Something smells after about about 2 hours of cutting

[Glidergider]

I've got a problem. I've got some long jobs. After about 2 hours of continuous run time, something smells of that metallic electric smell. Brushes, I'm thinking and maybe the Hitachi router. As a boy, if you ever had a slot car racing set, you know what I'm talking about.

I took the hitachi brushes out and examined them. They looked ok. They were just under a half inch long.

Should I put some oil on these brushes as a precaution? If so, what type? I can't find my manual, and I'm wondering if there is a regular maintenance requirement.
Thanks,
Dave

[davereagan]

I think oil on brushes would be a big mistake and the motor would not run right after. Motor brushes are self lubricating as far as I know.

[Haydn]

Is it the router that smells?
If it is, check that the fan and air ways are clear, most wood routers have a fan at the base or top of the spindle housing to draw air over the coils, if this gets blocked or restricted then the coils can over heat, eventually the windings will burn out. This is why most variable speed routers will only go down to 8000rpm as not enough air will pass over the coils to disipate the extra heat. Don't oil the brushes, they are carbon and self lubed. I'd take the top off the router body, blow it out with an air line and check that the bearings are ok whilst its open.

Good luck

Haydn

[Madclicker]

Yep, it's the brushes. They are a consumable and burn up. I have the same router and have been through several sets now. The router still runs strong, but I never push it past a 50% duty cycle...1 hour on and 1 hour off.

[Glidergider]

The router runs cool to the touch. I'll check the air circulation, but generally, I see the lower chips flying due to the exhaust air from the router.

Madclicker, do you recall how short I can let the brushes go before replacing?

[Haydn]

The brushes on my dewalt are 1" long when new, I think Madclicker is probably right. I imagine your brushes have springs behind them which are part of the brush? You could stretch the spring a tad for better contact on the rotor, or buy some more.

Haydn

[Glidergider]

Yes my brushes are spring loaded. They didn't look bad when I inspected them. I think I just go over the duty cycle on them as MadClicker mentioned. I didn't know it had such a short duty cycle.

[Madclicker]

The replacement brushes have a wear line on them...about 3/8" from the end. I don't remember how the originals were marked, maybe a line, maybe stepped. I'll locate the manual and see. I know it was in there. You want to replace them well before you reach the wear limit. It just takes a few minutes of running the motor with copper/copper to ruin the commutator.