"budget" DIY wedge for astrotrac.

[stan26]

Okay, so its currently a little rough around the edges so don't look too hard! and I broke my last hacksaw blade which means there are a few bolts to be cut down to a more sensible length, but otherwise it all seems to work a treat!

I originally brought the astrotrac to get out in the country side away from the LP, but now the missus works evenings and I need to be at home to look after the little ones, that doesn't really happen anymore. So I need to make use of the astrotrac at home. The Giottos tripod and manfrotto 410 geared head that I have are OK for the astrotrac but its still a bit of a challenge to get it polar aligned for any lengthy subs, and still a little flimsy. I want to get the best out of the astrotrac and for this I need a sturdier mount and ideally something I can leave permanently polar aligned.......I just happen to have a concrete/steel pier in my garden!  so the next step was to make/adapt an adjustable wedge that can be bolted onto it.

The only materials I had to buy was the two pieces of 6.5mm Alloy plate sourced from a local fabrication workshop for £5 cash. The rest of the hardware/materials used were found at home. The reason I went for the 6.5mm alloy plate is because its very easy to work with, even with your average Argos mickey mouse tools/drill bits you can soon whittle out the require holes/shapes, plus its very sturdy, good enough for the astrotrac and camera/lens combo. 

Its fully adjustable in both alt az. The azimuth is adjusted using bolts that go through bed nuts that are sunk into the two square tubed lumps bolted on each side. The adjustment bolts go up against another upright bolt that is threaded through the pier base and comes up through a slot cut out in the bottom plate of the wedge to allow it to move about an inch left to right (or west east), just like adjusting the az on an EQ mount. The black knobs are from an old vixen refractor I cut up to make into a guide scope. The hinge nuts are countersunk into the plate to allow a completely flat surface for the astrotrac to lay flush against. The astrotrac is held in place by 3x 4mm threaded rods and wing nuts. This means is super solid and bolted in the same place each time. Once aligned I will carefully tighten the main M14 center lock nut to hold it all firmly in place. 

Its a bit crude, but its the best I could do with limited money and time to spare, Its a also stronger than the pictures suggest, once everything is tightened its absolutely solid with no play/flex. I reckon even if I had to buy everything used it would have still came in under £30. 

Hopefully I 'll get a chance to use it tonight and assuming everything is okay I will make it look a bit more pretty and then carry out a drift alignment..

Stan 

[Kropster]

Fantastic..... and SO economical.

You must be very satisfied with this bit of DIY!

[Alien 13]

Nice the ultimate barn door tracker..

Great job.

[StuartJPP]

Good work there, nicely done.

I assume you are going to cover it when not in use? Poundland do a BBQ cover for get this...£1, well they used to, probably a summer thing, failing that a thick rubble bag will do tied down at the base.

Could get a bit crusty after a while if permanently left outside if not stainless steel though I am sure if you treated them with some WD40 or grease you could stave off corrosion for even longer.

[JamesF]

Very neat  I do like that.

James

[stan26]

Cheers Guys, when you consider the cost of wedges, i.e the astrotrac wedge which is £300!!, if this "does the job" for a fiver I think I'm onto a winner! 

Stuart - I have an empty 25ltr plastic drum with the bottom cut off which I place over the top of the wedge held down to the pier post with bungies. Any moving part will be getting a coating of adhesive lube to help protect it further.

My poor old pier is looking a bit "weathered" now 

[Peter Drew]

Another DIY classic, well done! 

[stan26]

So far so good, tonight's drift align yielded perfect round stars with 5 minute subs at 200mm in both the southern and western sky. The fog rolled in before I had a chance to push it further. I'm amazed at how finely adjustable it's turning out to be. I would love to get 10min subs at 200mm but I'm not sure if an unguided astrotrac is up to it. Either way I'm going to give it a go!!

[mbaddah]

Incredible! 5min at 200mm unguided is perfect alignment in my books