Thread: Wadkin PK Crown Guard.
19th May 2021, 02:09 PM #1
Wadkin PK Crown Guard.
I was looking at a photo of Auscab's crown guard column - the column with the crank handle at the top to raise/lower the crown guard.
It seemed odd - or at least the mounting hole at the bottom seemed odd.
PK1.jpg Auscab's column (PK 1857 of 1956).
Odd? Yes it's ~9/16" or so diameter. The column is held on by two 1/2" BSW (12tpi) bolts. One goes through the hole, the other in the curved slot (to allow the guard to be pivoted clear of the saw blade). So a ~9/16" hole would be appropriate - but I'm used to the massive hole in mine. 7/8" diameter to be precise.
PK2.jpg My column (PKA 800 of 1945).
So I searched and found a restoration wallace did in 2019. It looks to also be ~9/16" - so I guess mine is the odd hole size .
PK1a.jpg Wallace's column (PKA 628 of 1941).
A friend offered to make me a new pin - with a 7/8" shank and a 1/2" BSW threaded end. But we had no way of machining a hex head, so we opted for a bush - with the head shaped like a Wadkin washer (turned not stamped, and with a chamfer on one edge). OD = 7/8"; ID = 1/2"; flange 1 3/8" x 5/16" thick.
Trial fit in the hole.
Remove, coat with oil, reinsert and apply bolt.
And while we were at it, a matching washer for the slotted side.
Note: the slot is 5/8" wide, which looks to be consistent over the three column bases I looked at.
One disappointing thing is: the bolt isn't OEM Wadkin and out of curiosity I measured the thread. It 1/2" 13 tpi - which means it's been tapped UNC. And I suspect that tapping out a 1/2" 12tpi hole with a 1/2" 13tpi tap is going to leave a bastardised threaded hole . It's holding so far, with no sign of impending failure.
Lucky we didn't make a new pin - with a 1/2" BSW 12 tpi thread !!
Cheers, Vann.Gatherer of rusty
Proud member of the Wadkin Blockhead Club .
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20th May 2021, 10:13 PM #2
Nice fix Vann .
The older BSW English bolts are a lot nicer than the new stuff we get to choose from now at hardware stores aren't they .
There's about an extra 30% more meat to the head with some of them .
I remade a set screw for the Robinson Thicky the other day by re heating and hammering out a bolt head square then grinding . worked well . I may have to do some bolt heads too for one section of the Robinson but its a bit more involved with having to add weld .
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