Laser distance measurer

Glen Yasharian

New Member
Joe:

Can I ask what the part number is for the RAM mount you are showing in the photo? I looked on their website, but, I don't see anything that exactly matches your picture.
 

Joe Paulin

Active Member
Sure thing, Glen. I pieced three different RAM mount parts together to get what I wanted.

They are all "B" size parts:
RAM Tough-Claw Small Clamp Base with Ball, Part # RAP-B-400U $32.49
RAM Composite Double Socket Arm *Short Arm*, Part # RAP-B-201U-A, $9.49
RAM Ball Adapter with 1/4"-20 Threaded Post, Part # RAM-B-237U, $8.99

So $50 for the mount system. I use a Seco rod that is 1.25" in diameter. If you use another rod, just make sure the clamp will fit it. RAM says the clamp above will fit any diameter from 5/8" to 1.5". And they make bigger ones as well.

RAM Mounts are great, you can do so much with them. Their laptop mounts for vehicles are great as well if you do alot in the field.
 

Glen Yasharian

New Member
Joe: Thanks for the specs. I had added some extra padding to a SECO data collector cradle to get it to hold my Leica Disto, but, it doesn't work the best, or give a definite reference point, so I will look into the RAM
 

John Troelstrup

New Member
Hey my RAM mounts came today, I am pretty stoked! I tried it out quickly, it works out great! Can't wait to shoot some offsets in with this Deadly Duo. Just change the measure reference point to the 1/4-20 threaded mount point on the LDM and bam now I have horizontal distances to the center of my rover rod. NICE!
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Joe, Congratulations on a very slick set up. I really like it. I do a lot of tree location and building locates... This is a perfect setup.
I wonder if the Javad Victor Bracket holder would work just as well?

A question about field usage. I received my Bosch and able to connect it via Blue-tooth to my Triumph, however I was not predictably successful in getting the distances to transfer to the Triumph in offset mode. Sometimes it went and sometimes not. I am sure it is all in the order of the button pushes.

Would you mine outlining the sequence of buttons for a typical offset location shot via white box offset?
Also, in my limited experience, it seemed everytime I turned the Disto off that I had to go to the Triumph bluetooth search screen to have it find it each time as opposed to automatically linking up just by turning on the disto. Is this true in your case as well or am I missing a step?

Thank you so much
John
 
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Joe Paulin

Active Member
Hey John,
Hard to say about the Javad Victor Bracket holder, it's hard to see detail in the picture on the website. The type of mount is similar, utilizing the RAM balls. Seco makes a claw clamp with a 1" (RAMS "B" size) ball on it (Seco # 5200-160) that would be even nicer than the RAMS clamp that I am using, but it is twice the price and I didn't see the need for such a light object being held.

I do have to manually reconnect the Bosch every time I turn it off - I just leave it on instead. It would be great if it auto connected to the LS when I turn on the bluetooth in the Bosch, but that doesn't seem to be the case.

There seems to be two ways to connect to the LDM in JField. One works much better for me, but I am still experimenting as well.

First, tun on the Bosch and then turn on the bluetooth in it.
From the Home screen of the LS, tap the bluetooth icon at the top of the screen. At the bottom of the screen there are three buttons: Configuration, Accessories & Scan.

You can connect through tapping Scan, selecting the Bosch and tapping Connect, but I have troubles doing it this way and when in the Offset workflow it doesn't recognize the LDM.

Instead, tap Accessories, select the Bosch and hit connect. After it connects, you should see a new screen showing the different measuring reference points for the Bosch (front, back, 1/4-20 mount, etc. For my mounting, I select the 1/4/20 mount. If you tap the distance box in that screen, it will take a shot and display the distance which you could check if you want. Once you have this set, you can back out to the home screen and start measuring.
 

John Thompson

Active Member
I bought a GLM 50 C on Joe's recommendation. (Thanks, Joe!) My son 3D printed a bracket to mount it to the SECO quick attach on the bottom of the LS. I haven't used this much, just a few trials so far, but it looks like a nice setup. The LS and LDM can rotate together in azimuth, which helps find the red laser dot at a distance using the camera crosshairs. The LDM can pivot in the vertical plane. The 1/4-20 thread mount on the Bosch is aligned with the center of the pole when the LDM is horizontal.
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A couple tweaks to J-Field would really help:

For the Survey by Offset routines, the LDM button on the LS grabs the slope distance from the Bosch via Bluetooth. In every case I can think of, it needs to use the horizontal distance instead, which the Bosch calculates with its internal incinometer.

Also, if the crosshairs on the Set by Compass screen were extended to the edges of the screen it would be easier to set the azimuth to a target that is above or below the camera height.
 

