RAS 115 power loss.

I

Ilovemyras115

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Joined
Sep 29, 2020
Messages
14
Hi. First time in any forum. Read thousands. Never posted.

My RAS 115 which has worked hard kept fading with a sort of rattly sound. Over about 5 minutes.

I've dismantled it. Everything looks perfect on the mechanisms.

I've ordered new brushes which say they're 12mm long. The ones I've removed are 11mm long.

Am I missing something here?

I need the RAS functioning asap. So help appreciated.
.thanks.

I've got pics if the brushes but not sure how to upload.

Rich.

 
Are you sure it's not a problem with the power coming from the socket/outlet? I have had a few occasions where my domino XL and R090 have pulsed in older houses with dated wiring.
 
It's not the brushes.

People always think it's the brushes when the tool behaves eratically, but it never is the brushes. If the brushes go, your tool just stops, out of the blue, and does not start up again. When you open it up, you see these very small stumps of brushes with a tiny spring sticking out of the top of one of them. Festool makes their brushes like that, to make sure they go out when there's still carbon in touch with the rotor, and are not worn down all the way to the copper ending which could damage the copper contacts on the rotor.

Perhaps it's the cord, as suggested above, or perhaps the electronics module. Those are the things I always check first.

Process of elimination - take a standard non-festool electric cord with two open wires instead of a Plug-It connection, and check two things:

1 - Bypass the plug-it socket from the tool and connect the mains wire directly to the electronics module. If your sander works fine now it is the cord or the socket.

2 - If the problem stil exists, now also bypass the electronics module and connect the mains wire directly to the brushes. This can be done without problem. If this still does not solve the problem, it is the motor. Which is a costly repair.
 
Ilovemyras115 said:
Hi. First time in any forum. Read thousands. Never posted.

My RAS 115 which has worked hard kept fading with a sort of rattly sound. Over about 5 minutes.

I've dismantled it. Everything looks perfect on the mechanisms.

I've ordered new brushes which say they're 12mm long. The ones I've removed are 11mm long.

Am I missing something here?

I need the RAS functioning asap. So help appreciated.
.thanks.

I've got pics if the brushes but not sure how to upload.

Rich.
Click to expand...
Welcome to the forum.

Does your RAS have a speed control knob on it?
 
Scott in Bend said:
No Plug-it cord on my US version RAS 115.  It is a hard wired connection and that would be the first place I would look at internally.  Then the speed controller.
Click to expand...

Ha, it is such an automatism to look at a faulty Plug-It connection with Festool tools, I forgot the RAS doesn't have one.

But, as you say, the cord could still be the problem and have an internal fracture.
 
ultane said:
Ilovemyras115 said:
Hi. First time in any forum. Read thousands. Never posted.

My RAS 115 which has worked hard kept fading with a sort of rattly sound. Over about 5 minutes.

I've dismantled it. Everything looks perfect on the mechanisms.

I've ordered new brushes which say they're 12mm long. The ones I've removed are 11mm long.

Am I missing something here?

I need the RAS functioning asap. So help appreciated.
.thanks.

I've got pics if the brushes but not sure how to upload.

Rich.
Click to expand...
Welcome to the forum.

Does your RAS have a speed control knob on it?
Click to expand...

It does.
 
Every time I’ve had an RAS cutting in/out issue it has been the cord where it enters the tool body. I believe it is because of the way you have to bend the cord to get it in the Systainer. I’m really good at trimming the cord and getting it connected back to the tool.

Tom
 
thanks for replies,  Ive been busy and not checked the group so sorry for not replying. 

I will try bypassing the motor cable or changing it, not sure how I go about that but I shall try. It doesnt have a quick lead connector thingy. just a standard lead.

I have reassembled the machine after hoping I had discovered the fault. or possibly the cause.

It would appear that the tool has been used with the cowl loose (the little green lever left undone) and this has melted/rubbed the back of the pad ( the normal grinder pad with a nut in the middle) clean through the dust cowl  for about an inch there is daylight where the cowl has sat lopsided and the back of the backer pad has worn through, still woring fine but shows neglect. it had actually left plastic from the cowl on the backer pad which i had to scrape back to discover this plastic wasnt originally there. this looks like its caused huge friction and put a lot of strain on the motor.  i had leant it to someone who said it stopped working, then spat plastic at them and worked again.

I used it for about 30 seconds happily then it failed after lending it....

When I tried it today it very slowly span and the body got red hot from only 5 seconds of run time?

i could load a video but not sure how.

 
tjbnwi said:
Every time I’ve had an RAS cutting in/out issue it has been the cord where it enters the tool body. I believe it is because of the way you have to bend the cord to get it in the Systainer. I’m really good at trimming the cord and getting it connected back to the tool.

Tom
Click to expand...

Thanks Tom, I'll take a look. would this explain the motor getting red hot from a few seconds use?
 
Ilovemyras115 said:
I will try bypassing the motor cable or changing it, not sure how I go about that but I shall try. It doesnt have a quick lead connector thingy. just a standard lead.
Click to expand...

You already mentioned you took the tool apart. Just look where the wires go. Unscrew the wires of the switch and the electronics module, and connect the mains lead directly to the motor.

Ilovemyras115 said:
When I tried it today it very slowly span and the body got red hot from only 5 seconds of run time?
Click to expand...

The body got hot because of the low RPM, there is a fan connected to the motor that needs to go full speed to blow enough air over the motor to cool it.

Considering how your motor runs, but slowly, makes me think it is not the cord that is the problem, but the electronics module that controls the speed. It can also still be the motor itself, a burned field coil.
 
Ilovemyras115 said:
Did the video link above work?
Click to expand...

Yes, I saw the video. What I would like to know, does the spindle really turn, but slowly, or does it vibrate in place? The focus on the spindle was too short for me too see.
 
Well, you definitely get different behaviour on different speed settings, which highly suggests the electronics module is the culprit.

To be sure, just connect the mains wire directly to the terminals of the brushes, by-passing the electronics module. If your RAS runs at full speed again you know there is no problem with the motor, or the brushes.

I doubt strain on the motor from friction is the cause as you suggest in your last video. The RAS is meant to eat up material and doesn't stop for a bit plastic.
 
Ill try as you suggest this evening. So i will touch the two brush terminals with mains power. Connect then switch on of course.

Am I ok to leave the original lead connected, and using a new lead just liven up those terminals?

Im considering that the plastic melted up nicely, then the tool was switched off allowing them to weld together over a good 15% of the rotating surface on the widest point giving it maximum leverage then the tool was asked to fire up welded togther putting alot of dead load on it?

Anyway, ill do as you suggest and post results.

thankyou for the time.

rich
 
Ilovemyras115 said:
Am I ok to leave the original lead connected, and using a new lead just liven up those terminals?
Click to expand...

I don't know exactly what you mean by that, but when I'm repairing a tool/troubleshooting, I take out what I don't need because clutter is the last thing I need. It's just a few screws.

Take photos on your cell phone during the process so you know how to connect it all back.
 
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