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Re: jammed makita an923 nail gun
On most all nailguns when the trigger is activated air pressure is released from the headvalve causing the headvalve to open and fire the piston. If air leaks through the headvalve orings or through the headgasket port to headvalve, it will not fire. Try applying light grease to headvalve orings and make sure that headgasket is sealing around vent hole. If it fires then replace orings in headvalve for long term repair. Secondary problem is worn safety parts and trigger or trigger pin. If these parts are worn the trigger will not push the trigger valve pin all the way in when you bump fire the gun. With air supply disconnected, apply pressure to safety while depressing the trigger and check thet the pin is moving all the way into the trigger valve. Adjust or replace as necessary. Enjoy
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Most nailers have two types of triggers available. One is a bump fire and the second is single shot that is activated by releasing the trigger, placing the contact foot against the work, then depress trigger. Bump fire trigger May fire two nails if you place then depress. Check your parts manual to determine which trigger is installed. (Some brands have built-in switch to activate bump) good luck
Double fire is usually caused by trying to use a bump fire trigger system as single fire (place on work then pull trigger). If however the gun double fires when bump firing, replace the trigger valve. Some nailers have the ability to select bump or single fire. The selector for bump or single fire is usually on the trigger or just above or below the safety actuator. Other brands offer different triggers available as a part number.
When trying to determine what nail to use, look for the model number of the nailer. Letters associated with the model number will give you a clue. Example; the letters RN in the model number indicates Round head Nail. The angle of the nail is easy to determine. Just measure the angle formed by the path of the driver and any straight line of the rails.
Most nailers have a two position setting on the trigger to allow for single fire or bump fire. If set on bump fire, the gun will work better when you bump fire the gun instead of placing the gun on the work then depress trigger. Bump fire works best when safety spring has good tension. Easy test. Make sure that the safety spring is in place (with air hose removed, contact foot should spring back quickly when pushed against work). With air connected, hold trigger and quickly bounce the gun against the work. If the gun does not fire when you bump, the trigger is most likely set to single fire. With trigger set to single fire, you must place the gun against the work, then depress trigger. If the gun shoots two nails while set to single fire, most likely worn trigger or worn out trigger valve. These parts are not expensive and are easy to replace. Good luck
If the trigger is set to single fire, you will need to place the gun against the work then pull trigger as you have done. Try setting the trigger to bump fire and try again. If hear a thump inside the gun, remove the head and check that the head valve in not stuck from lack of lubrication. Easy test, remove the nails, remove trigger pin, remove trigger and manually push trigger firing valve. If the gun fires then suspect faulty trigger or safety arm not lifting enought to activate the trigger valve. Good luck
Assuming that you are using the correct nails. This will usually happen if you have bump-fire trigger and are trying to place the gun on the work then pull trigger. Replace the safety spring if weak and bump-fire only (spring should be very firm). If you have single fire trigger, replace the trigger and the trigger valve for good operation. If you have always been bump-firing and now double firing, replace the safety spring and trigger orings. Good luck
If no air is leaking from the gun, take out the nails, remove trigger by removing 3mm hex head bolt to expose the trigger pin. With air connected and side door open so that you can see the feeder, quickly depress the trigger pin with finger. Gun should fire. If gun does not fire (only makes air sound at trigger) dissconnect airline, remove head and lube headvalve with white grease and reinstall. Test again. If ok replace trigger. If still no joy, replace trigger valve with new factory or generic (part # TVA6). If gun fires but does not activate the feeder claw, remove two 6mm hex bolts from front of gun and split apart upper and lower body and check white oring (part # 149885) Good luck
Best practice is to bump fire the gun to prevent double fire. Do not place the gun on the work and pull the trigger. This takes practice while using at an angle. Works better if the nose piece has rather sharp points to help nose to stay in postion while you bump. With trigger depressed, practice without nails bumping/hitting wood at different angles untill you can bump hit at the spot that you need the fastener. If the gun double fires while bump-firing, most likely all the safety/trip parts are worn/loose. Not expensive to replace. Good luck.
New user will jam the gun/ nails because gun was most likely not bump fired. Placing the gun then depressing trigger will usually cause double fire in the hands of new user. New user should practice on scrap lumber bump firing at many angles till they get the idea; or give them a training period with a nailer that has a single shot trigger (they may develop bad habits with single shot however).
Safety foot and lever inside of trigger are not pushing the trigger pin all the way in. To verifty that the gun will fire, remove the nails to allow for dry fire. Remove the trigger to reveal the trigger valve. Hold the gun against old coiled rubber hose or soft wood. Very quickly depress the trigger pin all the way in. If the gun fires, adjust safety foot and trigger so that the trigger pin is fully depressed when your bump fire. If the gun will not fire after adjustment, remove the head and lube headvalve/orings with silicone paste lube.