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kemmer
07-08-2007, 09:42 AM
What do you guys like better for setting pitch and slope? using a laser rotating level or a transit? also what brands do you recommend

DVS Hardscaper
07-08-2007, 10:41 AM
What do you guys like better for setting pitch and slope? using a laser rotating level or a transit? also what brands do you recommend

For setting block - laser lever

for setting fall for a patio and to measure the elevation of a patio - a good 'ol string line and line level

Bill Davis
07-08-2007, 10:44 AM
I use a laser level for everything now. I have a Spectra spinning laser. Spend the money and buy a self leveling laser. You will wonder how you ever did with out it.

D Felix
07-09-2007, 10:23 PM
I won't use a string line and string level ever again if I can avoid it... I've had too many string levels go bad on me to trust even a new one.

Besides, we've got a single grade Topcon laser. Why go with something you can't trust (string level) over a great piece of trustworthy equipment??

PerfiCut L&L
07-09-2007, 10:38 PM
Transit and line level works great for us. Would like to look into the laser levels, but I dont have any experience with them so Im not sure what to look for in a good one without spending a lot of unecessary money.

D Felix
07-09-2007, 10:41 PM
Good one = self leveling, rotating, with a good servicing dealer. In our area, that means a Topcon. Forget CST/Berger. They are decent, but you won't get me away from Topcon anytime soon.

kootoomootoo
07-09-2007, 11:10 PM
Mexican lazer level

Henry
07-10-2007, 07:06 AM
D Felix, care to tell me how you set up that single grade laser for a patio?

D Felix
07-10-2007, 06:46 PM
Put it on the tripod with the uphill side of the transit facing the direction of the house and the downhill side facing away.

Turn it on, punch in the desired slope and walk away.

Of course, it's not always that easy (almost never), and there usually is some math to do to check that the laser is set up right, but it gets close enough for what we do...

Henry
07-10-2007, 08:07 PM
What about a grade matching laser? It doesn't have an lcd screen to show the percent of slope. I guess you have to set up at the low point and adjust to the high, or vice versa?

D Felix
07-10-2007, 09:47 PM
Not sure what a grade matching laser is.

Usually I start at the high point (i.e. door threshold) with the laser set to grade, then adjust the detector up the stick the appropriate amount for excavation purposes. The detector is then set for the day; if the laser is set up in the correct spot, the detector will read correctly anywhere in the excavated area.

Kubota130
07-10-2007, 10:33 PM
I do all of my concrete leveling for footings forms and wall heights with a measureing tape and transit...What I learned on and am comfortable with.

ChampionLS
07-11-2007, 02:25 AM
I do all of my concrete leveling for footings forms and wall heights with a measureing tape and transit...What I learned on and am comfortable with.

I started that way too. The problem is, it takes two people and you always need to focus in on the tape. If your working over a long distance, you need to yell or use walkie talkies to communicate. With the laser you just use your storypole (tape) and have much freedom. The only drawback would be something to hold the storypole, so you don't have to lay it on the ground each time.

pls8xx
07-11-2007, 10:32 AM
For good vertical control on construction projects there are two ways to go, an auto level or self leveling laser. Which one to buy first depends on the type of work done. If all your jobs are dirt grading of large areas such as building pads and parking lots, then I would get the laser first. For smaller areas that include elements needing more precision the auto level is the better first instrument.

There are some things an auto level can do that a laser can't. For example it can help you see into a fill area. Ever wonder do you need to undercut? Run a plate compactor over an area then, with the compactor running. stand the grade rod 3 to 4 ft away and set the auto level 20 to 50 away and take a look at the rod. There is a big difference in what you see in the scope depending on what's deep in the fill. You have to do this on a lot of fill areas(good and bad) to get good at it.

For most work the laser has sufficient precision. But it does not compare to that of an auto level. Yes, I've seen the specs. But the precision noted is that of the laser beam while the overall accuracy is a function of the laser system, consisting of beam unit, receiver, and rod. Some systems are better than others. Make a dozen high precision shots with a laser spotted around a 1 acre tract and then repeat with an auto level. You will see what I mean.

