McMaster Carr ha s all you can stand, as well as correct wrenches.
R
On Tuesday, June 16, 2026 at 01:38:37 PM EDT, Tisha Hayes
<[email protected]> wrote:
Yes, those Bristol-Spline screws are almost unreasonably durable; You can
torque them to incredible levels and you would almost be certain that the screw
would shear off. The black-oxide ones do seem tougher.
Torx would be a good replacement, maybe not as high of a torque-out rating but
probably more than enough for the application in a radio.
About 15 years ago I bought up a bunch of the shaft-collars and Bristol-Spline
screws from FairRadio and I know that I received them. I used them on two
restorations where the hardware was broken/missing. For the life of me I cannot
find any of the ones I thought I had left.
If someone had been around during the St. Juliens Massacre (when so many R-390/
390a's were left to rot) that would of been an excellent source for an
unlimited amount of impossible to find hardware (along with the mini-BNC's,
connectors, plugs, oscillator modules, crystals and slug racks).
Ms. Tisha Hayes, AA4HA
On Tue, Jun 16, 2026 at 12:28 PM Renee K6FSB <[email protected]> wrote:
might i suggest next best thing to Bristol spline would be torx which are not
too difficult to obtain and much less chance of cam-out than allen.
Renée, K6FSB
On 6/16/26 10:13 AM, Jacques Fortin via R-390 wrote:
Hi Fred,
IF EVER you found a valid source for the Bristol ones, let us know !
Allen head ones are more easy to find...
Use the largest head recess size (3/32").
But resist the temptation to buy the Stainless Steel ones: these are less
"tough" than the black oxide coated steel ones...
And for the square nuts... I already "made" some from standard 1/4" hex
nuts.
File or grind those on three sides. I prefer brass to the steel ones
however...
73, Jacques, VE2JFE in Montreal
Aha! I'm looking for six to ten of the 4-40 x 1/2 inch Bristol socket head
cap screws for the BFO and BW shaft clamps. One square nut (if available)
would be helpful as well. If not, I'm sure there would be Allen head screws
at my local hardware store.
But What didn't work for the ham I got his from was a mix of slotted and
Phillips screws -- the heads wore out quickly.
-Fred
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