Takahashi Focuser Sideplay

[jock1958]

I’ve got a small amount of sideplay on my Tak FC 100DL focuser tube.

It became noticeable when racking the focuser in and out with my heavy duty 31mm Nagler attached.

I’ve tried adjusting my FT focuser and little grub screws on top of the focuser tube but that just makes it stiffer in operation. 

Apparently it’s a common trait of Tak rack and pinion focusers, has anybody else experienced sideplay on their focusers and should I be worried or not?

IMG_6362.MOV

Edited October 18, 2019 by jock1958

[John]

The focusser on my DL was a little stiff when I got it so I adjusted the grub screws slightly which has made it spot on. No side to side movement on mine though

Have you tried adusting the screws on the bottom of the focuser that tension the pinion ?. They are under the plate that covers the pinion mechanism:

[jock1958]

Thanks for that @John I’ve fitted a Feather Touch focuser and followed there installation instructions to the letter as well as adjusting the two small grub screws on top, no real improvement though. 
I’ve also been in contact with Ian King who I bought the scope off, he suggested sending the focuser back for the Takahashi techs to carry out some adjustments. 

[mikeDnight]

I tried adjusting my DC focuser shortly after I bought the scope, as it was quite stiff. Using the three grub screws to adjust the tension I ended up making a bit of a mess of things, ending with very noticeable image shift. I phoned Nick Hudson at True Tech, who told me to remove the pinion, loosen off the three grub screws so the draw tube slides freely. Then he said to tighten each grub screw equally, counting the turns on each, until the draw tube friction moves smoothly. Then reassemble the pinion, gently tightening the two screws. It took me a couple of attempts, but the focuser image shift and the initial stiffness that prompted my intervention disappeared. I also attached the Tak micro focuser. It seems image shift is the result of the three grub screws being unevenly tightened!

[John]

3 hours ago, mikeDnight said:

I tried adjusting my DC focuser shortly after I bought the scope, as it was quite stiff. Using the three grub screws to adjust the tension I ended up making a bit of a mess of things, ending with very noticeable image shift. I phoned Nick Hudson at True Tech, who told me to remove the pinion, loosen off the three grub screws so the draw tube slides freely. Then he said to tighten each grub screw equally, counting the turns on each, until the draw tube friction moves smoothly. Then reassemble the pinion, gently tightening the two screws. It took me a couple of attempts, but the focuser image shift and the initial stiffness that prompted my intervention disappeared. I also attached the Tak micro focuser. It seems image shift is the result of the three grub screws being unevenly tightened!

Thats very similar to Vixen's advice for their R&P focuser (lower one for refractors):

http://miltonhill.us/Tele/Vixen_Focuser.html

It does work !

 

[jock1958]

Thanks @John and @mikeDnight I can only see two little grub screws on top of my focuser either side of the tension knob? 

I think I may start from scratch by removing the Feather Touch focuser, adjusting the little grub screws on the top then re-installing and adjusting the FT focuser.

Ive attached a couple of photos of the top of my focuser tube assy and another short video of the sideplay I’m experiencing. I’ll keep you posted.

As a side note Ian King contacted Takahashi about my problem and they said it’s impossible to avoid sideways movement on rack and pinion focusers as there is no particular way to adjust them but they could try and improve things by adding more grease and shim inside.

 

[mikeDnight]

I'd forgot the DF and the DL have just two grub screws, where as the DC has three. There are shims inside the DC focuser as I found out after my dismantling escapade. I suppose adding another or adding slightly larger shims may help, which is something I hadn't considered. It might be that there will be some residual image shift but it should be pretty well controlled. With my own DC scope, I can use 300X with the target remaining in the centre of the field during focussing, so image shift isn't much of a problem, but I'm purely a visual observer and I may be less effected by it than others may be.

Below is an image showing the three grub screws on the DC version.

[John]

I wonder if the FT dual speed addition has any side affect on the stability of the focuser ?

I don't get sideways play with my R&P focusers - the tension on the grub screws on the top of the focuser pushes the drawtube onto the guiding strips / shims which seems to keep the drawtube from moving from side to side.

 

[jock1958]

Thanks for your input @John & @mikeDnight In the morning I'll whip the focuser assy off and have a peek inside to see how its put together before attempting to adjust the FT focuser and small grub screws. If all else fails I'll send the focuser assy back to Ian King.....hopefully not in bits!

[heliumstar]

On 20/10/2019 at 15:39, jock1958 said:

Thanks for your input @John & @mikeDnight In the morning I'll whip the focuser assy off and have a peek inside to see how its put together before attempting to adjust the FT focuser and small grub screws. If all else fails I'll send the focuser assy back to Ian King.....hopefully not in bits!

How did this play out in the end?

