how to machine angle iron flat on all sides. (2024)

M

matridium

Plastic
Joined
Sep 30, 2015
  • Dec 14, 2015
  • #1

I need to mill some 3/8 angle Iron flat on the back sides and at least one of the insides of the bend. the angels is 4" x 4" and 24" long. The outsides needs to be square or perpendicular to each other. the inside part should be parallel to the outside machined surface.
I was think of clamping the angle upside down to two angle blocks on the milling table and indicating it in, but the surface is really rough and rusty.
i suppose I can try to get it close and take a shallow cut first then indicate the newly cut surface and re-cut, and then flip the cut surface against the angle plates and star the other side. Another idea I had was to clean up as much rust as i can with an angle grinder and abrasive pad. Then clamp that part to the table, and then mill just the 3/8 edge and then flip that 3/8 edge over and rest it on the table when I clamp to the angle plates, this will at last get me close to fat to table.
I have not had to do anything like this on the scale so any incite will help.

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington
  • Dec 14, 2015
  • #2

3 vises with 4" tall soft jaws
Mill outsides flat and perpendicular
Switch to short jaws
Mill one or both insides flat

L

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
  • Dec 14, 2015
  • #3

The part will warp, so you will end up with a curved angle iron.

Larry

jscpm

Titanium
Joined
May 4, 2010
Location
Cambridge, MA
  • Dec 14, 2015
  • #4

Consider using a wire brush on a drill to clean off any flaky rust or corrosion first. Scrubbing with acid like oxalic acid then rinsing can also get rid of embedded rust (use gloves and protective gear, oxalic acid is potent stuff, you can find it at hardware stores).

When you have rough pieces like castings or corroded work you can use carbide grippers to hold them in a vise (see Jergens for an example: Jergens Inc.GRIPPER, 1/2 SQUARE CARBIDE). Bore a couple of pockets in a slip of cold rolled, insert the grippers and put them on the movable side of your vise jaws.

O

onecut

Hot Rolled
Joined
Jun 27, 2013
Location
england-newcastle upon tyne
  • Dec 14, 2015
  • #5

Take the head of your mill off.Put your clarkson chuck in the nose of machine put a stub arbor in chuck.Two side and faces one smaller diameter than other.(Say 9ins dia+7.5 diam) or as long as dias have at least half inch difference in diameters. Then a spacer thickness of finished wall,The smaller dia cutter goes on right then spacer then other cutter-So that means the big cutter will be maching the outside face of the angle iron, whilst the smaller cutter will be maching the inside face.Then clamp job down to table, and straddle mill the 4 faces will have no taper on and be dead square-Obviously you will be clamping the job close to edge of table-this will allow you to drop the larger cutter into water channel-or until you have set the smaller cutter to finished thickness of wall-which both are the same thing

metalmaster10

Stainless
Joined
Apr 18, 2012
Location
Indiana, USA
  • Dec 14, 2015
  • #6

I think the real question is "how flat/square/parallel?" Are we talking tenths or a few tho?

If just a few tho (which is all I would expect. As said, expect warpage)

I have milled some "flat" on outside edges by just throwing it in a vise "flat up" and skimming a side, then putting the "good edge" against my vise jaw and a piece of poly flat on the rough edge to hold it pretty well perpendicular.
Worked fine for my needs however, if I was looking for tenths I wouldn't have started with angle iron.

**Edit:
I missed the part about 24" long....that changes everything. Yeah, expect warpage!

I would still try it, but I would limit my expectations.

E

extropic

Stainless
Joined
Dec 3, 2010
Location
WA, USA
  • Dec 14, 2015
  • #7

This could get interesting.

Subscribed how to machine angle iron flat on all sides. (4)

Richard King

Diamond
Joined
Jul 12, 2005
Location
Cottage Grove, MN 55016
  • Dec 14, 2015
  • #8

What brand, model and size of your machine? How many and kind of Vises? Like Metalmaster said whats the tolerance spec's?

Going to be a one time or production job. In a hurry? Going to drill holes or weld them later...more info here is better...

Ries

Diamond
Joined
Mar 15, 2004
Location
Edison Washington USA
  • Dec 14, 2015
  • #9

angle iron is a structural product.
ironworkers, who assemble structural steel consider 1/8" to be precise, and often settle for tolerances between 3/8" and 1/2".

The way that machine builders deal with structural products is usually to drill and tap, or weld on drilled and tapped blocks, then use a second piece of precision ground steel bar held on with set screws, that can be adjusted until they are level and true.
Thats how my plasma cutting table was built, for example- no using the structural steel as bearing surfaces, but attaching a flat piece of steel to it, shimming or screwing it flat, and then running bearings against that.

O

Onepass

Hot Rolled
Joined
Jun 2, 2014
Location
Kansas City
  • Dec 14, 2015
  • #10

I have to do that kind of thing all the time. You got a Bridgeport? Or a horizontal? Tolerances? All that makes a big difference how you do it. Angle iron is never a perfect 90 degrees. You need something that is 90 degrees to your cutter face. Back jaw of vise(s) or angle plate(s). Let's say you use vises. Since the stationary jaw is your datum , put the angle iron in the vises with a small block of material between the part and the moveable jaw. You don't know how true to each other the inside and outside surfaces are and you want it registering on your datum surface. Cut the top surface to a bare minimum clean up, preferably with a sharp tool like a HSS fly cutter. ( to minimize the stresses you are going to put in the angle iron.) use an end mill to skim a flat along the narrow edge of the part. turn part over and cut put machined side against the back jaw and put the same block between the angle iron and the moveable jaw. Skim cut the face with a fly cutter and again cut the edge with the side of the end mill. After you cut the second side, you will have a much closer to 90 degree angle. Now you can set the angle iron up in the vises with parallels under it so that the surface of the inside of the angle iron is above the jaw. Tap it down until both parallels are in contact. Fly cut the inside face. Turn over and repeat. Depending on how flat and true you need, you may have to recut the angle iron until you like it. Every time you cut it you will release more stresses. Depending on your tolerance, you might need to stress relieve it before your finish cuts.

