What's the latest on construction lasers?

[dave_k]

The Topcon RL-VH4DR can be steered via remote control.

Where does a tape measure come into play with using a rotating laser as a 90-degree reference?

Thanks for your time ...

I'm not sure what you mean by tape measure. Are you referring to the "chalkline" feature of the Topcon laser? If so the beam is rotating pretty fast and you can see it but it's sometimes hard to get a fix on it. The 2 target reflectors that come with the laser have a special coating that allows you to "capture" the beam and instead of rotating 360 degrees you can use the reflector to draw a line with the beam and the beam bounces back and forth along that line so fast that it looks like a continuous"chalkline".

Working on a layout all day with a laser in a dark building causes eye strain and fatigue especially if you have to keep waiting for the dot to come by. At the end of the day you really appreciate the chalkline. It's great for cabinet installations too.

[dave_k]

If I was a small contractor doing a lot of foundation layout this is the instrument I would buy http://www.topconpositioning.com/pro...olites/dt-200l You can turn any angle with it, not just a 90 it works as a builders level and it has a laser diode in the telescope that would allow one man to set up the instrument site a point then run down and mark that point then go back to the instrument and turn the next angle.

The downside is that they aren't cheap you're going to pay upwards of $3k for one

[dave_k]

As I told you earlier I don't have any experience with that laser in that application and my experiments using a drywall laser to layout foundations was a failure. I did find a video of the laser you are looking at. It's in Spanish but you can see how it works, how bright the beam is and they demo the chalkline http://www.youtube.com/watch?v=Obtg_aMIhrY

[tjbnwi]

I really ilke the laser chualk line. I use it more than my rotary.

My laser chualk line (Laser Mark) can be used with a detector. It has a pulse mode that allows the dector to sense the line.

For squaring up my 5 point Stanley works very well.

Tom

[dave_k]

I really ilke the laser chualk line. I use it more than my rotary.

I use my PLS2 more as a carpenters level than a layout tool.

The chalkline function on the Topcon lasers is very convenient for layout. If you are working alone you can set up a reflector on a mark 100' away and start to dial in the beam at the laser. Once the beam hits the reflector it goes into chalkline mode.

My laser is 12 years old has a lower powered red beam, which isn't visible in daylight and doesn't have a remote control. The same model today that RedOak is considering buying has a remote control and uses a more powerful green beam which Topcon claims is 20% more powerful than my model and more easily seen in daylight.

When I tried to use my laser to square a 100' foundation about 10 years ago it didn't work.

The combination of the better beam and remote control on the current laser means you can set up the instrument over a point then walk down to the far point, set up your target and dial the laser in by remote control. This is what the current sales lit is saying anyway, whether it works in job site conditions is another matter.

A couple of weeks ago in a PM I suggested to RedOak that he get the salesman out to do a demo using this laser outdoors to see if it works in a real world environment.

I don't think he is going find much in the way of real world experience using this laser for foundation layout but I could be wrong. For one man layout the Topcon theodolite with the dot laser in the telescope is an obvious choice but to be honest very few small foundation contractors have one man laying out foundations. The big guys use total stations which can easily be operated by one man alone but you can get a relatively cheap transit in the $600 - $800 range http://www.southern-tool.com/store/d...-300_level.php and a professional grade laser with tripod and a receiver for around $1k which is cheaper than the Topcon theodolite and could probably challenge the green beam laser once you buy the tripod and remote. Chances are very slim that you won't have someone on site that can be on the dummy end of the transit. To me that package represents the best value and far more useful for a foundation contractor.

If you are an interior contractor that occasionally has to lay out foundations I'd go the route of the RL-VH4DR-GC. Otherwise it would be the transit grade laser combo and if working alone was a constant issue then the theodolite with the dot laser. You can layout from surveyors offsets with the transit, you'll only get one mark at best with an interior laser. It's just going to be a far more useful, flexible and cost effective buy in my opinion.

[David Meiland]

I want to comment briefly on the PLS90 for foundation layout. It's easy to do and works well, but you have to expect to use the detector. You may have to construct your first corner batter board a little differently than normal, because the easiest way to use the laser is to shoot a line across both legs of the near corner simultaneously, but it can only do that if placed outside both of those legs... so you build that corner as an "inside" corner instead of the usual outside corner.

[RedOak]

David: Thanks for the drawing. It helped clarify your point about using the PLS 90 for setting up 90-degree batter boards.

