Max 890s coil nailer does not advance nails when operated.
The gun has been serviced by two different tool repair shops but never fixed.It will fire a nail,if you pull the trigger one shot at a time,about every 4th shot.If you just hold the trigger it will fire the first shot but not advance the coil of nails any further.Any suggestions before I toss it away?
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Try ez test to check for proper operation. Remove nails and air supply, point nose of gun up then down again. The driver should not move from the top of cylinder position. If driver is moving up then down replace the driver oring. If driver oring seems ok then connect air supply and bump fire the nailer without nails against soft wood and door open so that you can see the driver and feeder moving. Bump fire the gun and make sure that the driver is moving all the way back up to top of cylinder and the feeder is moving rapidly back and forward. If movement seems ok then hold the nose down on soft wood and depress and hold the trigger. This will fire the gun but driver will stay at the bottom position and not return until you release the trigger or lift the gun. When holding the gun with the driver down position, no air should leak out the top or bottom of the gun. If air leaks out bottom, replace lower bumper, if air leaks out the top replace the upper bumper. Good luck
Some trigger valves (tva6) are sensitive (defective?) however there are some things you can try to change how the gun acts. I have noticed that the brand of oil has an effect on the orings. Some brands will swell the orings, I like Paslode nail gun oil. Do not wash the gun with gasoline or wd40. Use diesel. Change the nail depth setting one position. Lowering the air pressure will make a difference. I find that most operators use too much pressure. A stronger safety spring under the trigger will separate the trigger and firing pin quicker. Finally you could use single fire trigger. Good luck
There is no adjustment that can be made to make the safety work or not. When new, the SCN45 had a safety system that prevents the nailer from firing unless it was pressed against a surface. If your gun fires without the safety being compressed, it has somehow been bypassed either by being jambed or tied in the firing position or the trigger lever is wedged so it can't operate properly. Below is a site that has a great breakdown of your tool that you can reference to see what parts may be missing. This is an older tool and many parts are no longer available. Senco SCN45 Coil Nailer Parts
If no air is leaking from gun, miss-fire is usually caused by worn or too tight piston oring or lack of lubrication. Easy test. Disconnect airline, remove nails, point nose of gun up then down. Driver should stay in uppermost position. If driver moves up then down within gun replace piston oring and retest. Set pressure to about 100psi. Good luck with repair.
check the fuel cell first, there is an expiration date on the bottom and out of date fuel can cause a problem. As far as repair it depends on where you are located. You can try going to somebody like Lowes or Home Depot and asking them or look in your phone book under tools repair for a local service repair center that might be able to fix. If you are around Ohio I can help you with the problem.
Nailers that use strips of nails (one nail directly behind the other) will sometimes drive two nails at once and is caused by damage to the driver. The nails are so close together that the driver will hit the first and part of the second nail head. Coil nailers, as your an451, use nails seperated by welded wire making it very difficult the the driver to hit the second nail. Usually when a coil nailer shoots two nails, it is acutally the trigger valve that acutates twice (two very rapid fires). Two very rapid fires is caused by faulty trigger valve. I have seen a roofing coil nailer fire one nail and a second nail drops out of the gun. Caused by weak / malfunction of nail feeder or wire used to weld nails together is too thick.
if u are right nails for gun,then make sure when u put coil in and feed in front of firing pin the nails are straight with pin and connecting wires are not bent causing nails to fall out of alingnment.
Your nailer shares design features with Milwaukee and Ridgid. All three brands experience the same issue. Lets go thru a series of simple tests to determine the problem. First and most simple test, manually load the nails and fire the gun untillmiss-fire. Upon mis-fire disconnect air, open latch and check if the driver is all the way up into the cylinder or is partially down blocking next nail. If driver is down blocking next nail, replace the driver oring and retest. If driver is up all the way, remove nails, reconnect airline, leave latch open and fire gun against rubber (old tire or coiled up waterhose/airhose) this time holding the gun down and keeping the trigger depressed. In this position, the driver will remain down and feeder will remain retracted. With feeder retracted and screwdriver in hand carefully check the spring tension on the feeder (should be rather firm tension on spring and the feeder must retract with good force). If no tension or weak, replace feed spring. When you finally release the trigger, the driver will retract and the feeder should return with good force. If feeder does not return with force, replace orings and spring behind feed piston. If all tests are ok, remove head, check lower bumper in gun for cracks or missing pieces. Replace as necessary. Lube all orings with silicone lube available at Lowes in the plumbing department. (Danco brand) Good luck on your repair and email your questions.