making sqare holes in steel

Is this a through slot or a blind slot? If it's a through slot, then you can use a 1/4" lathe bit and stroke the slot end square using a mill quill or lathe carriage feed. Or, you can broach the hole if you go to the trouble of making up a guide. If it's a blind slot, then you could EDM it, I suppose.

GWE

Sounds like a job for a shaper.

Harry C.

Me thinks you mean a pocket 0.250" x 0.500" x ?? deep. If'n you don't have an EDM handy, consider drilling four very small holes at the pocket corners first, gets rid of most of your filing work. If your part can stand it, drill right at the corners so you actually make the pocket a bit wider and longer right in the corner. With a very small drill, the extra clearance is almost undetectable.

Follow up from here with a small endmill.

If you mean a through hole, then its very easy to just file the corners square. Or broach on a lathe.

Karl

1] Calculate the four corners and drill 4 tiny holes so that they are tangent to the corners. Rough with your choice of end mills and fnish with the smallest you can get for your depth, there will be minimal material to file away

2] Call the engineer and see if he really needs em square cornered[my personal favorite method]

What is the procedure for broaching on a lathe? I thought it was done using a press. Since I have no experience with the procedure, could you be more specific?

thanks T.Alan

Have you considered a Watts Brothers Tool Works floating chuck drill? Truly amazing tool for boring square, hexagonal and octagonal holes. 'Tain't cheap but fun to watch.

Watts Brothers Tool Works 760 Airbrake Ave Wilmerding, PA, 412-823-7877

Theory

This is easy to show, hard to describe. In this case, for 1/4" square, mount a 1/4" tool bit in a tool holder so its aligned with the axis of the lathe. Sharpen bit so it cuts on one side. With the lathe off, and your part held in a faceplate, four jaw, or whatever, rock the carriage back and forth. Move cross slide to incease depth of cut. I've seen an article on this somewhare, maybe someone can post a link.

Same idea can also be done on the mill, but the quill lever is nowhere near as stout. easy to break something in your mill.

Karl

One of the old PM articles showed how to make a lever-operated broach that attaches to the tailstock. Looked a lot like a collet closer. You could hold the work in the chuck or mounted to the crossslide or toolpost.

Anyone have that article? I'd like to see how this is done, too.

Back (way back) in high school, my welding teach could make perfect

1/2"X 3/4" slots > I need to make a slot with square ends in a steel bar (0.25" wide and

Even if it is a blind slot you can rig a lathe bit as a broach. To do this you need to cut a slot in a piece of rod to retain the tool bit. The idea here is to restrain the tool bit in the rod so you can stroke the quill and the cutting edge of the tool bit can nibble away with each stroke.

You lock the brake on the spindle tale a small cut, advance the table a few thousands and stroke, advance, stroke, advance etc.

This goes pretty fast.

Dan Miller Mar 9, 8:10 am show options

Newsgroups: rec.crafts.metalworking From: Dan Miller - Find messages by this author Date: Wed, 09 Mar 2005 08:10:28 -0800 Local: Wed, Mar 9 2005 8:10 am Subject: making sqare holes in steel Reply | Reply to Author | Forward | Print | Individual Message | Show original | Report Abuse

I need to make a slot with square ends in a steel bar (0.25" wide and about 0.5" long). I'm thinking of using a 2 flute end mill and then sqaring up the corners with a file but wonder if there is a more precise way do do this with a broach or something? Any suggestions?

Thanks

Dan Miller

Shaper, or a shaper head on a Bridgeport.

John Martin

Great, thanks for all of the suggestions. I'll give it a try. the slot is through so that should simplify things. I'll mill with a two flute cutter first and square up the ends with a 0.25" bit. Problem will be holding the bit but I think I can drill a hole in a piece of drill rod and set a 0.25 bit at a 45 degree angle to the rod with a set screw inserted along the axis to hold it in place. That way the tip can reach the far side of the slot without the holder having to enter. I guess the other option is to use a bit holder that will fit in the slot, mount the bit perpendicular to the bar, and scrape one corner at a time with say a

0.125 bit. The slot dimensions are 0.25 wide by 0.5 long through a 5/8 round bar.

Additional suggestions welcome.

Thanks

Dan

Roger Shoaf wrote:

Aha! Thanks, T.Alan

How deep is your slot? Why not mount the 1/4" bit end on, and just grind enough of a rake on the end to let it cut well as you crank it in? No real need for your proposed 45 degree slot.

Good Luck DoN.

I can dig it up on my home PC. I'll try to do that.

It's a good 'trick' for occasional light use. When doing this, you are basically using the lathe as a shaper, or slotter (a specialized shaper). The lathe's moving carriage becomes, in effect, the ram of the shaper.

Dan Mitchell ============

Many lathes have lever operated tailstock rams. These would be acceptable for LIGHT use such as suggested. The typical lever tailstock mechanism on a lathe is much weaker in construction than the typical lever operated 'armstrong' shaper.

Dan Mitchell ============