133 replies to this topic

[GOLGO13]

Found this thread which had some similar discussion https://www.cloudyni...g/?fromsearch=1

Maybe the metals heat up a bit in use from friction?

[Stewc14]

Won't to change the question, but another problem I have had with feather touch is getting the diagonal tight enough. Especially with binoviewer on with the eyepieces.It really wants to spin around way to easy.if everything is not tightened down you could lose the viewer and eyepieces fast . Anyone ever had this problem? I have it on my 228 mm tmb. I believe it is the 3.5 inch model.

[peleuba]

Won't to change the question, but another problem I have had with feather touch is getting the diagonal tight enough. Especially with binoviewer on with the eyepieces.It really wants to spin around way to easy.if everything is not tightened down you could lose the viewer and eyepieces fast . Anyone ever had this problem? I have it on my 228 mm tmb. I believe it is the 3.5 inch model.

 

What end cap are you using on the FT?   One of the terrific things about the R/P FT focusers is the ability to attach different end caps/visual backs.  I would recommend getting the adpater from StarLight Instruments that allows you to use A-P threaded fittings.  Then purchase the 3 knobbed visual back from Astro-Physics.  Officially its called the 2" Adapter with Brass Locking Ring (part #ADA2003A).

 

With this setup, you'll not have nay problems holding anything. 

[Kunama]

Won't to change the question, but another problem I have had with feather touch is getting the diagonal tight enough. Especially with binoviewer on with the eyepieces.It really wants to spin around way to easy.if everything is not tightened down you could lose the viewer and eyepieces fast . Anyone ever had this problem? I have it on my 228 mm tmb. I believe it is the 3.5 inch model.

The best endcap I found for securing a diagonal to the FTF3545 is the 2" Clicklock one from Baader:  #2956241.  I have it on my TMB152/1200. 

AgenaAstro have it:  https://agenaastro.c...35-2956241.html

 

Edit:  Just looked up Paul's suggestion which is also much better than the usually supplied 2" comp ring from FT.

Edited by Kunama, 01 May 2020 - 06:28 PM.

[junomike]

Good afternoon, my name is Jon Joseph and I am the owner of Starlight Instruments.
I will go a little more in-depth on the issues regarding the damaged focuser.  Inside the pinion block, there is a brass brake lever in which holds the pinion shaft.  The pinion shaft of the focuser sits inside 2 u-shaped openings in the brake lever.  When the brake thumb screw is tightened, pressure is applied on the entire length of the brake lever and not on just 1 spot where the thumb screw touches the pinion shaft.  The problem is that the u-shaped openings of the brake lever were completely worn away in which allowed the teeth of the pinion shaft to wear a groove on the flat of the brake lever and this allowed brass shavings to get into the reduction assembly.  If Starlight Instruments was contacted early on about any questions regarding the focuser, Starlight may have been able to do a repair under warranty but the damage done was so excessive that brass shavings from the brake lever was in the teeth of the rack, in the reduction assembly and the brass shavings got between the drawtube and Teflon tape and damaged the roller bearings.  I have attached 4 photos for reference.
The damage to the focuser was from either over-tightening the brake thumb screw or from moving the focuser with the brake engaged or a combination of both.
Photo#1 shows a side view of the damaged brake lever.  Photo#2 shows the damage to the brake lever and the groove that the pinion shaft caused on the bottom of the brake lever.  Photo#3 shows what a used brake lever looks like.  Photo#4 shows Mr. Moore’s pinion assembly.  You can see all the brass shavings in the roller bearings. 
With the amount of damage, we do not feel that it was the fault of the product and that is why we were not able to do a warranty repair.  We had to do a complete tear-down and rebuild of the focuser using a complete new planetary assembly and brake system.

Photo#1.jpgPhoto#2.jpgPhoto#3.jpgPhoto#4.jpg

Fair enough, but the (your) literature states otherwise (to use the Brake) and there's also no disclosure/warning not to do so.

Something to consider (including) with this otherwise amazing product.

[John O'Grady]

Fair enough, but the (your) literature states otherwise (to use the Brake) and there's also no disclosure/warning not to do so.

Something to consider (including) with this otherwise amazing product.

As Mike and other's have pointed out, there's sufficient ambiguity in Jon's report for this particular focuser failure report and what the instructions state.

