Trimble 3305 DR - THe scale factor 

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Pesho
Posts: 4

Joined: 1/31/2009
Topic  Trimble 3305 DR - THe scale factor       Flag »  Reply »
Hi everibody, I'm new one here.
In my new job unfortunately the Total station is not Leica 1200, but Trimble. I was surprised by scale coefficient that is calculated by a tool which is different from 1.00. Why the Leica tool doesn't calculate this coef. and do I need to change to 1.00, especialy when I do the Unknown station and co-ordinates of reference points are absolutely correct, but the Trimble has any doubts in them?
Thanks
  Saturday, January 31, 2009 at 10:12:10 AM
Thomas LaCorte
Posts: 62

Joined: 10/17/2008
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
Hi Pesho, Please elaborate and reword your question. We are not sure what your asking? Ok ?Tom
  Sunday, February 01, 2009 at 10:14:36 AM
Pesho
Posts: 4

Joined: 1/31/2009
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
OK, Thomas

I do the orientation of the station using the "Unknown station" method.
 After that, the Trimble reports to me that the scale coefficient is 1.0035 (e.g. today).
 Do I have to correct it to 1.0000, because, if I later do "stake out", this coef. will correct all my measuring later?
And - I cannot download the data from the tool to my computer. Any suggestions. please and thanks?
  Tuesday, February 03, 2009 at 2:54:25 PM
Thomas LaCorte
Posts: 62

Joined: 10/17/2008
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
Well here is what I would do because the scale coefficient diff. of 1.0035 to 1.0000 is 0.35' in 100 feet. I believe it should be corrected to 1.0000. But you should never assume anything of course. So let's don't. I would layout a square with 90 angles and 100.00 foot legs and use a steel tape or chain!! Then run some assumed coord. around this 100' square. Then plop the gun up in the middle and do an "unknown station" see what scale coefficient it gives you. then do some stake out to your known points with the given coefficient and then change it to 1.000 and do stake out again. Did you land on the same point? Another words Pesho I would not feel comfortable doing anything with the gun until I could prove it against some known distances. And the kind of scale coefficient diff your getting should be 0.35' in 100.0 feet so you wont need a large area to perform this. A couple of tries and I'm confident you will figure out what is going on. Try it and write me back and let me know what you discovered. I would do this right away. Before doing any layout. It could be that a prism constant setting is off causing the solution to fit itself to your known coord system with a 1.0035 scale factor. No matter what anybody tells you about this you should prove it to yourself on the ground against known distances.
  Tuesday, February 03, 2009 at 9:49:06 PM
Isleno
Posts: 42
Location: Gonzales, La USA

Joined: 10/20/2008
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
Thomas is on the button.  I always, everyday, measure a known distance with the gun to start the day and again to end the day.  This is a habit developed back when the EDMs were delcate.  The prisim offset value is the bigest source of a bust.
  Wednesday, February 04, 2009 at 8:02:42 AM
Pesho
Posts: 4

Joined: 1/31/2009
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
Hi, everybody.
Today I was on the site for the first time. I did the orientation of the station using the method "unknown station" and I picked up four new points. Unfortunately the result is: after the pick-up the points they were mirrored with respect to the line connecting the two known backside points.
Can you give me a glue - what and where I have changed by mistake. I am sure I didn't swap the main points which I watched for the orientation.
We here use co-ordinate system where X=North, and Y=East. Thanks in advance!
  Friday, February 13, 2009 at 2:22:47 PM
Pesho
Posts: 4

Joined: 1/31/2009
Reply  Re: Trimble 3305 DR - THe scale factor Flag »  Reply »
It's me again. I did some thinking and I figured out, that the behavior of the tool is as it's co-ordinate system is turned upside-down - the numbers on north axis increase going to south.
The East coordinates are normal. And when I pick up a point to the north of me, in AutoCad it appears to the south of me.
Where is the mistake in the initial presettings of the Trimble?
  Saturday, February 14, 2009 at 9:47:17 AM

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