[Walky]

A customer I'm building a machine for has placed his eyes on the Bosch Colt (PR20EVSK) router from Amazon, since he'd like speed regulation and the local options are very limited (I don't want to use the "local router + SuperPID" option this time, since maintenance could become a problem). The existence of precision collets for it is nice, and the router itself seems to have a pretty good reputation among CNC builders.

Regarding this, I have some questions:

a) Can we safely use a 220V -110V step down transformer with this router?

b) How beefy should the transformer be?, does the start up sequence consume more than normal?

c) How efficient is the so-called "constant response" system in it as compared to everyday's built-in speed control? Could it be affected somehow by the voltage conversion process? e.g.: the circuitry relying on 60hz mains (we use 50hz).


Thanks in advance.

[Walky]

Found some info here:
http://www.cnczone.com/forums/diy-cn...hp_router.html

So far it seems promising.

Any suggestions?

[Walky]

By the way, would the ~750W Bosch with built-in speed control be significantly better at lower speeds than a 530W Makita with an external (passive) speed control?

[Al_The_Man]

It looks like you would need around .75Kva transformer.
The PID unit has a slow start so there is not as much inrush you may see directly across the supply.
A universal motor has poor speed regulation normally even when using the simple Triac speed controls, the up side is it has high torque under load.
You only get decent rpm control with feedback such as the PID unit.
Frequency is not an issue with Universal motors, they operate down to DC.
Al.

[Walky]

It looks like you would need around .75Kva transformer.
The PID unit has a slow start so there is not as much inrush you may see directly across the supply.
A universal motor has poor speed regulation normally even when using the simple Triac speed controls, the up side is it has high torque under load.
You only get decent rpm control with feedback such as the PID unit.
Frequency is not an issue with Universal motors, they operate down to DC.
Al.

Thanks Al

I actually use an SPID on my router and it's great; on the other hand, I have close to zero knowledge about passive speed controls, other than the "torque drops with lower speeds" rule. I don't need the router to go to an exact RPM value, nor need to keep aluminum-cutting torque , but it needs to be enough for plastic cutting.

The router we can get locally is a 530W Makita, but the torque would possibly be worst at low speed (using a passive control, I mean) than the slightly more powerful Colt (also, I'm still unsure about the "constant response" circuitry the Colt specs brag about, and if it really makes any difference compared to basic speed controls or it's just blah blah).

Now, I'm not sure about how much better would the Colt's low speed torque be as compared to the "Makita + passive speed control" combo, as to justify the extra expense the Colt implies (shipping, transformer, etc).

[Al_The_Man]

Now, I'm not sure about how much better would the Colt's low speed torque be as compared to the "Makita + passive speed control" combo, as to justify the extra expense the Colt implies (shipping, transformer, etc).

With a universal motor torque increases fairly proportional to load but at a cost of rpm control unless feedback is used, the 'constant response' could indicate some kind of feedback method?
Al.

[Walky]

Thanks

I've been explaining the pros and cons to the customer and he'll decide shortly which way he'd like to go.