UNIVERSAL POWER TRIMMER
Introduction
Because a metallic cartridge case stretches after a number of firings, it becomes necessary
to trim it to proper length so it will chamber properly. Your Lyman Universal Power Trimmer
is designed to do that chore with ease and precision. Its patented Universal chuckhead accepts
all U.S. metallic cartridge cases except .50/70 Government and cartridges of similar rim
diameter.
Conversion to another caliber is quick and easy, since you need change only the pilot. Be
sure to use the correct pilot for your particular caliber.
Additionally, your new Lyman Power Trimmer is capable of quickly and easily cleaning
primer pockets.
Included with your Trimmer are two cutter heads, two wire end brushes (large and small)
for cleaning primer pockets and a hex wrench (5/64") which fits all the lock screws on the
machine.
Caution
The Power Trimmer is not a toy
and is intended for use by or under
the supervision of adults. The
guards for both the cutter head and
primer pocket cleaning brushes
must be in place whenever you run
the Trimmer.
Operation Notes
The 110 volt Trimmer is fitted with a 3-prong cord plug which must be used in a grounded,
3-prong wall socket like most common electrical tools. Purchasers of the 220 volt Trimmer
must purchase and attach their own cord plug to insure said plug will fit into the given 220
volt wall outlet.
Once your Trimmer has been connected to an appropriate electrical supply, the motor’s
off/on operation is controlled by the rocker switch found on the frame under, and slightly
below, the cutter assembly.
For your safety, use the rocker switch to turn off the Trimmer and unplug it before changing pilots, cutters or steel brushes.
If your Trimmer hums, but will not run when plugged in and switched “On”, the motor
cover may have shifted in shipment and bound up the motor drive. Loosen the three cover
screws, realign the motor cover and tighten the three screws. Plug in and turn “On” to test.
Before trimming cartridge cases for the first time run the motor, with cutterhead in place,
for about one half hour. This allows the motor bearing to “break-in” and the cutterhead will
then deliver full torque for case trimming.
Your Power Trimmer is an end-cutting tool which, when in operation, may seem to have
an off-center condition in the cutterhead and pilot. This has no detrimental effect on the precision trimming of cartridge case mouths.
Mounting
Your Power Trimmer is supplied already mounted on a composite board. Using the board
as a base, your Trimmer may be fastened directly to the top of your reloading bench. Some
reloaders prefer to clamp their Trimmers in a vise and this composite board can be held firmly in the vise jaws without damaging the Trimmer’s casting. You may, of course, discard this
board, since it is part of the product packaging for safe shipment.
Installing the Pilot
With the unit unplugged, loosen the lock screw on the Case
Trimmer’s cutter head. Select the appropriate caliber of pilot and
insert it all the way into the cutter head (see Figure A). Now
tighten the lock screw.
Preparing the Cases
Before trimming, cases must be full-length or neck sized 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 an accurate
vernier, or dial, 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 or a similar reference.
Locking the Case In Place
Place the chuckhead in the “Open” position by turning
the ball handle counter-clockwise until it stops
Slip the head of your deprimed cartridge case into the
chuckhead cams and press the rim of the case against the
side of the steel alignment ball as shown in Figure B. The
case will snap into position with the cams engaged in the
cartridge case’s extractor groove. Be certain the case is
straight and that both cams are engaging evenly.
With the chuckhead lock still open, feed in the chuckhead shaft, with cartridge, so that
the pilot enters the cartridge case neck and the cutter face is touching the case mouth.
Tighten the chuckhead on the cartridge case by turning the knob handle clockwise.
DO NOT USE EXCESSIVE FORCE WHEN LOCKING
THE CHUCKHEAD.
Leave the pilot and cutter in this position as you adjust the
Trimmer. Please note that at this time the Trimmer has not
been turned on.
Adjusting the Cut
Two knurled adjustment collars located on the head shaft
assembly (see Figure C ) provide for both fine and coarse
adjustments. Before making any adjustments, hold the large
ring with your finger and turn the small ring counter-clockwise
four full turns. This will leave about 3/32 of an inch space
between the rings and allow room for fine adjustment. Make
Insert pilot into
cutter head and
lock in place with
allen wrench.
Both fine and coarse
length adjustments are
provided.
Power Trimmer (continued)
Figure A
Figure B
Fig.
C
certain the cutter face is positioned against the mouth of the cartridge case and slide the adjust-
ment collars in tight against the side of the Trimmer's base casting. Tighten the lock screw in the
small ring.
Beyond this point, fine adjustment is all that is necessary.
