Brunton Pocket Transit - Mount-Head Assembly & Staff Level V3 by Biketool

Last crawled date: 2 years, 12 months ago

This mount head set should allow anyone to bring only a pocket transit and this printed mount along in their luggage or pocket, acquire a broom handle or staff of proper length, perhaps some stakes and flagging tape or a can of spray paint to mark where readings are taken, and be able to survey an area with reasonable accuracy anywhere in the world.
I have not found any available unbranded Jacob staff or tripod mount-heads for use with Brunton pocket transits, certainly not at a price appropriate for the inexpensive unbranded transits. This collection is intended to provide someone with most of the parts (except for non-magnetic screws, nuts, and washers) needed to assemble a mount-head assembly for use with a measured staff or broomstick to mount the Brunton for use in determining horizontal angle with the (magnetic declination screw adjustable) magnetic compass as well as to rotate it 90 degrees on this pivoting mount head for use with the internal vertical axis spirit level scale for use as a clinometer to measure the angle up or down to the target or tie-in point. Used with a staff rather than a bullseye bubble levelled tripod, the clinometer readings will always be rough, but I have included a wrap around zip-tie on bullseye two axis bubble level platform to attach to the staff itself for an inexpensive 30mm bubble bullseye stuck down with 3M double sided scotch tape. The bullseye mount slides up and down the staff so you can glance a quick staff level check when taking a clinometer reading. With the bullseye 1-2 degree accurate vertical clinometer readings can be taken without needing to acquire a tripod in keeping with this being a pocket size surveying system requiring only a broomstick be purchased locally. The files currently posted are a v2.5(2.6 adds a bubble leveler for your Jacob staff) of the project and are far stronger than the first files posted to the project. One edit required is to center the hole for the tightness adjust clamp screw by 1mm, I just drilled it out rather than edit and re-print, that is the only edit holding me back from tagging this as finished. In a big re-edit I might either make the clamp's bottom bracket thicker, double or curve it, change the infill %, or just do away with adjustability as I currently just have the clamp at it's tightest setting and just slip the Brunton into the clamp, it is tight enough but bows the bottom of the bracket rather than getting tighter. I am seriously thinking to reprint the bracket (with the holes edited) in PLA and do a lost-PLA aluminum cast. http://makezine.com/projects/guide-to-3d-printing-2014/metal-casting-with-your-3d-printer/ The lower pivot, peg, and staff cup are glued together with glue made from ABS plastic dissolved to goo in hardware/paint store grade acetone(not watered down nail polish remover), I also acetone/ABS goo glued the clamp pivot disk to the upper pivot after trimming all brim and filing trimming everything flat. I found that filing or sanding the tips of the clamp 'teeth'to a squared off edge gave me a far better grip on the Brunton mounting grooves than the rounded ends my 0.5mm extruder tip printer left me with. So far I am happy with calling the basic design final with problems with this model resulting from imperfect infill and temperature settings.
10-8-2016 v3, (as yet unprinted)Added more plastic to the bridge of the transit clip, have some ideas for a stronger v4.
Thoughts on Brunton and inexpensive copy pocket tranists
https://en.wikipedia.org/wiki/Brunton_compass
The Brunton Pocket Transit was designed by and named after David Brunton, a mining engineer in Colorado. The Brunton when used with this head mount set is functionally a non-telescopic pocket sized theodolite combining a magnetic compass and bubble level clinometer to measure horizontal and vertical axis through several several sighting methods using mirror, peep sights, and even sighting out of field of view and pressing the lock button to save a rough heading. Patented in 1894 with main features finalized by 1914 but still in widespread everyday use by engineers, geologists, archaeologists, and surveyors worldwide, it is known as the M2 Engineer's or Artillery Compass to the US military. Years ago Brunton manufacturer William Ainsworth & Sons Inc and when they collapsed the new Brunton Inc changed most models from a non-magnetic metal body to tough ABS plastic. (I am not a lawyer, the next bit is my amateur supposition not in any way a deceleration of fact, an actual practicing attorney in your jurisdiction should be consulted to determine the truth of what follows.) The patents (and name trademark) https://en.wikipedia.org/wiki/Generic_trademark have long expired on this tool so it is possible to find quite inexpensive 100% legal examples made by several manufacturers for as low as $20(US) including international delivery in 2016 which, if carefully tested for calibration before using in the field, can function as well as ones made by the Brunton company costing several hundred $US. There are some decorative rather than fully functional brass and nickel plated examples made in India which are not made to the highest standards, these are not recommended, even in the 1890s Brunton specified the then precious metal aluminum for the lightweight body of his pocket transit. My example of the ~$20 Brunton (seems to be a non watertight functional copy of that sold as the ComPro by Brunton inc) was fully functional, I did have to replace the fragile sighting window wire with a snipped 0.5mm sewing needle, and to bold the scratch sighting line I masked both sides leaving a 0.5mm unmasked strip along the unpainted scratch sighting line with Scotch magic tape and marked the line with a black Sharpie marker.
The next step up for around $50-60 is called the CST/Berger or Harbin Geological Compass DQL-8 and probably others as time goes on, it is compatible with my printed mount head too (these appear to be non-waterproof versions of the standard modern Aluminum Brunton). It is another Brunton expired patent design clone, it has a metal case, the black aiming line applied to the mirror, and inductive needle motion damping, I don't see much advantage to buying a Brunton branded transit over the Harbin one except perhaps ability to have it serviced or re-weighted for southern hemisphere easily at the Brunton inc. factory, though for the price you could get another Harbin if you break it with a DIY fix. The DQL-8 appears to be ready to use without any hacking around vs the $20 transit which has all the vital calibration done and mechanical parts installed but needs some work like the aim line applied to finish it. I much prefer my smooth metal induction damped Harbin pocket transit but functionally you can do most of what you need with a no-name basic plastic Brunton. One important difference is that the Harbin has a place to pop out the retaining wire loop holding the glass to get at the compass needle for re-weighting it with copper wire for use in the southern hemisphere if needed.
The Brunton is great for the many applications it is designed for on tabletop, hand held, with a staff, or tripod for highly portable site surveys, establishing property lines, or registering a claim, geological formation dip and strike measurements, maybe even making a detailed topographical map just to name a few uses for this true engineer's multitool.
If instead you instead need a quick tough compass for shooting azmuths in point-to-point over land movement and then keeping on a heading while walking day or night in any weather, or finding yourself on a map I highly recommend the US Army's lensatic compass or similar sighting compass.
If you got your Brunton without instructions this excellent Brunton manual will give you very complete instructions on how to use your transit in nearly every possible way, I have also attached the .pdf in the attached files. http://www.manualslib.com/manual/219471/Brunton-Transit.htm
Here is a declassified story of a CIA team doing a covert field survey of new American ICBM launch silos back in the early 1960s mostly using tripod mounted Brunton transits and public survey maps. They did this in order to evaluate the risk and potential accuracy of KGB teams doing the same from public roads and fields, mapping and targeting for Soviet ICBMs against those American missiles in their launcher silos. https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/vol11no3/html/v11i3a06p_0001.htm
History and examples of using a Brunton.http://oldtopographer.net/the-topographers-tools/brunton-pocket-transits/
Developed on OpenSCAD, .scad files attached.
Additional Information:https://en.wikipedia.org/wiki/Survey_markerhttps://en.wikipedia.org/wiki/U.S._National_Geodetic_Survey