Re: neutron detector rings (fwd)

[John Blackburn <jblackbu@uiuc.edu>]

Hi Peter,
Eric and I have finished your machining job for the n-det upgrade.

We tested the n-det holding fixture by suspending the ends of the aluminum 
channel and loading up a positioning tube with a large aluminum slug of ~ 
40 lbs.  The eight brass tipped set screws held the AL. slug steady even 
when Eric pounded the slug with a dead-blow hammer.  We are of the opinion 
that if the clamp rings do not exist, the eight brass tipped set screws and 
positioning tube will hold the n-det in place.  No one has told Eric or I 
if the clamp rings exist.   As it stands, 1-1/4" 5/16-18 Socket head cap 
screws are what we use to connect the positioning tubes to the AL. 
channel.  If clamp rings do exist, then the 5/16-18 Socket head fasteners 
should be replaced with countersink fasteners in order for the clamp rings 
to sit flush on the web of the channel.  If not replaced, the clamping 
rings will sit flush on the heads of the socket head cap screws and not the 
web of the channel.

On another note, do you remember when we assembled esc array?  We had to 
use washers as shims to increase the diameter of the esc array.  If I 
recall correctly, we used two 1/4 flat washers stacked together per 
detector element. This moved the esc array out by ~0.090 inch +- .014" on 
the radius.  In order to avoid using more washers when installing the new 
heavier detector supports, we should have the thickness of the washers 
machined from the PVC.  Using washers as shims might prove a bit tricky 
when installing the new heavier n-det detector support packages.

Thank you,
John Blackburn

At 02:31 PM 6/10/2005, you wrote:
>Dear John,
>
>You don't need to change the Autodesk drawing defaults. Just
>write somewhere, all positions should be within 200 um, or whatever
>you want to specify. The workshop simply does not know which
>precison is needed.
>
>We can ask concerning English taps and drills. If they don't have it
>we could send them from the US, but then it would be easier to change
>the drawings.
>
>With best regards
>
>Peter
>
>
>On Fri, 10 Jun 2005, John Blackburn wrote:
>
> > Hi Peter,
> > I use Autodesk Inventor default settings for dimensioning. I'm used to
> > knowing what types of tolerances I need when I do the construction 
> drawings
> > myself.
> >
> > BTW, NPL buys the tools to match the job, not change the job to match the
> > tools.
> > We buy metric drills and taps when we need them for a job.  Is it a 
> problem
> > to find sources of tooling for ANSI Unified specifications?
> >
> > Thank you,
> > John Blackburn
> >
> >
> > At 10:38 AM 6/10/2005, you wrote:
> > >Dear John,
> > >
> > >Thanks for your drawings. We looked at them and have
> > >only few requests.
> > >
> > >- Could you replace the 1/4 screws/threaded holes with
> > >   M6. They only have metric thread cutters and drills here.
> > >
> > >- Please specifiy the required tolerance of the hole positions.
> > >   Otherwise the Swiss workshop will try to achieve the last
> > >   signifcant digit on your drawing, which is not necessary.
> > >
> > >Please send the new pdf's to Francoise and myself.
> > >
> > >With best regards
> > >
> > >Peter
> >
>
>Peter Kammel  /  pkammel@uiuc.edu
>Department of Physics, Loomis Laboratory
>University of Illinois at Urbana-Champaign
>1110 West Green Street, Urbana, IL 61801
>Tel (217) 333-5424 / Fax (217) 333-1215