Replacing captive washers on thumbscrews

[dartmoor]

Ok, I have never been very good at this. So can any one tell the best technique to re-attach a captive washer to a seagull thumbscrew?

Thanks in expectation!

[Hugz]

From main site FAQ's

http://www.saving-old-seagulls.co.uk/faq/faq.htm


The cup washer has fallen off my clamp bracket screw, and though I have a new cup washer from you, cheap, there is little left to fix it too!

Common problem. The bronze screws work harden and bits drop off. The best way is to file off some threads to make a new blank length you can push through the new cup washer, not too long, you must to be able to peen over a little of the protruding screw, to hold the washer on. You can either use a small hammer or a cold chisel and hammer and put a X in the end or grip the ball end of a hammer against it in the vice. Whichever method you use it helps to heat the end up, with a blow lamp to soften it first.

Note from Brian Corrie, heat the end to dull red, then quench with water, otherwise it will become brittle and break! Thanks Brian.

You can drill and tap a thread into the end of the thumbscrews, then fit the washer that way, with a small screw, but often the screws get damaged.

I find it awkward getting a hammer within the u bracket so prepare the thumb screw so the cup washer is a tight fit and then place a block at the back of the U and using the thread, screw the bolt into the washer.

[dartmoor]

Thanks for that. It is a tricky job - as a matter of interest does anyone know how they did this in the factory? Did they have a special tool?

[NeilF]

I took the small screw-route - I drilled into the end of the thembscrew shaft and tapped with a 3mm tap. A ss 3mm screw with just enough length to jam into the bottom of the hole and leave a mm or two clear of the thumbscrew washer to allow it to turn freely - it does the trick without any whacking with hammers.

[charlesp]

The factory used a tool a bit like a thick aluminium drift with a steel ball bearing at the business end, and a cut-away section to clear the other side of the clamp.

[electrosys]

I took the small screw-route - I drilled into the end of the thembscrew shaft and tapped with a 3mm tap. A ss 3mm screw with just enough length to jam into the bottom of the hole and leave a mm or two clear of the thumbscrew washer to allow it to turn freely - it does the trick without any whacking with hammers.

I also took the small-screw route - but with a difference. Made-up some s/s washers from scrap s/s plate, dished 'em using sockets and a hydraulic press, then drilled the ends of the thumbscrew shafts.
Got some pan-head s/s screws, ground away their heads so that the slot just disappeared (making the heads as low-profile as possible), then coated their threads with JB Weld and dropped a matchhead amount into the hole, and inserted the screw with a thin sacrificial O-ring below the washer. Cleaned-up the excess goo, and when hard, simply cut away the O-ring with a blade. Job done. Did 5 pairs in the one morning.

[NeilF]

I used countersunk screws and little ss washers to get the profile low (and ground down the end of the thumbscrew shaft to suit) and I didn't tap all the way down to to bottom of the hole so that you could really jam the screw in.

[Charles uk]

I've repaired them with the stainless steel cup washers that come with the stainless transom screws, I just drilled & tapped an M6 hole in the end & loctited the countersunk caphead into the thread just to be sure.

I never bother fixing them now, unless they're the toggle type fitted to the QB's, as you can't get them any more, I just fit the stainless ones, the job is done in 2 minutes, & it seems to be the cheapest way to do it.