Is Full Boar mitre saw motor arcing normal?

[Noyade]

G'day Bunnings Team.

I purchased the Full Boar 305mm (FBSCMSDB-20305) sliding compound mitre saw yesterday afternoon from Bunnings, which was on clearance.

I was late setting it up and it was getting dark at around 1900hrs before I finally turned it on.

The electric arcing was like the 4th of July.

New brushes of course, but I've never seen anything like it on a powered tool before.

It is so bright it 'shines' through the plastic motor housing and is more prominent when the switch is released.

I thought after a few goes the brushes might settle down - but no.

I tried again earlier this morning.

Before...

After...

Note the crimson colour, it's not a photo abnormality - that's the arcing shining 'through' the plastic.

Can this be normal?

Cheers.

[MitchellMc]

Hi @Noyade,

As you know, seeing sparks through the grill is quite normal for a brushed tool, and until they bed in, the sparks can be more noticeable. However, being very familiar with tools, just the fact that you've noticed that the sparks seem more prominent than what you'd typically expect concerns me. What you're explaining sounds more like when a brush has completely worn through, and the metal retainer or spring for the brush is contacting the motor.

In the interest of safety, I feel it would be best to return the tool and exchange it for another if there are any left or receive a refund. If the next one does the same, I'd be happy for you to continue using it.

Given that this is a bit of an odd one, I'll contact the store and let them know you'll be coming in to swap it over. I'll reach out via PM for more details.

Please let me know if you have any questions.

Mitchell

[Nailbag]

Hi @Noyade 

The higher the power of the motor the more sparks you will see when new from the brushes. 

Rule of thumb with any AC power tool is if it still performs power wise as expected then it’s the brushes simply bedding in. If power/performance is affected then the motor has a faulty armature and the tool should be replaced/returned.

Faulty armatures are also usually associated with a strong electrical smell and possibly light white fumes and you will hear arcing sounds. 

If performance is normal then the brushes should settle down within 30min of use. 

The prominence of the arcing when you let go the trigger is a reversal of electrical polarity to initiate the brake to stop the blade faster. More obvious on lower quality motors and even far less on cordless. 

Though not in your case, any totally worn out brushes causing metal on metal result in the motor randomly stopping. Decent brushes have restrictors to prevent damage. 

if in any doubt take it back as per @MitchellMc 

Nailbag

Nailbag

[Noyade]

Thanks very much @MitchellMc and @Nailbag.

"If performance is normal then the brushes should settle down within 30min of use."

There is no loss of power and you are absolutely correct - by the end of the day the lightning show had settled down. 😁

Cheers!

[MitchellMc]

It's great to hear that the issue resolved itself, @Noyade. I'd agree that it sounds like the brushes were bedding in.

Mitchell

[Nailbag]

Fantastic to hear @Noyade This is a very common scenario and can occur with any high-powered AC motor from vacuum cleaners to blenders!