www.ModulusArms.com
January 14, 2016
www.ModulusArms.com | Heavy-Duty Universal AR-15 80% Jig Instructions
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Milling Rear Shelf:
The end mill should already be installed in the router. Move the base of the router
until the tip of the end mill is at the first line in slot “B” as shown in Figure 19. Place the router into the
opening labeled “B” and into the open cavity at the end of the opening as shown in Figure 20. Be sure
not to touch the sides of the opening when you start the router. Start the router and allow it to come
completely up to speed. Start to move the router removing material. Start by moving in a semi-circular
motion in small clockwise steps. Press down firmly to prevent the router from lifting. Do not try to move
the router in one straight direction but rather in smooth half circles removing small amounts of material
as you proceed. Join the drill holes and then start to widen the opening until you reach the template.
When you reach the template, trace the inside diameter of the template in a clockwise motion. Be sure
to remove as much material as possible before touching the template or tracing the template. Do not
push hard against the template. A gentle touch is enough. Mill the rounded corners in the template last,
as they are most likely to chatter. When the opening is the same size as the template turn off the router,
wait for it to completely stop and remove it. Adjust the router base so the end mill is at the next mark
on the depth gauge. Continue in this pattern until you reach the bottom of the depth gauge.
Note
: DO NOT INSERT OR REMOVE THE END MILL FROM THE TEMPLATE WHILE THE END MILL IS
SPINNING. THIS IS DANGEROUS AND THE MOST COMMON CAUSE OF BROKEN END MILLS OR
DAMAGED JIGS/LOWERS.
Note
: Be sure the end mill is very tight in the router. Tighten it as much as possible. Check
regularly
Note
: If the router begins to whine or vibrate during milling, turn the router off and remove it
from the template. Inspect the end mill and be sure there are no chips jammed into the teeth of
the end mill. If there is, use a tool to remove the stuck chips. A small screwdriver or pencil works
well. Be sure not to damage the teeth.
Note
: If you have a shop vacuum, use it. Run the vacuum whenever you are milling. If you do not
have a shop vacuum, stop regularly are remove the chips. If they build up, they can become
stuck between the end mill and the template and melt. This build up can be removed from the
end mill with sand paper. Use of a cutting fluid or WD-40 is recommended.
Figure 19: Rear Shelf Depth Setting
