ADJUSTING THREAD RING GAUGE LOCKING DEVICE per ANSI
Item 1: Locking Screw
The locking screw is an extended shank bolt with a slotted head. The locking screw male threaded end screws into the internal thread of the adjusting screw. The locking screw shank fits inside of the sleeve. The locking screw head tightens against a shoulder machined into the ring gage blank.
Item 2: Sleeve
The sleeve is a short tube that works as a spacer and locating dowel. The sleeve fits over the locking screw shank and between the adjusting screw inner face and a shoulder machined within the ring gage blank.
Item 3: Adjusting Screw
The adjusting screw is threaded externally and internally and is
split longitudinally. The adjusting screw male thread screws into an internal screw thread machined into the ring gage blank. The adjusting screw internal thread accepts the locking screw male thread.
Item 4: Body
The body is the main part of the thread ring gage in which the thread
ring gauge threads are located.
Item 5: Adjusting Slots
The adjusting slots allow the thread ring gage body to flex as the
thread ring gauge is sized.
Item 6: Adjusting Slot Terminal Hole
The adjusting slot terminal holes allow the thread ring gage body
steel to be annealed near the major diameter to facilitate flexing
as the thread ring gauge is adjusted.
Item 7: Locking Slot
The locking slot functions similar to an adjusting slot during thread
ring gage sizing, allowing the threads within the body to be opened
To work with the locking screw assembly, remove the seal.
If sealing wax has been used, it can be dug out or melted out. If
hot glue has been used, it is easier to remove, but still needs
to be pried out.
After the sealing wax has been removed, unlock the locking assembly
by turning the locking screw to the left, counterclockwise, a few
The adjustments to the thread ring gauge body are made by turning
the adjusting screw. Turning the adjusting screw to the right, clockwise,
exerts pressure through the sleeve against the shoulder inside the
thread ring gage body assembly hole. The shoulder is visible on
the left hand side of the thread ring gauge body as shown above.
This pressure opens, or spreads, the thread ring gage body. Conversely,
turning the adjusting screw to the left, counterclockwise, reduces
the pressure through the sleeve against the shoulder inside the
inside the thread ring gauge body assembly hole. The reduction of
pressure allows the thread ring gage body to be closed, or constricted.
This opening and closing of the thread ring gauge body allows the
thread size to be adjusted.
Once the thread ring gage has been properly adjusted against a
truncated master thread setting plug gauge, the locking assembly
needs to be activated. The locking assembly is activated by turning
the locking screw to the right, clockwise. The tightening of the
locking screw exerts a pull between the shoulder immediately under
its head, and the internal threads of the adjusting screw. The locking
action is accomplished by the locking screw forcing the adjusting
screw to expand which forces the external threads into the threads
in the wall of the thread ring gage body. The thrust of this action
is absorbed up longitudinally by the sleeve. The clamping action
is accomplished by expansion of the adjusting screw equally in all
directions and not by the application of any eccentric forces that
tend to distort the thread ring gauge or upset the adjustment. The
locking pressure is taken up centrally in the locking screw itself
as the reacting support is directly under the head of the locking
screw in the form of the shoulder in the thread ring gage body.
A properly fitted sleeve serves as a dowel to maintain the alignment
of the thread ring gauge body.
To avoid tampering with the completed adjustment, either sealing
wax or hot glue needs to be used to cover and conceal the adjusting
This data is provided for general information only. The intention is to provide accurate information; regardless; errors may exist in the supplied information. If accuracy is critical, base your final decisions on the data provided in the root document: B47.1; which is a copyrighted document. To purchase a copy of an engineering document visit an Authorized Reseller.
Original Posting: March 2007
Last Revised: 12/3/2018
Refer comments/corrections to firstname.lastname@example.org.