I went looking for instructions on the FT3545 (which I have) and found the TEC documentation instructions state that the brake was designed as a second method of adjusting tension.  Maybe one shouldn't follow another vendor's instructions for care and use of FT product but its another data point that seems to be consistent with Star Light instruments own instructions on the focuser (as Mike points out above).

 

To Jon (owner of Starlight Instruments), if you could explain the proper operating use of the brake that would be helpful for everyone monitoring this thread.  For me, it's not clear if this type of damage can only happen when the brake is fully engaged or just partially.  As there are instructions for your product that seem to contradict what you indicated was the source of operator error damaging the focuser, it would be helpful if you could clarify what you meant by the following statement:

 

 

The damage to the focuser was from either over-tightening the brake thumb screw

Maybe this means 'locking' or very nearly locking the brake (and adjusting focus).  If not, then the current instructions need correcting to either state that the brake should not be used to adjust tension at all or some clarification needs to be added as to how to use it to properly adjust tension in order to avoid damaging the focuser.  

 

Currently, I'm using the brake tightened a small amount in order to increase the tension.

Is that not the correct thing to do?

Edited by John O'Grady, 02 May 2020 - 02:41 PM.

[Kent10]

Currently, I'm using the brake tightened a small amount in order to increase the tension.

Is that not the correct thing to do?

And, I too, use the brake/tension screw as you did, John.  I am sure many others do as well.  I have used it this way for all my Feather Touch focusers and with the same eyepieces.  Although the one with my Dob wouldn't require as much tension because it never points down.  But I am still using it to adjust the tension and not disengaging it when I move the focuser wheel.  Yet none of these other focusers ever had the same problem as the one on my Tec 200. 

[areyoukiddingme]

Fair enough, but the (your) literature states otherwise (to use the Brake) and there's also no disclosure/warning not to do so.

Something to consider (including) with this otherwise amazing product.

I agree that there's a bit of ambiguity. I looked at the links in your post 19 to the Starlight instructions, which state:

 

Focusers with the Brake Option

" . . . The Brake consists of a lever arrangement internal to the pinion block. By adjusting the thumb screw on the pinion block this lever presses a friction pad onto the pinion thereby increasing the torque that is needed to turn the focus knobs. If the thumb screw is turned all the way in the pinion shaft and the draw tube will be locked. Opposite this thumb screw is a small set screw that is adjusted during the assembly of the focuser. Please do not make any adjustments to this. It is used to set the proper distance of the brake to the pinion shaft. If it is tightened too much damage to the brake can result. We use a thread locking compound on this set screw to prevent it from moving."

 

So the main screw operates the brake, and if tightened far enough locks the focuser in place. So it seems that one thing is not to touch those other screws. 

 

The part that I'm also having a hard time following is if that screw wasn't the cause, can the brake itself cause the damage?

 

My guess is that locking down the screw to hold a heavy load in place is fine, but moving the focuser when the brake is engaged tightly is a problem that could lead to severe wear with time.

 

But the brake has to be engaged at least somewhat, otherwise the focuser will slip under the weight of a heavy eyepiece.

 

Figuring out how to distinguish enough from too much pressure on the brake is what is difficult to follow.

 

One thing that is clear, if there's any hint of movement that is not smooth and there's sound, it is time to stop and get professional advice before the possibility of doing damage.

[Kent10]

One thing that is clear, if there's any hint of movement that is not smooth and there's sound, it is time to stop and get professional advice before the possibility of doing damage.

In retrospect, I wish I had talked to Starlight earlier but I wasn’t sure anything was wrong. At first, what I heard was a very faint click sound only in some spots that I had to put my ear up against to hear and I couldn’t be sure where it was coming from and I didn't always hear it.  It was very faint.  And sometimes the focuser would rest in what felt like a slot (this was also very subtle), but the next day it wouldn’t.    It wouldn't click either.  It took me a while to diagnose and describe the trouble I was having.  The clicking sound then got louder and that is when I started this thread.  But then the clicking would go away again.  The brass dust could have told me something was wrong but I thought perhaps this was normal break-in.  Honestly, I was thinking. . . .  this is a Feather Touch and they are great focusers so there can't be a problem with it.  It wasn’t until I saw the dust regularly and the clicking had been evaluated as certainly coming from the focuser and probably not normal, that I thought I better contact Starlight to see if they had a solution. 

