Which cutter

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Which cutter

This topic has 8 replies, 6 voices, and was last updated 6 March 2019 at 19:41 by John Reese.

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5 March 2019 at 13:35 #398801
Peter Russell 4
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@peterrussell4
I have some bronze PB102 bar 1/2 in square that needs milling down to 7/16 square.

Its about 3 inches long

Ive previously tried with a 25 and 50 mm face cutter with indexable bits but it was a bit clunky.

What cutter would any one recomend and what approach ie diagonally across or start on one edge and work across the with or straight from one end to the other with a cutter wide enough to cover in one pass.
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5 March 2019 at 13:35 #9565
Peter Russell 4
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@peterrussell4
Milling square bar
5 March 2019 at 13:52 #398802
JasonB
Moderator
@jasonb
You could put some decent non ferrous tips into your face cutter that will make a world of difference.

Alternatively a small flycutter would make quick work of it and that is what I would most likely reach for.

If you want to use a milling cutter than 16mm or 5/8" 4 flute and one pass centrally along all 4 faces taking 1/32" off each. If you don't have that diameter than next one down and do it in two passes.

Edited By JasonB on 05/03/2019 13:53:02
5 March 2019 at 13:52 #398803
not done it yet
Participant
@notdoneityet
9/16" end mill would do. Even half an inch would suffice with one cut.

Your problem with large diameter face cutters is that the cutting edge is contacting the workpiece edge at near to 90 degrees. Smaller cutters will have an attack angle approaching a tangent to the edge(s) and thus produce less cross forces on the cut, thereby lessening the noise generated.

Edited By not done it yet on 05/03/2019 13:56:27
5 March 2019 at 14:35 #398812
Anonymous
Depends on the mill of course, but I'd grab a 5/8" or 3/4" endmill from the drawer; whichever size comes to hand first.

The other issue is the material. If it's cold drawn it'll go banana shaped if you skim one side. Best to stress relieve first – apply heat, let it soak for some minutes and then quench.

Andrew
6 March 2019 at 11:01 #398927
Howard Lewis
Participant
@howardlewis46836
Being cautious, I would not try to take off in one cut.

In this way, the noise / impact is less, and if the material does stress relieve itself, and distort, hopefully, the shallower finishing cut will remove the distortion.

With, hopefully, a flat face, now 1/16 shallower, this can be used as a datum to rough and finish the opposite face.

With two faces parallel to each other, these will hold the bar whilst the final two faces are machined.

A fly cutter set so that the tool only just overlaps the long edge of the material, and fed in gently, along the length of the material, may be the way to do the job.

Howard

Edited By Howard Lewis on 06/03/2019 11:03:53
6 March 2019 at 11:03 #398928
JasonB
Moderator
@jasonb
Would that not leave a bar less than 7/16" sq if you take 1/16th off one side and some more off the opposite?
6 March 2019 at 11:09 #398930
Howard Lewis
Participant
@howardlewis46836
Jason,

Sorry, was not clear. It needs only 0.03125" off each side.

I am thinking in terms of taking, say a 0.025" cut, measure, followed by a finish cut off one side, turn over and repeat on the procedure on the second side.

If you are worried about distortion, take a 0.020, and follow up with repeated small cuts to clean up to size.

Howard
6 March 2019 at 19:41 #398989
John Reese
Participant
@johnreese12848
If using a face mill or fly cutter bring the cutter into the work from the side rather than from the end. That will give a shallow angle of approach for the cutter and eliminate the banging.
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