Alternative to the Crayford focuser

[gajjer]

Hi everybody and happy Christmas

I am fed up with my focus control, having had it slide out of focus when I slew from a horizontal position to a vertical.

I know this is going to cost me. I'm looking for a rack type focuser. Any suggestions or experience would be welcome.

 

cheers

gaj

[gajjer]

Ooops should have said it's for the Equinox 80

cheers

gaj

[PeterCPC]

I think that you should have a go at adjusting the existing focuser first. My ED80 does not lose it's focus like that. Try tightening it up a bit.

Peter

[gajjer]

Hi Peter

yes did try that and thought I had sorted it but with the Atik and the filterwheel hanging off it, it seems to have proved too much. I don't know if the extra cold night had anything to do with it.

Problem is that there are very few nights available and I have had problems with it since getting the heavier camera. I just want it sorted.

cheers

gaj

 

[ronin]

Check out the TS site they seem to sell an assortment of focusers at not insane costs, equally having looked insane is a matter of opinion, they still seem costly. The TS site seem to refer to them as Monorail.

Another thought is stripping yours down, cleaning all the surfaces and rollers and reassembling. Thoughts being that as they rely on friction the surface and/or wheel inside may have grease  onthem so you lose the required element of friction.

Check out also 365Astronomy, they have a selection of replacement focusers.

AST seem to have 2 monorail focusers, both are TS but I cannot easily see them on the TS site, at AST they are €179:

https://www.astromarket.org/accessories-5/focuser--focusmotor-5/refractor-focusers-5/

[gajjer]

Thanks Ronin, that's really helpful. I guess I have nothing to loose in stripping it down. I think I saw a post on that somewhere.

cheers

gaj

 

[StarryEyed]

The cold will cause some isssues but this can be resolved with a little attention.

Crayfords require fine tolelernces for friction to work and adjusting the focuser for (during) UK mid winter tempratures  is the best solution.

I have often thought that a rack and pinion offers the best mechanical operation but by itself doesnt over come slippage of the focuser tube which is still dependant on tension/friction somewere in the focuser.

I had a lot of trouble with the crayford focuser on my WO FD80 when I first got it when I had an SBIG 2000 hanging off it imaging at the zenth. To his credit Ian King who I bought the scope from sent me out a new replacement micro focuser but this behaved exactly the same way . This was also in cold conditions -5 from recollection (was about ten years ago).

I noticed two thing when I tighned up the friction on the focuser to stop the focus tube slipping the microfocuser would start slipping (or stop working). In the end I opened up the focuser and when I adjusted (breaking the glue holding the locking screw in place) the locking screw for the micro it would work for a while and then start slipping again as the locking ring loosend and backed off. In the end when I had everything adjusted I used some lock tight to prevent the micro locking ring backing off. The focuser has been good ever since, it needs a little clean and tweak everynow and then but still works well. I dont image with it any more other than perhaps the odd snap shot with a DSLR but it can hold the camera at the zenith and I can use the microfocuser.
 

I personally think a rack and pinion focuser removes one area for potential problems slippage between the spindle and focuser tube but can also add another with the gear mesh in either case understanding how they work and tuning yours to suit your conditions is the way to go.

I am pretty sure if you spend an hour with it it will be better than is was.

[Mr Spock]

The Baader SteelTrack is highly regarded and shouldn't have any slip or flexure under weight.

[Moonshane]

Before you spend lots, adjust it as best you can then use some elasticated thread to offer support.  Loop it round a set screw on the scope draw tube and on the focuser housing with just the right tension. Will cost about 50p.

I have seen this in use at the Astronomy Centre and bound it's a great solution.

[nicoscy]

1 hour ago, Mr Spock said:

The Baader SteelTrack is highly regarded and shouldn't have any slip or flexure under weight.

 

A good enough focuser but the TS R&P focusers are superior to the Baader. Tried both of them...

[gajjer]

Thank for all your inputs guys. I really do appreciate it.

I have decided to go with the Baader. I've ordered it and await it's arrival.

As you all know, we get precious few opportunities to get out there and do our stuff. I am not a late night imager. I set up my kit on the night and it's all packed away by 11.30pm.

Perhaps when I retire that will change. So I do appreciate if I spent time on the Crayford it could be made better but I just don't have the time. So this year, my winter fuel allowance

has gone towards another piece of kit. Thank you all.

I was out the other night and it just seemed a catalogue of failures; the focuser being just one. First the laptop wouldn't load PHD ( it could not find a DLL) - to which my response

was "Well I haven't had the b****** thing." Possible much louder than necessary to an inanimate object. It was cold and I could see doom ahead of me. But I did not give up. Then it would not

recognise my guide camera. Getting very peeved now. Then everything is fine as I set-up on Vega. Great. Getting the hang of this focusing millarky. So now I slew to IC1805 and nothing.

Binning at max and long exposure and no sign of it. ( I did not realise I was seeing hot pixels ) Eventually just on the verge of giving up I realised the tube had slipped 30mm!

It took all the joy out of the night. I did refocus and get some images but I vowed to pay whatever it takes.

Rambled off a bit there! Sorry. But again, thanks for the advise.

I may still rip the Crayford apart and do a redesign. But that will be in the warm weather.

cheers

gaj

[gajjer]

Phew!! Well that took longer than expected.

The final part has arrived. Seems that Baader decided to change the design of the adapter.

So, now I have the bits, does anyone know of a good tutorial on how to fit it to my Skywatcher Equinox 80 Pro?

I understand that The Sky at Night mag did something a while back but that ship has sailed.

I'm sure I will manage but it's always nice to have advice from someone who has done it.

cheers

gaj