How do I drill square holes ?

Phil,

To see how "they" would do it ... have a look at the video link I posted in this thread.

MichaelG.

all the above is a bit irrelevant as im guessing phil's required square holes are for the original PANSY rocker arm design. this design is fundamentally flawed as the rocker arm bearing isnt substantial enough, and also the rocker arms are supposed to be used to set the valves which many have found to be extremely difficult.

i fitted double rocker arm bearings on my version, with adjustment for the valves being on the valve spindle.

cheers,

julian

Another way is to make a broach , so that as it is pushed through keeps opening up the corners .

A broach is fairy simple to make , a one pass from broach will work as well, but there are situations where these are not the best way.

There are square drill setups that use a triangular drill bit etc, but they do leave a radius in the corners.

(Fizzy et al) All these techniques are regualrly mentioned in ME so a good reason for reading back numbers while vegitating in front of the TV and for those "not buying ME because it is all about Locos" you can learn general techniques for use on other projects. Also it shows the value of articles that may repeat stuff shown before, but not for a few years.

Finally it shows the value of ME as a printed magazine. Here is someone building a 40 year old design (as it happens to be a very good one). Nobody will be looking for the copies of electronics mags in 2054 nor wanting to read the ME(W) articles on CNC or stepperheads but I bet someone will be building a Pansy. (and the then late Phil's loco will still be chuffing round a track - Phil when you make the toolbox engrave your name on the inside like the builder of mine did).

Posted by jason udall on 23/10/2014 09:09:01:

Watch out for distortion ..ideally you need a die to support far side..now how do we make the die...

Edited By jason udall on 23/10/2014 09:10:10

I'd make the die for this particular one-off from a small block of ally or hard plastic such as Nylon.

Steel buried inside the regulator, are you sure about that? If it is stainless steel it becomes a different ball game as it becomes dependent on the grade of stainless being used. My advice is file as near as you can before using any form of punch. If you use a punch with any form of guide spigot on it you will only be able to push it in a few thou as the material you are trying to shift has nowhere to go. Remove the punch, go back to the file and file a little more material out from the corners and the metal you have displaced, repeat the process until you have your square hole. If you try to force it through in one go it will push the metal from the back of the hole and make one hell of a mess or burst your punch. If you are making this from mild steel don't it is dangerous(rust is the problem) and any boiler inspector will not pass the boiler. Make it from gunmetal,bronze or stainless.

.

Bazyle,

That's astonishing, if it's true

MichaelG.

There is always EDM (spark eroding), laser cutting, and water jet cutting. I still say file it, preferably from bronze, gun metal, or stainless.

Ian S C

To all concerned the length of time this topic has been open he could have done it with a file it's only one hole for goodness sake

Roy

There have been threads on here in the past of course covering similar problems.

Done it. Made a broach from silver steel and tapped it through, just needed a clean up with a file afterwards but assembled now and happy with result

Cheers, Phil