Cutting a small I beam frim

[Chris HammondParticipant @chrishammond37041]

Hi all

I need to make a small i beam out of mild steel bar stock. (L) 700mm x (d) 20mm x (w) 15mm.

Would you recommend small cuts either side single pass with a roughing 4 flute, followed by a finishing cutter?

Or do a side to depth then flip it over? Worried about warping.

How do i get that radiused inner profile – with a ball nosed end mill? Any help much appreciated.

Chris

[Chris HammondParticipant @chrishammond37041]

[vintagengineerParticipant @vintagengineer]

I would use a horizontal mill or the same type of cutter in a vertical mill. It will give you a better finish. I would cut one side then the other and straighten it if needed.

[Chris HammondParticipant @chrishammond37041]

Thanks vintageengineer – I don't have a horizontal mill – I have a Chester Cobra hobby mill.

It has a long table though.

[Bill Davies 2Participant @billdavies2]

If it's bright mild steel, skim each face equally, possibly in a couple of passes, to get rid of the stresses in the outside 'skin'. It will still move a bit, so you might still, as vintageengineer says, need to straighten, but it would be much less.

I had a stab at making drilling vice many years ago, cutting out the central section on a horizontal mill without skimming the outside, and was amazed how far the work 'moved' when I removed from the vice.

Bill

[John ReeseParticipant @johnreese12848]

Shars sells corner radius end mills. I assume Shars sells in the UK.

[John ReeseParticipant @johnreese12848]

I wrote this in another post:

If I were making the I beam I would use a long bar for a fixture, Cut a groove to accept the raw material, grub screws on one side to force the stock to one side of the groove. Provide hold down clamps at intervals to hold the material against the bottom of the groove. Move the hold downs as needed to let the cutter pass.

The traditional I beam has a 1:6 taper on the inside of the flanges. Newer wide flange or H sections have parallel flanges. If you want to do the tapered flanges you will need a form tool as your mill can not nod the head. If you know someone with a Deckel style tool grinder it would be quite simple make a single lip form cutter out of a drill blank. Cut the groove with a standard end mill and finish the flanges with the form tool.

I hope this was helpful.

[JasonBModerator @jasonb]

I would use hot rolled (black bar) for what you need 16mm square would be about the smallest section to start with.

First get rid of the scale by leaving it in brick cleaning acid from builders merchants for 1/2 – 1 hour until the scale has flaked off. reason is the scale will blunt cutters.

Make up a fixture as described above and first rough down to overall size taking alternate passes off opposite sides.

The rough out the groove followed by finishing cuts.

Radius corner cutters are easily made from an old cutter that has started to blunt, just grind a small radius on the corners freehand and away you go. You can also buy tapered milling cutters that could also have their corners knocked off. I often use this method when fabricating or cutting from solid when I want to simulate cast or forged parts. The fillet around the oval flange and also the cylinder end flanges show a fillet formed like that. There really is no need for fancy grinders and exact grinding.

One other option for the tapered flanges if you don't want to get or make a tapered cutter is to simply tilt the work (and fixture) by the required angle which is easily done by adding a packer under one side

This is setup for a 3.6degree taper you would just use the side of the cutter against the flange rather than cut the bottom.

J

 

Edited By JasonB on 17/01/2017 07:53:39

[Chris HammondParticipant @chrishammond37041]

Thanks all, this is most helpful stuff. I appreciate you taking the time to reply.

[Chris HammondParticipant @chrishammond37041]

Anyone know of a reasonably priced stock supplier for smaller sized stock? Or would somewhere like eBay be a better bet?

Thanks.

Edited By Chris Hammond on 17/01/2017 09:08:57

[JasonBModerator @jasonb]

I use this e-bay seller for black bar etc

M_Machine also do black bar and many other ME materials

[Chris HammondParticipant @chrishammond37041]

Thanks Jason.

[Author]

Posts