THE UNIVERSAL CASE TRIMMER
A metallic cartridge case will stretch after a number of firings and it then becomes necessary to trim it back to its proper length so it will chamber properly. The Lyman Universal
Case Trimmer accepts all U.S. metallic cases. To convert to another caliber you need only
change the pilot. Also included is an Allen wrench, which fits the lock screws in the adjustment rings and cutter head..
Mounting
The base casting is drilled so the trimmer may be fastened directly to the top of your
reloading bench. This is the recommended method of mounting. Some reloaders prefer to
clamp their trimmer in a vise when using it. If the trimmer is to be used in this manner,
Lyman recommends that it be fastened to a block of wood. The wooden block can then be
held firmly in the vise jaws without damaging the base casting.
Installing the Pilot
Loosen the lock screw on the case trimmer’s cutter head, open the package containing the
Universal Trimmer pilot and insert it all the way into the cutter head (see Figure 13). Now
tighten the lock screw.
Preparing the Cases
Before trimming, cases must be full-length or neck-resized and deprimed. Pilots are
designed to be used only with sized necks.
Measuring the Cases
You will need an accurate means of measuring case length. We recommend that a good
vernier caliper be used. When your cases have lengthened to the point where they exceed the
maximum case length allowable for your cartridge,
they must be trimmed. For a list of “Maximum
Case Lengths” and suggested “Trim-To Lengths”
see your Lyman Handbook.
Locking the Case in Place
Place the chuck lever in “open” position and slip
the head of your unprimed cartridge case into the
chuck head as pictured in Figure 14 (pg 38). By
pressing the rim of the case against the side of the
Insert pilot into
cutter head and
lock in place with
allen wrench.
Figure 13.
steel alignment ball, the case will snap into position
with the cams engaged in the extractor groove. Be certain the case is straight and that both cams are engaging
evenly.
Slide the cutter shaft in so the pilot enters the neck of
the case and cutter face is touching the case mouth.
Then, rotate the check lever to “lock” position.
Do not use excessive force when locking the chuck.
Slight thumb pressure on the lever is sufficient to hold
the case firmly. Leave the pilot and cutter in this position as you proceed to adjust the trimmer.
Adjusting the Cut
Two knurled adjustment rings, located on the cutter
shaft (see Figure 15). provide for both fine and
coarse adjustments. Before making any adjustments,
hold the large ring with your finger and turn the small ring counterclockwise, four full turns.
This will leave about 3/32" space between the rings and allow room for fine adjustment.
Make certain the cutter face is still positioned against the case mouth and slide the adjustment
rings in tight against the side of the base casting. Tighten the lock screws in the small ring.
Later models have a series of indicators each representing .001 inch of travel on the shaft.
Used as reference marks, they enable the user to return to an approximate setting for various
cases without time consuming trial and error testing.
Adjust the cut a little at a time, checking your case length with the vernier caliper after
each cut. When the correct “Trim-To Length” has been reached, tighten the lock screw in the
large ring.
Processing Your Cases
Once the trimmer is in adjustment, your entire lot of cases may be processed to bring them
all to the correct length. As you turn the crank handle, keep an inward pressure on the cutter
so that it is always bearing against the case mouth, but do not force it. Variations in finished
case length would likely be caused by inconsistent pressure applied against the cutter head
during the trimming process. If the case mouth sticks against the cutter head after trimming
either too much pressure is being used or the pilot is not installed firmly against the cutter
head. After trimming, small burrs will be present on the case mouth. These can be easily
removed from both inside and outside the case mouth with your Lyman Deburring Tool.
Keep a Master Case
When a reloader is working with several different calibers, it is wise to retain a master case
of the correct length for each cartridge.
This reduces adjustment time since the master case can be snapped into the chuck and the
cutter quickly brought into adjustment against its mouth.
Both fine and
coarse length
adjustments are
provided.
Half turn of chuck
lever locks case
firmly in place.
LOCK
Figure 14
Figure 15
Universal Case Trimmer (continued)
Maintaining the Trimmer
Powdered graphite or light oil on the cutting shaft will provide proper lubrication for
smooth operation. A light film of oil or grease will protect steel parts against rust.
Power Adapter Instructions
An optional adapter is available to quickly and simply convert your Universal Case Trimmer
to a power trimmer (Item #7862001). To install, first securely mount the case trimmer on a
bench or table. Unscrew the cutter head from the Universal Trimmer shaft and slide it out of
the trimmer body. Next, remove the cutter head from the Power Adapter and slide the Power
Adapter shaft into the trimmer body. Reattach the cutter head to the Power Adapter shaft.
Insert the hex shaft into the chuck of a hand drill or power screwdriver and tighten securely.
Make sure your power source is in line with the trimmer shaft. Install the proper pilot and
adjust the stop collars to the desired lengths.
Caution
1. Always wear proper eye protection during reloading.
2. Only use the trimmer adapter with electric hand drills or power screwdrivers operating
between 140 and 1000 RPM. Do not use with a drill press.
3. The power source should be supported during use so that the trimmer shaft is not bearing
the full weight.
4. Power use will cause more wear to the trimmer shaft and bearing than hand operation.
Occasionally lubricate the trimmer shaft with light machine oil.
5. Read and follow all safety and operating instructions supplied with your electric drill and
Lyman Universal Case Trimmer.
1 Trimmer Body 7994433
2 Cutter Head Assembly** 7822011
3 Stop Collar, Fine 7994416
4 Stop Collar, Coarse 7994417
5 Set Screw 8-32 x 1/8” (2) 7994418
6 Shaft Assembly 7994432
7Chuck Head Cap* 7994404
8 Compression Spring*(2) 7994410
9 Retaining Cam, RH* 7994409
10 Retaining Cam, LH* 7994408
11 Chuck Head Knob* 7994421
12 Chuck Head Base Only* 7994403
13 Pan Head Screw#6-32*(3) 7994428
14 Head Shaft Assembly 7994430
15 Hex Nut 9/16"-18 7125559
*These items may be ordered from Lyman
as a complete Chuck Head Assembly, 7994434.
** Replacements available in a two-pack, 7822203
Key Part Description Part #
Key Part Description Part #
Universal Case Trimmer (continued)
UNIVERSAL CASE TRIMMER
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