Homemade feather touch focuser

[Ampthill]

Here is the feather touch focuser Ive made for my cpc800, Its made from anodised aluminium,

with a hardened silver steel race for the ball bearings, Its turned out to be a 9:1 ratio, and

seems to work great!, (Also saved myself £300 !!!).

[knobby]

That's beautiful ! Well done ...

[DirkSteele]

Amazing!  I have a feathertouch on my C11 (it is great) and that looks just like it.

[souls33k3r]

That certainly looks the part. Any chance sharing the love?

[Peter Drew]

Good job!. Nice to see Ampthill mentioned, I moved up North from Park Hill, Ampthill, good memories.  

[Chriske]

Nicely done...!

I always use dual speed knobs too to allow smooth action, saves me tonnes of money.

[paulastro]

What a beautiful job you've made of it too, top man (or woman?) ! 

[Stu]

Cracking job! Very skillful  

[Gina]

Yes, beautiful   A really professional job

[Stub Mandrel]

On 22/12/2017 at 15:16, Ampthill said:

Here is the feather touch focuser Ive made for my cpc800, Its made from anodised aluminium,

with a hardened silver steel race for the ball bearings, Its turned out to be a 9:1 ratio, and

seems to work great!, (Also saved myself £300 !!!).

That looks pro!

I've been looking at making a  'daisy wheel' reduction system, how does yours work? Any pics of it in pieces?

[Dave_D]

ooohhhh shiny

[Ampthill]

20 hours ago, Stub Mandrel said:

That looks pro!

I've been looking at making a  'daisy wheel' reduction system, how does yours work? Any pics of it in pieces?

The way it works is this, Insde there is a brass barrel with three holes drilled into the side of it, three 7mm ball bearings go into these holes

,the end of the brass barrel has a 2mm hole in it, that has a piece of 2mm drill as the "fine" spindle,it has a recessed area that the bearings

 run on, the O/D of the bearings run in a hardened tapered steel barrel, The bearings are "loaded" by a brass nut that runs on 1.5mm ball bearings.

The coarse knob is fitted to the brass barrel, and the fine knob is fitted to the 2mm spindle.

This web page should give a better understanding.  http://helixgate.net/tmb1.html

I found the most difficult piece to make was the recess in the 2mm spindle, as it has to be perfectly true and round, or it will feel lumpy

in use.  Bigger bearings or smaller spindle would give a finer ratio.

  While im on the subject, Ive found a great way to make the knurlled knobs, If anyone wants details, let me know!

[Peter Drew]

The same principle is used in many geared focus mounts but kudos in successfully making such a precision component yourself!  

[Astrobits]

I made these several years ago. Found a Chinese web site that had the diagrams that guided me. It didn't mention the tapered barrel, I had to find that out for myself and determine the best taper angle. The tapered barrel and shafts I made with Stainless steel having found out that brass was too soft.

Here's the web site, suggest using Google Translate:

http://bbs.astron.ac.cn/thread-54988-2-3.html

Nigel

[Stub Mandrel]

Thanks, this is a lovely machining challenge to take on!

[Chriske]

I always use these, rather cheape.

http://www.orenelliottproducts.com/planetary-reduction-drives
Need some tuning, well performed it'll give you the same smooth action as any 300£ focuser.

[Gina]

Wow!  They take me back - we used those on wireless sets in the 50s and 60s for fine tuning

[Chriske]

I know Gina, nowadays we use them in our telescopes, isn't it funny...?
Point is they really work perfect as dual speed knobs. You only have to add 2 knobs, and that's one reason we have printers for ...

[Ampthill]

Ive made a better coarse knob, and re-anodised the black parts, I think it looks better now !.

[Chriske]

The knobs are really nice...!
If I'm not mistaken these are not knurled. I think it is a milling job, correct..?

Edited December 26, 2017 by Chriske

[Ampthill]

5 minutes ago, Chriske said:

The knobs are really nice...!
If I'm mistaken these are not knurled. I think it is a milling job, correct..?

I made them on my lathe, with a vee tool set at 90 deg to normal, then scrape it down the side making a groove (5 thou at a time),

then with a pointer on one of the change gears at the back of the lathe head, move the spindle round to the next tooth and repeat. 

What you get is very nice evenly spaced grooves, Gears could be made like this too !

[Chriske]

Nicely done, ver nifty...!

[Gina]

Wow!!  That's a labour of love

[AdrienB]

Hello,

That focuser looks really nice ! Congrats !! and thanks for sharing !

I've been trying to make one for a little while but can't seem to get the taper right (I think). Outside the barrel things seem fine and smooth when holding the bearings with my hands, but as soon as i put it in the barrel it locks up.

If you have some tips I would greatly appreciate it 😃 

 

Right now I'm working my way through a couple taper angles to see

Also found a nice way to do the recess by turning the rod in a reamed hole in a sacrificial block with a hand drill (horizontal) while cutting with an end mill (vertical)