Dual Speed Focuser

[hornedreaper33]

@Fraunhoffer 

Sorry for the slow reply, I was on holiday. When you remove the orange bearing plate, the weight of the mirror will slowly push the threaded shaft and bearing assembly out. Don't worry nothing will drop out. The mirror will stop and you will have a slightly sad looking telescope. Watch the installation video for the Feathertouch focuser if you want a proper look:

 

Edited February 28, 2019 by hornedreaper33

[Adam Long]

On 13/02/2019 at 21:30, Chriske said:

These units don't look very professional, I know. But when 'tuned' there's as good as any expensive dual speed focuser.
I've don this dozens of times.

When it arrive ,see how it performs. It probably will run very difficult(due to the thick grease inside).
If so, let me know, and I'll post some additional pictures how to proceed to make these work with 'butterly smoothness'.

Hi Chris, I've built a dual speed plywood Crayford thanks to the information in this thread. It works pretty well, but I'd love some more info on tuning for 'buttery smoothness', if possible? Many thanks.

[Adam Long]

Bump... low speed not working well (slipping) at low temps recently, would appreciate any advice on tuning. Thanks!

[markse68]

If it’s the thick grease getting thicker with cold temps could you maybe flush it out with lighter fluid and replace with something less viscous?

[Adam Long]

Thanks, I've already done that on assembly, wondering if I went too light with bike chain oil and need to put some grease back in?

[Southstorm]

On 12/02/2019 at 00:23, Chriske said:

This a drawing I made showing the completed unit from different angels. The bleu parts I do print these. Years ago when I did not had that 3D-printer yet we use to make them out of resin.
If you decide to use these BD601 units and you have printer, let me know, I'll send you the STL files.
The large knob is the 1:1 and the smaller one is the 6:1
Almost forgot, to fasten the large knob you need two M2 screws(they're not included)

Hi Chriske, I know this was from a few years ago, but I am trying to accomplish the same thing with my 3D printer.

 

Would you be able to share your STL files if you still have them?

 

Thanks in advance,

Brandon.

[gazza25]

if needed in the uk 

https://www.ebay.co.uk/itm/252950162537?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

[gazza25]

or this

https://www.ebay.co.uk/sch/i.html?_dmd=2&_ssn=anonalouise&store_cat=0&store_name=mainlineelectronicsltd&_oac=1&_nkw=ball drive

[Giovanni Boato]

I watched all over the internet for a 3d printed version, seems like nobody did it yet, so I had to.
I'm still refining the tolerances a bit, but it's very promising. It probably won't ever be as good as a metal one but considering I made it with steel balls from the old magnetic toys and a few screws I was surprised it worked in the first place.
If anyone is interested I'll probably upload the f360 project on thingiverse as tolerances need to be tweaked from 3d printer to 3d printer.

It's a planetary gear equivalent made with balls instead of gears.

The two white rings are used to compress the balls against the central shaft ( The untreaded parto of an  M4 bolt  cut to length ).
I used M2 hardware for that because I had it on hand and I wanted it to be as compact as possible, you can easily edit it to make it work with M3.

The outside knob is connected to the central piece through a slot.

All the parts need some careful sanding to get the correct fit, I recommend printing at 0.1 layer height.

Edited January 30 by Giovanni Boato