files to make round holes square

[marcros]

I have some m6 holes to make square to take the square shank of a m6 coach bolt. there are 20 in all in 1.6mm aluminium. to make it slightly more tricky, it is a through hole in square tube, and only one side needs squaring.

I believe that the way to do it is with careful marking out or a 3 square needle file. Try as I might, I cant see anything small enough to fit in my Dremel that would have any strength to it. this is a one off job for now, but small files are useful tools.

the Vallorbe version is £12, a draper version 3 for £5. I dont do much metalwork, but I wouldn't expect that aluminium is too tough on files. Any thoughts on which to go for or alternatives?

 

[Spectric]

If I was looking at making a square hole in sheet ali I would not be drilling a hole and looking to file it square, in a metalworkshop I would use a flypress and punch & die but as a diy job then you need a similar solution. So I would drill the 6mm hole in the ali, get myself a piece of 6mm steel plate and drill a hole in this to accomodate the square, now using a coach bolt through the ali, through the steel and fit nut and washer, now tighten slowly and the square shank will pull into the ali. Hope this gives you the idea.

 

[Inspector]

So any reason you don't buy some square files? They come in a variety of sizes and cuts.

Pete

 

[chaoticbob]

I really wouldn't bother with the Draper files - they're cheap for a reason. They do cut (just), but the teeth aren't so sharp as Vallorbes - and sharp is what you need for cutting aluminium. The Drapers will clog very quickly and drive you mad.
A mid-range alternative might be the Tomé Feteira offerings from ARC Eurotrade . I haven't yet tried them, but they look good. For aluminium you should go for cut 0, which is the coarsest cut.
Whichever way you go, chalking the file helps. Because aluminium is so soft it has a tendency to squash into the file and stick there rather than falling off in chips. The chalk makes it harder for the aluminium to stick to the steel.
Good luck, Bob.

 

[marcros]

If I was looking at making a square hole in sheet ali I would not be drilling a hole and looking to file it square, in a metalworkshop I would use a flypress and punch & die but as a diy job then you need a similar solution. So I would drill the 6mm hole in the ali, get myself a piece of 6mm steel plate and drill a hole in this to accomodate the square, now using a coach bolt through the ali, through the steel and fit nut and washer, now tighten slowly and the square shank will pull into the ali. Hope this gives you the idea.

so the steel as a backer piece? it is tube, and some holes are 300mm inside, but it may work. I like the idea.

 

[marcros]

I really wouldn't bother with the Draper files - they're cheap for a reason. They do cut (just), but the teeth aren't so sharp as Vallorbes - and sharp is what you need for cutting aluminium. The Drapers will clog very quickly and drive you mad.
A mid-range alternative might be the Tomé Feteira offerings from ARC Eurotrade . I haven't yet tried them, but they look good. For aluminium you should go for cut 0, which is the coarsest cut.
Whichever way you go, chalking the file helps. Because aluminium is so soft it has a tendency to squash into the file and stick there rather than falling off in chips. The chalk makes it harder for the aluminium to stick to the steel.
Good luck, Bob.

you know, you see a brand name and I already knew the answer- otherwise I would have bought them! thanks for the confirmation.

 

[toolsntat]

so the steel as a backer piece? it is tube, and some holes are 300mm inside, but it may work. I like the idea.

How wide are the walls of the box section? Perhaps this method will cause it to deform?
Can you get inside the section ends?
Sometimes the square on these modern coachbolts are not so crisp at the corner.
Apart from a file to file it perhaps a biggish file with the handle removed the square tang might be forced at the hole and wiggled to give a "broaching" effect
Cheers Andy

 

[marcros]

it is 19mm tube in 1000mm lengths. I need holes at each end and 2 or 3 in the middle somewhere.
I am making this (the video goes on and on and on, but if you skip to bits you will get a summary).

.

pop riveting it may be an alternative. I dont have a riveter but I dont have a file either! just looking for a reasonably cheap, reasonably low effort method that will produce a decent job. I dont know how strong rivets are. I possibly should have bought steel, but I dont have a welder either!

 

[flh801978]

You will do this easily with a square file
drill the hole 6.25 on the side you want the square hole and a few strokes of the file will open it out to square
minutes job

 

[novocaine]

I've been trying to work out how to level my lawn, I was planning a roller then, something else. now I know what else. so thanks.

I have a set of drapers along with countless sets of much better. they are cheap because they are smaller which at times is a god send.
stress razors from deforming the hole with a couch bolt would leave me worried if it's going to take any abuse, but at 6mm, meh, not enough to worry about and the sofa bolt should have a taper to it's square so it will pull in easy enough.

a quick file to the the corners isn't going to hurt either. as to a backer, use a bit of wood.

or, as you've alluded to, rivet it. a hand riveter from ebay is about a 10 quid and quit possibly has the rivets you need too. it will last this job with easy and most likely a few hundred more. (now waiting for someone to say they are rubbish and will break the first time you use it)

 

[marcros]

I was more concerned about the strength of the riveted joint than the riveter.

if you do use this leveller, sit down before you look at the price of a ready made one. the proper term is a lawn lute.

 

[novocaine]

I can assuage your concerns a little bit, we used to build hovercrafts with rivets. now that is how you flatten a lawn (and a lake, and ducks, and the occasional bystander).

I won't be buying one. I'm still trying to work out how to make my own roller. I'm thinking of filling a tube with concrete and letting set before removing it.

 

[AES]

Personally I wouldn't worry too much about brand names. You're obviously not into metal working, except when "needs must" so any files (square, warding or needle type) will do the job, especially if we're only talking ali. As well as the tip above about chalking the file, you can quite easily clear clogged teeth (it will happen anyway with ali) any sot of sharp spike, sharp knife point, etc, etc, will clear clogs. Done often is better than not so often!!!!

Ditto cheapo pop riveting "pliers", any sort from the local DIY shed will do the job. Buy a 2"set" (20 quid or less?) and you'll get enough rivets thrown in to complete the job.

HTH

 

[marcros]

Thanks all.