Re: [CAD_CAM_EDM_DRO] Re: VFD Selection

This brings up a question about an idea I have had floating around in my
mind for some time. Has anyone attempted to build a spindle out of
one of those "ER" extensions. A long one of course, seven or eight
inches may allow enough space for a set of bearings and a drive pulley.

Just a thought that has been rolling around in my head for some time
now. Since these are normally built to reasonably tight tolerances I
could see this as being feasable for both a plain bearing spindle and a
ball bearing supported spindle. An ER extension can be had for around
$100 dollars which is not a bad price considering what a full blown
cartridge spindle would cost.

Thanks
Dave




Leslie M. Watts wrote:

>Drew,
>
>oh..gosh I think it was ER-25. Could be anything though.
>It's just a standard LIGHT duty engineering design... preloaded DB
>duplex angular contact on the work end and radial on the other.
>Prehard stressproof or 4140 shaft... a little soft but would last
>a while. I think the parts cost was a couple hundred, but machining would
>be a fortune unless you do it with sweat equity.
>
>Machining spindles requires some fairly serious precision.
>Could be done on hobby machines providing you have a hobby
>cylindrical and surface grinder!
>
>One trick to make things like this easier to build is to
>use lower tolerance bearing, housing, and shaft specs
>and then finish machine the spindle collet internal taper
>on the spindle itself. Of course then the precision is
>ruined if you ever replace the bearings.
>
>To put thinks in perspective lower tolerance might mean
>+/- 0.0004 instead of 0.0001".
>
>Les
>
>
>
>Leslie M.Watts
>L M Watts Furniture
>Tiger Georgia USA
>(706) 212-0242
>http://www.lmwatts.com
>Engineering page:
>http://www.lmwatts.com/shop.html
>CNC surplus for sale:
>http://www.lmwatts.com/forsale.html
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>http://www.lmwatts.com/signwp.html
>
>
>
>
>-----Original Message-----
>From: Drew Rogge [mailto:drew@...]
>Sent: Tuesday, April 13, 2004 5:32 PM
>To: CAD_CAM_EDM_DRO@yahoogroups.com
>Subject: Re: [CAD_CAM_EDM_DRO] Re: VFD Selection
>
>
>Hi Les,
>
>What type of collet or tool holding setup did you design the spindle
>for?
>
>Drew
>
>Leslie M. Watts wrote:
>
>
>>I do think I have a design for a belt driven angular contact or tapered
>>roller bearing spindle that could be run from a single phase 120vac motor
>>at fixed speed (least costly), a dc motor/servo amp, or a phase control
>>(voltage)
>>dc motor over a limited rpm. It would have torque due to the gearing down.
>>I could try and find it for you if you have the capability to do precision
>>(+/-0.0002") machining with your tools.
>>
>>Could you tell me more about what you want to cut and how fast? Sounds
>>like we are getting more into Milling machine territory. A steel cutting
>>gantry type machine is usually not in the hobby relm.
>>
>>Les
>>
>>
>>
>
>
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