Chuck wobbles

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Greetings - just "joined up" after first purchase of Bosch Equipment (10.8 GOP/GSR Kit, + GDR), and getting very pronounced eccentric rotation in the GSR chuck (i.e. the chuck doesn't rotate true upon it own axis), which rotation seems to diminish to a theoretical focal point some 6 or 7 inches in front of the chuck. By any chance, were you able to conduct your dial-gauge test at distances from the chuck other than just 150mm? Most of the drill/driving accessories I use are doing their work within 2 or 3 inches max from the chuck (the chuck is where the wobble is at its worst). Just a guess here, but wouldn't a drill which hasn't been properly engineered to run true throughout the axis of rotation of the motor, need to be calibrated so that the focal point of least wobble is somewhere in front of the drill body where the workpiece would typically be, perhaps at a theoretical average distance of, say, 150mm, in order to achieve a compromise to keep production costs within the profit/cost targets of out-sourced cheap manufacturing? I only ask, as I have an own-brand Argos drill bought in an emergency which displays no worse wobble characteristics as the GSR just bought today. Anyway, I hope you will forgive my playful ignorance in the matter of powered hand-tools - I've only a very little more experience with professional machining equipment from a bygone era where engineering was of a standard unlikely to ever be seen on these shores again, and unlikely to be found in Argos. Question is, has it been found in Malaysia?

Roscoe:
Original from andy smith on 18.09.2012, 20:58
hi andrew
sorry for delay but here we go
with body off drill lightly clamped in a vice (battery up) and a 225mm length of 10mm tool steel round bar clamped in the chuck and a imperial dial guage on a magnetic base fixed to the bench running against the bar at 150mm from chuck face
gsb 36v li = 9 thou
gsb 10.8 = 11 thou
gsr 10.8 = 11 thou
gsr 10.8 = 12 thou   old machine
also tried two really old desoutter pneumatic 1/2 inch chuck drills (when i say old 15 years+) both measured
6 thou
as i said in 110v chargers thread not a scientific test  but im happy with the outcome 
just to finish bar ran true enough for me jacobs chucks on air drills ran true but plastic covers on all bosch chucks wobbled like buckled bike wheels not a good site really
anyone who wants to convert readings to metric is welcome but i think most of us still like good old imperial

hope this helps andrew
andy

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1978
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Plumber / Heating, air conditioning installation
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hi roscoe
as i said earlier in the thread it wasnt a scientific test
but i stick to my word, visible runout on any drill especially a new tool should go back to the supplier
as i am employed by a company not self employed i dont think my boss would be happy with me spending half a day dooing a test to put results on the bosch forum
as i said earlier all the chucks on my bosch drills wobble but the runout on the drill bits is not visible
if i drill a 3 mm hole in a damper shaft for a rolled steel pin i expect a 3 mm hole if i drill a 4.8 mm hole for a rivet i want a 4.8mmhole with runout i would  a 3.1 or 4.9 no good to me
if you cant put your 3 mm drill bit on your pencil cross and drill a tight 3 mm hole then that drill is crapand should go back
i think to prove your point to your supplier i would purchase a quality 10mm chuck and try it if its better take both to your supplier a show them
as i have said many times in this thread i would not accept visible runout

hope this helps

andy