this tool last only 5 hour before break . the current project be 250 sf of hardwoord flooring in my own house , with another 350 sf to follow . the wood be mill austrialian brushbox , which have above average hardness but probably softer than oak . I decide rent and use a commercial floor sander be too risky , and that a hand hold could get the job do . my 15 year old Black & Decker -lrb- 3x21 , 3.4 amp , hot , noisey , no dust removal , no switch lock -rrb- would bog down with 120 grit at a slow rate of coverage and require frequent vacuuming . so I upgrade to the Bosch 1274dv -lrb- 3x21 , 6.6 amp , quieter , 1-1\/4 dust port -rrb- , gamble that the size and power could spin 80 grit at a reasonable rate of coverage . the other rave review about the ergonomics be true . get a dust port be fantastic in that , when hook up to a medium size shop vac , almost no dust be put into the air or leave on the floor during sand . the machine remain cool under continuous duty and the switch lock allow you hand and finger to relax . I still need headphone with both the sander and the shop vac go . as for muscle , I can report that Bosch 's 6.6 amp be good enough for dyi'er to make two pass -lrb- 250sf , 80 & 120 grit -rrb- in about 6 hour . unfortunately , the tool do not last that long . about 3 hour in , I have a power cord accident , something that never occur in 15 yr with the B&D; . the cord be sweep into the slot behind the rear roller . the motor be scream , the cord be fly around , the machine be twist out of my grip . it take about 8 seconds to get control of the machine and figure out how to unlock the power switch . during this time I be wonder whether I will get this thing shut off before I get electrocute as it gnaw through the cord . unfortunately I be kill . no , just kid . cord extraction require some strong tug and a large screw driver to pry away pressure from the roller . the tough rubber cord survive and be in acceptable condition . I then do what anyone would do -lrb- with the exception of a Bosch engineer -rrb- , wonder why they could not make the slot just a little smaller or the cord just a little thicker . much later I find the user manual warn `` the cord can be drag into belt housing and become entangled with the pulley . '' nice . so the machine go back into service , only with a thump-thump-thump . after two more hour , I notice the power drive be start to slip unacceptably . I take the tool apart , look for some kind of clutch mechanism in the gear train . find a lot of german high precision and material quality , but no clutch . while reassemble the machine , I find the trouble . the rubber drive belt be miss tooth and start to wear through . Bingo . during the power cord accident , the cord jamb the drive roller but the upper drive gear continue to spin , take out tooth in the drive belt . I calculate the cost per hour of buy this tool and consider blast Bosch with a zero-star rating . instead I decide to include they service & repair organization into the total picture . log online , I find that in this metro area -lrb- Silicon Valley -rrb- they have several affilated drop off shop and one factory service\/sales center . I stop by the factory center , buy a $ 7 belt out of local stock , and install it myself . after one day of down time the machine be now back on the job and work fine . so Bosch be back up to four star , but only because they service organization and inventory save they butt .