Was going to put this in DIY but probably better here. Just looking for a bit of help with a restoration project I am in the middle of.
I recently received a Vibroplex Brass Racer (the rare-ish EK-1 version that is long obsolete). It was cheap enough, probably because the keyer PCB was missing and also it was in rough shape and missing a base screw.
I bought a new cable for it (pictured) which I am going to splice the end off and attach connectors on then affix to the brass base.
So far so happy with it. Problem is one of the wood base screws is missing. Vibroplex documentation and spare parts order forms don’t state the size of the screw. I went to buy some M4 20mm screws. They are marginally thinner (about 0.0000000000001mm thinner) and about 3mm shorter.
The hardware shop only does M4 20mm then leaps to M4 30mm. Way too long. I am thus assuming the screw might be an American size bolt?
Does anyone know what the Vibroplex Brass Triangle Racer wood base screw size is? I’d be super grateful as it is the only thing I need to finish the restoration off at the moment.
I was also thinking of adding a little Kanga keyer PCB or something in there, but then I would also need the little rotating dial sticking out the side too, per the original design.
For the Vibroplex Brass Racer (including the EK-1 version), the mounting screws used to secure the brass mechanism to the hardwood base are typically #8-32 x 1/2" machine screws.
However, since the EK-1 version specifically houses a keyer circuit board inside the wooden base, you may find variations depending on whether you are referring to the screws that hold the base plate to the wood or the screws that hold the brass assembly to the base.
Screw Specifications for the Brass Racer
Screw Location
Specification
Vibroplex Part #
Main Mounting (Brass to Wood)
#8-32 x 1/2" Pan Head (Brass or Zinc)
BR-22 (8041)
Vertical Block Screw
#8-32 (Length varies)
BR-21 (8044)
Rubber Foot Screws
#4 x 1/2" Wood Screw (Approximate)
VC24 (8021)
Important Details for the EK-1 Version
The EK-1 is unique because it contains an internal electronic keyer.
The Wood Base Mounting Screws (BR-22): These are often specifically noted in parts lists as part number 8041. They pass through the bottom of the wood base and thread into the solid brass mainframe.
Clearance: If you are replacing these, ensure the length does not exceed 1/2 inch. Using a longer screw can bottom out in the brass frame or, in the case of the EK-1, potentially interfere with the internal battery compartment or PCB.
Clearly not as I found nothing in Kagi. Did you use an LLM? For the screw size information that is. All I found was the parts order list and exploded diagrams.
It’s almost M4 in size so ask Google “nearest US bolt to M4” and it says 5/32 of an inch.
5/32 = 0.15625in
0.15625 * 25.4 = 3.969mm
3.969mm is a bug’s doodah smaller than M4 so meets your description.
In US bolt terms a 5/32in diameter bolt is a #8-32 UNC i.e. #8 at 32 turns per inch.
Measure the bolt you have to determine the length you need.
It’s even easier than that. Just google for #8-32 x 1/2" machine screws and there are loads of links. We have made such a half arsed attempt at metrication that you can still find all these imperial things easily.
