The head itself weighs about 160 lbs so unless you have a mechanical advantage with a pulley arrangement, this is what the joist would see. Maybe I’m missing something?
Ollie
From:
Sent: Friday, January 20, 2012 2:41 PM
To: grizhfminimill@yahoogroups.com
Subject: RE: [GrizHFMinimill] Re: Counterweight Arrangement
The weight to balance the head cant be much above 50lb which should not be a problem provided you have a secure fixing to a joist. If you are worried you could always put in a spreader across a couple of ceiling joists to share the load#
Gerry
Leeds
To:
From: ofick@bendbroadband.com
Date: Fri, 20 Jan 2012 13:41:36 -0800
Subject: RE: [GrizHFMinimill] Re: Counterweight Arrangement
Be careful. Ceiling joists are only designed to support the weight of the dry wall and insulation. They are not designed to hold
Ollie
From:
Sent: Friday, January 20, 2012 1:37 PM
To:
Subject: [GrizHFMinimill] Re: Counterweight Arrangement
Hi Roger,
Thanks for the comments. As far as a pulley arrangement, I'd have to run a cable straight up to a ceiling joist if I wanted the lifting force applied at the spindle end. I wouldn't be able to use David's slick semi-hidden version inside the vertical column. Over the weekend, I plan to play, I mean do a controlled scientific experiment, to see if there any advantage to my idea. One big drawback is an overhead cable will get in the way, versus David's semi-hidden version. It could be that my cure is worse than the disease, especially where David says he is very pleased with his results. I will find out this weekend.
Regards,
Karl
--- In GrizHFMinimill@yahoogroups.com, "Roger Blair" <Roger.Blair@...> wrote:
>
> Karl,
>
> (IMHO)
>
> Issue 1.
>
> To compensate some for gib play, attach the counterweight near the spindle end of the head, and ensure that it is heavier than the
> head weight enough to hold the spindle/tool in the same angular position as when the tool loads into the work. (eliminating slack
> motion)
>
> Issue 2.
>
> In theory, adding a second pulley at or near the spindle end of the head will introduce a much greater moment arm on the vertical
> column than from the center of David's single roller to his attach point, and the higher the head position is on the column, an
> extended arm will cause the column to bend more. If there is a measurable effect, only stiffening the column will correct for that.
>
>
>
> Roger
>
>
>
> From: GrizHFMinimill@yahoogroups.com [mailto:GrizHFMinimill@yahoogroups.com] On Behalf Of kr98664
> Sent: Thursday, January 19, 2012 02:09
> To: GrizHFMinimill@yahoogroups.com
> Subject: [GrizHFMinimill] Re: Counterweight Arrangement
>
>
>
>
>
>
> Hi David,
>
> I like your idea to use a nylon strap, especially how well the bend radius compares to the more typical steel cable. I had already
> been planning to do that.
>
> While brainstorming the installation, I got to wondering if there was anything to be gained by applying the lifting force at the
> spindle end, away from the gibs. There will always be some amount of play as the head rocks up/down on its gibs, so I'd like to take
> out as much play as possible by lifting the spindle end of the head. Granted, the pulley arrangement would no longer be as clean and
> simple as your design, so there would be a trade-off.
>
> --- In GrizHFMinimill@yahoogroups.com <mailto:GrizHFMinimill%40yahoogroups.com> , "a3sigma" <dcclark111@> wrote:
> >
> > Hi Karl,
> >
> > My counterweight scheme continues to work very well for me. See my files at:
> >
> > http://groups.yahoo.com/group/GrizHFMinimill/files/D.C.%20Clark%20stuff/
> >
> > Note also my thrust washer file. I have several sets remaining, and my offer still stands to give a set to any member who sends me
> a SASE. Email me off list for my address.
> >
> > David Clark in Southern Maryland,
> >
> >
> >
> > --- In GrizHFMinimill@yahoogroups.com <mailto:GrizHFMinimill%40yahoogroups.com> , "kr98664" <kr98664@> wrote:
> > >
> > > Hello All,
> > >
> > > I've been looking at options to minimize the Z-axis drop on my Micro-mark mill. I've read plenty about gas lifts and
> counterweights. In both cases, the upward force is close to the vertical column. No matter how well the gibs are adjusted, any play
> is magnified and the spindle end can still tip down a tiny bit.. My thoughts are if I apply the lifting force (via a counterweight)
> near the spindle, this will practically eliminate any Z-axis play, even more so than a gas spring or counterweight nears the gibs.
> > >
> > > Any thoughts? Am I out in left field?
> > >
> > > Thanks,
> > >
> > > Karl
> > >
> >
>
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