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Posted by on May 18, 2008, 5:51 am
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Alan Bain wrote:
> In the process of making Watch screws (14BA and smaller) from carbon
> steel, I have been experimenting with slitting them. Normally I use a
> screw head file, but this can be somewhat time consuming so I tried a
> slitting saw in the lathe. I mount the screw in a tapped brass block
> clamped to the vertical slide and run in gently at centre height to the
> slitting saw.
>
> This sort of arrangement I find works well when making larger screws
> (4BA and larger), but with a 8 thou slitting saw and slow backgear
> performance was somewhat hit and miss; sometimes a beautiful slot was cut,
> other times the slot was very Vee shaped with ragged torn edges and
> in one case the slitting saw lost a tooth (but the screw was undamaged)!
>
> I have a feeling that this may be because I am using a cutter
> of too coarse a pitch (the finest saw I could find had a tooth spacing
> greater that the diameter of my screw head and normally I try to ensure
> that at least two teeth are in contact with the work. I should
> be interested to know if this is a plausible explanation?
>
> Alan
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Posted by on May 18, 2008, 1:14 pm
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Hi Alan
I think that the others have covered te main things, namely that the
teeth on the cutter ned to be finer, also the cutter could be smaller
with support cheeks. J&L list an .008" wide x 3/4" dia with 1/4" hole
with 40 teeth, I am using a .010" one to slit brass 3 times at 120
degrees running at 10,000 rpm dry, not silver steel I know but it
shows they work!
I would also avoid plundging the cutter into the end of the job and
pass the screw head under the saw, ie put the cutter in the lathe
chuck and hold the screw shank in a holder on the cross slide and then
wind the slide in to cut, plenty of coolant and you will get a perfect
result.
You will also get a flat bottomed slot.
Peter
Alan Bain wrote:
> In the process of making Watch screws (14BA and smaller) from carbon
> steel, I have been experimenting with slitting them. Normally I use a
> screw head file, but this can be somewhat time consuming so I tried a
> slitting saw in the lathe. I mount the screw in a tapped brass block
> clamped to the vertical slide and run in gently at centre height to the
> slitting saw.
>
> This sort of arrangement I find works well when making larger screws
> (4BA and larger), but with a 8 thou slitting saw and slow backgear
> performance was somewhat hit and miss; sometimes a beautiful slot was cut,
> other times the slot was very Vee shaped with ragged torn edges and
> in one case the slitting saw lost a tooth (but the screw was undamaged)!
>
> I have a feeling that this may be because I am using a cutter
> of too coarse a pitch (the finest saw I could find had a tooth spacing
> greater that the diameter of my screw head and normally I try to ensure
> that at least two teeth are in contact with the work. I should
> be interested to know if this is a plausible explanation?
>
> Alan
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Posted by Mark Rand on May 18, 2008, 4:39 pm
Please log in for more thread options On Sun, 18 May 2008 10:14:34 -0700 (PDT), petercolman45@hotmail.com top
posted:
>Hi Alan
Do you read books upside down?
Mark Rand
RTFM
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Posted by Steve on May 18, 2008, 5:32 pm
Please log in for more thread options
> In the process of making Watch screws (14BA and smaller) from carbon
> steel, I have been experimenting with slitting them. Normally I use a
> screw head file, but this can be somewhat time consuming so I tried a
> slitting saw in the lathe. I mount the screw in a tapped brass block
> clamped to the vertical slide and run in gently at centre height to the
> slitting saw.
>
> This sort of arrangement I find works well when making larger screws
> (4BA and larger), but with a 8 thou slitting saw and slow backgear
> performance was somewhat hit and miss; sometimes a beautiful slot was cut,
> other times the slot was very Vee shaped with ragged torn edges and
> in one case the slitting saw lost a tooth (but the screw was undamaged)!
>
> I have a feeling that this may be because I am using a cutter
> of too coarse a pitch (the finest saw I could find had a tooth spacing
> greater that the diameter of my screw head and normally I try to ensure
> that at least two teeth are in contact with the work. I should
> be interested to know if this is a plausible explanation?
>
> Alan
The speeling in the title reminded me of a related mistake. Quite sometime
ago the department secretary typed up a "Business Case for a Slitting Saw".
Unfortnately she typed an "h" instead of an "l". Took quite a while before
she was allowed to forget it.
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Posted by Mike Whittome on May 19, 2008, 6:03 pm
Please log in for more thread options >
>> In the process of making Watch screws (14BA and smaller) from carbon
>> steel, I have been experimenting with slitting them. Normally I use a
>> screw head file, but this can be somewhat time consuming so I tried a
>> slitting saw in the lathe. I mount the screw in a tapped brass block
>> clamped to the vertical slide and run in gently at centre height to the
>> slitting saw.
>>
>> This sort of arrangement I find works well when making larger screws
>> (4BA and larger), but with a 8 thou slitting saw and slow backgear
>> performance was somewhat hit and miss; sometimes a beautiful slot was cut,
>> other times the slot was very Vee shaped with ragged torn edges and
>> in one case the slitting saw lost a tooth (but the screw was undamaged)!
>>
>> I have a feeling that this may be because I am using a cutter
>> of too coarse a pitch (the finest saw I could find had a tooth spacing
>> greater that the diameter of my screw head and normally I try to ensure
>> that at least two teeth are in contact with the work. I should
>> be interested to know if this is a plausible explanation?
>>
>> Alan
>
>The speeling in the title reminded me of a related mistake. Quite
>sometime ago the department secretary typed up a "Business Case for a
>Slitting Saw". Unfortnately she typed an "h" instead of an "l". Took
>quite a while before she was allowed to forget it.
>
>
Speeling? :)
--
Mike Whittome
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> steel, I have been experimenting with slitting them. Normally I use a
> screw head file, but this can be somewhat time consuming so I tried a
> slitting saw in the lathe. I mount the screw in a tapped brass block
> clamped to the vertical slide and run in gently at centre height to the
> slitting saw.
>
> This sort of arrangement I find works well when making larger screws
> (4BA and larger), but with a 8 thou slitting saw and slow backgear
> performance was somewhat hit and miss; sometimes a beautiful slot was cut,
> other times the slot was very Vee shaped with ragged torn edges and
> in one case the slitting saw lost a tooth (but the screw was undamaged)!
>
> I have a feeling that this may be because I am using a cutter
> of too coarse a pitch (the finest saw I could find had a tooth spacing
> greater that the diameter of my screw head and normally I try to ensure
> that at least two teeth are in contact with the work. I should
> be interested to know if this is a plausible explanation?
>
> Alan