Square Holes

I need to cut a number of 10mm square holes in 6mm MS plate (about 20) and the cost of a rotary broach is too expensive.

Has anyone made their own square push broach ?

Was also thinking of drilling a 10mm hole first then using a rotary broach tip held in a guide to punch the square holes with a press.

Paul.

Hello Paul,

I don't know if this would suit your purposes, but it's a good method to know anyway...and it works!

Best regards,

Steve.

If a rotary broachj is too expensive have you thought buying a push broach, still not cheap but may come somewhere between the two options you have, try Steelmans also worth costing out laser cutting

We have talked about making square and hex holes in the past so worth having a search

Might be worth getting a quote for the plate supplied with them laser cut. Check with your nearest laser shop.

I would like a push broach but still expensive which is why I asked if anyone had made one.

Laser cutting is not an option as I already have the profiled plate. Just needs the holes.

Regards, Paul.

Paul,

Do the holes need to be truly square?

If not, then the broaching job would be much easier if you pre-drilled oversize, at [say] 11mm diameter.

MichaelG.

Edited By Michael Gilligan on 19/03/2015 08:08:03

LH Sparey did an article on making your own broaches 26th March 1953

PM Sent

Rotary broach can be done with the simplest equipment, see:

http://mikesworkshop.weebly.com/rotary-broaching-on-the-mill.html

Mike

Looked at this last week as wanted a square hole in a bar. On the web, search Sherline Products Tips page, look at tip 20, an article on making a broach from square silver steel, which I believe is listed on College Eng web site

Thanks for the comments.

Michael G, No the square holes do not have to be completely square. I am bolting the hornplates of my traction engine to the boiler and want the head of the bolt to look like a round head rivet. To stop them turning, I am making the end of the bolt near the round head a square shape, similar to the square on a coach bolt (if that makes sense).

Michael C. The rotary broaching in the mill idea looks promising. Will give it a go.

Thanks everyone, Paul

10mm hole and a nice sharp 8mm square file?

2 minutes tops per hole 40 minutes workout for all 20

nice and cheap

If its just to stop bolts turning then file will do, I did some the otherday in some axle bracket castings to take coach bolts, drilled 1/64th larger than 1/4" bolt dia and filed out the corners.

Button head socket screws look quite like firebox stays, thats what I used on my fowler.

We do lots of square hole broaching at work, both pull (through) and blind (push). We always drill a larger pilot hole than the square AF to reduce the load on the broach. With push broaching - which is what you look like doing - you can essentially just take out the corners if your male square is anything like - I,e, it doesn't have rounded corners. We did a test on an aluminium handle broached 8mm square, with a 10mm pilot hole. The handle spindle failed first in torsion.

Maybe I am missing something, but if the hornplates have square holes, and the bolts are like rivets on the head, how will you turn the bolt with the square shank in the square hole to tighten it? A coach bolt pulls into the wood, but that is pulled in with a nut on the other side of the joint, I assume in your case it will be screwed into a blind hole in a boiler stay.

Chris Gunn

Hi Chris,

The bolts/rivet have a nut which is tightened.

I have changed the design for attaching the hornplates on my Ruston to comply with the details shown on the Aus. code. Our codeshows the hornplates attached to the bottom of the boiler (under the fire grate) and to a mounting plate in the upper side of the boiler. My inspector queried the original design and I decided not to cause any problems and change the design.

Paul.

That sounds a bit like how Haining did some of his ploughing engines, fixing through the foundation ring and a bar that fits in teh gap where the top of tehboiler curves down to the hornplate.

Though I do know of engines being built down under that use the threaded hollow stays to mount the hornplates so maybe some inspectors are OK with them. You can just see the back three fixings as they have not been screwed all the way in, there are nine in total

OK Paul, I was missing something, and I get it now. I would imagine that this is easier than trying to position the mounting holes in the hornplates from the boiler stays as we tend to do. However on larger scale engines I would be concerned that nothing is pulling the hornplates in to the boiler half way up the boiler at the front. The cannon shaft would probably do it at the back.

Chris Gunn

On the agricultural machinery I have helped build over the last 15 years we use some coach bolts through 50 x 100 steel tube, we drill through bolt size (it's usually 10 mm), then on the head side drill it out to just under the point to point diameter of the square, stick the bolt in and belt it hard with a hammer. Ian S C This trailer takes 2 large hay bales, and feeds them out the back as it's towed around the paddock, better than using a pitch fork, and feeding the hay off the back of a ute on a cold and frosty morning.

.

Paul,

Developing Ian's very practical approach, a little: ... If you turned a chamfer on the square of your bolt, you may be able to draw it into the round hole using the nut [instead of using the big hammer]. ... might be worth a try on some scrap.

MichaelG.

That was my thoughts also.

Ian S C