Bruce in Bangkok wrote:

One Idea is to modify an existing set of rolls, actually used for
softening dried squid. The have brass rolls about 1-1/2 inch in
diameter, about 8 - 10 inches long, with quite deep serration but the
separation between the rollers is adjustable and I am considering
modifying one of these by adding a hopper to direct the grapes into
the rollers and a mount to hold the thing on the side of a barrel.


That sounds like a very good starting point.
Brass is used in a lot of pumps used by small wineries and home
winemakers. The large production operations sometimes try to reduce
their exposure to it, because traces of copper can inhibit the
fermentation. Copper's activity as a fungicide is the reason to try and
reduce exposure to the metal when trying to ferment. However, brass and
bronze have been used for a long time in the wine and juice industries.
You would not be adding copper if there is no wear or contact
between the rollers or other metal parts.
The serrations are almost a necessity to keep the berries feeding
through the rollers consistently, otherwise, you will have to apply
pressure on the fruit to keep it feeding between the rollers on
occasions. It is real common for the screw augers feeding the large
crushers, to bridge, when too much unstemmed fruit enters the hopper.
No matter what the size of the unit, it works best if you can feed it
progressively and control the amount of fruit going through the rollers.
The hopper of my antique crusher was made from hardwood. A lot of the
hoppers on crusher frames sold to home winemakers and used on some
crushers throughout the industry are fabricated from mild steel and
coated with a food grade paint.


What are you using for a press? Are you pressing straight off the
crusher? Or, are you fermenting on the skins and then pressing?

Russ