Both of these instrument types have a compensator for the self leveling. Though it rarely happens, a sticky compensator will cause big problems. Never use an instrument for the first time without checking the compensator. This is easily done with the auto level. Focus on the rod and while looking through the scope, turn the leveling screw most in line with the shot. In the scope you will see the horiz. cross-hair pull off the reading then quickly return to the same place it was in a smooth fluid motion. If it doesn't, then don't trust that instrument for any grade work!

Checking the compensator on a laser is not so certain. Make a fine precision shot to a point 200 ft from the sending unit, then mis-level the instrument a bit and see if the reading returns to the same as before.

Check older units from time to time. Though I have seen this less than 10 times over 30 years, bad grade shots can get very expensive.

For both instrument types there is a big difference in the cheapo and the pro gear. You get what you pay for. In auto levels the better instruments have bigger glass that works better in low light, more magnification for better readings at a distance, a wider field of view, and less sensitivity to how close the focus adjustment must be.

With lasers there are a lot of trade offs, beam strength to battery life, distance to rotation speed/ receiver sensitivity, a top cover for unit protection or cover feet that cause dead spots. A lot of the ease of using a laser, along with precision. is dependent on the receiver rather than the sending unit. Get the more expensive receiver with greater vertical initial response. Pay close attention to the bracket rod assembly. There can be dead spots on the rod where the receiver can not be moved to, plus a lot of time can be taken moving the receiver from one rod section to another where you have a large sloped project. In short, look at the whole system as it will be used!

For laser use, make up a 1 ft rod boot. A rod boot can be a 1 ft long stake with a longer slat attached to the back. the rod is set on the boot so that it is raised exactly 1 ft and the longer slat is held against the rod back. The 1 ft is then added to the observed rod reading. Use of the rod boot will overcome dead spots on the rod and also save swapping the bracket to another rod section when many shots are taken close to the rod divisions.

Kubota130
07-11-2007, 12:06 PM
I started that way too. The problem is, it takes two people and you always need to focus in on the tape. If your working over a long distance, you need to yell or use walkie talkies to communicate. With the laser you just use your storypole (tape) and have much freedom. The only drawback would be something to hold the storypole, so you don't have to lay it on the ground each time.

You are absolutely right about the long distance communication problem however it is much easier to build the footing or tie the westcon forms together with two people and for that reason there is always another guy with me. The laser would be much easier and is something I will start looking into in the near future but for now the transit does the trick.

ChampionLS
07-11-2007, 09:55 PM
What I like about our laser best, is the Auto-Leveling ability. A good majority of the time, I dont even use the tripod (unless being in an open yard) You can place it on a porch, BBQ grill, even a pallet of pavers. If something (or someone) bumps it..even taps it, it will stop rotating and alert you that it's been bumped.

Secondly, the receiver is double sided. You can stand in front, or behind the storypole and still see the display. For almost all landscaping/hardscaping I set the accuracy to +-1/8" This will allow you to get things "close", since your taking readings on gravel and stone. For really precision work, you can set it to +-1/32", but you better be leveling the Hubble Telescope!

I've compared mine (CST Berger) to a friend's Dewalt and I don't like the Dewalt receiver at all. Not enough sensors (it gives you a window of about 1") to work in. The CST is about 3". It also has 3 Audio levels and silent. Quick beeps go down, slow beeps go up, constant your level!.

Another feature of the CST (my model) has the grade feature. Wanna do a driveway that slopes 14" from garage to street? No problem. You can angle the beam and take a reading at both street and garage level. When the laser is at the right setting, anywhere you take a reading while using the story pole is the proper grade. Only thing better would be a plug in power pack to keep the laser running off batteries. It uses 4 "D" batteries and they last approximately 40 hours. (an entire season of use)

Henry
07-12-2007, 06:57 AM
Champion, that garde feature sounds like what I was asking about earlier in this thread. Do you have to set up the unit right at the spot of your closest reading for that to work? Can you explain?

