Cleaning up an edge on a piece heavy steel plate

[simonl]

So I'm in the shed and the time has come to use a piece of 16mm plate that I've had for a few years. The 250mm x 1300 long plate was cut with oxy lpg and it was my first attempt so the edge is terrible.

After grinding most of the slag and dogs off (cutters don't like that stuff) I find a piece of reasonable sized steel that is reasonably flat and tack weld it to the plate roughly square to one of the sides. This becomes my reference to DI off to get it close to parallel on the mill.

I can edge mill about half the length at a time before I have to reset and re-clamp to the table after once again indicating from my reference bit of steel.

Ignoring the wear on the mill, I reckon I get it within about 10 - 15 thou of straight.

Anyone else know of a better way to mill the edge flat on a piece of plate that is longer than the working envelop of their mill?

Obviously I'm not talking micron accuracy here, just to neaten the edge up.

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[simonl]

Marrying up the two cuts can be a challenge but with a bit of "feel" and a final spring cut climb milling i can seem to blend in the two.

Also to save on milling cutters, I used a roughing cutter for this.

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[pipeclay]

Seeing that you have room to clamp, have you considered using machined blocks placed into your Tee slots and mounting your plate up against these, they only need to be snug in the slots and only a couple of inches long and only two would be required.

[simonl]

Hi PC,

Thats a much easier option if one of the long sides were straight.

On this particular piece, both sides were like a bread knife so impossible to use the opposite side as a reference.

Once I got one side done, I did pretty much what you suggested for the other side except I was a little lazy and just spaced the newly cut side from the edge of the table using 123 blocks.

Its worked OK.

Simon

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[Michael G]

On this particular piece, both sides were like a bread knife so impossible to use the opposite side as a reference.

Use some dowels or something as spacers to support the edge in two places, machine then turn and machine the other side.
Longer than your mill table could be tricky - maybe tack a bit of angle onto one edge to act as a pseudo straight edge, machine the other side then remove the angle, dress back the tacks and machine parallel to the previously machined sides.

Michael

[racingtadpole]

Use some dowels or something as spacers to support the edge in two places, machine then turn and machine the other side.
Longer than your mill table could be tricky - maybe tack a bit of angle onto one edge to act as a pseudo straight edge, machine the other side then remove the angle, dress back the tacks and machine parallel to the previously machined sides.

Michael

That’s what I did with an off cut of 10mm plate that was nearly twice the length of my table, except I used a length of flat bar. Worked really well.

[simonl]

Hi Michael & tadpole,

Yep that's essentially what I did. It worked well.

I just thought id put it out there in case others had a better method. Being a self taught machinist, I just never know if there's a better way.

Simon

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