I have no argument with the fact that it may be a good idea. Your
statement "In a drilling machine the MT arbor is in there so tight
as it never gets removed so it should not fall out." is not quite
true. Drilling machines do not just use drill chucks. Drills with MT
shanks are also used. In the course of a day the drill size may be
changed many times.
Certainly use a drawbar if you wish. The main problem is that some
people assume that the draw bar should be graunched up really tight
and this is not necessary, particularly with a drill chuck. Every
tightening means a loosening and with most MT mills that means a
thump on the drawbar and therefore a thump on the spindle bearings,
IMHO the fewer the better.
The only time the drawbar needs to be really tight is when using MT
collets to hold drills or milling cutters where the tightening
actually grips the cutter.
Richard
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?
Richard,?
I started all of this. All I am saying is in my milling
machine when I put in an MT3 arbor with a drill chuck for
"DRILLING ONLY" I use a drawbar because I think it's a
good idea.?
In a drilling machine the MT arbor is in there so tight
as it never gets removed so it should not fall out.
?Whereas in a milling machine I remove an arbor maybe 3 or
4 times a day and I don't tighten them tightly (just
firmly) to enable easy removal.
For safety reason I think I prefer it held by an arbor.
Dave
Borneo
Sent
from my Samsung device
-------- Original message --------
From: "Richard
edelec@... [7x12minilathe]"
<7x12minilathe@...>
Date: 19/07/2017 3:18 p.m. (GMT+08:00)
To:
7x12minilathe@...
Subject: Re: SV: [7x12minilathe] Taper size
?
Why oh why do people not read and understand what is
written before making comments!
The original post was in response to the statement that
a drill chuck should be held with an arbor in a milling
machine when drilling.
I stated that it should not be necessary as the drill
chuck should be held by the taper exactly as it is in a
drill press (with knock out MT).
At no point did I discuss using a drill chuck to hold a
milling cutter.
Hands up all the posters who use a drawbar to retain
their chuck in their tail stock.
Richard
?
Richard,
A drawbar is definitely needed in a milling machine.
Most end mills have flutes with a right hand helix
which exerts force in a downward direction which can
pull the end mill down and out if a collet. I have
seen jobs ruined such as blind pocket work and mill
tables scarred up by an end mill that drifted
downward. This happen most often to the
inexperienced and it has also happened to me until I
learned the hard way. Always use a solid end mill
holder of the Weldon type having a set screw on the
end mill flat held in by a draw bar. That is what
those flats are for besides preventing rotation of
the end mill in the holder. These holders are
available for all standard end mill shank sizes.
Of course there will be instances that prevent one
from using these holders but they are the exception
and not the rule.
Dick