D Felix
07-12-2007, 06:03 PM
You don't need to set up a grade laser closest to anything. You simply need to have it oriented in the correct direction relevant to what you are trying to grade.

Picture a flat disc that is level all the way around. That is what you have with a regular laser level. Now if that disc was a clock face, and you tipped up 12 one inch and kept 3 and 9 level, that's what a grade laser does. You simply have to make sure that you have 12 o'clock uphill and 6 o'clock downhill relative to what you are trying to grade.

I did find out the other day that a window will reflect back the beam and throw off what you are trying to shoot elevations of!! Fortunately I realized it very quickly and other than a moment of panic there was no harm done!

Henry
07-12-2007, 06:22 PM
D, does your laser have an lcd screen or number pad where you can see or punch in the amount of slope you want?

D Felix
07-12-2007, 09:24 PM
Yes, it's very easy. Level is 00.000, 1% is 01.000, etc. Each digit is individually scrolled through, so setting it is fast. From the time I turn it on to the time it starts spinning usually takes less than a minute.

I'm not sure just how high you can set the percentage... I've had it up to ~5% before, but I don't know what the specs are on it off hand.

FWIW, we've got two detectors for the one laser. We discovered several years ago on a big retaining wall job that we had a need for two sticks running in different locations at different elevations. Both detectors are view-able from both the front and the back side, though I rarely look at them when adjusting. Fast beep means down, slow beep is up!

ChampionLS
07-13-2007, 02:27 AM
Henry,

It can get a little tricky. You have to use logic to understand how the grade feature works. Heres an example:

If your doing a driveway that has a 2 foot slope over the entire length (street is 24 inches lower than the garage) and the driveway is 100 feet long, the optimal place for the laser is in the middle (50 foot mark). when you angle the beam, it angles from the laser's point of origin. Some lasers let you angle the "x" and "y" axis, however this one only lets you angle one direction. You set the laser up with the axis towards the street/garage. Now when you angle it, half the beam goes up, and the other half goes down. (imagine the beam is pivioting on the laser) The buttons have no gradation, it just slowly angles. If I'm working by myself, I'll lean the storypole up against the garage and set the receiver 1 foot higher than level, then pressing the button on the laser until the beam reaches the receiver. If I loosen the receiver and slide it down 24" and check at street grade should beep level. The laser is now set for my work.

Alternately, you can put the laser at the high point, or low point, and use just one half of the angled beam for reference.

Where are you in NJ? If your looking for the same laser, I have a brand new one in the box (laser, receiver, carry case, story pole, tripod) It's a CST LMH-GR model.

Henry
07-13-2007, 07:09 AM
Champion, thanks but I already bought one. By the way, Wayne is in north Jersey about 20 mins. east of NYC.

The laser I bought is a topcon with the grade match feature, arrived yesterday. It works the way champion described, adjust until you hit your mark, which I think is useless if it has to be set in the middle of the work area. I didn't put much thought into it when buying it because I needed to replace my old, basic laser. While waiting for it to arrive I started thinking about how the hell it works and how I probably spent a couple hundred more than I needed to.

pls8xx
07-13-2007, 11:56 AM
It's raining here today. So I'm reading over this thread. About those lasers ...

D Felix said ...
Turn it on, punch in the desired slope and walk away.

Of course, it's not always that easy (almost never), and there usually is some math

ChampionLS said ...
It can get a little tricky. You have to use logic to understand how the grade feature works.

and Henry asks ...
care to tell me how you set up that single grade laser

The beauty of those grade lasers is that you set the laser to give the same plane as the the grade should be and you get to use the same rod setting all across the grade area. The trick is to orient the laser to the line of slope and set the proper % of grade.

There are ways to find the correct slope line and % of slope, but it looks to me that many here are just using the fudge factor to set up the unit, rather than knowing how to really use the equipment. Reminds me of someone finding a block and paver supplier, reading a brochure, and bidding a project.

