cut motor reving up and down

[happy]

doing a cut out about a half inch deep and the motor stopped in mid cut when i stopped it I tried it again and it cut for a inch and done the same thing and broke the bit I done a test on the cut motor now it goes up to normal speed and drops down a little and keeps doing this any help would be appriciated.

[chief2007]

Check the brushes, they may have dust blocking them, also check the wiring on the circuit board attached to the motor,
Make sure it is not loose.

Might also ensure the ac motor switch is not closing intermittately

[AskBud]

doing a cut out about a half inch deep and the motor stopped in mid cut when i stopped it I tried it again and it cut for a inch and done the same thing and broke the bit I done a test on the cut motor now it goes up to normal speed and drops down a little and keeps doing this any help would be appriciated.Are you carving wood or Corian? May we see the MPC?
AskBud

[happy]

I will check the switches and brushes also it was 3/4" cherry I was cutting the back part of the eagle in the wilderness plan I cut the back out in 2 passes about 3/8" at a time I was half way through the second pass.

[bergerud]

Is this an old machine or a new one? If it is an old machine which had a vibrating QC, you may have the classic inductor or capacitor breaking free from its circuit board.

[happy]

It is a new C machine with about 230 hrs with about 120 hrs on cut motor I had to replace it, called carwright this morning they said its a loose wire or switch checked ever connection on top and on bottom dont know why it would stop all of a sudden, dont know if something heats up and kicks out.

[happy]

Also when the speed goes up and down it is not alot but you do notice it

[Digitalwoodshop]

Some speed changes is normal..... Broken Bit... Not.... Remember to watch the Cut Hours Counter, 250 and you want to be thinking about changing the brushes. They stop working about 298.... +-

AL

[bergerud]

If it is not the right cover switch and all the connections are good (including the X termination connections), it must be something loose in the motor. Have you checked the brushes? Sometimes the little braided wire can come out of the brush and a poor connection results. There are also clips and wires inside the motor to check.

[happy]

anybody know how much the brushes cost?

[bergerud]

Not much ($10?) but you have to buy them from LHR I think. Is there something wrong with yours?

[happy]

don't know yet I haven't taken the motor out yet to look at it, I was talking to somebody else and they said my problem could also be in the X terminal circuit board any body heard of this

[chief2007]

Yes, the connections for the ac motor go through that board, it is located in the bottom of the machine.

I have a C machine as well - Works great now that I have the "bugs" out of it - I had to replace my cut motor @ 95 hours, cracking on the housing near the flex shaft connection, I have also changed the X terminal board. Mine died and would not advance the belts.

Check your top brush on the motor (easiest to get to), My guess is your bushes should be OK with the hours on the cut motor. Blow out the cut motor as well, dust can get in there, I have had that happen to me, dust got between the brush and the windings and the motor fluctuated speed and then stopped turning, but the machine kept trying to carve. I just happen to be there or most likely I would have broken a bit.

If the problem still occurs after checking the motor and blowing out the dust, then the X terminal board might be the problem.

[happy]

Thanks chief I'll give it a try

[dcalvin4]

Thanks chief I'll give it a try

Ask Bud inventory reduction has brushes and cheap shipping
denny

[Digitalwoodshop]

I agree, a inspection of the inside of the Cut Motor is in order.... The best way is to remove it from the machine and then remove the brushes then remove the screws and open the motor. Remember that there is a screw inside the muffler hole.

Blow the dust out of the machine... All machines have dust inside the motor as cooling air is sucked inside at the slits in the case at the brushes and thought the motor and out the muffler... The motor cooling fan has 2 parts, inside the motor and suction of air from the electronic area.

Looks for any loose connections or wires that have touched moving parts...

The X Termination Board is under the machine and has the Q1 Transistor that is the electronic on and off switch for the Cut Motor controlled by the computer. It also passes the signals to the X Servo Motor. On 3 of my 4 early machines while using the vibrating QC the C1 Capacitor Snapped off due to vibration of the thin copper wire. With a vibration free Rock or CT this almost never happens... In defense of the QC..... I and MANY just waited TOO long to replace a BAD QC and that vibration killed the C1 and on the Power Supply the L2 Coil.... change the QC when needed and all the bit holders and your Good to GO....

Use a WIDE screwdriver to remove the plastic caps of the brushes... I cracked one using too thin a screwidriver.... It acted as a Wedge in the Slot...

When you put the Stator and Armature back into the Cut Motor as it needs to pop into the Sweet Spot... spin the motor looking for a smooth spin... And watch for pinched wires....

And DUST Collection... I have a picture someone sent me of a BURNT X Termination board... I suspect a Dust Collector was being used and the Hood and Machine was NOT Grounded... This let a HIGH VOLTAGE Static Charge build up on the frame of the machine and it is always seeking a path to GROUND.... And the Static Discharges INTO the X Termination Board and the 115 Volt AC RETURN PATH or as we know it.... The WHITE Wire in a Electrical Outlet.... Black is HOT 115 VAC and White is RETURN.... Tied to the Power Company Transformer AND GROUND....

Good Luck,

AL The other Chief.... US Navy Retired Chief.... FCC(SW) Fire Control Electronics... Guns, Missiles, Computers and Radars...

Found this on a Navy Facebook Group I belong to.... My Day job for 20 years.... The 70's TV Ad is of a Ship just like the one that I was on in 1989 in the Gulf before the first war... I was on it for 4 years and this is what I did....
http://www.youtube.com/watch?v=8cxq089KMRA