no-go. Using my LMS mill measurements and #7 1/2 lead shot, assuming that
you could fill the column side to side (neglecting the rough finish for
minute), you could get about 2.45 pounds of lead per vertical column inch.
My column measures 18 5/8" from the top of the column to the pivot bolt at
the bottom. Assuming 11" of vertical head movement, that leaves you 7 5/8"
inches of vertical room for the weight, or enough room for about 18 3/4
pounds of lead. Even assuming a vertical head movement of only 8", you'd
still only be talking about a weight in the neighborhood of 24 pounds. If
you went to poured lead rather than lead shot, you'd improve that some, but
I don't see that it would be enough to do the job.
-----Original Message-----
From: GrizHFMinimill@yahoogroups.com [mailto:GrizHFMinimill@yahoogroups.com]
On Behalf Of Bill Williams
Sent: Sunday, January 22, 2012 10:21 AM
To: GrizHFMinimill@yahoogroups.com
Subject: Re: [GrizHFMinimill] Re: Counterweight Arrangement
Rob Potter wrote:
>
>
> Bill,
>
>
>
> That's an excellent idea. But it would take something with
> considerable density. In the system I've been working on I was
> planning on running a cable down through the column, through the bench
top, to a cluster of 4"
> PCV tubes arranged vertically. I'd been planning on filling the tubes
> with lead shotgun shot, which would give me the ability to precisely
> adjust the weight (I was going to use a cluster of tubes rather than a
> single tube so that I can keep the vertical dimension down). Looking
> at the volume of a standard 25 pound bag of lead shot, I'd guess that
> there wouldn't be room for 2+ bags (actually, the volume of same)
> inside the column - but that's such a good idea that I'll do some
> measurements and report back.
>
>
>
> In the meantime, another problem would be keeping an internal weight
> from rubbing against the sides of the column. Anyone have any ideas?
>
>
>
> Rob
Well Rob, I was actually considering how to counterbalance the head
on my Sears & Roebuck drill press! This has a tubular column that is
reasonably well finished inside. Having a good supply of lead on hand I
thought to cast a counterweight in the form of a cylinder that loosely
fitted the tube. This provides the additional advantage of a pneumatic
damper on the head movement! Since I have a floor drill press the travel
available is enough to allow for half the weight and double the travel!
The secret to this approach is in a thin, flexible, cable with enough
strength to do the job! I have not seen the inside of a minimill column but
I suspect that there might well be enough height to let a weight have twice
the head travel! Take some measurements and let us know!
Bill in Boulder
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