Below is a simple real life type drive project, 40 foot drive, with a curb difference of a half foot. From the design data, is there anyone here, other than me, that can tell one how to determine from the shown laser location, where the line of slope will fall and what the % of grade for the laser should be? Would anyone even want to know?

http://i9.photobucket.com/albums/a93/pls8xx/laser1.jpg?t=1184341767

D Felix
07-14-2007, 10:48 PM
What you show would probably be more of a PITA to set up with a single grade laser than what it's worth. Mostly because of the trial and error involved in aligning the laser.

In your case, I would orient the laser parallel to the drive with the X+ on the house side and the X- on the road side. The slope percentage on the top part of your picture is 5%, set up one stick for that and leave it there. The other stick would then "float" and use the math to get the side-to-side slope adjustment with the laser set at level. It would be a lot of back-and-forth to the laser, but probably less time than it would take to set it up via trial-and-error.

Not sure whether the "cross slope 0.2" or 5% cross slope should be correct, you've essentially got it marked both ways...

pls8xx
07-15-2007, 08:14 AM
Trial and error? I don't think so.

But if there are some here that have not learned how to do it, don't feel bad. I've had a long career of cleaning up after architects and engineers that couldn't design that drive, much less build it.

On arriving at the site I would ask that the laser be set up at a location that will be out of the way for construction and the elevations of the garage and the two points on the curb are shot to verify they are correct. About 3 minutes later I will give you a target to align the laser on (a spot along the red line in the graphic below. The laser will then be set to have a 6.56 % slope along this line.

The rod is set on the garage floor and the receiver is adjusted to "on-beam". The rod is then taken to the low side curb location and if your math was correct the same rod setting works there too. The same rod setting is then used to do all of the drive shown below shaded in green. (Move the receiver up on the rod however many inches you need to control subgrade.) You can also use a standard transit to do the same thing.

As I said, the work to determine the line of slope and % should take about 3 minutes. Explaining the how and why will take a bit longer. I don't mind sharing my tricks if someone wants to learn.

http://i9.photobucket.com/albums/a93/pls8xx/laser5.jpg?t=1184499324

Henry
07-15-2007, 09:13 AM
I got the 6.5% slope but wasn't sure about the line. Of course the garage floor should be level across so that number doesn't change. I thought you would use the center of the garage as your top point and offset the low point by half the driveway width but that's not what you did. I'm ready to learn, when does class start?

pls8xx
07-15-2007, 10:18 AM
Guys, this ain't rocket science. But you do have to understand some things about plane surfaces. A plane is flat, like the surface of a still lake, in which case the plane is also level in all directions. But a plane can also be tilted. D Felix was right on tract when he said ...

Picture a flat disc that is level all the way around. That is what you have with a regular laser level. Now if that disc was a clock face, and you tipped up 12 one inch and kept 3 and 9 level, that's what a grade laser does. You simply have to make sure that you have 12 o'clock uphill and 6 o'clock downhill relative to what you are trying to grade.



In the graphic below I've used Google sketchup to do just that.

http://i9.photobucket.com/albums/a93/pls8xx/plane.jpg?t=1184507654

In the graphic above are three views of the tilted plane. In the top one a line has been drawn from the very highest point to the very lowest point. This is a line of maximum slope. If another line is drawn parallel to the this line. it too will be a line of maximum slope.

There is also a line across the plane such that it is level. Any other line parallel with it will also be level.

Thus an important property of lines on a plane is that parallel lines always have the same % of slope. The amount of slope may vary from level up to the maximum, but any two parallel lines, no matter what the direction, will have the same slope.

The bottom view of the graphic shows the plane from above. Note that the line of maximum slope is perpendicular to the line that is level. Any line of maximum slope is always perpendicular to any level line of the plane.

Are you with me so far?

