My tablesaw wont speed up and run. Bosch 4000 ten inch. It makes a klunk and starts to turn and slowly speeds up until its running, but still makes a knocking sound
Ten inch saw, its frequently exposed to moisture on outside work...It fails to run smoothly, switch or capacitor or something damaged perhaps? can you tell me what would cause this. the bearings turn freely and its easily turned over by hand and spins but the motor is not working properly.
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Re: My tablesaw wont speed up and run. Bosch 4000 ten...
Is it spinning the blade at all? If it is then it is unlikely to be an electrical fault. Have you considered a motor bearing fault? If the motor bearings are worn, it could turn freely by hand, but when powered up it would stutter and stall. The motor is basically a big electro-magnet so if the armature has enough lateral movement, when it is magnetized it could rub against the stator.
If the machine is buzzing, but not spinning the blade it is more than likely going to be caused by a faulty capacitor as this is the component that gives the motor the initial 'kick' in the right direction to get it spinning.
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Make and model might help but here's two ideas:
1) Remove muffler and clean it. They can get plugged up with carbon and the saw will run at low RPM but will quit because of excess back pressure when you try to rev it up.
2) Set the high and low speed carb settings. Start the saw then gradually increase engine speed until full throttle. Screw the hi-speed needle in slowly. If RPM immediately drops, back it out until Rpm increases, then starts to drop. Screw back in until peak rpm reached, then starts to drop. Back out to peak, then 1/3 turn more.
Set low speed so engine runs smoothly but chain does not turn.
Hope this helps.
Here's what I was taught.
- Wear hearing protection.
- Start saw.
- Adjust low speed screw... turn in slowly until engine falters, then back out a bit until engine sounds happy.
- Place screw driver in high speed screw, apply full throttle, adjust high speed..... turn in ... rpm shoud increase, ten drop off... back screw out until maximum rpm, then a tiny bit more to make sure the mixture is not too lean.
- Chain saw should now be happy.
I've worked on some table saws with problems like you describe, a couple needed a new speed control unit (Bosch PN 2610997306) in the motor. If all the wiring to and inside the motor is OK and not shorting out anywhere, that's the next part you should look at.
The speed control on your table saw works by sensing what's going on in the field. If you replaced the speed control circuit board and the motor still runs out of control, the next item to replace is the field.
Sounds like the low speed fuel adjustment is out of whack....you can reset it by turning it in all the way clockwise...then as a starting point, turn it out 1 and 1/2 times, start the engine and slowly adjust the screw until the engine starts to choke out..when this occurs, turn it back in until it starts to choke again...then you need to set it somewhere in between to find the "happy medium"....thew high speed screw is adjusted after you get the engine idling properly...if you haven't messed with this then I wouldn't worry about it..unless you have poor high speed operation, then you will need to set the high speed screw...the object here is to obtain the best low to high speed throttle...if , when you throttle up the saw, the engine bogs or goes to high speed slowly , here is where you adjust to get the best throttle response...use small increments until you achieve the desired response
You can find the 4000 manuals and parts diagram at bosch tools online. You will need a new armture Bnew bushes and possibly field. I would also replace the bearings and motor speed control circuit board.
Bosch does not sell the motor assembly.
Turn unit upside down and remove the Plastic body - approx 6 screws.
Thake a digital camera and take LOTS of pictures of dissassembly as you will need them later. Blow unit clean and work neatly keeping all parts in labeled bins for reassembly. Don't attempt this job when your pressed for time.
Before you start check to see if this machine is still under warranty!!
Call customer support listed on website if you run into a problem.
Good Luck !!
I found that the remaining problem was a intermittent at the switch, which disassembly and cleaning resolved.
Tilting the motor / blade assembly down allows access from below, to the 3 screws fastening the controller circuit board cover on the brush end of the motor. From there, one can easily test exposed wires for power supply, see that brushes are contacting and clean accumulated sawdust.
I had a customer bring me a saw with this same problem. All components tested OK on my growler. I went on a limb since the speed control and the armature tested OK. I replaced the feild since to me it seemed to be the only component that could cause the motor to run in reverse. Tool now works properly and have had no more problems with the tool.