View Full Version : Preferred method for breaking edges?

10-10-2008, 11:46 AM
I've looked through the old posts, and I haven't found many examples of what folks do to break edges either on the lathe or mill. There is one post in particular which explains how to break edges using countersinks but that post is really about craftsmanship in general.

I see pictures of projects and most have beautiful edges on them. The breaks are consistent and even. I then look at my things and the edges, while deburred, look uneven and somewhat amatuerish. In my head, (and believe me there is a TON of conflicting activity there!) it seems a waste of time to hit dimensions on a piece only to wind up with these edges.

So, what do people do? I use one of those Shaviv de-burring tools with a B-10 blade. Is that good enough? Is there some special technique for make the break width consistent on pieces from the mill? Mine tend to vary as the tool "bites" into the burr.

10-10-2008, 11:49 AM
I always just used a file.

10-10-2008, 12:42 PM
Files here too!

10-10-2008, 12:45 PM
With milled parts in non-ferrous the straight edges can be finished nicely on a router table.

Using the router table, my experience is a better finish using a fence rather than the bearing on the bit.

10-10-2008, 12:50 PM
8" Mill-Bastard. (and a little practice)......;)

Just an old habit, EVERYTHING, gets a deburring with my trusty old Nicholson. Before I put in the vise for the first cut, after each cut, and at final finishing. Everything......

10-10-2008, 01:17 PM
I use a Noga deburring tool (top-;eft in the picture), which works great, but a short chamfer on long edges looks very nice to me.

This is a DRO head mounting bracket I made for my Millrite. I used a Sandvik RA-245 facemill to mill the flats. This facemill has the inserts in a 45 lead angle, so I just drop it down a little and it makes a beautiful chamfer:


10-10-2008, 02:18 PM
For straight edges on the mill, usually an 8" Nicholson Mill Bastard that is kept at the mill. I've also used Lazlo's technique of cutting a chamfer, sometimes very small, maybe 1/16" flat. Also used corner rounding mills once in a long while.

For outside edges on the lathe, a 12" Nicholson Lathe (yes,that's right) Bastard is kept at hand. The Lathe Bastard has a more biased tooth that works very well on spinning cylinder edges, but it will tend to want to walk axially, so be careful close to the chuck. Also longer than the Mill file to keep hands clear.

For hole, if small enough, I use a counter sink of various sorts. I have them up to 1.5". Larger generally gets a half round file or the debur knife like Lazlo mentioned.

For irregular or otherwise problematic areas, the debur knife or a variety of files.

It all depends... Then again, I don't often finish my stuff to the level often displayed here, so take that with a grain of salt.

10-10-2008, 02:30 PM
For the lathe I have 45 degree tools, for inside and outside.
Milling is filing, but for the round corners I learned at work to use a short, ground to a point small triangular file, a small handcutter (and used without caution a hand cutter). Good for all insideous work.

10-10-2008, 02:38 PM
I use a file most times. If the work permits I use my stationary belt sander with a fine belt (or a worn one). It takes practice with either method to make an even break without any gouges. The secret to filing an edge is to stroke the file directly parallel to the edge contacting the entire edge at once. No more than one stroke and then clean it of pins if you are looking for a quality job.

On the CNC mill I use a countersink or a carbide 45 degree router bit and program it to break the edge. It's a lot like cheating. :D

BTW, if you are spot drilling holes use a spot drill slightly larger than the final hole size. Instant already deburred hole.

10-10-2008, 04:44 PM
A file for outside edges and ID edges I use one of several deburring tools I have.

10-10-2008, 06:05 PM
8 inch mill bastard file on every thing. A man that knows how to use a file can build the world.

Lew Hartswick
10-10-2008, 06:22 PM
I find mill bastards a trifle coarse. Second cut is realy easier to get a
nice clean edge.

10-10-2008, 07:03 PM
8" Simonds american pattern here.

10-10-2008, 09:03 PM
My turn ...

Someone here suggested that I use a hacksaw blade, then wrap some emery cloth around it and spray it with WD40 ... to knock down the edges. It worked great.

I also bought one of those somewhat inexpensive tumblers for brass to finish them off. I was totally impressed with the results.



10-10-2008, 09:06 PM
After years of filing i also use emery cloth to sand the small fine burrs off edges, scotch bright pads, and a\lso a 3 m deburring wheel mounted on my 8 inch delta grinder it works awesomwe and leaves a supwer nice pro looking broken edges. When i use this wheel to deburr a part i automatically charge my customer an xtra 40 bucks just cause it looks so nice. Beer Store here i come.

Paul Alciatore
10-12-2008, 01:13 AM
I have probably used all of the above. My favorite is a 12" mill bastard file, fine cut. The weight seems to help you get better control. Of course, your files need good handles for control. And DO clean the file's teeth before working: a steel or brass wire brush is good for this. Just brush along the teeth. You will be surprised how much better a clean file cuts. A drop or two of oil brushed in with an old toothbrush will help keeping the file clear of chip buildup.

Proper work support is essential. A vise is the best and I swivel the vise at 90 degrees to the work bench to have the filing line directly away from me. Use soft jaws to prevent maring the work. As said above, long strokes are best: preferably the full length of the edge. I use light srtokes to take off a little each time and hopefully average out any errors. If you must file an edge in sections use different length strokes on each section to average out the transitions between sections. Filing is an art and a skill and practice makes better.

