# Speed controller



## ranman (Oct 27, 2017)

Wasn't sure the best place to ask this.... but since it involves bits... I put it here.
A long time back, I read about some types of speed controllers being harmful to routers. Mines a Porter Cable 960. I think no load is 27500.
Widest bit I'd probably ever use is a 2" diameter slot cutter.
What's the good, the bad and the ugly on speed controllers?


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## Herb Stoops (Aug 28, 2012)

Get a 15+ amp. one if you do. I have them on both my router tables and I start slow and dial in the speed acording to the way they sound, you can pretty well tell when the speed gets too high.
Herb

https://www.rockler.com/router-speed-control


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## ranman (Oct 27, 2017)

Herb Stoops said:


> Get a 15+ amp. one if you do. I have them on both my router tables and I start slow and dial in the speed acording to the way they sound, you can pretty well tell when the speed gets too high.
> Herb
> 
> https://www.rockler.com/router-speed-control


I wasn't sure what the difference is from cheap to expensive as far as if any of them harm the motor.
These are new to me.
I've been looking at different ones and saw this. It's a good demo but he should have had the camera on a tripod and been in a different room when he plugged it in.
https://youtu.be/8Ywh8stK7L4
The video tells me that 1/4 inch shanks should be avoided with large bits.


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## ranman (Oct 27, 2017)

Here ya go Herb.
https://youtu.be/2uiByAnSS2k

https://www.walmart.com/ip/DT2234-C...9RPM-LCD-Display-Speed-Meter-Tester/562778841


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## Herb Stoops (Aug 28, 2012)

OH.........I didn't know you wanted to know how to take a digital remote one apart. I use a plug in one, and the most important part is your ear, you can tell darn fast when the bit is too running fast. The main thing is getting a controller that is rated for more current than the router is rated.
Or you can use the old way and put a marble in your ear and when the marble falls out it is too fast.
Herb


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## CharleyL (Feb 28, 2009)

When you use a speed controller, be it one built into the router, or one that you plug the router into, just remember that when you slow your router down, the cooling fan inside it also slows down. You can overheat the router and it's internal speed control if you try to get full power out of it at the slower speed. It isn't very linear either, so half speed really requires a load of less than half of the router's rating. A brief overload and it should be fine. Push the router for more and you will cook it or the speed control. Keep the load down when slowing the speed. 

Charley


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## ger21 (Feb 10, 2019)

The good? It slows your router down.
The bad? It reduces power.

Your better off with a variable speed router, imo. And you can't have too many routers.

There's no problem running a slot cutter at 27K, as the cutter is very very lightweight. But with big heavy bits, you'll definitely want to run them at half that speed.


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## ranman (Oct 27, 2017)

ger21 said:


> The good? It slows your router down.
> The bad? It reduces power.
> 
> Your better off with a variable speed router, imo. And you can't have too many routers.
> ...


The only router that will fit the custom lift that I made has to be identical in all dimensions to my PC router body.... So it is what it is. I have a second but newer of the same model. Besides, external would be easier to adjust.

Let me add that I'm relatively new to this, so how router speeds affect things like burning or other bad behaviors will be a learning experience.


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## ranman (Oct 27, 2017)

CharleyL said:


> When you use a speed controller, be it one built into the router, or one that you plug the router into, just remember that when you slow your router down, the cooling fan inside it also slows down. You can overheat the router and it's internal speed control if you try to get full power out of it at the slower speed. It isn't very linear either, so half speed really requires a load of less than half of the router's rating. A brief overload and it should be fine. Push the router for more and you will cook it or the speed control. Keep the load down when slowing the speed.
> 
> Charley


Thanks Charley, I hadn't thought about the cooling issue. Nothing I'd ever do would constitute production work, but worth noting. My router is "open to the elements" not enclosed, so that might be a plus.


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## ranman (Oct 27, 2017)

Herb Stoops said:


> OH.........I didn't know you wanted to know how to take a digital remote one apart. I use a plug in one, and the most important part is your ear, you can tell darn fast when the bit is too running fast. The main thing is getting a controller that is rated for more current than the router is rated.
> Or you can use the old way and put a marble in your ear and when the marble falls out it is too fast.
> Herb


I just posted the video to show that for a cheap tachometer, it's a bit impressive as far as accuracy.... the guy seemed surprised that it was as accurate as it tested out to be.
That said, I have been taking things apart since I was barely out of diapers.... so much fun to see how stuff tics.
Marble falls out when you get hit by a piece of carbide?
I know what you mean about listening to the sound, but I don't have enough router time under my belt.