Fine adjustment is accomplished by turning the large collar counter-clockwise. One complete
revolution of the large ring equals approximately .020” change in cutting depth.
Latter 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.
Slide the transparent cutter guard into position and turn on the Trimmer using the Off/On
rocker switch. Loosen the chuckhead slightly and run the cartridge case mouth over the pilot.
Now tighten the chuckhead.
Adjust the cut a little at a time, checking your case length with your caliper after each cut. Do
not exceed the .010” feed capability per cut which equals a half-turn of the large collar.
When the correct “trim-to” length has been reached, tighten the lock screw in the large ring.
Processing your Cases
Once your Trimmer is in adjustment, your entire lot of cartridge cases may be processed to
bring them all to the correct length. Do not apply too much pressure on the knob handle. Use
only light pressure and let the cutter do the trimming. It is important that each cartridge case be
inserted onto the turning pilot while the chuckhead is slightly loose. This is to ensure optimum
case and pilot alignment. After alignment is achieved, tighten the chuckhead, apply light pressure
against the knob and trim your case.
After trimming, small burrs will be present on the case mouth. These can easily be removed
from both inside and outside the cartridge case mouth with a tool like the Lyman Deburring Tool.
Case lengths should be verified frequently to be certain no further adjustments are necessary.
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.
Keep a Master Case
When a reloader is working with several different chamberings, it is wise to retain a master
case of the correct length for each cartridge. This reduces trimmer adjustment time since the master case can be snapped into the chuck and the cutter quickly brought into adjustment against its
mouth.
Primer Pocket Cleaning
Cleaning of your primer pockets can be done quickly and easily using the small or large steel
cleaning brushes provided with your Power Trimmer. Before installing the appropriate size
brush, first turn off the Trimmer using the rocker switch and unplug it from the wall socket. Next,
remove the transparent brush shield and screw the appropriate diameter steel brush into the high
speed brush adapter at the rear of the trimmer. Tighten the set screw to secure the brush. Slide the
brush shield over the brush, plug the electrical cord into the wall socket and operate your
Trimmer with the Off/On rocker switch.
Power Trimmer (continued)
Caution
This high speed device cleans primer pockets quickly, with a light touch. It is easy to
enlarge primer pockets so don’t overdo it!
Maintaining Your Trimmer
Powdered graphite or light oil on the stop collar shaft assembly will provide proper lubrication for smooth operation and protection against rust. Keep the unit dust-free by covering it
when not in use. The electric motor requires no lubrication.
Changing the Cutter Heads
If it becomes necessary to change the cutter head, this can be done by simply unscrewing
the cutter head from the Power Trimmer in a counter-clockwise direction. Hold onto the
primer pocket cleaning brush on the high speed motor shaft while unscrewing the cutter head
in order to keep the motor from rotating. The hex wrench supplied for the cutter can be used
as a lever to break the cutter head loose by inserting it into the pilot set screw.
1 Brush Shield Tube 7994393
2 Sheet Metal Screw 7994389
3 Motor Cover 7994348
4 Wood Screw 7994361
5 Adapter Plate* 7994369
6 Electric Cord Set* 7994352
7 Cord Strain Relief* 7994381
8 Stop Collar Fine* 7994416
9 Stop Collar Coarse* 7994417
10 Steel Brush Small 7994360
10 Steel Brush Large 7994359
11 Brush Adapter Assembly 7994365
12 Socket Head Cap Screw* 7994386
13 Motor 110V* 7994378
13 Motor 220V* 7994379
14 Button Screw 7994387
15 Button Screw 7994385
16 Cutter Spindle* 7994373
17 Belleville Washer* 7994375
18 Oilite Bearing* 7994383
19 Chuck Head Assembly* 7994366
20 Stop Collar Shaft* 7994380
21 Bearing Assembly* 7994447
22 Set Screw 8-32 x 1/8 7994418
23 Nylon Ball 7990076
24 Cutter Shield 7994391
25 Cutter Assembly** 7822011
26 Ring Connector* 7994388
27 Chuck Head Knob 7994370
28 Fan 7994357
29 Solderless Terminal* 7994382
30 Roll Pin* 7994358
31 Rocker Switch* 7994392
32 Mounting Board 7994368
33 Trimmer Body* 7994371
34 Ball Knob* 7994390
Not Shown:Hex Wrench 2992876
* Factory Serviced Only
**Replacements available as a two-pack - 7822203
Key Part Description Part #
Key Part Description Part #
Power Trimmer (continued)
Power Trimmer
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