Dobs direction finder

[spaceboy]

It's one thing to have the tools but it takes experience to use them properly. I have some tools at my disposal but I still manage to bodge things. You should see the state I made of a hole I tapped the other day, the bolt looked like the Leaning Tower of Pisa by the time I'd finished.

I have a collection of pi**t tap holes. It's not so bad on small threads but the bigger bolts can be a pain due to the thread pitch when you start the tap. It always wants to pull against the upright. In the end I gave up and now I get all my thread started in the mill and then finish off by hand.

I'm a bodger myself so your not alone Scogyrd. All the gear no idea

[JohnR]

You are right, to a point.......

When the scope is slewed round on a un levelled base the ota will rise and fall, but, and here is the point, the Wixey will tell you that.

So, using the gemrad get the scope slewed round to the correct az, then set the alt using the Wixey. Remeber the Wixey is measuring the 'actual' ota angle relative to horizontal, not to the base so the angle of the base is irrelevant.

Gary

I've had this window open for ages now,trying to work out how to explain my reasoning but its just making my head hurt

Something along the lines of : a circle on a level base is 2 dimensional and the gemred can divide that into 360 equal segments.

A circle on on uneven base is 3 dimensional -looked down on it would appear elliptical (very slightly).The gemrad will divide that into 360 segments too,but those segments will not be of equal width around the circumference

Don't worry,even i think i'm going slightly mad

[JohnR]

-10C here tonight Spaceboy and everything kept on working fine.

[xmal]

-10C here tonight Spaceboy and everything kept on working fine.

I have got one of these on back order- waiting for stock at Axminster. I would like to mod the LCD display with an LCD one. I just wonder how difficult it would be to do that? Maybe the LED will work better in low temps and you won't have to keep shining a torch on it for a reading....

I will look into it when it arrives.

[gary1968]

The figures you are using above are in degrees and minutes,where 60mins =1 degree.So for eg 359d 29min is near enough 359.5 degrees,so you would add .5 degrees.

Easy way to guesstimate it is 15min =0.25deg, 30min= 0.5deg, 45min= 0.75deg

ie 358deg 58min is only just short of 359deg

Right, lets see if I have this right in my head....

Just now according to astromist polaris is 59 35' 05" alt and 00 25' 37" az.

So, in az polaris is almost 1/2deg. from true north, yeah? I would need to move the scope 1/2deg. to the West, is that right?

God my head hurts......

Gary

[JohnR]

Yes,that right Gary

[JohnR]

I have got one of these on back order- waiting for stock at Axminster. I would like to mod the LCD display with an LCD one. I just wonder how difficult it would be to do that? Maybe the LED will work better in low temps and you won't have to keep shining a torch on it for a reading....

I will look into it when it arrives.

A nice red LED display would be simpler to use,but way out of my bodging abilities

[xmal]

A nice red LED display would be simpler to use,but way out of my bodging abilities

Just had a look on ebay to get a "feel" for the LEDs. It states:

-40°C to +85°C operating temp

Obviously it would use more battery though.

[irishbloke]

I've been looking at instructions on how to wire leds up. Surely it might be easier to light up the displays with red leds that could be turned on and off as needed.

[gary1968]

Yes,that right Gary

Glad I have that sorted out in my head now.... Thanks John. Although to get Polaris coords. I have now found that Pocket Stars on my PDA shows the Az coords. as degrees, not hrs/mins/seconds so I will be using that me thinks.

Now to take the pivot bolt into work and center drill and tap it to suite the Gemred, make a wee braket and get it all fitted.

(Although as I bought mine of evilbay it is not known as a gemred it is a Machine Dro) It was about £8 more expensive but it is the same thing, I dont like to wait for things so I took the chance and ordered it anyway.

[spaceboy]

-10C here tonight Spaceboy and everything kept on working fine.

-10c and you were out in it. I was thinking -0c and I'm not taking the gemred -2c and I'm not taking myself

It must be on there for some reason ??? Unless they made the sticker wrong I think if it gets to cold I will drop them in my pocket just to be sure but it's good to know if I didn't notice how cold it is that they should be OK. Thanks JohnR

Is there a thread any where for info how to use wixey and setting circles. I'm doing all this and I don't have a clue how to work them. I understand the idea of hrs, minutes etc but the simple 360' idea is more on my level of intelligence.

[Moonshane]

Moonshane has been making dew straps and for a small fee I'm sure he could knock up some small ones for wixey & gemreds. He offered to make me one for my 127 skymax but TBH the whole dew thing seemed to much hassle & expense so I sold the MAK.

ha ha I have only just made my own proto-type for dewstraps so cannot claim to be in production just yet. still making a footswitch for my little sewing machine.

It's actually quite easy to make them but if someone's struggling I can certainly put a few together.

