Baader NT Steeltrack Focuser - Issues :o(

[AdeKing]

Hi All,

I'm hoping that someone out there might be able to assist me.  I have just received a new Baader Classic NT Steeltrack focuser from 365Astronomy, and so far am bitterly disappointed, as the focusing action is far from buttery smooth.

This is the original version of the Steeltrack and is not the new Diamond Steeltrack version.

When the focuser is at its most inward point of travel and you start to extend the drawtube the travel is initially buttery smooth and a pleasure to use, but after approximately half a turn of the coarse focus knob the focusing action becomes very stiff and remains stiff for another half a turn (and a scraping sound is heard), after which the action frees up again for another half a turn before it becomes stiff again.

I have checked the usual suspects and have loosened the knob for the brake and have backed off the allen key that applies pressure to the focuser shaft.

To my inexperienced eyes, this behaviour suggests that the focuser shaft is slightly bowed and is exerting more pressure against the focuser barrel through some parts of its revolution than in others.

Before I get in touch with 365Astronomy to request that the unit is swapped, are there any obvious adjustments that I might be missing which could account for this behaviour?

The focuser did not come with any user instructions explaining what the various allen adjustment screws do, so I'm wary about fiddling with anything too much.  All I have touched so far is the thumb screw that operates the brake and the recessed allen adjustment screw which puts pressure on the focuser shaft.  Looking into the inside of the focuser from the tube side, I can see that neither of these bolts is touching the drawtube or the focuser shaft.  

I know that these focusers are generally well regarded, so if anyone can give me some pointers, I'd much appreciate it.

Regards,

Ade

[alanjgreen]

Ade,

There are 6 allen screws visible on the top side.

- two large centre screw are holding the bearing block in place which fastens all four roller-bearings.  Leave these alone.

- four small screws either side are the bearing adjustment screws and can be used for adjusting the drawtube to align with the optical axis of your telescope

See page 7 (its for the new focuser but the screws on the top are the same)

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi-x5Xvpe_UAhUIZ1AKHSfJBcEQFggiMAA&url=http%3A%2F%2Fwww.kkohki.com%2FBaader%2Fbds%2FDBSmanual.pdf&usg=AFQjCNHHGRuHhS-jhW2UwNWrBnuJxexaKQ

If its out of collimation then the drawtube may be catching somewhere as it slides in & out. The four small screws can be adjusted

If I were you, I would return it (as you just got it) and get them to send one that is "as new". I once received one in a similar state from FLO and they just swapped it for another one and all was well.

 

Alan

 

[LightBucket]

It won't be out of collimation, if it was the stiffness would be there all the time...

Check the collimation with a laser collimator first, if you start messing with those screw mentioned, you could have all sorts of issues... ? And you will need a good laser collimator to put right...

i had a similar issue with a focuser recently, and like you it seemed like a bent shaft as it was stiff very turn at the same point, my problem turned out to be the fine focus assembly, there is a small screw that hold the fine focus assembly in the focuser, when that screw was loose all was good, but when tightened it caused problems, as it pushed the whole assembly very slightly out of line,  but it has to be tight to stop the fine focus assembly rotating when you focus....so how could I overcome this...well I realised that the fine focus assembly was not a dead fit into the focuser, there was a tiny amount of play until the screw was tightened, hmmmmm, in the end I put some shim around the assembly and pushed back into its housing then the screw was just nipped up a tiny bit, the shim was more than enough to stop the issue and also it does not rotate when focusing....

so check that out, loosen the little screw, it should be right at the edge on the underside of the fine focus assembly, and see if the problem stops, if it does then that's the issue...

 

 

[Moonshane]

before you do anything drastic, it could be that one of the wheels is touching the body as it is too close. they are held on the spindle by little grubs. if you think I am correct try loosening a grub and move the wheel half a mm or so out.  hope this works.

[SteveA]

If I were in your shoes, I would simply contact the supplier and arrange a replacement unit. You have paid good money and should expect the goods to be in perfect condition and clearly they are not. You may well be able to resolve the issues yourself by making adjustments etc, but in my opinion you shouldn't have to be doing that.

Steve

[AdeKing]

@Moonshane thanks for the suggestion, you are partially correct as this has sorted part of the issue for me.  

The coarse focus knob on the fine focus assembly was rubbing against the focuser body, and removing the fine focus knob and loosening the grub screws in the coarse focus know allowed me to slide it away from the focuser body, which has freed things up significantly and made the focus action lovely and smooth.....mostly.  

However, there is still a point once in every revolution where the action becomes noticeably stiff compared to the rest of the travel.

@LightBucket I can't see the grub screw that you are speaking about.  On the bottom of the focuser where the thumbscrew for the brake is located, there are two small grub screws, one the the far left and one at the far right just where the fine focus assembly enters the focuser, is this the screw that you're talking about (see photo)?

@alanjgreen thanks for the instructions posted above, I have not been able to find any instructions on the internet for this particular model, but its good to know that those for the newer model are still relevant (in parts).  

Although I've managed to improve the action significantly, I have contacted 365Astronomy about a return and exchange.  I'm not 100% happy about having to do this much fiddling with a unit straight out of the factory.  I understand the need for fine-tuning and collimation (if necessary) once its installed onto the OTA, but I don't think that the actual focus action should need significant tinkering out of the box.

Thanks for all of your help guys, and I'll let you know how I get on 

 

[AdeKing]

@SteveA thanks Steve, thats my feeling, I have improved it significantly by slightly moving the position of the focusing knobs, but there is a residual issue and I've contacted the supplier about a return and exchange.

Ade

[LightBucket]

Yes that looks like the correct screw.... just loosen a bit and then re try and see if it makes a difference, loosen it too much and when you turn the focus knob the whole thing will turn, which won't matter just re tighten a bit....

[AdeKing]

Just to conclude this thread I thought I'd let you know that I sent the affected focuser back for an exchange.

I contacted Baader directly, and they were very helpful and provided  instructions on adjusting the collimation of the tube on the original Steeltrack (attached).

The supplier tested my return together with another three they had in stock and two of the three had the same issue.

Anyway they sent me the one that didn't have the issue and I'm glad to report that it's lovely to use and free from the issues experienced previously.

Ade

E_Steeltrack-Adjustment.pdf

[LightBucket]

Glad to got it sorted

[AdeKing]

Me too, it took a couple of weeks to get it sorted but it's all ok now.