 

I was disappointed I had to ship my precious Tec 200 focuser away, but I took the FT focuser from my Tec 180 and am using it now.  It is working great!  The repaired focuser is supposed to return to me on Monday.  I am going to tighten the tension using the top screw but I don't know if I should use the bottom brake screw or how much I should use it or if I should use it and then disengage when I turn the focuser wheel, which would be very inconvenient.  I change eyepieces a lot.  It seems engaging and disengaging the brake a lot might also cause wear.  Not sure.  I also focus a lot because as the temperature changes, the focus needs a tweak.

[Kent10]

I received my beautiful focuser today.  It is beautiful and I am glad to have it back.  it is already on the Tec 200 and ready for viewing tonight.

 

One thought on why this might have happened.  It is only a passing thought, of course.  Upon receiving the focuser today, I loosened the brake screw on the bottom all the way before I turned the knobs.  I wanted to check to see how well it was working now.  It seems stiffer/tighter than when I 1st got it, even with the brake screw almost out.  So even though I never turned this screw all the way in, perhaps it needed more turning than my other FT focusers and that started the problem. 

 

It still doesn't answer whether we are allowed to move the knobs while the brake screw is partially on, like I did and like all of you do, I assume.

[Kent10]

I enjoyed using the repaired focuser tonight.  It is very different from before the repair and, from memory, when I 1st received it.  I had the brake screw completely loose.   While pointed at zenith and with heavy eyepieces I did not need to use the brake at all.  I wonder if it will loosen with use.

[Kunama]

I received my beautiful focuser today.  It is beautiful and I am glad to have it back.  it is already on the Tec 200 and ready for viewing tonight.

 

One thought on why this might have happened.  It is only a passing thought, of course.  Upon receiving the focuser today, I loosened the brake screw on the bottom all the way before I turned the knobs.  I wanted to check to see how well it was working now.  It seems stiffer/tighter than when I 1st got it, even with the brake screw almost out.  So even though I never turned this screw all the way in, perhaps it needed more turning than my other FT focusers and that started the problem. 

 

It still doesn't answer whether we are allowed to move the knobs while the brake screw is partially on, like I did and like all of you do, I assume.

Having seen the design of the little brake pad and seeing the cuts on the pinion shaft adjacent to the pinion teeth I would suggest only to use the brake screw for locking into a position and ALWAYS release it to make changes to the focus position.

 

I just set my 152/1200 upright with the objective down on the carpet and then fitted my binoviewer/diagonal/eyepiece into the focuser, then using an Allen key I set the draw tube pressure by adjusting the socket screw on the topside of the focuser to the minimum pressure that would hold the focuser at the top.... this still left the action of turning the knob smooth without undue pressure.....  this way I wont be using the lock screw at all.

[Kent10]

That is right, Matt.  That is what I am going to do if I need more tension.  I also noticed my repaired focuser doesn't seem to have any grease while there was quite a bit on it originally.  My Tec 180 FT focuser appears to have had grease on it but it is dry after many years.  Not sure though.  It could just be dark now from age.  I wondered today if it should have grease or not.  It seems to work well without the grease but it is making a certain type of sound.

[Kunama]

I enjoyed using the repaired focuser tonight.  It is very different from before the repair and, from memory, when I 1st received it.  I had the brake screw completely loose.   While pointed at zenith and with heavy eyepieces I did not need to use the brake at all.  I wonder if it will loosen with use.

They really ought to specify that this is not a "brake" as such but a "locking" screw and should not be used for partial pressure......

[Kent10]

True, but on the other hand, I have not seen any problems others have had by using this screw for tension.

[Kunama]

That is right, Matt.  That is what I am going to do if I need more tension.  I also noticed my repaired focuser doesn't seem to have any grease while there was quite a bit on it originally.  My Tec 180 FT focuser appears to have had grease on it but it is dry after many years.  Not sure though.  It could just be dark now from age.  I wondered today if it should have grease or not.  It seems to work well without the grease but it is making a certain type of sound.

I cleaned the rack and applied some Dry-Lube to it, seems a bit smoother now.

Are your other focusers also R&P or are they Crayford style?

