Dewalt 611 hot collet nut

Ok, not technically a lowrider build (but IS how I ended up with the 611) but I figured maybe more help here than elsewhere.

The 611 has developed what i consider a problem. After running for even a short time, even free spinning, the collet nut becomes noticeably warm. Running for a few minutes, it becomes uncomfortably hot. Like, i-have-to-be-careful-changing-tools-hot.

At first, i thought it was just poor feeds/speeds getting me into rubbing, heating the tool and then the nut. My OTHER 611 did the same thing and then the speed controller gave up. I have no idea if the two things are related, but that one is still under warranty so I’m sending it in for evaluation. They said they’ll check to see if i misused it, but they don’t offer any suggestions on how they define ‘misuse’ so i can’t save them any work there. That one has never experienced excessive run times or anything other than wood, generally with 1/8 bits, occasionally 1/4…smaller than i would use by hand. Max cost is a full rebuild (assuming they wont warranty it), or about US$95…which I’ll pay if their definition of misuse isn’t favorable.

The only thing that comes to mind is maybe the bearings are giving up, creating extra resistance/friction that translates into more heat? If so, maybe the speed controller tried to push more current than it could handle? If so, maybe I’m about to cook the other one? That’s what concerns me right now, so I’ve taken it out of service (time to get back on that 660 speed controller, i guess) until i can get some ideas.

Anyway, if anyone has seen this and solved it, I’d like to know because I’m sure it’s less than a full rebuild to address now. And since I’m resizing primo, maybe its a good time to get a proper spindle for not-too-much-more than a full rebuild every once in a while. I DO have other uses for these routers.


They do get hot. Mine does too. Generally they’re not running as long as we run them, so they don’t have the best cooling systems.

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Yeah, but I’ve noticed a remarkable change for the worse. Just hoping somebody had good news for me. Worst case, it goes up in smoke and costs me $100 to rebuild.

I would guess the bearing too. The brushes are meant to wear out, you could check those. But I can’t think of how they would be heating up the collet.

My guess the abuse they are talking about is water damage or a break in the case. It may also be scare tactics.

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Yeah, i actually swapped brushes between the two when the speed control went out, mashing sure it wasn’t them. Both got unreasonably warm.

Guess I’ll just have to get off my dump and send the broken one in. Maybe i can get them to add a set of bearings to the box and save shipping.

Are you normally running at lower RPM’s? I think the fans in these routers are often specified to move adequate cooling air when running at full speed, but lower speeds move less cooling air. For shorter runs (i.e. handheld use) this would probably not cause problems, but in a table or CNC extended run times without enough cooling and that heat moves throughout the tool.

A while back on the SuperPID site, someone showed a CNC setup where they had mounted additional fans to the top of the router to augment cooling when run at lower speeds. SuperPID is most often added to single-speed routers, so those are even worse at cooling with reduced airflow.


Almost always, actually. Mostly because i haven’t been able to move it fast enough to keep chiploads I’m happy with. Resizing the primo might help with that, but it should be easy enough to test.

Wifey is occupying the garage as a dark room for now, but maybe by tonight i can sneak out there and just turn it on high speed to see.


The 611 has a speed controller though.

Even with the speed controller, I wouldn’t be surprised if the fan built in to the 611 doesn’t move enough air at low speeds for effective cooling when run for a long time.

Well, just running free air at top speed, it seems ok. Turned it down to 1 after the exhaust got warmer and after about a minute spindle was warm. Nowhere near hot, but warm. Back to top speed and surgery minute later it was noticeably cooler.

Of course, under load I would expect it to be much warmer (and it is).

I’m not convinced the bearings AREN’T failing, but I guess i don’t need failing bearings to explain the symptom.

Now I have to decide whether to take it out of cnc production or throw caution to the wind.

Been a while since I messed with the 660 diy speed controller. If i can’t get that going, i should probably get a proper spindle anyway. I think i do enough with this thing that it makes sense.

Thanks guys.

I’d run it till it dies, but that’s me.

I’ve been reading this thread out of curiosity. Now yesterday, I did my first ever bit change on a job to try running two different bits… the nut was hot as hell!!! I’m running a Dewalt 660 full bore, no speed control. Ran less than five minutes before changing bits. This seems way too hot.

Now my question is this: does running a vacuum shoe help cool the nut with the air flow around it?

It helps, but it’s still going to get hot.