HomeBrew2
Banned
Mostly just for the fun of it, I decided to buy and old Topcon GTS-2B [semi-]total station to check my boundary and do a complete topo so I can build a 3d model in AutoCAD.
This model instrument is pretty old but has EDM (electronic distance measuring) thru the telescope with digital display of slope distance but, the the angles are read optically, like a plain theodolite, via a small scope next to the telescope eyepiece. It's, nominally, a 6" (second) gun, with estimates easily to 2" on the micrometer scale.
Unfortunately, the old Topcon battery pack wouldn't hold a charge so, while I'm working that out with the seller, I cobbled an external battery pack out of an 8-cell AA battery holder, power connector from Radio Shack, and some new whizbang 2400 mAh NiMH batteries. Really like that 15 min charger!
I needed to check how well the old gun was calibrated so, I wrapped up a few horizontal angles with great results. The vertical? Not so good. I had to adjust out about 2' (minutes) of index error. Good to go now. I'm in the process of trying to find a local baseline to check a long distance but, for now, I was able to check the EDM vs a nice Lufkin chrome-clad 100' tape as well as a simple 2-peg test of 400+'. That seemed good too, +/- 0.02'.
I haven't been able to find a decent wooden legged tripod, cheap, so I'm using the aluminum one I got for my DeWalt laser level last year. (Reviewed on TBN previously.)
It just so happened that I was able to salvage an old, damaged prism and prism pole from a job in a previous life. It's been in my rafters for a decade or so. Perfectly functional now.
Because I'm working by myself for now, I used an old non-adjustable cheapo wooden tripod to hold the prism pole. It had some orphan head size that fit the pole diameter nicely.
So, that's the field equipment, but ... Seemed like it would be awfuly handy to have a little field computer/data collector. Long story short: I picked up a used PDA with Pocket PC 2003 and totally lucked-out to find TDS (Tripod Data Systems) had a free (not a trial or limited functionality) download of their COGO (coordinate geometry) software for my PDA. Some days I'm just plain lucky!
I got the boundary done Saturday afternoon. The equipment and proceedures worked really well. Good thing I did this before driving a bunch of steel in the ground for re-doing my back fence ... one corner monument was 30' out of position compared to the subdivision map (all others were well within 0.5'). Now I'll have to go search for and investigate adjacent monuments to see what the prob is. Never a dull moment
Cheers!
This model instrument is pretty old but has EDM (electronic distance measuring) thru the telescope with digital display of slope distance but, the the angles are read optically, like a plain theodolite, via a small scope next to the telescope eyepiece. It's, nominally, a 6" (second) gun, with estimates easily to 2" on the micrometer scale.
Unfortunately, the old Topcon battery pack wouldn't hold a charge so, while I'm working that out with the seller, I cobbled an external battery pack out of an 8-cell AA battery holder, power connector from Radio Shack, and some new whizbang 2400 mAh NiMH batteries. Really like that 15 min charger!
I needed to check how well the old gun was calibrated so, I wrapped up a few horizontal angles with great results. The vertical? Not so good. I had to adjust out about 2' (minutes) of index error. Good to go now. I'm in the process of trying to find a local baseline to check a long distance but, for now, I was able to check the EDM vs a nice Lufkin chrome-clad 100' tape as well as a simple 2-peg test of 400+'. That seemed good too, +/- 0.02'.
I haven't been able to find a decent wooden legged tripod, cheap, so I'm using the aluminum one I got for my DeWalt laser level last year. (Reviewed on TBN previously.)
It just so happened that I was able to salvage an old, damaged prism and prism pole from a job in a previous life. It's been in my rafters for a decade or so. Perfectly functional now.
Because I'm working by myself for now, I used an old non-adjustable cheapo wooden tripod to hold the prism pole. It had some orphan head size that fit the pole diameter nicely.
So, that's the field equipment, but ... Seemed like it would be awfuly handy to have a little field computer/data collector. Long story short: I picked up a used PDA with Pocket PC 2003 and totally lucked-out to find TDS (Tripod Data Systems) had a free (not a trial or limited functionality) download of their COGO (coordinate geometry) software for my PDA. Some days I'm just plain lucky!
I got the boundary done Saturday afternoon. The equipment and proceedures worked really well. Good thing I did this before driving a bunch of steel in the ground for re-doing my back fence ... one corner monument was 30' out of position compared to the subdivision map (all others were well within 0.5'). Now I'll have to go search for and investigate adjacent monuments to see what the prob is. Never a dull moment
Cheers!
