Re: CNC router build

2k. Re: CNC router build
Posted by: "Jon Elson" elson@... jmelson2
Date: Wed Apr 1, 2009 7:19 pm ((PDT))

JanRwl@... wrote:

> > In a message dated 4/1/2009 7:10:44 A.M. Central Daylight Time,
> > freshwatermodels@... writes:
> >
> > I don't want to get into building a spindle so am looking for alternatives.
> > I am wondering if there is a die grinder or dremel type tool that has
> > better bearings and might be quieter than a standard router motor.<<
> >
> > Jack: Google a firm by name Perske (sp?) (Germany). I haven't bought
> > from them in over 20 years, but they make DOZENS of kinds of spindle-motors with
> > hollow- and collet-shafts, etc. for use in such as X-Y machinery, also the
> > HF 3-Ø converter motor-generators for powering the HF versions. Sorry I don't
> > have contact info, but I just have had no need for their stuff in decades,
> > so lost contact info.
>

[Perske makes really nice spindles. They typically are 3-phase, run at
fairly high speeds, and require a Variable Frequency Drive (VFD) to run.
Some of these VFDs will function as single-phase to three-phase
converters, so you don't actually need 3-phase current at the service
entrance to run the spindle. They run quieter and are more powerful than
the hand-routers you'll find at the hardware store (not to mention the
laminate-trimmers or Dremel-type tools), and they should last longer
too. But they are considerably more expensive - with a VFD, you're
looking at $1500 and up, depending on how big a spindle you get.
However, this does compare favorably to the price of other European
spindles like Colombo and Fischer.]

> >
> >
>

There is also Precise, sometimes also known as Rockwell-Precise. They
have been making high-speed spindles since about 1960.
I have a 3/4 Hp Rockwell-Precise good for up to 54,000 RPM. The
earliest ones had universal motors and built-in cooling fans.
Mine has a 2-phase induction motor and needs an outboard cooling
blower. I have run it up on a jury-rigged drive and it works pretty
quietly.
These come up on eBay from time to time. Watch out for the AC ones,
though, as there is no standard off-the-shelf drive for them. They
originally used big motor-generator units for the AC ones.

[I've purchased some of those universal-type Precise spindles off Ebay, and all I can say is "buyer beware". Maybe I've just had bad luck, but the ones I've tried have all burned out in short order if they worked at all to start with. The company was bought out by Fischer, a German company, and now calls itself Fischer-Precise. If you do get one, make sure it comes with the collets you need, since the company wants $200 each for them. And if you want one repaired, you can pretty much forget about it - here's what I recently got from them in reply to a repair inquiry:

"Thank you for your inquiry. The Super 70 can be repaired if the armature and
commutator are still in good condition. Other wise we have no options as all
of our products today use brushless AC induction motors. We have no option to
obtain new armatures and commutators.

Assuming these 2 components are ok, all other parts are in stock. A repair
would be under $2000. We do issue an evalution charge which would be in the
range of $250 assuming the spindle can be repaired. This would be negated if
a proceed is provided."

Since the ones that burned up did have bad armature/commutators, this wasn't too encouraging. Maybe the brushless types work better, though...]



If size isn't a concern, there are Danly-Onsrud router motors, running
several Hp at 15000 RPM or so. These can be run from off-the-shelf VFD
units that will go to 400 Hz.

Jon

[Are these still being made? It seems like Danly sold out to Onsrud, who then sold themselves to ATS, which as far as I can tell is now a repair company only, not a manufacturer.]

Andrew Werby
www.computersculpture.com





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