A pantometer is a handy device which allows the easy and quick measuring of slopes for maps and charts.
The normal method for surveying a slope is to use ranging poles at each change in slope elevation. This method can be time consuming when you need to use both a clinometer and a tape measure. Not to mention the problem of a lack of hands to carry this all.
A pantometer is a fixed distance apart, 1m, which means you do not need to use a tape measure. Also, the protractor is fixed to the pantometer, which is one less thing to carry, loose and have to sight up every time. It still requires two people to operate, but it is a lot easier and quicker, and the results are more accurate.
Pantometers are difficult to find in educational catalougues (I have only seen one in Philip Harris) and are quite expensive. But, for about 10 quid ($15) and a couple of hours work, you can make your own.
Step 1: Equipment and Resources
To make a pantometer, you will need the following
x2 meter rulers
x2 2cm x 4cm pieces of wood, between 1m and 1.5m long
x1 10cm long, 4cm gauge dowling (or which ever you prefer)
x8 drawing pins
x1 360 degree protractor (I shall explain why)
150cm of string or cord
x1 eye curtain hook
4cm of tubing
x1 small weight or anything suitable
wood saw (optional)
medium gauge sandpaper
paint brush (optional)
Araldite (or other epoxy glue)
Step 2: Prep
The upright pieces of wood need to be quite substantial to weather all terrain.
Mine are made from a left over peice of kick board, which was 1m 60cm in length. Most pantometers are usually 1m square, but it is not important. Infact, I believe that a taller pantometer will be an advantage since you will not have to stoop to read off the measurments.
So, I cut the wood in half to give me two 1.3m peices and just sanded the ends off.
Step 3: Marking Up
You now have to decide which will be your leading edge and the measuring edge. This is important since it will make it easier to get things right when it comes to assembly and actually using the piece of equipment. (if you are not quite sure about what I mean, look on step ten, and the first picture. The measuring edge is on the left and the leading edge is on the right)
After that, take the measuring edge and place the protractor on top, lined up in its final position with its top edge aligned with the wood's top edge. You then need to measure the distance to the centre of the protractor (in this case 10cm) and then mark the wood all the way around to this point. This measurement will make sure that all the angles that are read off will be accurate. I tried to make sure I had perfect right angles all the way around.
Then mark further down the position of the top meter ruler. In this case, I marked it at 20cm from the top edge of the wood. This line only needs to be done on one side as it is just a guide for the drill. The drill point is what I have marked in the middle.
You also need to make a mark for the second meter ruler at the bottom of the wood. I took mine 10cm from the bottom edge.
You now need to repeat this for the leading edge. Make sure you use the exact same measurements.
Step 4: Optional Painting
When the pantometer is used, the angle is sighted, not to the leading edges top surface, but 10cm below that (or what ever is the central measurement of your protractor) With that in mind, I felt that a small black line may not be enough of a visual, so, I decided to paint the top of the leading edge in black.
Actually, it was black board paint or nothing, since that was the only thing in the cupboard.
Some unforeseen side effects of this were;
It was easier to differentiate the leading edge from the measuring edge.
It stopped the sandy disintegration of the cut wood (it was obviously cheap stuff)
Its up to you weather or not you want to paint. To be honest, I am glad I did.
Step 5: Drilling
Its now time to drill the pivot holes that will hold everything together.
This is where I used the G-clamp since I don't have a vice. Its merely there to hold the wood in place. I didnt want it jumping about and messing up my measurements.
I used a 4mm drill bit because although I want the dowel and meter ruler to be able to move and rotate, I don't want to put any undue pressure on them.
After drilling the hole, I found that the hole was too small for the dowel. So, I took a round file, and carefully widened it a little. As you can see in the last picture, the fit was still snug though. With the dowel pushed though, it did not fall out or move.
This needs to be repeated 4 times on both the top and bottom of the leading and measuring edges.
Step 6: Dealing With the Meter Rules
Lay out the leading and measuring edges so that the meter rules can be laid on top. You are going to need to mark out where the holes are supposed to go.
I made sure that the end of the ruler matched up to the edge of the wood, so that the pantometer would be exactly 1m in length.
After marking out both ends of both rulers, you can then drill the holes.
Step 7: Doweling Up
Next, you need to fit the dowel.