L

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
  • Dec 14, 2015
  • #11

You can buy aluminum in nearly straight and square extruded shapes. Look for architectural angle, which has the inside and outside angles made with a 90 degree angle, leaving the legs with uniform thickness. If you do not try to mill it to a different dimension, it will stay more or less straight.

Structural steel shapes do not stay straight if you mill a face, and the inside angle is never 90 degrees as purchased.

Larry

P

PeteM

Diamond
Joined
Jan 15, 2002
Location
West Coast, USA
  • Dec 14, 2015
  • #12

I've had pretty good luck with Finegrain's approach -- post #2; multiple vises. One variation is to clamp one leg of the angle in the vises, and then support the other leg with planer jacks to keep them from deflecting in the cut. I register the angle on the fixed jaw and use a soft wood shim on the moveable jaw to crush-clamp the tapered side.

Big aluminum angles (up to 6" legs) cut this way have stayed straight and square (used to extend a table of a 14" wood planer). Also have milled 4" steel angle this way to get rid of the taper on the inside of the legs and remove the scale, but more to fabrication tolerances.

redlee

Titanium
Joined
Apr 2, 2009
Location
Beaver County Alb. Canada
  • Dec 14, 2015
  • #13

Is Angle Iron available "Cold Rolled"?

A

adama

Diamond
Joined
Dec 28, 2004
Location
uk
  • Dec 14, 2015
  • #14

^ not sure about that large, but over here i can easily get it upto 50mm from th local supplier the further afeild ones website is always down over night.

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
  • Dec 14, 2015
  • #15

Check the head on the mill to be 90 degrees to the table vise.
Machine cuts should be taken with very small depth of cut.
Backing up the angle iron with wood or other scrap to avoid deflections.

S

stephen thomas

Diamond

Staff member

Joined
Jun 3, 2001
Location
downhill from Twain\'s study outside Elmira, NY
  • Dec 14, 2015
  • #16

Often use structural steel for machine elements and fixturing, and square up a fair amount of it. I like to start with stuff that is at least 3/8" thick, though, and 1/2" or thicker preferred. Usually longer than what you are considering, but similar ballpark.

I have milled it, in a couple vises, with planer jacks to resist spring under the cut.

Use heavy paper to protect vise jaws or angle irons from the first raw/rusty surface. It won't affect accuracy one whit, first cut which will probably spring a little anyway.

I prefer to run stuff like that on the planer, though. As long as you stop it from sliding, and put a little support under a wide angle, it takes very little to hold and machine on a planer.

smt

67Cuda

Banned
Joined
Oct 22, 2008
Location
West Coast, CA
  • Dec 15, 2015
  • #17

Home shop machinist question if I've ever read one here on "Practical Machinist".

Tom

Last edited:

M

matridium

Plastic
Joined
Sep 30, 2015
  • Dec 16, 2015
  • #18

67Cuda said:

Home shop machinist question if I've ever read one here on "Practical Machinist".

Tom

Yup and I did that so I can get more opinions on how to do this job.
Tolerance .010" out of this I will be happy. From what I can tell this material is Hot rolled.
I only need to make two of these angle irons flat. But now after reading many replies I can see the length will be an issue, so i have another idea to cut down to 4 angle plates 8" long and use them more like feet.
If you want o know why I am need these angle milled flat you can see my other reply on "home shop Machinist"
I do have two vises I have one 6" and one 5". I also have one 8" x 8" X 6" angle plate, and one 6" X 6" X 6" angle plate. I have about 18" max travel on my milling machine because of DRO scale. If I removed it I would have about 20"
I have some parts that will need to be bolted and the surface needs to be relatively flat.

thanks Mike

O

onecut

Hot Rolled
Joined
Jun 27, 2013
Location
england-newcastle upon tyne
  • Dec 16, 2015
  • #19

lf you did it the way I suggested-straddle mill the job,you will be maching the 4 faces in 2 passes.Will be square and if you wanted +/-.001 with no taper you would get it.Easy set up clamped to table-no need to butcher knee plates,its a simple job.You should already have table stops which are just bits bar machined to fit in your table slots-put 4 of these spaced out the length of your job and tap the job up against these-if you cant get the length of travel on your m/c go as far as you can,loosen the clamps(leave the cutter in posistion)Put your hand on job and hold it to stop it moving. Now travese your table along so you can get the extra length-tap job up against stops and reclamp and finish-Whats hard about that

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
  • Dec 16, 2015
  • #20

I have stood angle clamped to 123 blocks going long way on the chuck and cut the throw away off with abrasive wheel on the surface grinder. Then set flat on chuck to grind top of inside flat and with dished back of wheel the inside side of the short leg. Then clamped to 123 block to get out side of the short leg.
Grinding can seem slower than milling but because set up is so quick , accuracy so easy and with little stock to remove can some times be faster that milling.
Angle is full of stresses but should stay in .010 and can be ground true with going back for a skim.
Often made SG back rails and end bump rails of split angle..46 H to k is a good wheel running wet. With a 36 wheel and not looking for a super finish one can full wheel the job for very fast grinding.

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how to machine angle iron flat on all sides. (2024)
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