Bosch GMS120 Digital Wall Scanner
Summary: this Wall Scanner is so unreliable that it can't even locate objects or structures whose precise position is already known.
Like many a tool buyer, I decided to spend the extra to get a fully-featured device. I thought that this Bosch would be a useful tool for the major house renovation I am undertaking.
My first few tasks were locating studs in standard domestic walls. The four walls I initially scanned were all plain partition walls, ie presumed free of any objects other than low-level socket wiring, plasterboard nails, and perhaps some cross-bracing in the studding.
No matter how carefully and methodically I used the Bosch - e.g. allowing it calibrate, moving to different areas of the wall, slowly re-scanning each area - the device appeared incapable of generating a distinct signal over a stud.
In each case I resorted to the traditional expedient of tapping the wall to locate the stud, and confirming its location and edges with a bradawl. Pathetically, the Bosch only identified about half of these located studs, and those results were swamped by the mass of false signals it generates over all areas.
The Bosch's final failure came when I ran it over a stud wall where the backside of the wall had been stripped of plasterboard, thus exposing the studwork. Scanning this wall clearly demonstrated that the pattern of signals from the Bosch had only a random correlation with the studs and other objects in the wall.
Using the Bosch in its cabling location mode, it was the same story - a mass of false signals that obscured any actual positive results. By contrast, a cheap DIY cable locator had no problem in pinpointing the target cables.
The Bosch is further let down by very poor instructions, which in particular do not have any troubleshooting guide that might help with the situations described.
Its possible that my Bosch is faulty; however there is no service indication displayed, and its main functions seem to be operable. The problem seems to be that the device is far too sensitive, and that it simply cannot cope with conditions outside of its design laboratory.
3 Feb 2015
This scanner is hit and miss and not as good as YouTube review videos would lead you to believe.
As a professional Joiner / Carpenter I expected a lot more from the Bosch brand, however considering the price it's better aimed at the DIY user thinking they are buying professional kit!
5 Nov 2014
Rubbish but may be defective
Bought this on recommendation,found it to be hopeless permanently detected electric cable even where there was none,then failed to pick up live cables right under it,also couldn't find studs In a stud wall but detected every drywall screw in the entire wall which meant it never stopped beeping!
Returned it the same day,screwfix to there credit refunded me no questions asked.
I think I had a lemon and it needed to be re calibrated but this has put me off buying another.
9 Sep 2014
Moving to a new house and thought that I do not know where anything might be in the walls. Tested it and found it amazingly accurate in finding electric wires piping or nails.
A definite must have.
4 Jul 2014