How would you do this

That's a job for a sharp cold chisel. You space the holes such that you drill every other hole, and then every hole in between, so they overlap. Then you use a chisel ground on the top side only, like a wood chisel, and chisel straight down against a hard plate. I use a 1-foot square of 1/2" steel plate for backup, one side for chiseling and the other side for bucking rivets.

With a little practice you can get a really clean cut. Then a light filing with a small mill file, and you're done. It's quick once you get a little practice with a chisel.

Ed Huntress

Gosh Ed,

With your background, I thought you'd recommend an EDM, water jet, or CNC plasma cut

Karl

Hey, smoke 'em if you've got 'em. I don't happen to have any of those. d8-)

I often lament the fact that we've forgotten how to chisel. If you practice, you can do amazing things with one, faster than most people suppose.

Something that really influenced me early in my reporting about metalworking was visiting the partly-restored Rogers Locomotive Works in Paterson, NJ. I asked about the machines and tools they used to build locomotives in the mid-19th century. They showed me boxes of files and chisels. No kidding.

Also, my uncle, who gave me his old South Bend 10L, wouldn't let me have it until I proved I could cut a cavity and a die-hole in steel plate with a chisel. Fortunately, he didn't make me prove I can used a scraper.

Ed Huntress

Where would be a good place to get some good quality chisels?

And files. Who makes good files these days? I'm in Seattle.

I need to cut a slot for a tool rest on a yard sale bench grinder that's missing one rest.

I got the welding bug, but I don't have much extra room for machine tools now in my shop.

Thanks,

Jeff Dantzler

Bah, scraping is easy. Actually, I used both the other day... I had just made a 5 x 14" aluminum box, 2" tall, 1/4" thick walls, 5 degree draft (yes, quite drafty.. I'm a lazy molder) and after hacksawing off the nub of a sprue left, I had about 1/8" to go before it's flat... well, damned if I'm filing that off, the scraper doesn't remove anything, so I grabbed an old

1/4" chisel and took it off in one layer!

How would anyone else do that anyway? It's not too thick (and tapers away from the top) so it wouldn't be easy to throw in a mill vise and make a quick pass on...

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Ed, That is similar to the situation in woodworking using edged hand tools - chisels, planes, scrapers. Are there any accessible references for metalworking chisel technique? The concept of building locomotives using files, chisels (and presumably castings!) is powerful. Fred

I get real good clean cuts my way.

I take my router. Chuck up my fiber disc. Clamp an angle iron bar in alignment with the 2 holes, on each end.

Zoom

my 2 cents

Old metalworking texts like the ones by Burghardt sometimes have good sections on bench work, including chisels.

Grant

Not glamorous, but a cheap and dirty way I have done this is by welding two pieces together, and grinding off the weld bead. Two identical elongated "L" shaped pieces can be placed together to form a slot.

d 3 flute endmill is the proper way...

gunner

metalworking

I did my apprenticeship in a steel works here in UK and one of the skills they taught was chiselling. You are right, they are a very useful tool that is rarely used these days. On the subject of locomotives and such, the skilled men who made them were called fitters. That was because the quality of cast and even machined parts was quite poor so all precision parts had to be made to fit by hand. Hence "fitters". It's times like this when I feel particularly old.

John

On Fri, 02 Jul 2004 07:03:27 GMT, Gunner calmly ranted:

Why 3 vs. 2 or 4 flute bit?

[ ... ]

2-flute will work quite well, and is commonly called a "slot drill" in the UK because it works so well for this. But 4-flute has a *serious* problem in this application.

All end mills deflect to some extent -- and for a 1/4" one the deflection can be significant.

With a 2-flute endmill (or most of the time with a 3-flute one), when the sides of the slot are being cut, there is nothing engaging the end of the slot. And there is an approximate balance in the forces generated by the two flutes, as they are removing approximately equal amounts of metal. When they are cutting the end of the slot, there is no counter force from the back flute. However, there are no flutes engaged with the sides of the slot, so there is little problem from the deflection, as long as you don't feed too fast, and create sufficient force to break the end mill.

However, with a 4-flute, while two flutes are cutting on the sides, a third one is cutting at the end of the slot, creating significant side force, which causes enough deflection it make for rather poor finish and slot-width accuracy. (The forth flute is cutting nothing but air behind the end mill, so it is not generating any forces to counteract the side forces of the front flute.

Ideally, one would use an end mill just a little too small, cut the slot, and then make two passes to clean the edges for an even better finish with the flutes not doing anything else.

But, of course, there has been nothing saying that the original poster has a milling machine in which to use the end mill, so this may be totally academic as far as he is concerned. :-)

Enjoy, DoN.

I have a lathe, the piece is small enough to mount in a cross slide, and I have a number of 1/8 two flute end mills, so I will try it, but it looks kinda iffy to me. I will also try the chisel method. Anything but endless frustration with files...

O.K. Any backing to the piece? Do you have a milling adaptor for the lathe?

In any case, I would suggest that you make perhaps four passes with that small an end mill. You don't normally want to cut more than

1/2 of the diameter deep (1/16") in a single pass, and you've got (IIRC) 1/4" to go though.

Good Luck, DoN.

On 2 Jul 2004 20:14:16 -0400, snipped-for-privacy@d-and-d.com (DoN. Nichols) calmly ranted:

Gotcha. Thanks, Don.

Ah, so the third (Gunner's Libertarian flute, no doubt) flute might throw the two forces out of balance and ruin the race, eh? Ed was right all along.

I can see how this could affect high-speed/force CNC ops, but how about manual? Wouldn't you see/feel this during the feed and simply slow down to compensate?

Good.

But at least he knows what to use if and when he gets a mill.

-- "Not always right, but never uncertain." --Heinlein -=-=-

Wondrous Website Design

A 3 flute endmill always has two loaded flutes in the work, and its far stiffer than a two flute so deflection and chatter is far less problematic. It also tends to cut a slot that is the same size as the endmill.. IE a .25 endmill tends to cut a .25-.2505 slot with decent surface finish

A 2 flute has only one flute carrying a chipload at a time. This causes it to chatter in the cut, and can make the slot rather oversize. The cutter also tends to far less stiff, with the attendant chatter and deflection problems.

A 4 flute has three in the cut, with good stiffness for good finish, but the flutes have greatly reduced chip carrying load and must be run slower. It for some reason also tends to cut a smidge oversize as well for reasons I dont have the answers for.

This may be of some assistance to anyone

Go to their Solutions button.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

I also forgot to mention that a 3 flute, like a two flute, will normally allow plunge cutting, unlike most 4 flutes. This means you dont have to drill a starter hole, you simply plunge the cutter into the work, then make your longitudnal cuts.

Another good site.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

A homemade one that I am using for the first time. It worked fairly well considering the small size of the end mill which I was nervous about.

The first pass I went 1/8 in deep. There was some chatter but not much. I pondered making a row of 1/4 inch holes and then just milling out the gaps and cleaning up the projections. It's a learning experience.

And then I gotta try the chisel thing...