[Kent10]

I wonder how consistent these focusers are.  It seems they can be set with different tension.  Someone like Yuri who has tested hundreds of them might know.

[Kent10]

I cleaned the rack and applied some Dry-Lube to it, seems a bit smoother now.

Are your other focusers also R&P or are they Crayford style?

I am not sure.  I have lots of scopes and lots of focusers.  I have even replaced my Tak 100 DL and TV focusers with Feather Touch.  I have always used the screw on the bottom to adjust the tension and have never had a problem.  Yet

[Rustynuts]

Good afternoon, my name is Jon Joseph and I am the owner of Starlight Instruments.
I will go a little more in-depth on the issues regarding the damaged focuser.  Inside the pinion block, there is a brass brake lever in which holds the pinion shaft.  The pinion shaft of the focuser sits inside 2 u-shaped openings in the brake lever.  When the brake thumb screw is tightened, pressure is applied on the entire length of the brake lever and not on just 1 spot where the thumb screw touches the pinion shaft.  The problem is that the u-shaped openings of the brake lever were completely worn away in which allowed the teeth of the pinion shaft to wear a groove on the flat of the brake lever and this allowed brass shavings to get into the reduction assembly.  If Starlight Instruments was contacted early on about any questions regarding the focuser, Starlight may have been able to do a repair under warranty but the damage done was so excessive that brass shavings from the brake lever was in the teeth of the rack, in the reduction assembly and the brass shavings got between the drawtube and Teflon tape and damaged the roller bearings.  I have attached 4 photos for reference.
The damage to the focuser was from either over-tightening the brake thumb screw or from moving the focuser with the brake engaged or a combination of both.
Photo#1 shows a side view of the damaged brake lever.  Photo#2 shows the damage to the brake lever and the groove that the pinion shaft caused on the bottom of the brake lever.  Photo#3 shows what a used brake lever looks like.  Photo#4 shows Mr. Moore’s pinion assembly.  You can see all the brass shavings in the roller bearings. 
With the amount of damage, we do not feel that it was the fault of the product and that is why we were not able to do a warranty repair.  We had to do a complete tear-down and rebuild of the focuser using a complete new planetary assembly and brake system.

Photo#1.jpgPhoto#2.jpgPhoto#3.jpgPhoto#4.jpg

the new part does not have much clarence underneath the penion, how much clarance is there? im gussing .020"  you may want to add alittle more clarence no?  

[GOLGO13]

I enjoyed using the repaired focuser tonight. It is very different from before the repair and, from memory, when I 1st received it. I had the brake screw completely loose. While pointed at zenith and with heavy eyepieces I did not need to use the brake at all. I wonder if it will loosen with use.

Glad to hear you're back up and running. Hopefully this will not happen again. It's good for other users to understand how to properly use the device to avoid a similar fate.

It probably was a situation where the original focuser was not properly setup and you were having to compensate with a method that caused damage eventually.

Hopefully this will result in some updated documentation for the user.

I think I will read my documents for my focuser a little more...though a different manufacturer.

Hope all keeps well out there.

[Rustynuts]

 what you want to do is  loosen the lock, then adjust the screws that squeeze the draw tube first. so the draw tube  holds the weight.

  I dont know how much weight you are using on the feather touch but from the pics posted the lock was tightened way too much wile the pinion was turning grinding the brass. I suspect you did not adjust the screws for the draw tube first. If the adjustment is correct, you wont need to tighten the lock much at all, leave it loose or very little pressure.

This is how I set up and use all my  focusers.  There is a limit to how much weight the focuser can hold without the weight creeping back down. You will need to check with starlight for your model.

 

For my needs, I had to go to the now discontinued  AP giant 4 inch focuser for my 228mmf9 TMB! This solved my problem.

The 3.5 inch isn't beefy enough!  for big refractors we use, There should be a heavier focuser available!

[Kent10]

 

  I dont know how much weight you are using on the feather touch but from the pics posted the lock was tightened way too much wile the pinion was turning grinding the brass. I suspect you did not adjust the screws for the draw tube first. If the adjustment is correct, you wont need to tighten the lock much at all, leave it loose or very little pressure.

