound. You have to listen for it; it has a high pitch reminiscent of a tuning fork. Only does it for about 10% of the travel. No grinding, no binding.