I have the same issue with side play and in all honesty I think focuser on my Tak is not really up to standard overall. It's just ok in comparison to ES Hex one and the standard 2 speed Chinese one that comes with Altair 80ED-R.

[andrew s]

I thought the only felting Taks need was adding your initials in gold leaf.

Regards Andrew 

[John]

29 minutes ago, heliumstar said:

How did this play out in the end?

I have the same issue with side play and in all honesty I think focuser on my Tak is not really up to standard overall. It's just ok in comparison to ES Hex one and the standard 2 speed Chinese one that comes with Altair 80ED-R.

My FC-100 DL focuser is spot on for me now. I don't feel the need to add either the Tak or FT micro focuser. The adjustments that I made above seem to have lasted. It is better than my Vixen ED102SS R&P and I don't notice any disadvantages when using the Tak to the Moonlite on my ED120 or FT on my LZOS/TMB 130.

I'm not terribly fussy about my focusers though so others may feel differently. I do like them to work efficiently though and not to "slop" in any way.

 

 

[andrew s]

8 minutes ago, John said:

My FC-100 DL focuser is spot on for me now. I don't feel the need to add either the Tak or FT micro focuser. The adjustments that I made above seem to have lasted. It is better than my Vixen ED102SS R&P and I don't notice any disadvantages when using the Tak to the Moonlite on my ED120 or FT on my LZOS/TMB 130.

I'm not terribly fussy about my focusers though so others may feel differently. I do like them to work efficiently though and not to "slop" in any way

Your obviously young and your eyes still accomodate well, unlike mine.

It takes a few minutes each morning before I can read the paper on my tablet.

Regards Andrew 

[John]

23 minutes ago, andrew s said:

Your obviously young and your eyes still accomodate well, unlike mine.

It takes a few minutes each morning before I can read the paper on my tablet.

Regards Andrew 

I'm 60 so not too young !

 

[jock1958]

13 hours ago, heliumstar said:

How did this play out in the end?

I have the same issue with side play and in all honesty I think focuser on my Tak is not really up to standard overall. It's just ok in comparison to ES Hex one and the standard 2 speed Chinese one that comes with Altair 80ED-R.

The small amount of sideplay I described is only noticeable with my 2" diagonal & heaviest eyepiece fitted in this case a 31mm nagler. I re-adjusted the FT (MPA-TAK2.5) focuser referring to their detailed instructions including the adjustment of the grub screws on top of the focuser but sideplay was still there. 

At this point I contacted Ian King who I bought my Tak off, he did say it was a common trait of rack & pinion focusers but was more than willing to have a look at it and possibly send it on to Takahashi Europe.  Quote Ian King recieved from Takahashi Europe:  "It is impossible to avoid the sideway movement on rack and pinion focusers and there is no particular way to adust it. It is clearly more noticeable here as your customer is using a heavy eyepiece. If you can ship the focuser back we can try to improve it putting more grease and maybe a shim inside."

I removed the focuser assembly and sent it back to him, he checked it out and found the focuser working well with minimal side by side movement and strongly suspected Takahashi wouldn't be able to improve on it,  Ian's experience was good enough for me and as far as I went with it.

I haven't delved any further into this sideplay or dismantled the focuser as described by @mikeDnight so it may be possible to add a shim to the rack or rack guide if your sideplay is unacceptable?

Not sure but have you replaced your Tak focuser with the FT?

 

 

 

Edited May 10, 2020 by jock1958

[Stu]

I’ve nee Ben a fan of Tak focusers, they just seem a poor design compared with many out there. My TS 72mm has a lovely R&P, why can’t they do the same?

I think the better answer is a full FT replacement, it really does finish the scope off beautifully. I use the FT-2025BCR with an A20-304 adaptor. The trouble with the micro focuser is that it still uses the same drawer tube assembly which is where the problems are I think.

[jock1958]

21 minutes ago, Stu said:

I’ve nee Ben a fan of Tak focusers, they just seem a poor design compared with many out there. My TS 72mm has a lovely R&P, why can’t they do the same?

I think the better answer is a full FT replacement, it really does finish the scope off beautifully. I use the FT-2025BCR with an A20-304 adaptor. The trouble with the micro focuser is that it still uses the same drawer tube assembly which is where the problems are I think.

In some ways Stu I'm inclined to agree. Theres no doubt the FT MPA-TAK2.5 focuser is a superb piece of engineering and it works incredibly well, however its a bolt on goody utilising a lot of the original Tak parts and inherent foibles! 

[Stu]

6 minutes ago, jock1958 said:

In some ways Stu I'm inclined to agree. Theres no doubt the FT MPA-TAK2.5 focuser is a superb piece of engineering and it works incredibly well, however its a bolt on goody utilising a lot of the original Tak parts and inherent foibles! 

