Easier way of putting multiple centres in bar end

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Subject Author Date
Easier way of putting multiple centres in bar end Boo 03-07-2008
Posted by Boo on March 7, 2008, 2:17 pm
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 Hi,

I am making a crankshaft for a Chunn Twin model aeroplane engine. This is an
inline alternate firing twin and the crankshaft needs 3 centres inline on each
end for turning the cranks and journals. I have a lathe and a mill but no
vertical slide for the lathe. I just wondered if there is an easier way of
doing it than what follows below :

1. Clamp faceplate to mill table

2. Clamp parallel to faceplate so that it is vertical

3. Clamp bar into v-blocks

4. Clamp v-blocks to faceplate / parallel so that bar stands vertical wrt mill
table

5. Centre drill 3 centres on one end of the bar by indexing mill table

6. Reverse bar / v-blocks and re-clamp so as to present other end of bar

7. Centre drill other end as before

8. Remove 10,000,000 clamps and bar from mill table

9. Rest of job as required...


Is there an easier way of doing this ? It seems a bit of a faff to have to
clamp the bar to blocks to a parallel to a faceplate to the mill table but I
can't think of a more straightforward way of doing it that will ensure both sets
of centres are aligned.

Many thanks,

--
Boo

Posted by pgp001 on March 8, 2008, 6:37 pm
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Why dont you machine flats on the bar first then you can do away with
the vee
blocks.

Phil


--
pgp001
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Posted by Boo on March 11, 2008, 8:26 pm
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> Why dont you machine flats on the bar first then you can do away with
> the vee blocks.

Thanks Phil, that's a good idea but the crank web between the two cylinders is
a full circle and I don't know if there's enough extra diameter on this
particular job to get away with it. I've a couple of other casting kits where
your trick will work though so thanks again for the suggestion.

--
Boo

Posted by Kevin(Bluey) on March 12, 2008, 6:43 am
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Boo wrote:
> Hi,
>
> I am making a crankshaft for a Chunn Twin model aeroplane engine. This
> is an inline alternate firing twin and the crankshaft needs 3 centres
> inline on each end for turning the cranks and journals. I have a lathe
> and a mill but no vertical slide for the lathe. I just wondered if
> there is an easier way of doing it than what follows below :
>
> 1. Clamp faceplate to mill table
>
> 2. Clamp parallel to faceplate so that it is vertical
>
> 3. Clamp bar into v-blocks
>
> 4. Clamp v-blocks to faceplate / parallel so that bar stands vertical
> wrt mill table
>
> 5. Centre drill 3 centres on one end of the bar by indexing mill table
>
> 6. Reverse bar / v-blocks and re-clamp so as to present other end of bar
>
> 7. Centre drill other end as before
>
> 8. Remove 10,000,000 clamps and bar from mill table
>
> 9. Rest of job as required...
>
>
> Is there an easier way of doing this ? It seems a bit of a faff to have
> to clamp the bar to blocks to a parallel to a faceplate to the mill
> table but I can't think of a more straightforward way of doing it that
> will ensure both sets of centres are aligned.
>
> Many thanks,
>


Mark the centers accurately .

Stand it on end and drill the centers on a floor mounted drill press .
Thats how I've always done it.

--
Kevin (Bluey)
"I'm not young enough to know everything."

bluey69@west.net.com.au

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