Re: [CAD_CAM_EDM_DRO] Re: small spindle ?

Roland,

Wouldn't the side load/deflection be within the stated runout?  Up to a point of course. 


By the way, a spindle with virtually no runout is not hard to make.  Just mount the bearings a little loose and use 3 or 4 screws in each end to position the bearing.  With patience both radial and axial runout can be below the ability to measure it.  Could likely even use ceramic bearings if they are first mounted in a race that the screws can bear against.  The cost would be little more than the cost of the bearings. 


The runout would depend only on the quality of the bearings.


By the way, why aren't spindles made with the outside rectangular?  They would be much easier to mount. 


ljg


ljg

 
Larry Guthrie
yrralguthrie@...
larry.guthrie@...


________________________________
From: Roland Jollivet <Roland.Jollivet@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Saturday, June 9, 2012 8:45 AM
Subject: [CAD_CAM_EDM_DRO] Re: small spindle ?

While the runout of any spindle should be optimum, that in itself is
insufficient to make a choice. What should be examined is a
side_load/deflection curve, which is hardly ever given.

Regards
Roland

On 9 June 2012 05:37, Jeffrey T. Birt <birt_j@...> wrote:

> **
>
>
> Should have been ‘below 0.001”…
>
> Jeff
>
> From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:
> CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Jeffrey T. Birt
> Sent: Friday, June 08, 2012 6:36 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: RE: [CAD_CAM_EDM_DRO] Re: small spindle ?
>
>
> Any decent ER11 chuck/collet will have run-out well below 0.0001”. The
> construction of the spindle in question looks to be a smallish DC motor,
> about the size of a battery powered drill, with a modified ER11 collet
> chuck attached to the motor’s shaft. This type of motor is not deigned to
> handle a side load like that. By comparison a spindle or spindle/motor
> (such as used in commercial routers) has much larger bearings that are
> designed for that type of work.
>
> The PreciseBits collets for the Colt come in two flavors, of which the
> lowest grade provides a run-out of less than 0.0006”, the PG grade collets
> are less than 0.0004”. When you move up to the larger router motors the UP
> grade collets can provide a run-out of less than 0.0002”. These
> collets/closing nuts fit right in place of the stock collets and closing
> nut; there is no ‘mounting’ of anything.
>
> Jeff Birt
>
> Soigeneris.com
>
> From: CAD_CAM_EDM_DRO@yahoogroups.com <mailto:
> CAD_CAM_EDM_DRO%40yahoogroups.com> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com<mailto:
> CAD_CAM_EDM_DRO%40yahoogroups.com> ] On Behalf Of Larry Guthrie
>
> Sent: Friday, June 08, 2012 4:46 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com <mailto:
> CAD_CAM_EDM_DRO%40yahoogroups.com>
>  Subject: Re: [CAD_CAM_EDM_DRO] Re: small spindle ?
>
> Jeff,
>
> I don't believe the motor used in those spindles is the same type as a
> battery powered drill. Why would they be? The bearings in any high speed
> spindle, small trim router motor, or a rotary tool such as the Proxxon are
> going to be radial bearings. Radial bearings are specifically called for
> when side loads are high. I suspect the bearings in the spindle in question
> (in the link) will last as long as the quality of the bearings used not the
> type of motor.
>
> However .0015 runout is pretty high for a spindle. It would have to be
> made pretty poorly to have that much runout. I can tune a drill press with
> a hammer and get runout that good (or poor). It's probably good enough for
> a hobby machine since it's too small to measure with most calipers. I
> suspect the poor runout specified is the result of the chuck used, not the
> motor bearings.
>
> Any idea what the runout of a trim router would be? Probably pretty low
> until the chuck is added. I would think that even a collet like the
> PreciseBits would be fairly difficult to mount to a router without
> increasing the runout. Seems to me that the only way to get precision for
> cheap would be a belt driven spindle. That would take the runout of the
> motor out of the equation.
>
> ljg
>
> Larry Guthrie
> yrralguthrie@... <mailto:yrralguthrie%40yahoo.com> <mailto:
> yrralguthrie%40yahoo.com>
> larry.guthrie@... <mailto:larry.guthrie%40yahoo.com> <mailto:
> larry.guthrie%40yahoo.com>
>
> ________________________________
>
> [Non-text portions of this message have been removed]
>
> [Non-text portions of this message have been removed]
>
> 
>


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