lead cropping spinner plate?

[N_Cook]

Whats it/process called and is there a name for the relatively common
situation where the blade is blunt or wrong speed or something. Leads bend
over before they are cut, so partially cut and floppy, and dozens are left
in place to short to adjascent pin or drop onto other areas. Not picked up
at visual inspection or ignored.

 

[Smitty Two]

In article <htm0oi$pfc$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

Whats it/process called and is there a name for the relatively common
situation where the blade is blunt or wrong speed or something. Leads bend
over before they are cut, so partially cut and floppy, and dozens are left
in place to short to adjascent pin or drop onto other areas. Not picked up
at visual inspection or ignored.

Generically I call that lead trimming. Best RPM is 1200-1500 for the
blades I've used, which are 3" or so diameter. You need a very sharp
blade to cut leads above the surface of the solder. If you trim down
into the solder just a bit, a dull blade will chop through neatly, and,
obviously, if there's no free lead remaining, it can't very well bend
over.

You don't describe your process. We have a custom engineered trimmer for
some round boards we do by the thousands, and we fixture some other
boards in a milling machine vise and run them past the cutter fairly
rapidly (40 inches per minute of feed.) However you do it, the board
must be fixed securely, as per any cutting operation.

 

[nesesu]

On May 27, 9:48 am, Smitty Two <prestwh...@earthlink.net> wrote:

In article <htm0oi$pf...@news.eternal-september.org>,

 "N_Cook" <dive...@tcp.co.uk> wrote:
Whats it/process called and is there a name for the relatively common
situation where the blade is blunt or wrong speed or something. Leads bend
over before they are cut, so partially cut and floppy, and dozens are left
in place to short to adjascent pin or drop onto other areas. Not picked up
at visual inspection or ignored.

Generically I call that lead trimming. Best RPM is 1200-1500 for the
blades I've used, which are 3" or so diameter. You need a very sharp
blade to cut leads above the surface of the solder. If you trim down
into the solder just a bit, a dull blade will chop through neatly, and,
obviously, if there's no free lead remaining, it can't very well bend
over.

You don't describe your process. We have a custom engineered trimmer for
some round boards we do by the thousands, and we fixture some other
boards in a milling machine vise and run them past the cutter fairly
rapidly (40 inches per minute of feed.) However you do it, the board
must be fixed securely, as per any cutting operation.

Yup, sure makes a mess when one corner of the board is not seated
properly :-(
We found that using this method on single sided boards with good lead
clearance holes led to a rash of cracked solder joints. I imagine that
that would be worse with lead free solder.

Neil S.

 

[N_Cook]

N_Cook <diverse@tcp.co.uk> wrote in message
news:htm0oi$pfc$1@news.eternal-september.org...

Whats it/process called and is there a name for the relatively common
situation where the blade is blunt or wrong speed or something. Leads bend
over before they are cut, so partially cut and floppy, and dozens are left
in place to short to adjascent pin or drop onto other areas. Not picked up
at visual inspection or ignored.

I think Ferguson when at Gosport was the last time I actually saw one , but
I don't remember the cutting action. Is it a knife action plain or serrated
or diamond/grit edged grinding action ?

 

[N_Cook]

I supose a term for the non-cropped bits could be "swinging chads"

 

[Smitty Two]

In article <htnr4s$q05$1@news.eternal-september.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

N_Cook <diverse@tcp.co.uk> wrote in message
news:htm0oi$pfc$1@news.eternal-september.org...
Whats it/process called and is there a name for the relatively common
situation where the blade is blunt or wrong speed or something. Leads bend
over before they are cut, so partially cut and floppy, and dozens are left
in place to short to adjascent pin or drop onto other areas. Not picked up
at visual inspection or ignored.



I think Ferguson when at Gosport was the last time I actually saw one , but
I don't remember the cutting action. Is it a knife action plain or serrated
or diamond/grit edged grinding action ?

Rotary blade, hardened tool steel. Dead flat on one face, ground to a
sharp edge from the other face. Flat surface obviously faces the PCB.