I have some heavy eyepieces which I used on this focuser and which I use on all my focusers.  Apparently, the brake screw was tightened too much and damage occurred.  But the puzzle is why did it occur on this focuser and not on my other focusers and not on many other people's focusers who have also used the brake screw to adjust the tension.  To use this screw to adjust the tension is in the Feather Touch instructions as well as the TEC instructions.  It is also very accessible while the top screw requires knowledge and additional planning to use it because you would have to have the hex wrench with you.  Or plan ahead of time as you did and as I am doing now after learning what can happen.

 

However, I still think this focuser was unusual in some way.  Perhaps the top screw was set looser than other focusers and then more tension was needed to hold even smaller eyepieces.  So naturally, at least for me and with my past experience using FT focusers and reading the TEC instructions, I used that screw to secure my eyepieces. 

[areyoukiddingme]

Hmm, after reading all this I'm feeling a bit puzzled.

 

On my Stowaway, if I completely loosen the brake, the focuser will fall of its own accord with a 2" diagonal and 22mm Nagler (for example). 

 

That means that the brake has to be partially engaged at all times, otherwise I'll have to re-focus every time I move the scope up in altitude. 

 

My strategy is to hold the scope up until it starts to slip, and add the smallest amount of braking I can to prevent slippage. Then I leave it there, using that amount of brake pressure at all time--and refocusing when I change eyepieces.

 

I hope this is not causing damage?

[Kent10]

I also have a Stowaway and have been using the brake screw for my eyepieces without a problem yet.  Maybe this is a different type of focuser?  I'll have to look.  Or is it just a smaller version.  Is there a screw on top we can use to tighten the tension instead of using the brake screw?  Once again, though, I don't recall hearing of any problems before and people must be using this brake screw for tension, I would think. 

[Rich V.]

To Jon (owner of Starlight Instruments), if you could explain the proper operating use of the brake that would be helpful for everyone monitoring this thread.  For me, it's not clear if this type of damage can only happen when the brake is fully engaged or just partially.  As there are instructions for your product that seem to contradict what you indicated was the source of operator error damaging the focuser, it would be helpful if you could clarify what you meant by the following statement:

 

"The damage to the focuser was from either over-tightening the brake thumb screw"

 

Maybe this means 'locking' or very nearly locking the brake (and adjusting focus).  If not, then the current instructions need correcting to either state that the brake should not be used to adjust tension at all or some clarification needs to be added as to how to use it to properly adjust tension in order to avoid damaging the focuser.  

 

Currently, I'm using the brake tightened a small amount in order to increase the tension.

Is that not the correct thing to do?

This is exactly what I'd like to get resolved with a written instruction from Starlight; I've also been using the "lock" screw as a field-friendly, tool-free method of tension adjustment for different weight eyepieces on my FT3545 for years.  I never "lock" it tight as I have no need.  It does state right on their website "Our original Brake Feature is included to allow for easy load adjustment of the weight on the focuser. This feature also allows locking the pinion/draw tube when needed."

 

We haven't heard back; would Jon Joseph, since he's already responded to this thread and must realize our confusion about this, please give the many of us who use his FT3545 focusers a proper instruction regarding focuser tension?  Surely there is a place on the Starlight website where complete instructions for their focusers could be made accessible?  I see none.  These are expensive focusers and we should be fully aware of the correct means we have to adjust them in the field.

 

My instructions from TMB for the FT3545 read similarly to TEC's  about the brake function:

 

"Because your Feather Touch focuser is so smooth in operation and moves so freely, it can only hold a limited

amount of weight (generally about 1 lb.) without drifting out of focus when the focuser drawtube is not horizontal
and has a significant vertical component. The focuser therefore contains an adjustable-tension internal brake system to allow astrophotography and visual use with heavy eyepieces without the possibility of focus shift.

The brake consists of a lever arrangement within the
focuser’s pinion block. Adjusting the thumbscrew underneath the pinion block causes the lever to press a friction
pad onto the pinion. This increases the torque needed to
turn the focus knobs. If the thumbscrew is turned all the
way in (only 1 to 1½ turns), the pinion shaft and drawtube
are locked into position at the desired focus for long exposure imaging. Visually, partial tightening of the internal brake offers a virtually infinite range of braking force to
accommodate various eyepiece and accessory weights."

 

If this information is incorrect, users as well as vendors should be advised of the proper use of these focusers.  It would be great if this were cleared up for everyone concerned.

 

Rich