|
|
Post by teakfreak on Mar 5, 2007 10:05:10 GMT
A few issues ago there was an article in MEW about drills for drilling (almost) square holes. Does anyone know if such drills are commercially available, and if so who makes them? I have a large number of 3/8" square holes to form in some door handles that I'm making and the thought of filing them all is not appealing! Nor do I have (or have the space for) a press for a broach.
|
|
hat
Active Member
Posts: 48
|
Post by hat on Mar 8, 2007 14:07:20 GMT
So that you don't feel ignored that nobody is answering your query I though I would try - but I haven't got a clue other than to drill and file
|
|
lancelot
Part of the e-furniture
Posts: 471
|
Post by lancelot on Mar 8, 2007 15:04:47 GMT
|
|
|
|
Post by havoc on Mar 8, 2007 19:36:58 GMT
The only way I know to drill non-circular holes is ultrasonic drilling or spark-erosion. But can you call that drilling?
|
|
paul
Member
Posts: 8
|
Post by paul on Mar 8, 2007 22:21:03 GMT
The only way I know to drill non-circular holes is ultrasonic drilling or spark-erosion. But can you call that drilling? LOL - you could take a look at almost any of my attempts Havoc, they almost always come out slightly oval (or worse!). |
|
JohnP
Hi-poster
Posts: 186
|
Post by JohnP on Mar 8, 2007 22:23:52 GMT
There was an article in ME years ago about using a triangular tool to "drill" a square hole. You had to make a guide piece which had a suitably sized square hole in it. Ideally the job is mounted in the chuck/faceplate with the guide piece clamped in place.
A guide hole is drilled which is the same diameter as the sides of the square.
The tool is a hardened triangular bar, so if you cut through it you'd see an equilateral triangle, the lengths of the sides are the same as the sides of the square. The end of the tool is cut off square (sorry!). You can either support the tool on an Oldham coupling or just use a long tool supported by the tailstock. The tool does not rotate but must be free to wiggle!
In use, it starts off with one side of the tool resting against a side of the guide piece. As the lathe rotates, the work rotates beneath the tool, which pivots around one corner of the guide piece until the tool buts up against the next side of the guide. If you think of the guide as a four tooth internal gear and the tool as a three tooth spur gear it might help. All the cutting is done by the tool scraping out the corners of the square hole it is cutting, so the end has to be properly square or it will just rub.
Hope that helps, I suspect it's a lousy description!
JohnP
|
|
|
|
Post by AndrewP on Mar 9, 2007 1:34:48 GMT
|
|
|
|
Post by Deleted on Mar 9, 2007 12:27:57 GMT
Hi
I read about a thing called a wobble broach for making hexagonal holes in allen bolt heads, maybe the same idea would work for square.
I'll try and find the description and post it later if anyones interested.
Regards
Trevor
|
|
|
|
Post by alanstepney on Mar 9, 2007 13:32:12 GMT
Could always buy a box of triangular holes and tie two of 'em together.!
|
|
Myford Matt
Statesman
There are two ways to run a railway, the Great Western way, and the wrong way.
Posts: 621
|
Post by Myford Matt on Mar 9, 2007 13:48:52 GMT
|
|
John Lee
Part of the e-furniture
Posts: 375
|
Post by John Lee on Mar 9, 2007 19:15:58 GMT
Crikey that is interesting Matt. Now I wonder if I have an application in which I could use it!  Regards, John |
|
Myford Matt
Statesman
There are two ways to run a railway, the Great Western way, and the wrong way.
Posts: 621
|
Post by Myford Matt on Mar 9, 2007 19:24:31 GMT
Hexagonal cylinders? MM |
|
|
|
Post by havoc on Mar 10, 2007 22:04:55 GMT
First time I ever heard of that. Well, we learn each day something new, don't we?
|
|
|
|
Post by havoc on Mar 10, 2007 22:12:34 GMT
Oh, you mean you also know how to drill trilobed holes like this:  EDIT: trick to drill round holes in thin plate is to put a piece of rag on your workpiece and drill though it. I also laughed when I heard it, but it works. |
|
paul
Member
Posts: 8
|
Post by paul on Mar 11, 2007 8:30:48 GMT
Oh yeah, I can do those no problem  I don't know if I could bear to cover the hole with a bit of rag - I'm paranoid about the drill being off-centre as it is, but with it out of sight..... <shudder> |
|
John Lee
Part of the e-furniture
Posts: 375
|
Post by John Lee on Mar 11, 2007 17:50:37 GMT
I am sure he meant centre it up and then put your rag in . I too am not sure why this would work but I will try it. Thin metal drilling. Back it up with a piece of wood and clamp all down tight. Its on breakthrough when it goes wrong because your drill has not engaged full diameter yet. Note: Drills always make 3 lobed holes, but not normally as pronounced as that.... ;D Ahh..workshop fun.. Regards, John |
|
|
|
Post by havoc on Mar 11, 2007 18:30:33 GMT
To be honest, those were the first holes I ever drilled for a ME project. I learned a lot since then.
|
|