Joe Paulin

Active Member
John Thompson, that mount is awesome! Even better than mine since the LDM is much closer to the center of the pole. For better or worse, with my mount there is so much adjustment with the balls, you have to be careful of the orientation and position of how you have things clamped to get the thread mount to line up with the center of the pole. But I am not worried about a few hundredths measuring with this. NICE JOB!!

You are absolutely right on the few tweaks needed. If the developers could get the LS to pull the horizontal distance off the Bosch, that would be golden. I think the best routine would be to shoot your distance manually with the Bosch, then when you are ready, tap the laser distance icon on the LS to bring in the distance that the Bosch already has. Right now when you tap the laser distance icon on the LS, it activated the laser and pulls in a fresh slope distance. Or if the LS could pull in the vertical inclination and well as the slope distance, J-Field could calc the horizontal distance automatically.

Also agree about the crosshairs - could we get them extended to the edges of the screen?

What do you say, Javad Dream Team, can you do it???

P.S., I really like using the resection routine in the offsets menu, it makes sure you are offsetting in the right direction (as opposed to distance/distance) and gives you residuals.
 
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John Troelstrup

New Member
I certainly second Joe's request for a little more development for this feature. It is so helpful with many aspects that I do on a daily basis. Locating trees, fence corners building corners and sheds. If the vertical could also be incorporated, Finish Floor elevations could be quickly obtained. This method of obtaining Finish floor actually works fairly well. Of course, it would not be a suggested method for Elevation certificates in a flood zone but for general design and information purposes, results of plus or minus a couple of tenths are fairly consistent.
 

John Thompson

Active Member
I did some tests and here's what I've found out.

Survey by Offset > Direct using the compass in the T-LS and the LDM is inadequate for most uses. The compass error and my pointing error amount to about 2.5 to 5 degrees, which at 20 feet is a couple feet off. So distance-distance, or better, resections are necessary unless I can somehow get creative with setups on lines or something. So 2 or 3 rover setups are required per point.

Pointing the laser to the target is made difficult by several factors:
The dot is hard to see at a distance. Red laser glasses would help. I have some on order.
The LDM turns the laser off every 20 seconds or so. It requires a button press to turn back on, which bumps the alignment.
It's difficult to accurately point the laser to the target at any reasonable distance.

So we redesigned the mount to add an arrow. A dowel would work fine too, but the arrow is straight and stiff. Plus, well, it's an arrow. The arrow makes it MUCH easier to use. It functions as a sight for rough alignment, a long handle to precisely move the laser, and also adds some stability.

I also found that using the Android app on my phone for controlling the LDM is more convenient than using the hardware buttons to turn on the laser every 20 seconds and to take a measurement. The phone probably works better than using the T-LS, since button presses don't move the setup and the LS would also have to turn the laser back on. Unless there is a way to keep the laser turned on. The phone app also keeps a history of measurements so you can check your work. So I've been typing horizontal distances into the LS with the keypad. Works ok. I suppose if you're not using the LS to collect the distance from the LDM you could use any make and model of LDM.

With the target 20-30 feet away from the rover pole, I can now accurately point the laser at the target in sun or shade in about 30 seconds without red glasses. So I plumb the rover rod, start the T-LS counting, and then work on pointing the laser. Works pretty fast. I shot 3 points by resection (9 setups) on a steel grain bin in 18 minutes.

Accuracy is good in the 20-30 foot range. I measured a point by resection from RTK shots at that range and the result differed from RTK directly at that point by about 0.05 feet.

Joe, looks like you have almost the same pole I do. PM me with your mailing address and I'll send you a mount like this if you like.
 

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Joe Paulin

Active Member
Good info John. Curious, did you do a compass calibration before your tests? If you didn't, doing one may improve the direct offset method. But I agree, distance-distance is better and resection is gold.
 

John Thompson

Active Member
I did a couple compass calibrations and 2-5 degrees is about the best I could get with pointing the camera crosshairs and reading the compass. Do other folks here consistently get better results? A couple feet may be ok for locating trees or other rough uses.
 

Joe Paulin

Active Member
I will have to do some tests with my LS. I generally use this at distances under 20' and most always have relied on distance-distance offsets or resections.

A note to people considering buying this LDM: Bosch specs the GLM 50 C as measuring up to 165'. That must be under perfect conditions with a reflector card. Outdoors for how we will use it, I think the practical distance limit is 30' in bright sunlight due to being able to see the laser dot on your target. I just don't want folks to be disappointed when they buy it. That being said, it is very useful, especially for the roughly $100 price point.
 
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