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## Biagio (Mar 2, 2013)

ger21 said:


> The good? It slows your router down.
> The bad? It reduces power.
> 
> Your better off with a variable speed router, imo. And you can't have too many routers.
> ...


Gerry, excuse my obtuseness- early in the morning over here. Is the speed controller built into the router not built on the same principle as an external one (triac)? There was a discussion a while back on another thread, I remember one of the members who is an electrical engineer clarified things regarding frequency and speed.


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## mgmine (Jan 16, 2012)

I have a cheap Harbor Freight one and it works fine. I bought one from another mail-order place for much more and it was identical to the HF one. The only thing I notice is that the router doesn't have as much torque, but still runs fine. I started using it when my speed control in the router stopped working.


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## Herb Stoops (Aug 28, 2012)

Go Harbor Freight!!


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## Nickp (Dec 4, 2012)

Biagio said:


> Gerry, excuse my obtuseness- early in the morning over here. Is the speed controller built into the router not built on the same principle as an external one (triac)? There was a discussion a while back on another thread, I remember one of the members who is an electrical engineer clarified things regarding frequency and speed.


Biagio...whether it does/does not work on the same basic principle (can't see why not) the major difference is the router's circuitry makes up for difference in load and compensates for a heavier load by providing more power. This is accomplished by a feedback loop to the controller by way of a speed sensor, typically located at the end of the shaft.

In contrast, the externals are set for a given amount of power and cannot sense the speed has changed (under load) in order to provide more power.

So one is a speed controller, the other just provides a set amount of power. Sort of like cruise control in your vehicle versus a set depression/position of the throttle...

Does this help...?


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## Biagio (Mar 2, 2013)

Thanks, Nick, it does.
I suppose all new variable speed routers have this inbuilt feature? I do not know whether other tools like drills and jigsaw have it? My long-in-the-tooth ones do not. 
I imagine the feedback is supplied by a Hall-effect sensor and a magnet on the shaft?


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## ger21 (Feb 10, 2019)

I'm no expert, but I don't think a lot of routers have an rpm sensor. I think they sense the load on the motor (through current draw maybe?)

Take a PC 7518. If you set it at say 16,000 rpm, and start to take a heavy cut, it will bog down for a second or two, then apply more power, and surge past the set speed, then settle back in. If you are starting and stopping the cut a lot, this "surging" is rather annoying. But it's still much better than an external speed control, where it won't get the additional power to maintain the set speed.
I've used a few VS routers that exhibit this behavior.
But this is a much older design. Newer designs are probably much better at maintaining speed. Maybe the newest designs do use an RPM sensor?

If you want the absolute best speed control for a router, look at the Super PID. www.SuperPID.com - Super-PID Closed-loop Router Speed Controller
It requires modification or your router to add an optical sensor, and is not really suitable for handheld use, but would be excellent in a table with a lift.
It has very fast response, and allows full power down to 5000 rpm.
I use one on my CNC with a PC 690.


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## Biagio (Mar 2, 2013)

@ger21, 
After reading Nick’s post, I did a bit of digging around, and came across the Super-PID. I thought to myself that it must have been quite a trick to miniaturise all that circuitry, into a module that fits inside a router housing. From what I understood, your Super-PID controller has an infra-red sensor, which is triggered by a reflective spot (I assume painted on to the shaft?). I gather some other types have a Hall-effect sensor, triggered every time a magnetic strip on the shaft goes past. As you say, this is a true rpm-based controller.
I could not get more clarity than that. It looked like a De Walt (611?) might have such a controller built-in, but a lot of guys seemed to want to replace it with the Super-PID, so I am completely uncertain.
But if, as you and I both seem to think, the average VS router does not have such a feedback loop, the controller is then a relatively simple solid-state device (or two: a diac and a triac). I cannot see why there should be a difference in performance between an inboard and outboard controller. In principle, such controllers allow the motor to draw current up to the design maximum (if not more), when the motor is forced to slow. The circuit does not “increase the power” as such. The extra current increases the torque, sometimes allowing the speed to increase again.
I suppose there is some current limiting circuitry to prevent motor burn-out in a total stall - this may impact torque.
Just my thoughts - remember where they come from.


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