ChampionLS
07-15-2007, 11:03 AM
Good example. It might be easier to show an X and Y axis, instead of using clock numerals. (also, the laser projects outward to, and past your jobsite boundries..so the clock face "circle" is just a visual example. It can be any shape)

pls8xx
07-15-2007, 01:40 PM
Controlling grades on a tilted plane is a matter of setting the instrument to align with the line of maximum slope, which is not easy to determine in a direct manor. The trick is to find two points that should have the same elevation and the line between them. Then remember that the maximum slope is perpendicular to the level line.

I'll now turn to the sample drive project. Some of what I have to say is about good design and part is about controlling the grade.

There is more than one way to skin a cat. The drive could be built by running a straight grade along each side of the drive from the curb grade to the garage. Since the curb is not level and the garage is, the two sides would have a different % of grade. Think of taking a 10" by 40" piece of heavy sheet aluminum and giving it a twist. No part of the metal is then flat. Same with the drive. Remember that on a tilted plane two parallel lines must have the same slope. If they don't, it's not a plane. Build the drive this way and you can leave the laser at home, you'll be doing it with string lines and form boards. If I'm building a drive next door with a laser. I'll be done and gone while you are still scratching in the dirt.

So the edges of the drive should have the same slope. But what slope? And if they are the same slope then one or both sides will need a transition to match drive to curb and garage.

The basic slope should be that of the straight line grade on the low side of the drive. I'll try to explain. If the low side is used, the transition grades fall on the high side and make for a smooth ride up the drive. Try to use the high side and the transition areas are backward from what they should be. Bump bump.

Good ....

http://i9.photobucket.com/albums/a93/pls8xx/profile-1.jpg?t=1184514891

Bad ...

http://i9.photobucket.com/albums/a93/pls8xx/profilewrong1.jpg?t=1184514868

What about that 0.2 cross slope on the drive? By doing it that way, instead of all the transition falling at the curb, some of it is moved up to the garage. You now have 0.3 to overcome with transition at the curb and 0.2 at the garage.

Also, lots that have a significant street grade are lots that have a general cross slope and the 0.2 drop across the drive will better fit the lot grade and look better too.

So now we know that both sides of the drive should be built with the edges having a 6.25% slope, the low side grade from curb to garage. Note: This is not the plane maximum slope.

Finally, I'm down to the heart of the matter, finding the line of maximum slope and the % of slope needed.

I start by visualizing a line drawn straight across the drive. From the low side up to the high side I gain 0.2 in elevation. From the high side I calc the distance to go down the edge of the drive @ 6.25% to get back to the same elevation I started from on the low side. The distance is 3.2 feet. See the graphic below.

http://i9.photobucket.com/albums/a93/pls8xx/laser2.jpg?t=1184516470

Looking at the triangle formed by this operation I can square the 10 ft distance across the drive, add the square of 3.2, then take the square root of the sum to find the distance of the third side shown in red. Since the red line is to be level, then the maximum slope line must be perpendicular to this line.

I only visualized this triangle to make the calcs. What I want on the ground is a line perpendicular to the red line of this first triangle. Since the 10 ft side was perpendicular to the drive edge, I can lay this same triangle out along the edge of the drive rotated 90 degrees. Now the red line is a line of maximum slope that I needed. The red line is extended with a string line as shown as a dashed red line.

The offset distance is measured to the laser and the same measurement is used down the line to set a target for the laser alignment to a line of maximum slope.

To get the amount of slope needed, I'll take a closer look at the lay-out triangle ...

http://i9.photobucket.com/albums/a93/pls8xx/laser3.jpg?t=1184518501

As in the graphic above, I begin at point 'A' and apply the grade change to 'B' as 3.2/10 times 0.2 = 0.064 Then the grade change 'B' from to 'C' 10 ft @ 6.25 % of 0.625 These values are added to get 0.689, the grade change 'A' to 'C'. The grade change of 0.689 across the distance 10.5 yields a 6.56% grade, the maximum slope for the plane.

If you have one of those fancy ass lasers you now have it aligned to the maximum slope. Punch in the 6.56% grade and you're good to go. Otherwise or if using a standard transit there are a couple of more steps.

Questions so far?