Indeed! In the past I’ve used a similar FeatherTouch Micropinion on a Televue Genesis. This worked superbly because the underlying tube and R&P are buttery smooth. I have another on order for my latest Genesis because I love fine focus!

[heliumstar]

Mine was very stiff from the get go

3 hours ago, jock1958 said:

The small amount of sideplay I described is only noticeable with my 2" diagonal & heaviest eyepiece fitted in this case a 31mm nagler. I re-adjusted the FT (MPA-TAK2.5) focuser referring to their detailed instructions including the adjustment of the grub screws on top of the focuser but sideplay was still there. 

At this point I contacted Ian King who I bought my Tak off, he did say it was a common trait of rack & pinion focusers but was more than willing to have a look at it and possibly send it on to Takahashi Europe.  Quote Ian King recieved from Takahashi Europe:  "It is impossible to avoid the sideway movement on rack and pinion focusers and there is no particular way to adust it. It is clearly more noticeable here as your customer is using a heavy eyepiece. If you can ship the focuser back we can try to improve it putting more grease and maybe a shim inside."

I removed the focuser assembly and sent it back to him, he checked it out and found the focuser working well with minimal side by side movement and strongly suspected Takahashi wouldn't be able to improve on it,  Ian's experience was good enough for me and as far as I went with it.

I haven't delved any further into this sideplay or dismantled the focuser as described by @mikeDnight so it may be possible to add a shim to the rack or rack guide if your sideplay is unacceptable?

Not sure but have you replaced your Tak focuser with the FT?

 

 

Interesting that this side play only a few of us experience. I went wide in search of this issue and it looks like most of Tak users don't experience side play. Mine is even worse than what I can see from your video.

[jetstream]

18 hours ago, John said:

My FC-100 DL focuser is spot on for me now.

Mine too- the TSA 120 adjusted up nicely, smooth as butter and no play.

[Saganite]

39 minutes ago, heliumstar said:

Mine was very stiff from the get go

 

Interesting that this side play only a few of us experience. I went wide in search of this issue and it looks like most of Tak users don't experience side play. Mine is even worse than what I can see from your video.

The R&P focuser on my FC100DC has exhibited this side play from brand new. I spoke to Ian King about it shortly after receiving it, when I met him at an Astro show somewhere, and he told me the same thing, ie, it is inherent in the design. It does not trouble me in use, but you  would be forgiven for expecting better from Takahashi.

I had my Denk bino mounted on it for a while, but that, plus eyepieces ,exacerbated the problem, so I  now use a smaller lighter bino on this scope. I also tend to nip the focuser lock down and then back it off which does stop the sideways 'slop' but is not ideal.

[heliumstar]

It's when you realise that mechanical is just as important as optical. With various SW I knew the focusers are so so except for 72ed which was great in my case. Hexafoc was always spot on as was anything on the many clones from China (Altair Astro 60ed and 80ed-r). Mind you the focuser on the Tak is not bad or unusable in any way. Just a little annoying. Almost as much as it might be worth splashing for FT one. If I would be 100% visual in Q mode then fine but in CB mode for EAA it's tricky getting focus.

Edited May 10, 2020 by heliumstar
added a sentence

[Stu]

On 18/10/2019 at 17:15, John said:

The focusser on my DL was a little stiff when I got it so I adjusted the grub screws slightly which has made it spot on. No side to side movement on mine though

Have you tried adusting the screws on the bottom of the focuser that tension the pinion ?. They are under the plate that covers the pinion mechanism:

I think I’m right in saying that the DL shares the larger focuser of the DF unit, which might explain why it is better for you than I find the DC. I always planned to put an FT on mine so didn’t want to spend more on the DF, if that makes sense?

[John]

Just now, Stu said:

I think I’m right in saying that the DL shares the larger focus of the DF unit, which might explain why it is better for you than I find the DC. I always planned to put an FT on mine so didn’t want to spend more on the DF, if that makes sense?

Quite possibly Stu.

My DL is the only Tak that I have ever used so that is all I have to go on

 

[jock1958]

1 hour ago, heliumstar said:

Mine was very stiff from the get go

 

Interesting that this side play only a few of us experience. I went wide in search of this issue and it looks like most of Tak users don't experience side play. Mine is even worse than what I can see from your video.

You’ve got me thinking about this again and especially as yours seems to have even more play and  stiff to use.

I tried winding the adjuster in and it does remove some of the play but then becomes unusable if you see what I mean.

The only things I can think that might be worth checking is the adjustment of the focuser  pinion to rack, also check the rack is securely attached to focuser tube.

I’ve measured the gap between the rack &  notch cut out in the focuser housing and it’s 0.010” / 0.25mm not sure if this has any bearing on side play and whether it acts as guide for the rack?

Let me know how you go and have you the same TAK as me?