[modeleng] Re: Milling Problem
- From: "Andrew Houston" <andrew@xxxxxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Thu, 3 Aug 2006 23:26:19 +0100
Lee
Maybe a red-herring, but I have had a similar problem when I forgot to lock
the unused axis after adjusting the cut. Milling cutter I was using was
1/2" so it just took a deeper cut.
Root cause. When cutting the "slot" - the initial cuts to full depth - with
a slot drill or end-mill the cut is "balanced" on both sides. When the
table is moved towards the cutter to widen the slot on one side, the nut is
hard against the feed-screw on the side away from the cutter. The back-lash
space between nut and screw is on the side towards the cutter, such that any
"grab" of the cutter will move the table towards it and increase the cut
depth. That's why that axis should be locked.
Problem will be much worse if the table gibs aren't adjusted or slide wear
has made the table "sloppy" or theres a lot of backlash in the table feed.
Of course, if the writer has used the table lock and is still getting a
problem, all I have said above doesn't apply.
Andy
-----Original Message-----
From: modeleng-bounce@xxxxxxxxxxxxx [mailto:modeleng-bounce@xxxxxxxxxxxxx]
On Behalf Of Lee Grant
Sent: 03 August 2006 11:01
To: modeleng@xxxxxxxxxxxxx
Subject: [modeleng] Milling Problem
I have just joined another new forum on a commercial web site and came
across this milling problem.
>>>>>>>" Hi, I have nasty and expensive habit of breaking end mills. The
last time, I cut a slot across a piece of 3/8" mild steel by making
progressive passes increasing the depth each time by traversing the work
piece toward me starting with the work on my side of the cutter. When I was
at the desired depth I needed to widen the slot so I moved the work piece
toward me clear of the cutter and traversed the work piece to the left so
that when I bought the work back toward me I would not be "climb milling".
Well as soon as the cutter hit the work it bit very hard and climbed around
the outside of the work piece, pushed it out of the way and destroyed
itself.
What am I doing wrong?
Arch"<<<<<<<
I thought that he may have been using a 4 flute end mill and plunge cutting
and suggested he try a slot drill or drop the end mill to the full depth and
then feed it side ways.
His reply
>>>>>>>>>"Hi Lee, Thanks for your reply. Actually I am approaching the work
from the side taking a full width cut each time until the desired depth is
reached. Then I move the work sideways and try to come back using the side
of the end mill and that is when the tool grabs (even with shallow cuts) and
climbs around the work. The has happened to me twice now with the same
disasterous result.
Arch"<<<<<<<<
Can anybody give me any better ideas. Or if you prefer the forum is at the
new MiniTech web site http://www.minitech.com.au/
Lee
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