Subject: Re: So I went and bought a Drill-Mill (address correction)...

From: [email-masked] (Jhko)
Date: 26 Sep 1996 01:37:29 -0400

Oops, I must be getting old. The email address I listed at the end of my
message is wrong. My correct email address is: [email-masked],*not*
[email-masked] (joeo is my work email address, at a different URL). 

Thanks in advance for the help,

Joe Osborn
[email-masked]

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From: [email-masked] (Jhko)
Date: 25 Sep 1996 22:53:37 -0400

Well, after reading Marsh Collin's article in 'Projects in Metal' Magazine
about fixing up his new cheap Drill-Mill, I couldn't resist buying one. I
rented a U-haul trailer and drove the 60 miles to Rutland and bought one
(turns out it must be the same Taiwan manufacturer as his, as the Taiwan
manuals look identical, though his came from Enco).

Anyway, after much hard work moving the crate, unpacking and getting the
drill mill up on its stand, I put an indicator on a small magnetic holder
on the spindle and indicated about a 6" circle on the table. The front and
back readings on the indicator were within about .0003". However, the
right and left readings (3 and 9 oclock positions, facing the mill) were
off by about .0025". I read this to mean the column is tilting slightly
side to side. 

Anyway, Marsh in his article said that he "levelled the baseplate casting"
and put "a couple of shims at the base of the column", after which a dial
indicator swung on the spindle barely "flickered the needle". 

Well, my question is, should I do the same on my drill-mill, and is there
anything I should worry about, based on your experience? Do I just loosen
the four large painted screws on the base of the column (assuming I can
get them loose), cut a couple of little pieces of .0005 steel or brass
shim stock, tilt the column a bit and try to shove a little piece in the
gap until my indicator readings improve? And what about levelling the
baseplate casting? I've heard of levelling a lathe,  but does this really
make sense on a cheap drill-mill? 

Or, do I just thank the stars that my drill-mill is as good as it is and
not worry about it? Will this lack of accuracy really make a difference
building live steamers? (By the way, I indicated a 2" circle on my
Sherline mill, and it didn't seem any more accurate).

Anyway, any comments based on great experience would be appreciated.

Best Regards,

Joe Osborn
[email-masked]

(Member of the Golden Gate Live Steamers)

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From: Roger M Weppelman <[email-masked]>
Date: 26 Sep 1996 14:18:31 GMT

[email-masked] (Jhko) wrote:

I put an indicator on a small magnetic holder
>off by about .0025". I read this to mean the column is tilting slightly
do I just thank the stars that my drill-mill is as good as it is and
>(Member of the Golden Gate Live Steamers)

Translating your .0025 per 6 inches to a one inch end mill gives only .0004 
deviation from dead flat on the face and .0004 X(cut depth in inches) deviation from 
dead verticle on the side. I personally would never see the deviation.

But if you decide to shim, I would suggest that you check out the following before 
you start:

1. Does the deviation change when you unclamp and reclamp the head at the same 
postion ?

2. Does it change when you unclamp and reclamp at different positions ?

3. Does it change when the down feed is at different positions?

My guess is that all of these will have some effect on the deviation and that no 
amount of shimming will make it perfect at all positions all the time.

Let us know what you find.

Roger Weppelman

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From: [email-masked] (Jhko)
Date: 26 Sep 1996 12:28:28 -0400

Joe Osborn
[email-masked]

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From: [email-masked] (MGE INC)
Date: 27 Sep 1996 03:10:59 -0400

In message <[email-masked]>  [email-masked] (Jhko) wrote:

>about fixing up his new cheap Drill-Mill,

Where can I get hold of PIM Mag for this article?

-mike
[email-masked]

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From: [email-masked] (PnP Nolan)
Date: 27 Sep 1996 11:07:16 -0400

In article <[email-masked]>, [email-masked] (Jhko) writes:

>g

Well, Joe it will depend who you talk to about this one. I too, own a
Mill/Drill with about the same amount of column lean and I have left it
that way. You are talking about an error of 0.0025 in a 6" radius. That's
just over 0.0004 per inch error. There are *no* Mill/Drills that can hope
to achieve that sort of accuracy anyway. The error is in a direction where
it cannot compound enourmously due to the limited amont of travel in the
quill.

When you are using an end mill, unless you are boring straight down for a
good length, the lean will not make enough difference to worry about. The
run-out error you get from down milling with an end mill is more than your
0.0025 lean can cause.

Similar applies to using a boring head. If a truly perpindicular (better
than 0.0004/inch) hole is required then just set up the work piece with a
dial indicator.

The lean can actually be a benefit when using a 3" Fly Cutter. You can
take a deep cut with the leading edge being 0.00125 higher up than the
trailing edge. The trailing edge then follows along with a 0.00125 clean
up cut for a very nice finish. Admitedly you can only cut in the one
direction to achieve this effect but it is a small price to pay for a
rough and clean cut in the one action.

Now before someone leaps in and says, "but the finished surface will be
concave," let me say that indeed it will be, but by such a small amount it
would not be noticable. If a flat surface is that important you should be
surface grinding afterwards anyway.

As an apprenticed Toolmaker for many years, I can assure you that it is
common practice that one never trusts the machine to be 'true' in any
given sense. If it is important that something be exactly perpindicular
then you always set it up with an indicator. You never know who used the
machine last so you always setup according to what you are going to cut
and not where you hope the machine should.

Peter Nolan