If you are holding the work in your hand to file, where you hold it will make a lot of difference. if you hold it near at the far end of the stroke, the work will tend to ride up into the file and cause problems. Hold it at the end where you begin the stroke for better results.

When filing corners or other sharp projections use a very light pressure and the thumb of the other hand on the left side of the file to prevent it from moving sideways and skidding across the work, marking it up.

I file very short edges (<= 0.5") with the file perpendiculat to the edge, not parallel to it. I find it easier to control the uniformity of the edge this way. Rest the file on the edge without moving it to get the angle set in your hand first, then stroke very, VERY lightly - the weight of the file or even less. Use your left thumb as above to prevent the file from drifting sideway. This works for me but your mileage may vary.

When filing, beginners should check the results after each stroke. After a while, as your hands gain the needed skill, you won't have to check as often.

A belt or disc sander can be good. DO USE EYE PROTECTION! These will cut much faster than a file so greater skill and a gentle touch is definitely called for. As with the file, where/how you hold the work will make a difference. If you hold it below the sanding point, the belt will try to draw the work into itself making depth control harder. Hold it above that point and the force of the belt will try to swing it clear giving better control. Using a grinder is much like a sander.

For holes, countersinks or combined drill and countersinks (a.k.a. center drills) are probably best. I like the O-flute countersinks. They seem to have the least chatter for a very nice finish. I have also been experimenting with spotting drills and combined drill and countersinks lately. These are used before drilling the main hole and can save time. But you must be quite sure of the depth or some post-drilling work will be necessary. With any of these, do use the depth stop for fine control and uniform appearance. The first thing I always do with a new drill press is beef up the depth stop.

One of my favorite drills for sheet metal and plastic work is the step style drill. These are the ones with about 6 to 10 steps of different diameters. They make excellent holes in sheet metal and plastics and as a bonus, the small step between sizes does a great job of cleaning up the edge. All you have to do is set the depth stop on the drill press to bring that edge into contact with the edge. After drilling the holes, flip the work over and hit each one again to clean up the bottom edges of the holes. Fast and neat! These drills come in inch and metric sizes from about 1/4" up to 1" diameter.

All of the above requires skill. The more you do it, the better you will get. They do make edge cutting machines: they have a 90 degree, Vee groove with a cutter at the bottom. I have never even seen one, but they seem fool proof and I guess they work well on 90 degree edges.

10-12-2008, 02:37 AM
Filing is one of those things you learn to do almost first in metalwork class in school- so I've been told anyway. You didn't pass if you couldn't make a toolmakers vice, accurate all around, with only a file. Somebody long ago found out that a tiny edge raised on a piece of metal could be used to advantage (after they got the bleeding stopped). The file was born.

That has got to be among the most useful of tools in the shop. I do now believe that learning how to use a file in the many ways it can be used is definitely one of the most valuable skills in metalworking, or in any material as far as that goes.

Having said that, I usually debur on the drum sander. :) The drum is about a foot in diameter, it's covered with foam rubber, and it takes one of the standard sizes of belt sander belts. I wrap the drum with string to compress the foam rubber, then slip the belt on, then pull the string out. The foam layer in addition to keeping the belt on, allows for a 'softer touch' when bringing a workpiece into contact with the belt. Like anything, there's a learning process, but you can do all manner of de-burring, shaping, etc, and once the belt is broken in (or partly worn out) you can get very smooth results. One of my projects sometime soon is another one of these, since I like to use the worn out belts for polishing, wheras a good belt makes removing material easier.

I do use files a lot as well.

10-12-2008, 08:43 AM
I sometimes have to champher a lot of slots in 1/4 to 3/4 plate. Leaving the setup alone, I use a countersink in the mill and dial it down to just take the burr off the slot.

10-12-2008, 03:59 PM
I use an inserted deburring tool, I've worked out how to use it on external and internal edges & it does a great job.
I do use a file or linisher on decorative jobs though,

Rich Carlstedt
10-12-2008, 10:09 PM
I'm with Lazlo on this
The Noga deburring tool works great.
What I find is that they are used incorrectly most times .
Not so much as to use, but the technique .
You don't need to grip them like you are a mountain climber on the side of a clift ( Too stiff !)
Grab them, but keep your wrist loose.
Lean the handle somewhat in the direction you intend to go, and draw the tool across the edge
as if you only needed too remove .001.
The depth of removal is controlled by the blade, NOT your application.
I hate to use the word limp wrist, but for bores, you drag the cutter
around , again by leading with your end of the tool, and the cutter trailing.

I have two handles ,one red, and one blue.
The red has bits for steel, and the blue has my Aluminum chamfer tool.
You should not use these improperly.
Let your tool float, and you will get very even chamfers !
Practice will help you see this quickly


10-12-2008, 10:32 PM
When I worked as a file clerk jerk at the V.A. we had a saying

"Today is the first day of the rest of your file"


10-13-2008, 04:45 AM
I'm with Lazlo on this The Noga deburring tool works great.

I agree. I have a couple; the double bur tool for sheetmetal and the handle that accepts the deburing blades.
Files, stones, HSS steel, knives or whatever is at hand works OK also.