If your throughfeed moulder is not producing a quality product, here are some causes and solutions.

Snipe on the left side:

1. Created by the left side spindle and on the leading end of the part.
Probable causes: (1) Not enough pressure on the LSH chipbreaker. (2) LSH guide too far away from the cutterhead. (3) Un-square ends of stock. (4) Holdover rolls not holding stock against the right side guides. (5) Left side guide outside the cutting circle. (6) Right side cutterhead not set to the right side guide. (7) Bottom feed roll on the top roll shaft. Solutions: (1) Increase the chipbreaker pressure. (2) Adjust the left side guide towards the cutterhead. Be certain the knives do not hit the guide. (3) Adjust the chop saw to cut the ends square. (4) Adjust the infeed holdover rolls. (5) Check the setting of the left side guide to the left side cutterhead with a straightedge. (6) Check the setting of the right cutterhead to the right side guide with a straightedge. (7) Serrations pull stock away from the right side guide. Replace rolls.

2. Created by the left side spindle and on the trailing end of the part.
Probable causes: (1) The left side guide is not holding the stock tight. (2) The left side guide is not parallel to the RS guide. (3) The right side guide is not parallel to the referencing guide. (4) Chipbreaker is too far away from the cutterhead knives. (5) The chipbreaker is un-square with the bed. Solutions: (1) Check the setting of the left side guide to the left side cutterhead with a straightedge. (2) Realign the left side guide. (3) Realign the side guides. (4) Adjust the chipbreaker closer to the left side cutterhead. Do not permit the chipbreaker to hit the knives. (5) Check the chipbreaker for sliver, wear or damage. Repair or replace.

3. Created by the left side spindle and on either or both end of the part.
Probable causes: (1) Bowed stock. (2) A snipe from the right side can cause a snipe on the left side. (3) Both sides of the stock are not held down by the feed rolls (usually only with wide material). (4) Narrow stock. (5) Chipbreaker is hitting the feed roll when running narrow material. Solutions: (1) Feed stock into the machine with the bowed edge against the infeed guide. (2) Fix the snipe on the right side first. (3) Space feed rolls out across the width of the material. (4) When running narrow stock, set the guides and chipbreakers as close to the cutterheads as possible without hitting the knives. (5) Remove a feed roll across from the chipbreaker.

Snipe on the right side:

4. Created by the right side spindle and on the leading end of the part.
Probable causes: (1) The cutterhead is behind the right side guide. (2) The right side guide is too far from the cutterhead. (3) The infeed guide is not parallel. Solutions: (1) Check the setting of the right side cutterhead with a straightedge. (2) Adjust the guide towards the cutterhead. Do not permit the guide to hit the knives. (3) Realign side guides.

5. Created by the right side spindle and on the trailing end of the part.
Probable cause: The right side cutterhead is outside the right side guide. Solution: Check the setting of the right side cutterhead with a straight edge.

6. Created by the right side spindle and on either or both ends.
Probable causes: (1) Un-square ends of stock. (2) The right side guide is not parallel with the infeed guide. (3) The left side guide is not holding the stock tight. (4) The referencing cutter is not set to guide. (5) The infeed guide is out of parallel to the referencing guide. (6) The holdover roll is across from the right side cutterhead and not the referencing guide or infeed guide extension. (7) Bowed stock. Solutions: (1) Adjust the chop saw to cut the ends square. (2) Realign the side guides. (3) Set the left side guide to the material. (4) Check the setting of the reference cutter to the reference guide with a straight edge. (5) Realign the side guides. (6) Use the longer reference guide. Adjust the infeed guide extension. Adjust the holdover roll. (7) Feed stock into the machine with the bowed edge against the infeed guide.

Source: Mereen-Johnson. For information call 612-529-7791 or visit Mereen-Johnson.com.