As far as my ceiling joists, I'm in a basement shop with 2x10 joists supporting the floor above. If adequately secured, I don't think the extra weight of a counterbalance system would be an issue. With that said, one thing I quickly learned is that a vertical cable near the spindle would drive me nuts. I started rigging up a mock-up but quickly decided an overhead counterbalance cable is not my cup of tea.
I also learned that with properly adjusted gibs, it didn't really matter where I applied the lifting force. I rigged up a dial indicator and the amount of drop never changed.
This leads me back to how best to limit the head drop. I liked the nylon web and weight arrangement, as that is well out of the way and dead simple. However, I'm toying with filling the vertical column with some sort of potting compound for extra rigidity, so I don't want to run anything inside the column. This also rules out the LMS airspring kit.
Based on current wind conditions and my medication level, my plan du jour is to run an external gas spring on one side, as previously mentioned in this discussion.. At first I was leery of this, thinking this side force could cause trouble. Then I realized this new twisting motion might be beneficial. By trying to rotate the head side-to-side, this will put some extra tension on the gibs, and possibly help limit head drop even further. That's my theory, anyway, and it makes me happy to think so. (I'm in my happy place now, and am not sure I want to leave.)
Stay tuned for eventual updates.
Karl
Karl
--- In GrizHFMinimill@yahoogroups.com, gerry waclawiak <gerrywac@...> wrote:
>
>
> 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 UK
>
> To: GrizHFMinimill@yahoogroups.com
> From: ofick@...
> Date: Fri, 20 Jan 2012 13:41:36 -0800
> Subject: RE: [GrizHFMinimill] Re: Counterweight Arrangement
>
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> Be careful. Ceiling joists are only
> designed to support the weight of the dry wall and insulation. They are not
> designed to hold high point
> loads. This is what has discouraged me from using the ceiling joist option.
>
>
>
> Ollie
>
>
>
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>
>
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>
>
> From: GrizHFMinimill@yahoogroups.com [mailto:GrizHFMinimill@yahoogroups.com] On Behalf Of kr98664
>
> Sent: Friday, January 20, 2012
> 1:37 PM
>
> To: GrizHFMinimill@yahoogroups.com
>
> Subject: [GrizHFMinimill] Re:
> Counterweight Arrangement
>
>
>
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>
>
> 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, USA
>
> > >
>
> > >
>
> > >
>
> > > --- 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
>
> > > >
>
> > >
>
> >
>
>
>
> size=1 width="100%" noshade color="#a0a0a0"
> align=center>
>
>
>
> No virus found in this message.
>
> Checked by AVG - www.avg.com
>
> Version: 2012.0.1901 / Virus Database: 2109/4755 - Release Date: 01/20/12
>
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