I installed approx. 600 sq. ft. of hardwood in a new home. There were marks about 1/16" long on the front of the boards at each staple. These were very fine lines which only affected the finish ( not the stain ). I was asked to replace the boards which I did, only to notice a different mark. These were exactly 3 1/2" from the front of the boards. Different mark and location from the first time. Before using the nailer this time, I inspected the base and found no burrs or any other type of imperfections on it. As I wanted to make sure that there was not a repeat of the first time, I applied painters tape to the plate. This apparently did not do the trick either. Now I have a small 1/16 radius dent. Both times I was told that it must have been something that got imbedded in the plate and also the tape. Checking the tape, I found no evidence to support this. The tape was slightly dirty but no tears or definite marks at all. Oddly enough, the damage always occurred in the same proximity on the floor. Not all the floor had damage. It was always in the middle of the room. I also had installed another 700sq. ft. at another home and had no damage of any kind. I called in another professional installer to take a look and he also was baffled. I had him use my nailer on one of his jobs to see what would happen. He called me back to say the nailer was working perfectly and there were no marks. ( the nailer was given to the contractor at the time the damage was noticed so that there was no way anyone could say it had been tampered with ). Could someone please enlighten me as to what could be happening. I am to replace these boards again and would like to know what it causing this in order to take appropriate safety measures prior to installing again. The only thing I can come up with is that there may be an underlining problem which is causing the nailer to do the damage. Any views? Thanks

without seeing it , couldnt really entertain a reasonable explanation..

the only thing i can think of is are the screws that hold the plate in recessed or out slightly?

Agree with James. Perhaps it has something to do with the product. As a reference I know Mannington has different install specs for some of their exotic engineered hardwoods. By using an alternate tool, dimples were common. That's my take, by looking at it from another perspective.

The screws are well recessed into the plate and the plate has no burrs on it. This is a maple floor.

I also was considering this, but the fact that it is not throughout the floor makes this unlikely in my eyes. This is a maple floor ( not Mannington ). I am being told ( both times ) that something must have lodged itself between the plate and floor and then came loose at a later time. This seems plausable, but the fact that the damage occurs roughly in the same area in relation to the floor makes me question this. Also, every precaution was taken to ensure that this did not happen when doing this the second time. After removing the damaged area, the floor was swept and then vacuumed. The only other thing I can come up with, is that perhaps there is an underlining problem causing the stapler to do the damage. Could it be that the subfloor is not properly fastened to the joists, thus causing excessive recoil when nailing? What do you think? Thankyou for your input.

Sounds like the bumper stop is worn down or compressed. The nailer has a rubber bumper at the bottom of the cylinder to stop it from going too far.

This stapler is a Bostich and is almost new. It has put down approx. 2500 sq. ft. Could this still be the case?

Only thing I can think of is rjust hitting it to hard with the mallet.

probably not. Some floor finishes are very brittle from the side kind of like a windshield on your car. from the top its tough as nails but tap it on the side and kaboom. Could have the pressure a little high or if the floor is one of those nice Chinese imports thats not really a true 3/4 that could add to the problem.

If this was the case, would I not be having marks through out the floor? I don't. The marks only seem to be in the center of the floor ( both times ). Also I have installed approx. 700 sq.ft. in between the first and second time on this floor. There was absolutely no marks any where on that 700 ft. This is why I am thinking that there is perhaps a problem with the sub floor in that particular area of the floor. What I am thinking is that perhaps there is excessive recoil and that is what is causing the stapler to make the marks. What do you think of this senerio? Thanks for your input.

Thats a plausible scenerio. What are you nailing into. OSB or plywood? Has it been damaged by rainfall during construction? Can you be certain your comprerssor is running the same PSI? And are sure you hitting it with the same force? Lots of variables.

I can certainly tell the difference in fastening to old plywood and new, same with OSB and some thats been damaged by water.