[ Mark Haas wrote in 180610 MMDigest:

> I am currently restoring an Ampico B and the grid has degraded beyond
> any usability.

Mark Haas inquired about the availability of replacements for the
frequently deteriorated celluloid grids of the Ampico "B" pump spill
valve.  I have, for several years, been replicating these for my own
use using 3D printing technology, and am willing to make them available
to the wider community.

I have tried both of the two main materials used in the FFD (Fused
Filament Deposition) process, PLA and ABS plastics and find that either
give satisfactory results.

Many people (including myself) have a general aversion to "plastic
parts" which fail us all-too-often.  It is well to remember that
celluloid itself is one of the earliest plastics to be developed,
unfortunately, it does not age well, particularly when exposed to
various environmental conditions.

First developed in 1948, ABS plastic has a much better performance
and longevity record, and should last at least as long, and probably
much longer than celluloid.  See
https://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrene 

For those interested, a comparison of ABS and PLA for 3D printing can
be found at http://3dinsider.com/pla-vs-abs-plastic-pros-cons/ 

If Mark hasn't found it yet, he will eventually find that the same
[celluloid] material, with the same faults, was used in the "B" pedal
regulator curtain valve.  I also replicate that grid.

I also developed the digital files to replicate the grids in the
expression regulators (the ones with the round holes) but I have not
needed to replace any of these as they seem to survive in better shape
than the pump and regulator grids.  I don't know if this is because the
chemical formulation of these is different, or because they are better
protected in the interior of the regulators and are under somewhat less
stress.  Interested parties can message me privately for details.

John Grant

 [ Spill Valve Grid
 [ http://www.mmdigest.com/Attachments/18/06/12/180612_000347_Spill_Valve_Grid.jpg