[dpantoin]

Hi All,

I have a question. I inherited a single-speed B&D router from the 1980s (barely used, though) and I want to repurpose the motor (new purpose to be determined).

Do those motors use gears to produce 22,000 RPMs? Or is that the RPM of the shaft itself (I call it native speed)? I have not bee able to find that information anywhere.

22,000 strikes me as too fast for anything and I'm not sure how pulleys can help at that speed. Oh, and it not soft-start.

Any input would be appreciated.

Thanks,
Daniel

 

[Cherryville Chuck]

No gears. It's armature and field coilds are wired to produce that speed. You can get speed controllers that will allow you to slow it down for other applications. Anytime you start spinning bits more than 1 1/2" in diameter you need to slow the speed down and lots of routers back in that period did not come with an integral controller built in. The separate controllers cam only be used with universal type motors and can not be used with a tool that already has one built in.

 

[woodknots]

Daniel - I have an old B&D router, model 7616 type 4. The label on it shows the speed as 23000 rpm.

 

[DonkeyHody]

I think your opportunities to repurpose a router motor are fairly limited. The shaft speed is so high and torque so low that you'd need to gear it down quite a bit to get a speed useful for anything else. These motors don't like to start under load. I think its best use is as a router. Save yourself some grief and find another motor to repurpose.

 

[CharleyL]

My old B&D 1970's 1 hp fixed base router is rated for 18,000 RPM. Those with higher speeds tend to be laminate trimmer type routers with less than 1 hp ratings and smaller motor diameters. The one that I have was made and sold for many years and became a DeWalt with a yellow top when B&D began offering Industrial rated tools. I'm not near my shop, so I can't give the model number of it.

Charley

 

[woodknots]

Charley - mine is from the mid 70s - labelled as B&D "Best" and rated at 1 HP and 23000 rpm

 

[Mycrossover]

I think your opportunities to repurpose a router motor are fairly limited. The shaft speed is so high and torque so low that you'd need to gear it down quite a bit to get a speed useful for anything else. These motors don't like to start under load. I think its best use is as a router. Save yourself some grief and find another motor to repurpose.

I never tried it but if you could find the right flex cable it might make a nice "Foredom" style tool for bigger 1/4" shank stuff. Most flex cables are for drills and can't handle the speed. It might get into places a straight electric die grinder can't and it is a lot more powerful. Ther are no electric rt. angle die grinders.

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[dpantoin]

Daniel - I have an old B&D router, model 7616 type 4. The label on it shows the speed as 23000 rpm.

I was going by memory when I posted the message. It turns out that the router's speed is 25,000 RPM. The model is B&D 7516-04 Type 1, 120V, 8.5 Amps (1.3 HP, I guess).

Daniel

 

[dpantoin]

No gears. It's armature and field coilds are wired to produce that speed. You can get speed controllers that will allow you to slow it down for other applications. Anytime you start spinning bits more than 1 1/2" in diameter you need to slow the speed down and lots of routers back in that period did not come with an integral controller built in. The separate controllers cam only be used with universal type motors and can not be used with a tool that already has one built in.

Would a basic router from that era have a universal motor? My limited knowledge of power tool motors would tell me it is, but I wonder. As I mentioned elsewhere, the model is B&D 7615-04 Type 1.

Also, isn't there something about damaging motors that were not built to be run at slower speeds? Or is that precisely what the separate controller would take care of? Even then I think there's a limit to how slow motors can be run even if they're meant to be. (For ex. my Makita 1.25HP owner's manual specifies not to use it at 10,000 RPM too much even though it can go down to that speed if needed.)

I'm a newbie when it comes to electric motors and what I've read/seen about them amounts to a steep learning curve. My interest in motors in an interest in building new machines (bandsaw, larger lathe, disc sander) that could get expensive if purchased new (or even used).

Daniel

 

[dpantoin]

I think your opportunities to repurpose a router motor are fairly limited. The shaft speed is so high and torque so low that you'd need to gear it down quite a bit to get a speed useful for anything else. These motors don't like to start under load. I think its best use is as a router. Save yourself some grief and find another motor to repurpose.

Yes, I'm not all that optimistic at this point. But at 25,000 RPM, I find it hard not to burn the wood, except by moving really fast along the workpiece (safety issue).

D

 

[Cherryville Chuck]

Would a basic router from that era have a universal motor? My limited knowledge of power tool motors would tell me it is, but I wonder. As I mentioned elsewhere, the model is B&D 7615-04 Type 1.

Also, isn't there something about damaging motors that were not built to be run at slower speeds? Or is that precisely what the separate controller would take care of? Even then I think there's a limit to how slow motors can be run even if they're meant to be. (For ex. my Makita 1.25HP owner's manual specifies not to use it at 10,000 RPM too much even though it can go down to that speed if needed.)

I'm a newbie when it comes to electric motors and what I've read/seen about them amounts to a steep learning curve. My interest in motors in an interest in building new machines (bandsaw, larger lathe, disc sander) that could get expensive if purchased new (or even used).

Daniel

Yes those motors would have been universal type motors. https://en.wikipedia.org/wiki/Universal_motor Older speed circuits used rheostats to control speed. Newer models alter the frequency I believe and are supposed to retain torque. Even at that I think there is a practical limit. In practice, when you hear a power tool lug down it is starting to pull higher amps which produce heat which will damage the wiring. As Andy pointed out, these type motors don't produce a lot of torque, especially at high speeds. Motors that have capacitors (usually in a box on the side of the motor) have way more starting torque and generally more torque a running speeds too. I'm not sure what other tool needs to run at 20,000 plus rpm so a capacitor motor is probably a better choice in most cases and a washing machine motor can often do what you need and cost nothing to salvage out of an old washer.

 

[DaninVan]

Make a nice turbine for a small wind tunnel... (just thinking outside the box here)

 

[Mycrossover]

Would a basic router from that era have a universal motor? My limited knowledge of power tool motors would tell me it is, but I wonder. As I mentioned elsewhere, the model is B&D 7615-04 Type 1.

Also, isn't there something about damaging motors that were not built to be run at slower speeds? Or is that precisely what the separate controller would take care of? Even then I think there's a limit to how slow motors can be run even if they're meant to be. (For ex. my Makita 1.25HP owner's manual specifies not to use it at 10,000 RPM too much even though it can go down to that speed if needed.)

I'm a newbie when it comes to electric motors and what I've read/seen about them amounts to a steep learning curve. My interest in motors in an interest in building new machines (bandsaw, larger lathe, disc sander) that could get expensive if purchased new (or even used).

Daniel

Virtually all routers have universal or brush type motors. Other type motors are not generally built for those high speeds. With more new stuff going brushless every day, that might change but any old and virtually all current routers are of that type. If you have a single speed router, a speed control will work. Before trying to swing a bigger bit, make sure the opening in the base is big enough for it or you would have to modify the base. That old router may not have enough power to handle a big bit. You would hve to take very shallow passes and there is less power at reduced speed. Cheap and dirty is the Harbor Freight router speed control for under 20 bucks. I like the heavy duty model from MLCS but it is probably costs more than that old router is worth. I have an old 1 1/2 hp Milwaukee that I use my speed control with.

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