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Author Topic: Terminals on Vacuum Relay  (Read 2785 times)
W8JI
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« on: September 04, 2012, 07:02:25 AM »

I have some old Jennings glass vacuum relays that have an unusual connector screw. It is a four point very small slot. It appears to be flat, not sloped depth like a phillips. It also does not taper in from the walls.

I have almost every bit available in universal screwdriver kits, including security bits. None fit.

Anyone know what it is??

 
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K8AXW
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« Reply #1 on: September 04, 2012, 09:12:09 AM »

Tom:  Doesn't an ordinary blade jeweler's screwdriver work? 
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KD0REQ
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« Reply #2 on: September 04, 2012, 09:40:10 AM »

I thought long, long ago in a world far, far away I had encountered some double-flat-blade screws.  they were on some sort of older connector, iirc.  apparently somebody else found them, for they got on Da Wiki...

http://en.wikipedia.org/wiki/List_of_screw_drives

>> Cross-recess screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This type is usually found in cheaply made roofing bolts and the like, where a thread of 5 mm (0.20 in) or above has a large flattened pan head. The sole advantage is that they provide some measure of redundancy: should one slot be chewed up in service, the second may still be used.

« Last Edit: September 04, 2012, 09:44:36 AM by KD0REQ » Logged
VE7DQ
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« Reply #3 on: September 04, 2012, 08:57:12 PM »

Could it be a 4-flute bristol?  They're rare, but not unheard of.
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KD0REQ
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« Reply #4 on: September 05, 2012, 12:42:26 PM »

http://www.mgs4u.com/bristol-wrench-spline.htm shows a cross-section in the table.  those are not the flutes we are looking for, from w8ji's description.
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W8JI
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« Reply #5 on: September 05, 2012, 03:31:06 PM »

Tom:  Doesn't an ordinary blade jeweler's screwdriver work? 

No. Maybe if I grind the point it will, but not stock!
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W8JI
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« Reply #6 on: September 05, 2012, 03:33:13 PM »

http://www.mgs4u.com/bristol-wrench-spline.htm shows a cross-section in the table.  those are not the flutes we are looking for, from w8ji's description.

Not a Bristol. I'll probably have to grind something. I hate ruining good tools, especially if I'm not sure what will fit.
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W9GB
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« Reply #7 on: September 23, 2012, 03:42:00 PM »

Quote from: W8JI
I have some old Jennings glass vacuum relays that have an unusual connector screw. It is a four point very small slot. It appears to be flat, not sloped depth like a phillips. It also does not taper in from the walls.
Yes, I always referred to it as a "cross".  
One of my Elmer's (now SK) said he first saw it in clock/jeweler usage.  
It is "flat" and pointed Phillips will not work.
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