THE TABLET MACHINE.
THE GROUNDLESSNESS of the second objection to tablet making by retail
druggists, namely, the necessity of possessing expensive machinery, can
perhaps best be shown by the illustrations here given. The simplest
and yet practical form of tablet machine known to the author is the
"No. 25" machine of Whitall-Tatum Company of Philadelphia (Fig. 1). The
price of this machine is about ten dollars.
Its chief disadvantage is that it works rather slowly, as the powder
must be put into the die by hand with a small tool furnished with the
machine. An automatically feeding machine of reasonable price is the
"Eureka" Hand Tablet Machine, furnished by the F. J. Stokes Co., of
Philadelphia (Fig. 2). This machine may also be obtained for motor
power.
Detailed directions for the putting up and the use of these machines
seem unnecessary here as they accompany the machine when sent out by
the manufacturer. A few points on the care of the tablet machine may,
however, be brought out in order to save the novice trouble and mishaps.
All compressing machines for tablet making consist essentially of a die
and two punches, an upper and a lower. It is important that these be
kept scrupulously clean and free from rust, nicks and scratches; for
unless these parts be perfectly smooth it is impossible to get them to
work properly. When not in use, they should be kept completely covered
with vaselin or else immersed in liquid petrolatum, in order to protect
them against rust. When required for use, the grease is removed from
them as completely as possible by means of a soft cloth.
[Illustration: Fig. 1
A simple yet practical form of tablet machine.]
In putting the die and punches into the machine, it is best to put in
the lower punch first, making sure that it has been pushed completely
down into its socket. Then put in the die, so that the top of the die
be exactly flush all around with the table of the machine. See to it
that the face of the lower punch be exactly flush with the top of the
die when the punch is at its highest point. Then insert the upper punch
in its socket; and let it enter the die before locking it in place, so
as to insure perfect alignment.
[Illustration: Fig. 2.
The Eureka Hand Tablet Machine. An automatically feeding machine of
reasonable price.]
When die and punches are to be removed, take out the upper punch first,
then the lower punch and die, which may come out suddenly and be
injured by knocking against the upper punch if the latter be still in
place.
When particles of the powder stick to the die or punches, they should
not be scraped off with a hard instrument, as this is liable to
scratch, but should be wiped off with a soft, slightly moistened
cloth. To prevent sticking, a little talcum may be used, sprinkled over
the powder and lightly mixed by stirring with a spatula.
When the upper face of the tablet splits off, we speak of "capping."
To overcome this, ten per cent. of fat starch may be added to the
powder. Should "capping" still occur, the amount of fat starch might be
increased. "Capping" may also be due to the use of excessive pressure.
It may furthermore be due to die or punches being worn or damaged. When
this has occurred, the best thing to do is to get a new set of punches,
or to have the damaged one refinished by an expert mechanic, preferably
the makers of the tablet machine.
It would lead us beyond the scope of this work to give detailed
directions for making tablets of all kinds. A pharmacist who has
equipped himself with a tablet machine and has developed the ambition
to make a general line of tablets[7] may be referred to Mr. Joseph R.
Wood's book[8] on this subject.