Insert the dowel through both the wood and the meter rule. When the end of it is flush with the wood, mark off the other end so you know where to cut. I again used my G-clamp to hold it steady while I cut off the measured end with the hand saw. I gave the ends a quick sand with the sad paper to remove any nasty sharp edges, then I inserted one of the drawing pins into one end. I found it easier to put the dowel into the wood then insert the pin as I had something firm to press against.
Once that is in, you can hook in the meter ruler on the other end, and push home the final pin, securing the two together. The meter ruler should swing freely, or at least move without too much effort.
This is where you start to connect everything up. Just repeat the above for the other three holes, and the pantometer should be taking shape with the leading edge and measuring edge both connected via the two meter rulers.
Step 8: Setting the Protractor
This bit can be a little tricky, and the protractor must be dead accurate in being aligned straight up and down the the wood. To achieve this it is also a sensible idea to mark out a 90 degree line so that you have something to centre the protractor on. If its don't correctly, you wont see the line.
The reason you need a 360 degree protractor will become apparent when you reach this stage. You obviously want 0 to represent the horizontal, and that is not possible for a 108 degree protractor.
To fasten your protractor to the pantometer, use your adhesive of choice. I like Araldite because it stick to everything, becomes rock hard and give you a lot of 'play time', just in case you make a mistake.
I mixed equal parts of Araldite together, then applied it to the back of the protractor. Remember to position the 0 on the protractor pointing toward the leading edge. Otherwise the pantometer will not work. Then it was just a case of sliding it into place, making sure I was correctly lined up and then just holding it in place for a couple of minutes.
Step 9: Stringing the String
The string is the variable against the scale in case you were wondering, and this is what you need to do.
Do you remember you made a mark all the way round on the measuring edge? This should be the reverse of the protractor. In the centre you need to screw in the eye curtain hook. Once that is in, securely tie one end of the string to it. (picture 1) Then securely attach the other end of the string to your weight. (picture 2) The weight can be anything, its only there to help maintain tension.
Next, take a 4cm (or what ever the width of your leading edge may be) piece of tubing, and with the scalpel, slit it all the way down. (Picture 3) Then attach it to the reverse of the leading edge, with the slit facing upward with a little adhesive. (Picture 4)
You can now push the string into the tube, and you should have a pretty good tension going, giving a clear reading on the protractor.
Congratulations. You have just built your pantometer!
Step 10: The Finished Product
When you have finished you should have a piece of equipment that looks like this.
The first picture is of the front with the two meter rulers (you can't see the bottom one) and the protractor mounted on the front.
Picture two is the front of the measuring edge, showing a centered and lined up protractor, with the 0 on the scale pointing towards the leading edge.
Picture three is of the back of the measuring edge. Attached to it is the string, dead centre to the protractor.
Picture four is of the back of the leading edge, showing the tube holding the thread and the weight tensioning the line.
Step 11: Storage
Its a big piece of equipment to store and transport, which is why I made it so that it can collapse down into more manageable size.
All you need to do is
-Remove the string from the tube on the leading edge.
-Pull the tack out from the top dowel on the leading edge.
-Pull the tack out from the bottom dowel on the measuring edge.
-Fold down the dowel from the leading edge to the bottom dowel of the measuring edge and re-secure with the tack.
-Fold up the dowel from the measuring edge to the top of the leading edge and re-secure with the tack.
-Bind the two together with the string.
Or, I also made a quick carry bag out of some calico which it can be slipped into.
Step 12: Using the Pantometer
This is a basic diagram of how the pantometer works.
The measuring edge and the leading edge (always move from left to right, same way you read) are placed vertically (it can be an aid to have a small hand-held spirit level if you want it very accurate) to the ground, and then either a positive (up hill) or negative (down hill) reading is given by looking at the position of the cross piece (or string) against the scale of the protractor.
When recorded in a table, the slope can then be recreated on paper, with elevations being given a 1m intervals.
This piece of equipment is very useful on line transects, especially what they exceed 30m in length. It is quick and efficient to use.
The main draw back which can also be seen as an asset is that the measurement is always per 1meter. Any hillock or pothole within that meter will be missed. Just with any surveying method, they all have their advantages and disadvantages.