Solving snipe issues on throughfeed moulders
Diehl Machines

Photo By Diehl Machines

What follows are troubleshooting tips for eliminating snipes on a finished part.

A snipe on the bottom of a finished part:
• created by the second bottom spindle and on the leading end of the part.
Probable causes: Cutterhead is set higher than the outfeed table. (2) Outfeed table is too far away from the cutterhead. (3) Lower infeed roll is too high. Solutions: (1) Check the setting of the cutterhead with the outfeed table with a straightedge. (2) Loosen the outfeed table and slide towards the cutterhead. Leave about 1/8 inch clearance between the swing of the cutterhead and the table. (3) Set the lower infeed roll 1/32 inch above the infeed table. (4) Check the setting of the first bottom cutterhead.

• created by the second bottom spindle and on the trailing end of the part.
Probable causes: (1) Cutterhead is set lower than the outfeed table. (2) Bed plate under the top spindle is too far away from the bottom cutterhead. (3) Lower outfeed roll is too high. (4) Long stock is unsupported after leaving the moulder. Solutions: (1) Check the setting of the cutterhead with the outfeed table with a straightedge. (2) Loosen the bed plate and slide towards the cutterhead. Leave about 1/8 inch clearance between the swing of the cutterhead and the bed plate. (3) Set the lower outfeed roll 1/32 inch above the outfeed table. (4) Place a table or conveyor under the stock to support it while it is leaving the machine.

• created by the second bottom spindle and on either or both ends of the part.
Probable causes: (1) Bowed stock was fed into the machine with the bowed side down. (2) Outfeed table is unlevel with the rest of the bed plates. (3) Deep snipe from the first bottom cutterhead. (4) The hold-down is not parallel with the bed plates. (5) Thin stock. (6) Snipe from the top cutterhead can leave the part loose. (7) Hold-down shoe is too short. (8) Unsupported pattern on the outfeed table. The pattern rotates to one or both sides. (9) Employee is lifting the stock to pull it out of the machine. Solutions: (1) Increase the depth of cut on the first bottom spindle; or increase the pressure on feed rolls and hold-down to flatten the part. (2) Check the shims under the outfeed table for equal thickness. Check for dirt or slivers of stock under the table. (3) Check the setting of the first bottom cutterhead. (4) Use a dial indicator to adjust the hold-down shoe. (5) When running thin stock, it is necessary to set the chipbreaker and hold-down shoes as close to the cutterhead as possible without hitting the knives. Thin stock finishes better if the ends are kept butted up. (6) Fix the snipe on the top first. (7) Slide the end of the hold-down shoe over the leading end of the outfeed table. Use a longer shoe. (8) Place a support on the outfeed table to prevent the part from moving. (9) Solve the feed problem. Place a table at the outfeed end of the machine.

A snipe on the top of a finished part:
• created by the top spindle and on the leading end of the part.
Probable causes: (1) Too little chipbreaker pressure. (2) Chipbreaker is too far away from the cutterhead. (3) Sliver is lifting the stock. Solutions: (1) Increase the chipbreaker pressure. (2) Slide the chipbreaker toe towards the cutterhead. Be certain the toe does not hit the knife. (3) Clean out the machine.

• created by the top spindle and on the trailing end of the part.
Probable causes: (1) Not enough hold-down pressure. (2) Hold-down is too far away from the cutterhead. (3) Excessive stock removal with top head. (4) Lower infeed roll is too high. (5) Chipbreaker is too low. (6) Bottom cutterhead is set lower than the outfeed table. Solutions: (1) Increase the hold-down pressure or lock the hold-down in place. (2) Slide the hold-down towards the cutterhead. Be certain the cutterhead knives do not contact the hold-down shoe. (3) Increase the depth of cut with the first bottom cutterhead and/or the first top cutterhead. (4) Set the lower infeed roll 1/32 inch above the infeed table. (5) Set the yield of the chipbreaker at 1/8 inch to the thinnest stock. (6) Check the setting of the cutterhead with the outfeed table with a straightedge.

• created by the top spindle and on either or both ends of the part.
Probable causes: (1) The hold-down is not parallel with the bed plates. (2) Stock may be bowed. (3) Unsupported pattern on the outfeed table. The pattern rotates to one or both sides. (4) Pattern is unsupported by the hold-down. The pattern rotates to one or both sides. (5) Long stock is unsupported after leaving the moulder. (6) Deep snipe from the first bottom cutterhead. (7) Thin stock. (8) Intermittent feed roll is too high or has too much pressure (only on machines with two top spindles). Solutions: (1) Use a dial indicator to adjust the hold-down shoe. (2) Run the stock into the moulder with the bowed face down. (3) Place a support on the outfeed table to prevent the part from moving. (4) Create a special hold-down for the part that holds the part down on both sides. Can be a counter-profile hold-down. (5) Place a table or conveyor under the stock to support it while it is leaving the machine. (6) Check the setting of the first bottom cutterhead. (7) When running thin stock, it is necessary to set the chipbreaker and hold-down shoes as close to the cutterhead as possible without hitting the knives. Thin stock finishes better if the ends are kept butted up. (8) Reduce roll pressure. Set the lower roll at 1/32 inch above the bed plate.

A snipe on the left side of a finished part:
• 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 (usually only on short 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.

• created by the left side spindle and on the trailing end of the part.
Probable causes: (1) Left side guide not holding the stock tight. (2) Left side guide is not parallel to the RS guide. (3) Right side guide is not parallel to the referencing guide. (4) Chipbreaker is too far away from cutterhead knives. (5) Chipbreaker is un-square with bed. (6) Infeed guide is not parallel with right side guide. 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. (6) Realign the side guides.

• 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) Slivers in the moulder. (5) Narrow stock. (6) 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) Clean the machine. (5) When running narrow stock set the guides and chipbreakers as close to the cutterheads as possible without hitting the knives. (6) Remove a feed roll across from the chipbreaker.

A snipe on the right side of a finished part:
• created by the right side spindle and on the leading end of the part.
Probable causes:
(1) The right side cutterhead is behind the right side guide. (2) Right side guide is too far from cutterhead. (3) Infeed guide is not parallel. Solutions: (1) Check the setting of the right side cutterhead with a straight edge. (2) Adjust the right side guide towards the cutterhead. Do not permit the guide to hit the knives. (3) Realign the side guides.

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

• created by the right side spindle and on either or both end of the part.
Probable causes: (1) Un-square ends of stock (usually only on short stock). (2) Right side guide is not parallel with the infeed guide. (3) Left side guide is not holding the stock tight. (4) Referencing cutter is not set to guide. (5) Infeed guide is out of parallel to the referencing guide. (6) Holdover roll is across from the right side cutterhead and not the referencing guide or infeed guide extension. (7) Bowed stock. (8) Both sides of the stock are not held down by the feed rolls (usually only with wide material). (9) Lower feed roll on the upper roll shaft. (10) Slivers in the moulder.  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. (8) Space feed rolls out across the width of the material. (9) Serrations pull stock away from the right side guide. Replace rolls. (10) Clean the moulder.

Source: Diehl Machines, a division of Mereen-Johnson. For information on Diehl Machines call 260-563-2102 or visit DiehlMachines.com.  For information on Mereen-Johnson call 612-529-7791 or visit Mereen-Johnson.com.

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