DIY dovetail bar

[dikman]

The dovetail bar on my Celestron frac is a short one and I couldn't adjust the scope enough to counterbalance some of the camera gear, so I thought "why not make one?". I melted some aluminium (from BMW suspension arms, so good quality) and cast some bars. I machined the thinner one so it would screw to the scope rings and powdercoated it green. It works fine, although there are a couple of machining marks on it (I really need to buy a flycutter for doing larger flat surfaces), and cutting the dovetail angles was a bit tricky, although I've since thought of a better way (next time).
One problem with powdercoating is the parts are very slippery so after the tube nearly slipped out of the saddle I glued a piece of thin leather to a piece of ally bar that fits over the clamp part, which also saves marking the bar itself. Seems to work ok.

[AstroViking]

Very clever work, Richard. Well done. I'd love to have a workshop where I could do that sort of stuff...

[bojan]

Very good :thumbsup:
I don't have facilities to melt aluminium (yet..).
However, some time ago I used Aluminum angle 40x40x6 (https://www.aluminiumtc.com.au/store/product/view/40-x-40-x-6-31/?pid=31) and formed a channel from two pieces like on attached sketch, joined together by couple of screws.
I also beveled the edge that goes into dovetail receptacle, however this is not strictly needed, because once the screw is tightened, the structure can't go out of the grip.

[dikman]

I like that, bojan, simple and effective. Wish I'd thought of that, it would have been a lot simpler than my method and it would have saved a lot of machining!

[bojan]

:thumbsup:

Those extrusions are very useful for lots of things... I always try to use them first - to save time, effort, and very often, money ..

[Boozlefoot]

Melted down Beemers rebirthed as scope parts......love it.

I've been using this for weird and wonderful jobs, light and super-rigid, and takes t bolts for fixing gear. I grind the top lip off the lower quadrant shoulder in the clamping range. @ $22.00 metre, gets you a lot of jobs done. Surprising how handy it is. Available from any of the websites dealing with the "homestyle" cnc machines/engravers etc. 40 x 40, also 40x80 if you want extra height for your accessory.

[dikman]

I first discovered that extrusion when I built my 3D printer (came as a kit, a large box of bits!) and yes, quite useful stuff.

[dikman]

I may have found a better way of making a dovetail by casting. I found several .stl files on Thingiverse to 3D print dovetails. While I wouldn't trust a 3D printed piece to support a scope it should give me a suitable shape to give a fairly accurate mold to minimise machining the casting.
Something for next time.