How to fix an old-style Sun-Mar Excel NE toilet

The Sun-Mar corporation sells a line of composting toilets. In 1989 I bought an Excel NE non-electric composting toilet for my cabin. Sun-Mar redesigned the NE toilet in 1998 to make it rounder and to hide the drum rotating handle.

In 2011 the gear that rotates the drum broke in half. I was able to fix the toilet using some epoxy glue and a rigid coupling.

The gear is held on to the rod with a roll pin. The gear fractured along the roll pin hole as seen in these pictures:

The gear appears to be made of epoxy resin so I reasoned that some slow-set epoxy glue would put it back together.

Tools and materials

  • slow-set epoxy glue
  • stainless steel rigid coupling
  • pipe cutters
  • vice grips
  • emery cloth
  • bench vice
  • rubber band
  • allen wrench
  • cotton swabs

I bought a stainless steel rigid coupling from Amazon. It's designated "Climax ISCC-050-050-S 1/2 X 1/2" Bore 1pc Split 303ss Coupling".

Some of the parts and tools are in this picture. At the top are the slow-set epoxy glue, a pipe cutter, and a roll of 1" emery cloth. In the middle are the three pieces of rod: the end stub, the gear half with the gear reattached, and the handle half. At the bottom are the rigid coupling and the allen wrench:


  1. Remove the broken gear pieces and clean them thoroughly. I soaked them in a mild bleach solution for a few hours.
  2. Pull out the rod from the front of the toilet and cut it with some pipe cutters about nine inches from the gear's roll pin. I used the same pipe cutters I use for cutting copper pipe. The process is much slower on thick stainless steel rod but it does work. I used a pair of vice grips to grip the rod while rotating the pipe cutters.
  3. Pull out the handle half of the rod completely from the front of the toilet and remove the gear half of the rod from the inside of the toilet.
  4. The pipe cutting process makes a slight ridge on the newly cut rod ends. The ridge must be removed before the rod will fit in the rigid coupling. I fit the two rod halves into a bench vice and sanded the ends with emery cloth. Make sure that the handle half of the rod will slide into the rigid coupling when the gear end of the rod is already firmly attached to the rigid coupling. This is important.
  5. Practice fitting the gear pieces back together on the rod and roll pin. Mix up a batch of slow-set epoxy, thoroughly coat all fractured surfaces, and reassemble the gear on the rod and roll pin. I used a thick rubber band to keep the pieces together while the glue cured. Use cotton swabs to remove drips of glue. Slow-set epoxy takes 24 hours to cure completely.
  6. When the glue is completely cured, use the pipe cutters to cut a small piece rod from the gear end of the gear half of the rod. This is to make it possible to reinsert the rod into the back hole and reengage the gear to the drum. I cut 5/8" from the end leaving 3/4". You'll see that the rod is shiny right next to the gear because it has been rubbing in the back hole. You want to keep the shiny bit.
  7. Attach the rigid coupling to the non-gear end of the gear half of the rod. Tighten the screws firmly.
  8. Insert the gear end of the rod into the back hole and wiggle the coupling end until the gear reengages with the drum. This will seem difficult until it suddenly snaps into place.
  9. Insert the handle half of the rod through the front hole and further into the rigid coupling. Make sure the handle is pointing down and that the rod is properly against the drum lock. Tighten the screws firmly.

I made a mistake when fixing the toilet (details follow) and ended up having to use two rigid couplings. Here's a picture of the finished repair job:

Mistakes to avoid

  1. Do not use bolt cutters! I originally assumed that the rod was solid and used some bolt cutters to cut it. This left the ends badly pinched and I had to cut off an inch from each end in order to get reasonably round ends. I used a second rigid coupling and a two inch piece of solid rod to make up the gap.
  2. Do not try to take out the gear once it's been reengaged with the drum. While it's difficult to reengage the gear with the drum, it's much more difficult to take it out again. I had to use a large screwdriver as a wedge and risked damaging the gear and/or the drum.


Thanks to Mitch Coleman and Jim King for parts, help, and sage advice during this project.

Copyright © 2011 Richard Heurtley. All rights reserved.