Kern DKM1 - Lots of Pictures

Sexy!

Awesome setup!

Very nice & well documented post!
Thanks for sharing,
chr.

Nice instrument. I have always wanted a DKM1. I have a DKM2 and have used a DKM3. Not sure why Wild series was more popular. I particularly like the DKM3 for astro work-broken telescope so that you can sight high vertical angles as easy as low ones.

I have heard musings that the sole advantage of the smaller Wild/Heerbruggs over the Kern/Aaraus was the tribrach system. It was MUCH easier (and cheaper) for traversing than the Kern setup.

I have about 3 sets of those tripods in my shed, and one in my truck that I still use to this day for backsights, with a prism setup that will mount on it...have not used the Kern since 1993.

We used (and I still ahve in the office) a Kern K1-8 with a DM500 EDM that attached to it with a big a$$ battery that hooked onto the side of the tripod. Was big, awkward, come with two different boxes to carry, was a great day when the boss bought a Pentax total station. Cant imagine going back to that after a few years of Hiper bliss and robotics.

Those "fourth leg" tripods were fine for setting up over a point in the ground, but setting up over a right of way monument was a REAL pain. The DKM2 did have optical plumb but there is so little motion on the leveling screws that the top of the mount must be nearly dead level to level the gun. I did prefer the optics in the Kern to the Wild (although both were good).

Andy

In defence of Kern centring....

To my mind there is no competition between the Kern Auto-Centring system and what has become the defacto standard viz., the Wild Heerbrugg tribrach system. Setting up the Kern tripod particularly in rugged ground conditions or steeply inclined terrain or indeed in flat standard conditions is much faster. A novice once shown how to set up the Kern tripod can replicate this with no difficulty but the same tends not to be the case with optical plumbs having to level the flat head and center the spot bubble.Checking the plumbing (by reversal of the centring rod) and adjustment is much easier. Target heights/instrument heights being similar the axis height may be read from the rod. The Kern centring was adopted by Fermilabs & Cern because of its superior repeatability and flexibility for high precision dimensional control.

Centring tripods can be set up at exactly the same height above the station - try this with a tribrach sys. Since setting up was so easy and quick Setting up twice on a station was not considered a problem. Thus the traverse was run prior to detailing. The traverse could as a consequence be computed, checked & plotted ready for the availability of the Detail radial obs. This worked well for the lone surveyor but was particularly useful where a number of teams were employed. Any Wild Heerbrugg users I ever talked to preferred to combine traverse and detailing in a single setup - they resisted setting up on a station twice - which meant that traverse closure could not be completed until the Topo detail shots had all been gathered.

Even if I used Wild, Zeiss or other equipment I would always use the Kern tripods with adapter plates. In the case of Geodimeters/Trimble I had the centring rods engineered for the correct instrument height using the centre-run marks on the footscrews.

The centring rod & locking head also appears to promote tripod stability- (GOOGLE Depenthal, Twists and Tilts of Tripods) I have found that Trig.heighting using the Kern is equivalent to standard heighting with a good quality level.

Disadvantages of the Kern System:-

Must have a divot to hold the ferrule of the centring Rod
Stations should preferable be near ground level
The ball head must be kept clean or pre-levelling tends to be insufficient - )this was not true of the two-footscrew instruments).

Having said the foregoing trained surveyors become so efficient at setting up other factors can have a more pronounced effect on output.

MapTack