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Old Jun 27, 2012, 06:24 AM
charles@littlewrongs.org.uk
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Duplex Tool Post Grinder

I've got a Duplex D27 toolpost grinder. The surface finish from it is far from perfect - I suspect that the bearings need replacement.
The manufacturers, as is their habit, suggest sending the spindle back for rebuild/exchange. I'm naturally sceptical of this practice being a tight git at heart. Has anyone replaced the bearings on one of these? Should be quite simple in my book or am I going to struggle with balance problems for ever more?

Thanks

Charles
Old Jun 27, 2012, 12:50 PM
Andrew Mawson
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Re: Duplex Tool Post Grinder

wrote in message
news:cfa6ff87-b959-4b99-84a9-2ee561eb4b41@googlegroups.com...

>
>I've got a Duplex D27 toolpost grinder. The surface finish from it is far
>from perfect - I suspect that the bearings need replacement.
>The manufacturers, as is their habit, suggest sending the spindle back for
>rebuild/exchange. I'm naturally sceptical of this practice being a tight
>git at heart. Has anyone replaced the bearings on one of these? Should be
>quite simple in my book or am I going to struggle with balance problems for
>ever more?
>
>Thanks
>
>Charles


Often surface finish problems on a tool post grinder are caused by too hard
a wheel being employed. White Aloxite in the softer grades is my favourite.
Remember - "the harder the steel the softer the wheel" Any mounting play and
as you say bearing issues will cause bounce and hence poor finish.

AWEM
Old Jun 27, 2012, 02:56 PM
Emimec
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n/a Posts
Re: Duplex Tool Post Grinder

<charles@littlewrongs.org.uk> wrote in message
news:cfa6ff87-b959-4b99-84a9-2ee561eb4b41@googlegroups.com...
I've got a Duplex D27 toolpost grinder. The surface finish from it is far
from perfect - I suspect that the bearings need replacement.
The manufacturers, as is their habit, suggest sending the spindle back for
rebuild/exchange. I'm naturally sceptical of this practice being a tight git
at heart. Has anyone replaced the bearings on one of these? Should be quite
simple in my book or am I going to struggle with balance problems for ever
more?

Thanks

Charles

We tighten our slides right up when using said type of grinder, any play
there will result in poor size and finish.
Bob
Old Jun 27, 2012, 04:56 PM
mark@ems-fife.co.uk
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n/a Posts
Re: Duplex Tool Post Grinder

Shouldn`t have problems with balance if you`re careful.Assuming they
are precision matched bearings there should be dot`s on them to line
up to get rid of any eccentricity.Doubtful if there`s anything fancy
in there anyway,but if there is the price will give you a fright.
As Bob says I`d be more inclined to make sure all the machine slides
are tightened up and that the wheel is dressed and balanced before
blaming the bearings.
I`ve worked with a few of these over the years and never really rated
them.A throwback to a bygone age when plus minus 0.005" was average
for a lathe.
Old Jul 02, 2012, 05:49 AM
Macabre of Auchterloonie
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n/a Posts
Re: Duplex Tool Post Grinder

mark@ems-fife.co.uk wrote:

> Shouldn`t have problems with balance if you`re careful.Assuming they
> are precision matched bearings there should be dot`s on them to line
> up to get rid of any eccentricity.Doubtful if there`s anything fancy
> in there anyway,but if there is the price will give you a fright.
> As Bob says I`d be more inclined to make sure all the machine slides
> are tightened up and that the wheel is dressed and balanced before
> blaming the bearings.
> I`ve worked with a few of these over the years and never really rated
> them.A throwback to a bygone age when plus minus 0.005" was average
> for a lathe.


*THAT* depends on the operator - my old motorised Cincinnati ex-treadle
lathe, which was worn in all the usual places would work down to a good
tenth of your quoted figure - if you knew how.

(Mind you, if you didn't, you could obtain a spectacularly scalloped
finish to your job.)

--
Old Nick
Old Jul 03, 2012, 04:59 AM
mark@ems-fife.co.uk
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n/a Posts
Re: Duplex Tool Post Grinder


>
> *THAT* depends on the operator - my old motorised Cincinnati ex-treadle
> lathe, which was worn in all the usual places would work down to a good
> tenth of your quoted figure - if you knew how.



> Old Nick


In the days before cad jockeys with no engineering
experience,tolerances were thought about and understood.
Therefore unless it was a bearing fit or some otherwise tight size
companies did not waste time trying to catch tolerances that were not
needed as it only increases cost.
If it was volume precision work the lathe still turned to a plus
tolerance and the work was ground.
I did not say that in days gone by they could not turn to accurate
sizes as your post seems to imply,rather that they did not waste their
time doing it if it was unneeded.
 


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