Re: CNC router build

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jack McKie <freshwatermodels@...> wrote:
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> Gary,
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> Thanks, do you use one of these?
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> Jack
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> --- On Wed, 4/1/09, Gary Davison <gld@...> wrote:
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> From: Gary Davison <gld@...>
> Subject: [CAD_CAM_EDM_DRO] Re: CNC router build
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Date: Wednesday, April 1, 2009, 8:28 AM
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> Jack
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> Look at one of these http://www.minicraf ttools.com/ 38481.html
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> They have better bearings and run quieter than a Dremel.
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> Gary
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> --- In CAD_CAM_EDM_ DRO@yahoogroups. com, Jack McKie <freshwatermodels@ ...> wrote:
> >
> > Dave,
> >  
> > This is primarily a precision cnc router for patternmaking, not a mill for machining metal, so coolant won't be an issue. 
> >  
> > I am aware of limitations of Dremel which is why I am looking for an alternative.  Yes, noise and heat come with high cutting speed.   I will probably be using carbide end mills exclusively.  Part of the plan is to build a sound enclosure but I don't know much about this.
> >  
> > One alternative I am considering is using a mini-mill head with belt drive retrofit.   This would allow me quieter belt drive and R8 collets but the max rpm would be about 4000.
> >  
> > 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
> >  
> >
> >
> > --- On Mon, 3/30/09, David LeVine <dlevine144@ ...> wrote:
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> >
> > From: David LeVine <dlevine144@ ...>
> > Subject: Re: [CAD_CAM_EDM_ DRO] CNC router build
> > To: CAD_CAM_EDM_ DRO@yahoogroups. com
> > Date: Monday, March 30, 2009, 3:50 PM
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> > Jack Mc Kie wrote:
> > > <SNIP>I have a router and a Dremel tool that could be used but I am
> > > considering some alternative hopeing to keep noise level down. Noise
> > > is a concern I'm not sure how to deal with. I'm considering making a
> > > box of some sort to house the router in and line it with some sort of
> > > noise absorbing material. Any cost effective suggestions on how to
> > > deal with noise supression would be welcome!
> >
> > 1. At high speed, everything gets noisy.
> > 2. At high speed things get hot in a hurry.
> > 3. A router or Dremel is not a good, precision spindle.
> >
> > If you have machining available, consider that a good, fixed speed
> > spindle may be better for your needs.
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> > Put something like a 5200 or a pair of 7200 bearings on the tool end
> > (angular contact preloaded bearings ensure good positional accuracy) and
> > a slightly loose bearing on the other (so the shaft doesn't bind.) A
> > 7200 pair is rated for 29,000 RPM, IIRC. For higher speeds, ceramic
> > bearings work but are /*spendy! */Driven by a belt and an induction
> > motor, such a spindle will be quieter, more robust (last longer) and
> > more accurate, but heavier. Remember, lower speed is always better for
> > bearing life. Smaller bearings and open bearings (especially with oil
> > mist lubrication to remove heat) will run faster and last longer than
> > shielded or sealed bearings.
> >
> > With a VFD and a 3 phase motor, you even get the variable speed
> > advantages, but with a weight penalty. You may need a cooling fan if
> > the VFD runs the motor slower than 75% of the rated speed.
> >
> > --
> > David G. LeVine
> > Nashua, NH 03060
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