Not perfect instructions, but here is what I did. Thanks also to the original poster Scott (aka dorkboy) for additional information and my neighbor Jeron for the tools and drilling.NOTE: All work should be done with the grinder unplugged! Since there may be variability in parts and grinders, be sure to double check everything listed on here yourself beforehand. This mod will likely void any warranty you may have.Analysis:
There are two possible conversions based on when your Macap M4 was manufactured. To check which you'll need to use, turn the empty grinder over and remove the 3 outer screws holding the bottom panel to the base. Look all of the way into the body to see how the motor is mounted to the body. There will either be 3 mount points (like mine) or 5 mount points (like the original poster's).
If you only have the 3 mount points, you will need to drill and tap holes to mount the worm gear to. If you have 5 mount points (only three are used, the other two are open), you should only need to drill holes in the case so that you can screw the worm gear into the unused mount points.The "3 mount point" (older revisions) conversion:
- #21 drill bit [needs to be verified, didn't write down at time of work]
- #10-32 tap [needs to be verified, didn't write down at time of work]
- thread oil (optional)
- small punch (we used a transfer punch as well as a center punch)
- small hex key (allen wrench) <need to check size and update post>
- small Phillips head screwdriver
1) Order from Chris' Coffee the Macap M4 stepless "conversion", which is ~$38 and includes:
1 x plastic toothed neck ring
1 x worm gear assembly which includes worm gear, 2 thumb screw covers and 2 screws
2) On the grinder neck, remove the 3 Philips screws holding the plastic neck ring to the upper burr assembly.
3) Remove the upper burr assembly by depressing the button and unscrewing it all of the way.
4) Remove the spring loaded "step lock" button (no longer used)
5) Replace the upper burr assembly. Just give it a few turns, no need to screw it in completely as we'll remove it again.
6) Place the new plastic toothed neck ring on the upper burr assembly, make sure it locks in place with the plastic tabs but no need to screw in yet.
7) Place the worm gear on the back center of the grinder body so that it matches up with the teeth of the new neck ring. The worm gear base should almost butt up to the inner metal circle. NOTE: The worm gear will completely cover the back body screw.
8 ) Center your drill points as much as possible and mark them with a punch or similar tool. The holes on the worm gear part are oval shaped, so there is some play if you are slighly off.
9) Once marked, remove the worm gear, toothed neck ring, and the upper burr assembly (so it's not damaged during drilling).
10) Using a punch and hammer, carefully punch the marked drill spots so the bit has guide points.
11) [Optional] Turn grinder over and remove 3 screws in base. Carefully pull the base plate out from under the grinder and set the grinder up right so the plate is on the side of the grinder. This is so any metal shavings don't end up in the wiring.
12) Using either a hand-held drill or a drill press and a #21 bit (VERIFY SIZES ON YOUR PARTS), carefully drill the holes into the grinder body taking care that the holes are straight. NOTE: The body is quite thick, nearly 1/4".
13) Use a vacuum, brush, magnet, etc... remove the metal shavings from the grinder.
14) Using a #10-32 tap and some threading oil, carefully tap the holes.
15) Again remove any metal shavings and also check the interior of the grinder body for any metal shavings.
16) Replace the upper burr assembly and the toothed neck ring. Secure the neck ring with the 3 small Philips screws.
17) Place the worm gear onto the grinder body and slide in to interlock with the toothed neck ring. Attach worm gear to body by using included bolts and a hex key to tighten.
18) Attach thumb screw covers to worm gear posts.
19) If you removed the base plate, reattach it now.
Test, dial in your grind, and that is it.The "5 mount point" (newer revisions) conversion:NOTE: I did not attempt this method, but the original poster did
You can follow the same basic instructions for the 3 mount point conversion, however you will need to align the drill spots with the existing threaded mounting points on motor body. To give your self some room for adjustments, you should use a larger drill bit than quoted as the thumb screws will hide the holes anyway.