Re: A Project for Tass

[Tom Droege <tdroege@veriomail.com>]

Ron,

How about making me a wooden form to try the dip stuff?  Just make it 4.5" 
in diameter and square at the end out of hard wood or plastic.  As Arne 
noted, put a step on the end so that the cap will stand away from the lens.

OK this means 4.5" diameter, then stepped to 4.3" diameter for the last 
1/2".  Say make it 6" long.  Drill a few 1/16" axial holes through it to 
allow me to get the mold off when it has cured.   I am not sure the tool 
stuff will work, but it seems worth a try.

Thinking about the problems of getting the hardened cap off, how about 
making it from several pieces bolted together.  One could then dip it in 
the tool stuff bolted together.  Then remove the bolts and pull the 
separate pieces out from the back side.  OK, how about making it from 9 
pieces.  Take 9 square posts and clamp them together.  Then turn the 
shape.  Now I have 9 pieces that make the shape.  I could hold these 
together with a couple of hose clamps and dip the end in the stuff.  When 
it hardens I could remove the hose clamps and pull the pieces out from the 
back side.

If you do this, I am sure you will have a better idea as to how to make the 
pieces so that they can be clamped together to make the form and then 
pulled out when the stuff has hardened.

Tom

At 10:41 PM 6/6/01 -0700, you wrote:
>hi Cary,
>
>i offered to make wooden caps, but the machined plastic caps sound way better,
>at least there's no concern about warping with moisture.
>
>so i'd be happy to pass the project to you.
>
>-ron
>
>
>On Tue, 5 Jun 2001, Tom Droege wrote:
>
> > Cary,
> >
> > Yep, I remember.  I believe that I just implemented your formula.  At 
> least
> > that is what the old correspondence indicates.  Possibly someone else sent
> > similar code, I don't really remember.  And I thank you very much for it,
> > if I did not before.  I always try to give credit.  At the moment, what 
> you
> > gave me seems to be working fine.  At least I was able to get it set
> > to  have the right coordinates for a star and still be right a month
> > later.  I think that is the acid test.  What more could I want?  Remember
> > this is throw away code since someone competent will do it right for the
> > real time code.
> >
> > As for the lens caps.  Ron Wickersham volunteered already.  I generally
> > just accept the first one to respond.  Possibly the two of you would like
> > to share the project?  Looking back I only replied to him, not the full
> > list.  Ron Wickersham <rjw@alembic.com> I am copying him with this.
> >
> > I sure don't want to discourage anyone with an  NC machine.  I am about to
> > go out for a few thousand dollars of machining for more camera heads.  In
> > general I don't ask people like you to do things like this.  This is just
> > work making a bunch of parts about which you don't have any say.  I 
> hope to
> > save you for something hard and fun for a fix.  Or something to improve 
> the
> > design.
> >
> > OK, I am about to go out for 15 more sets of camera parts.  TN-40 shows
> > these parts in some detail.   I am not too interested in improving things
> > at this stage as I have a working system.  So I know it would not be much
> > fun for you.
> >
> > Here are the parts with some description, and the price I paid.  The 
> prices
> > do not include a batch anodizing charge.
> >
> > Shutter servo bar.  Just a cut out plate of 1/4" Al.   This has the cut 
> out
> > for the servo motor.
> >   $12.00
> >
> > Middle Ring.  The round shell for the case.  It has one tapered end and a
> > step on the other.
> > $28.75
> >
> > Base Ring Plate.  Just the plate that covers the meander for the
> > cooling.  A rectangular 1/8" plate with 4 holes.
> > $6.00
> >
> > Lens ring.  Round with a square stepped hole to mount the 2" square
> > filter.  Has several steps and two flats to mount the Shutter Servo Bars
> > with tapped holes.
> > $72.00
> >
> > Base Ring.  This has the meander for the cooling channel and an "O" ring
> > groove.
> > $85.00
> >
> > Shutter Return Bar.  A shorter version of the Shutter Servo Bar.
> > $10.00
> >
> > Lens Mounting Plate.  A ring with 4 holes.
> > $12.00
> >
> > I am about to order 15 sets of the above.  Looks like it will cost 
> $3386.00
> > if the machine shop I use does not up his price.  I would at least be
> > interested in an opinion as to the price I am paying for machine shop
> > work.  These are probably not very interesting parts for you to
> > make.  There is the advantage that the drawings are pretty well proved
> > since this will be the third run for most of the parts.  If you are 
> willing
> > to review the parts and the cost I will send you a set of prints.  We are
> > currently updating the drawings so this is a good time.
> >
> > I am in no rush for this set of parts, so if you want to quote or donate
> > the parts (I am not really asking for a donation) it could be done at your
> > leisure.  As I say it does not look like a very fun way to 
> contribute.  But
> > the cost review would be useful to me.
> >
> > Tom
> >
> >
> > At 12:25 AM 6/5/01 -0700, you wrote:
> > >Ok...
> > >
> > >I'm the one with the CNC mill and I have been begging to donate to the
> > >project.  The local materials surplus house has had a supply of a nice
> > >machining plastic that would make excellent caps.  Let me see what I can
> > >turn up tomorrow morning.
> > >
> > >
> > >Also , remember  that code snip of Julian date algorithm that I sent you
> > >a few month ago?  Well, since then I've come up with a more refined and
> > >documented algorithm - Let me know if you're interested.  I also have a
> > >good sidereal time algorithm as well.
> > >
> > >
> > >-Cary
> > >
> > >Tom Droege wrote:
> > > >
> > > >  From time to time people out there volunteer to do work for 
> tass.  Here is
> > > > a project that a lot of you could do.
> > > >
> > > > I need lens caps for the tass cameras.  I have just not gotten 
> around to
> > > > making them.  What I thought of doing was to make a wooden form and 
> dip it
> > > > in the stuff you use to put a coating on tool handles.  I hope it 
> comes in
> > > > black.
> > > >
> > > > Any one out there want to make a form, and dip it in the stuff to 
> make 40
> > > > lens caps?  OK, if you are a machinist and have an NC machine you could
> > > > make them out of aluminum or something.  I will go for whatever works.
> > > >
> > > > If you are poor and can't afford to buy stuff (i.e. you are a 
> student or
> > > > young father etc..) I will buy the stuff that you need.
> > > >
> > > > The lenses are 4.48" OD.  I would make the caps 4.5"?  About 1" 
> deep would
> > > > be fine.
> > > >
> > > > Any takers?
> > > >
> > > > This just came up because I was trying to test MIKE and wished I had
> > > > something better than black cloths because I want to test the 
> motion and
> > > > the cloths will drop off in the process, shining bright light on 
> the CCDs.
> > > >
> > > > Tom Droege
> >
> >