Fork Mount plans.

[el_draco]

Fishing...
Does anyone have a set of drawings for an English fork capable of taking on a 800mm truss OTA weighing about 90kg? I can design it myself but like to avoid reinventing the wheel where possible

Rom

[JA]

Wow 800 - that's a cracker !

A mixture of fork mount design ideas/images here. If you sift through them to the relevant webpage there are some detailed ideas/designs with some.
https://www.google.com.au/search?biw=1745&bih=1029&tbm=isch&sa=1&ei=uBGzWvjwCsyY8wWSsYu4Bw&q=diy+telescope+fork+mount&oq=diy+telescope+fork+mount&gs_l=psy-ab.3..0i24k1.213024.214479.0.215830 .4.4.0.0.0.0.308.686.0j2j0j1.3.0... .0...1c.1.64.psy-ab..1.3.685...0i13k1.0.NE9QYsX6yU0# imgrc=iHEQ3XRBRDyp0M:

I found a few at the 500/600mm size. Here is one with an unusual amount of detail, not necessarily plans per se...
http://www.harpoint-observatory.com/english/diy.htm

AND ... Tell us more about your plans/goals for this interesting project.

Best
JA

[Wavytone]

What's the scope - approx aperture and focal length ?
Where will the eyepiece be ?

If this is a serious project I'd be looking for a mechanical engineer with the tools to do finite-element analysis on how the complete setup flexes and design accordingly.

Amateurs tend to go overboard in areas that don't need it structurally, while oblivious to stupid weaknesses elsewhere, the result being unnecessarily heavy/large and not particularly good in terms of flexure.

[el_draco]

Its a 22" F4.5 newt, a project I have been working on for a couple of years between "life events". I now have the OTA pretty much done and hope to have the mirror mountings sorted shortly.

The OTA is a modified Serrurier truss pretty close to the 200" Hale in appearance and really rigid. Completed, I am estimating 90+ kg, but the torque is going to be a bit much for My PMEII.

I've built big scopes before, including a 29" so I am aware of the issues involved in this scope. I like the English fork and have built a few in the past but not this big. Hence... the fishing trip. I'll check those links JA.

Ta

[billdan]

Hi Rom, if you feel a bit overwhelmed about building the English fork mount for that size OTA and you decide to look for a commercial solution.

Then have a look at the Mesu 300 Mount, it is designed for 50cm apertures weighing over 100Kg, fitted with Renishaw encoders it will give you goto and tracking accuracy of 0.02 arcsec.

Pictured below is the Mesu 300 sitting next to the Mesu 200.

http://www.mesu-optics.nl/mesu300_en.html

Cheers
Bill

[Stefan Buda]

I don't know what an English Fork Mount is but you could make two of my Alt_Az forks and bolt them end to end to make an English Yoke Mount.

I'll let the pictures talk:

[Stefan Buda]

More pics.

[strongmanmike]

Far out that's cool Stefan :thumbsup: love the box pattern approach for welding the forks. I was involved with building something similar (in appearance) in the mid 80's but using RHS and gussets etc :lol: to hold a massive Hale 200" style 18" F5 OTA, also made from RHS and gussets, but equatorially mounted using pillow block bearings.....ended up in the scrap yard just a couple of years ago :( :lol:

Mike

[el_draco]

Stefan,
Thats a pretty cool way to build a fork.:thumbsup:
Can you provide some extra specs pls.

Rom

[Stefan Buda]

I went though my archives and located the old DXF file, but I don't think I can attach it here. If you pm me with an email address I can send it to you.

[DarkArts]

You should still be able to find a few of these fork mounts (https://commons.wikimedia.org/wiki/File:AN-SPG-55B_Radar,_mid_1950s,_view_1_-_National_Electronics_Museum_-_DSC00625.JPG) around, and do some restoration. Might be a tad too big, though ..... :P

[el_draco]

Got one of those out the backyard already... Just manages to hold my binos steady... :rolleyes:

[OzEclipse]

Did Matt (Kunama) make the binos? :rofl: