Drilling small holes into steel screws below

[cplmickey]

On my Dart build the buffer beams are held to the frames by lengths of angle with 2 rows of countersunk screws holding the amgles to the buffer beams. The buffer stocks are held to the beams with a mixture of 8BA and 6BA fasteners, so small tapping drills required. Some of these holes coincide with the countersunk screws holding the angles. What methods are preferred to ensure the small drills don't break when they hit the screw underneath especially where the slot is. It strikes me that filling the slots with filler won't stop the drill from snatching sideways when it hits a slot and breaking. Would soft solder be strong enough to guide the drill? Any other thoughts please. Ian

[chris vine]

Is it too late to move the screws holding angle to buffer beam??

[uuu]

Could you fix the buffer stocks with a central spigot and big nut - ensuring they're nice and strong for when people try to lift the loco by its buffers? Then the 6BA and 8BA fasteners can be just cosmetic and threaded into the buffer stocks only.

Which is another way of saying I've no idea how to drill the small holes.

Wilf

[Jo]

You can buy/make non slotted screws that can be put in place while you drill for the other screws. I assume the buffer blocks are held on with studs in which case the studs will prevent the non slotted screws mounting the beams from rotating.

As Wilf says it is so tempting to lift a heavy loco using the buffers and 6BA/8BA threads will not hold the weight of a (7 1/4"?) Dart so you need to assume someone will attempt it in the future by the buffers so as a minimum the buffer outsides should have spigots that go through the beams and be secured from the rear. The little visible fasteners are for show. In which case you can cheat and only put the four "mounting studs" in the buffer stocks

Jo

[simon6200]

On my loco, I made the buffer stock screws dummies where they coincided with screws holding the angles. That still left 3 real ones and the stocks had a central spigot for strength.

[cplmickey]

Thanks everyone for the replies so far.
Similar to simon6200 I have left a spigot on the back of the stocks but there wasn't enough material to thread it to take a nut. I was hoping that would take the weight if someone lifted using the buffers.
I really like Jo's idea of using non-slotted screws so I'll look into that.
Ian

[Neale]

Any chance of removing any offending angle-fixing screws and taking the buffer screws right through?

Have to admit that my own tender buffers (haven't reached that point on the loco yet) just have a spigot to locate, then 4off 3mm bolts actually doing the holding-on. I worry a bit every time I see it...

[cplmickey]

Dec 15, 2023 21:08:48 GMT Neale said:

Any chance of removing any offending angle-fixing screws and taking the buffer screws right through?

Have to admit that my own tender buffers (haven't reached that point on the loco yet) just have a spigot to locate, then 4off 3mm bolts actually doing the holding-on. I worry a bit every time I see it...

Not sure this is possible as there's every chance that the buffer screws might still hit half and half on the edge of an existing hole. If I was starting from scratch I might look at this but with so much work done (the frames have been assembled previously) I'm reluctant to start again with new buffer beams. Ian

[doubletop]

Ian

I wasn't sure how I tackled it and went back through the photos. However, at some point I abandoned the four inner angles and put in a full width stretcher of solid 2”x 0.75” bar to make a far stronger arrangement. This stretcher is held in place by metric cap screws through the outer angles and frames. The outer angles more or less became cosmetic and only needed the minimum of fixings. It also makes all the difference when it comes to maintenance, The front buffer beam assembly is a breeze to remove. No fiddly nuts tucked up out the way.

Before



After





I know that doesn’t help that much because the problem you have is fixing the buffer stocks to the buffer beam when the holes are already there. As simon6200 said make the buffer stock screws dummies. On mine that’s the 8BA screws with the 4x 6BA holding the stocks to the beam. I had always thought that could result n a weak assembly but with the 3/16” rods through the heads I haven’t had a problem

Pete

[cplmickey]

Dec 16, 2023 3:47:44 GMT doubletop said:

Ian

I wasn't sure how I tackled it and went back through the photos. However, at some point I abandoned the four inner angles and put in a full width stretcher of solid 2”x 0.75” bar to make a far stronger arrangement. This stretcher is held in place by metric cap screws through the outer angles and frames. The outer angles more or less became cosmetic and only needed the minimum of fixings. It also makes all the difference when it comes to maintenance, The front buffer beam assembly is a breeze to remove. No fiddly nuts tucked up out the way.

Pete

Hi Pete, thanks for that. I need to look at this again with fresh eyes and see what I can do. Ian