Dave K: First, thanks for the posts, but you may have missed what I originally posted (Post #1). In that initial post, I was explaining that we were all set to purchase two separate laser products -- the Topcon RL-H4C and the PLS 90 -- but then the regional Topcon rep suggested that the Topcon RL-VH4DR might be able to do both jobs, and it was that curiosity that prompted me to ask the other members of the JLC forum board for their thoughts.

As we can get very good support from our regional Topcon people, we decided to give the RL-VH4DR-GC a try on our current job -- and the results of my solo setup work are published in Post #11.

If your worksite is relatively level, the RL-VH4DR is more than capable of handling 90-degree setup work. If it's late in the day or you have a cloudy day, the RL-VH4DR works even better for this purpose (because the need for a detector is virtually eliminated).

Here are the steps I found to work best (yours may vary):

(1) Choose a reference corner and pound a marker into the ground. Due to its large circular head, I found that a fluorescent orange tent line stake worked very well for this purpose (and drawing a cross target on the head of the stake works even better).

(2) Employing a massive base (like a cinder block laid on it side), set the vertical-levelling laser over the corner marker and use the plumb beam to center the laser diode on the head of said marker.

(3) Using a cinder block or equivalent as a base, lean the laser detector in the "target corner." I laid our LS-80A on its side for this purpose.

(4) Set the vertical-levelling laser to its rotation mode and carefully turn the laser unit to bring the rotating beam within the general area of the target corner (corner #2). I found that a 2x8 cut to the length of the cinder block worked well for adjusting the laser unit. Once again, check the laser unit's position by going to plumb beam mode and ensure that you're still centered on the reference target.

(5) Return to rotating mode and use the remote control to "steer" the rotating beam until the detector unit indicates that you are centered. In our case, I used the RC-40 remote control to steer the rotating laser until the LS-80A emitted a steady audible tone. As our detector unit has notches molded into its case (top and bottom when laying on its side), it was fairly easy to position and pound a 3/4" footing stake into the ground at this point.

(6) Return to the laser unit's end of the line and use the detector to locate the rotating beam on the opposite side of the laser unit. Once I had the detector centered on the beam, I pounded another 3/4" footing stake into the ground (a few feet outside of where the edge the footing trench will be).

(7) Using a steel tape measure, or equivalent, fix one end to the reference corner marker and measure the footing as per the foundation plan (toward corner #2). Once you have the distance measured, push a nail into the ground as a place holding marker.

(8) Tightly stretch a string line between the footing stakes and tie it off on one end (it is useful to have the line as close as possible to the ground for this step). Using a plumb bob or a quality level, scribe a transfer line into the ground adjacent to the place holding marker. If necessary, use a framing square to move the place holding marker to the transfer line.

(9) Now that you've located corner #2, pound another corner marker into the ground. Once again, I used a fluorescent orange tent stake with a cross target on it for this purpose.

(10) Using a suitable target -- I used stacked cinder blocks -- locate the fixed point beam that is emanating from the top/front of the laser unit. Mark the fixed beam on the target with a black marker, and use a quality level to transfer the mark to the ground. If you lean the cinder blocks carefully, one could also use a plumb bob for this transfer.

(11) Now that you've located the 90-degree line on the ground, pound another 3/4" footing stake (or equivalent) into the earth.

I'm no technical writer, by any means, but the preceding steps are how I went about setting three batter board stakes (footing stakes) and two corner markers. Once you get to this point in the process, the person laying out the subject foundation can use any variation of these steps to set up the rest of the job.

Please note that all of the footing stakes mentioned in the previous steps were placed well outside of where the trench edges will be.

As our Topcon rep had previously suggested we might try, I was able to use our Topcon RL-VH4DR-GC package to set up footings for a job with right-angles only. I have no way of knowing this for sure, but the Topcon DT-200L laser theodolite unit suggested by Dave K would probably be ideal for angles other than 90-degrees. As we run a very small operation that doesn't specialize in foundation work, however, the multiple duties that can be accomplished with the Topcon RL-VH4DR has proven to be cost-effective, thus far.

As I am not affiliated with any laser manufacturer, I purposely refrained from constantly referring to our Topcon model numbers because there are other laser units available that can level themselves vertically and that can be steered via a remote control -- the Stabila LAR 250 package is an example of just such a unit.