RE: [PSUBS-MAILIST] Lead Screw

[david cutajar <davecutajar@djcengineering.com>]

>From a "automation/machine designer/builder"
perspective, I like the lead screw system. I would use
a threaded rod parallel a shaft(or two depending on
weight of object being moved)(for anti-rotate of the
weight), cast the (lead) weight to any shape you want,
add a bronze nut and bushing during the casting
process.

McMaster has coarse threaded stainless threaded rods.
Get a multiple start thread for more speed if you
want.
You could load it up with lube & cover it with some
bellows. Stainless may not even be required.

I imagine it would be a very smooth operation, sturdy,
precise, with a small direct drive motor all it would
need would be a toggle switch for real nice control.

The chain /sprocket will of course work too, but seems
less professional and then you will have sag , or the
weight will have to slide on something etc. noiser
etc.

I may be biased, because chain / sprocket motion
regarded as "cheesy" for automation.

just my $.02

David Cutajar

--- Hugo Marrero <hmarrero@hboi.edu> wrote:
> Brian,
> 
> Also for submerged hardware, you can use aqualube
> (a.k.a. Gumby Cum). This
> stuff is pretty good, you can actually have a bolt
> submerged underwater for
> over a year and still will be ok.
> 
> Hugo
>   -----Original Message-----
>   From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org]On
> Behalf Of
> DJACKSON99@aol.com
>   Sent: Thursday, May 27, 2004 1:07 PM
>   To: personal_submersibles@psubs.org
>   Subject: Re: [PSUBS-MAILIST] Lead Screw
> 
> 
>   In a message dated 5/27/2004 11:04:39 AM Central
> Daylight Time,
> ojaibees@ojai.net writes:
>     Doug, can I get a stainless screw that is not a
> real fine thread? I
> think the fine thread could have a tendency to get
> stiff from debris
>   Brian
> 
>   Yes, if you google for "lead screw" or "ball
> screw" you'll find all types.
> www.mcmaster.com  stocks several varieties too.  But
> if your planning on
> using it in a wet environment I'm not sure a lead
> screw is your best
> solution.  I don't think it would take much sand to
> jam up any lead screw.
> The ones I have seen are always well lubricated and
> shielded when in unclean
> environments.  I have never seen one used submerged.
>  They do allow you to
> finely position a load, but being within 1/32" is
> not that important right?
> Someone suggested chain, and that is what I plan to
> use too.  The chain runs
> a loop from the drive sprocket to an idler sprocket
> and back.  I purchased
> some used stainless steel roller chain of eBay for a
> song.  But instead of
> relying only on the chain for the weight, you can
> use it to move a lead
> weight.  The down side is safety.  If a lead screw
> drive fails the weight is
> less likely to move, but if a chain breaks then both
> the weight and the
> chain are going to head down hill.  If anyone has
> experience with using
> "lead screws" in ocean like environments it would be
> helpful to hear your
> thoughts.
> 
>   Thanks
>   Doug Jackson
>   www.submarineboat.com
> 




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