I get the resistors from a fellow member with an ebay shop 330R 330 Ohm Carbon Film Resistors 1/2W 0.5W X 50 RoHS on eBay (end time 26-Dec-10 18:22:26 GMT)

the anchor wire I have just bought from Maplins and the phono ends also ebay. you'd need a controller though for sure. assuming it's the same sort of size as a 2" EP strao then it would only draw about half an amp so will work for ages on a battery and you could even potentially work off four AAs at 6v I suspect but not tried this.

[spaceboy]

http://stargazerslounge.com/equipment-help/120937-freezing-temps-motors.html Looks like I'm not the only one concerned about cold temperatures and equipment. I noticed talk about GT hand controllers LCD suffering due to cold so I assume this may be the same with gemreds LCD.

[irishbloke]

Just got my Gemred after a long back order! I'm delighted Spaceboy sorted me out with a very nice drilled bolt. I just got new base boards made at my wife's work so I'm going to have some fun over next couple of days getting it up and running!

How's anyone else got on with the mod?

Brian

[gary1968]

I haver mine all finished, just need a clear night when I have some time to test it......

Gary

[JohnR]

Poor weather means mines not been out for a while

To be fair to the weather ,a week of no viewing was down to me being a 'little sore' after having a speck of metal removed from my eye ... d'oh

[spaceboy]

Poor weather means mines not been out for a while

To be fair to the weather ,a week of no viewing was down to me being a 'little sore' after having a speck of metal removed from my eye ... d'oh

TBH I haven't wanted to try it during this bad weather I still have my concerns about this -0c thing. The one night it was clear it was -5 so just whet with the 8" in the obsy. My operation is next Thursday so doubtful I will get to try it out for a while but I would be interested to see how everyone else gets on. I have had a mess while inside and I'm confident it was the "best direction" to go. I tried sorting manual setting circles but you would have to keep adjusting the base to get it dead on north all you do with the gemred is press reset.

Sounds painful John did they get it out with a magnet? The worst metal is aluminum as they have to manually try and remove it while scraping off eye tissue as they do.

[spaceboy]

I haver mine all finished, just need a clear night when I have some time to test it......

Gary

Where's the pics then Gary???

[JohnR]

Sounds painful John did they get it out with a magnet? The worst metal is aluminum as they have to manually try and remove it while scraping off eye tissue as they do.

Yeah,got it out with a magnet ,then used some vibrating thing to go after the rust specks.It didn't hurt at all.............til the anaesthetic wore off then 3-4 days with v little sleep.

[spaceboy]

Rather you than me John! It's bad enough when I have to have a glaucoma test and the optician is poking my eye balls.

I do sympathize with you as I've had ark eye a couple of times so I know what it's like having sleepless nights because you feel like there is broken glass in your eye lids.

[JohnR]

Ha ha ,yeah i remember giving myself ark eye when i was a kid,trying to weld a hinge on a gate in situ. Woke up in middle of night in agony trying to work out how i'd got what felt like a sack of sand in my eyes.

[irishbloke]

I got my boards back together and managed to get the bolt locked off. I had made the mistake of not having used the nylon lock nut and the bolt was turning as I turned the mount. The lock nut sorted it all out and now the gemred is able to do its thing.

The cat cable isn't that long but I think I'll have another about the house. I'm thinking of using velcro or something to fix the display somewhere.

We've a good 7-8" of snow in the back garden and I'm not lugging the scope anywhere in this weather but I'm pretty confident the system should work as hoped.

Thanks again.

Brian

[spaceboy]

Although not "brilliant", it works and it was easily done.

Velcro circle on the base and one on the battery cover on the gemred. I have seen years ago white plastic cable clips that have sticky on the back. Once I find them ( if I do ) these will be stuck to the base to keep the cable a little more tidy.

[irishbloke]

Spaceboy,

I've been playing around a bit and the lead seems long enough to allow the gemred to rest on the edge of the side board above the alt bearing while attached by the magnets. This means it's a bit higher up and possibly easier to read the screen.

The magnets seem to be on the top of the gemred rather than the bottom like the wixey. so they wouldn't easily sit together. I think this will work well though. Get sorted on one axis and then the other.

Really need to get some clear ground to have a play with this.

:-)

[spaceboy]

I'm not one for cables every where hence why I put it on the base I also found the cable on these things a reasonably chunky and have a life of it's own so didn't want it tugging the gemred off a height. I must have got a duff anyway as my magnets are pants and don't want to grab properly. I will probably make a fixed bracket at some point and the cables will then be fixed better and more tidy but wanted to give the gemred a try out before I start racking my brain how to make one.

I can grantee the moment I have my operation and have to get around on crutches the skies will clear

I will have to make do with you Letting me know how you get on with yours. Do you have any pics how you mounted the gemred as it may offer some ideas.