Does anyone have experience using the German made KWM Bushing Tool ?
My personal experience is as follows.
Between my personal purchases and the NAWCC school, I have worked with all of the Commercially available Bushing machines that I am aware of including KWM. Without exception, they all have the same issues. Plate positioning for center location requires skill and luck. Spindles and reamer mountings are a loose fit in most cases.
The loose fits (I am sure not intended) assure that the reamer can properly ream a tight fitting hole since they can find the path of least resistance. Another words they are not turned into a boring bar that enlarges a hole such as being held in a chuck with runout.
While the Bushings replaced in bushing machines have the proper friction fit, the location of the bushing has not always been in a predetermined location. Close most of the time, but not to a consistent standard I wish to put my name on.
In the beginning, I used hand methods that I found were even more inconsistent in both bushing fit and bushing location. While those who use these methods on a consistent basis (mostly file the opposite direction) have always told me that they never fail. But based on my experience and what I have seen over the years, this is not true. Or they tell me that a typical movement can absorb such errors.
The reason I bring this up, is that if you do any amount of repair, you will have to deal with what others have done. Of course an 8 day american movement can absorb some errors, but its an accumulation of errors that will decrease its running efficiency from when it was new. And now what do you do when you run into a movement that cannot absorb errors.
My personal goal when repairing a movement is to return it to original condition with properly placed bushings. A running movement that is more of a ticker is not except-able.
Again personally, My solution has been to use a small Milling machine for bushing.
(1) The calibrated slides allow me to very accurately and quickly predetermine reamer location.
(2) The accurate and stable/rigid spindle with collet mounted reamer assures position and bushing fit.
(3) The Milling machine offers a quick and efficient method of properly depthing poorly placed bushings
(4) The Milling machine provide the option of very quickly and accurately grinding a Verge that is critical to a solid running movement.
The above bushing description is only a small example of what the mill can do for about the same cost as a bushing machine that can only bush.
When you consider all of the other tools it can replace and its capabilities, it has to be one of the best values one can make in any kind of repair work.
The use of a Mill for bushing and depthing is covered in the NAWCC on line education program as well as Workshop WS-120