I have run an older Woodmizer LT40 Super for almost ten years. In the last few months I have started sawing a lot of old, hand hewn barn timbers. The timbers are typically 8x8 or larger, 8 to 16 ft long, and northern hardwood in species (white oak, white and red elm, ash, basswood, etc). Many of the timbers can be over 100 years old, and can have some twists or bows in them. The main problem is that the timbers almost always have anywhere from a few to more like 30 or 40 nails in them. The nails are frequently iron spikes somewhere between 8d up to 16d in size. Steel nails are also common. What we want to do is the cut off the 2 hand hewn faces from the timber. I want to saw through the nails with having to pull them and scar the wood.
In general I think the Woodmizer is a great machine but for this situation it is a pain. I have tried a variety of different band manufacturers and both carbon and bimetal bands. None of the bands holds up to that many nails. We wind up spending days pulling nails - frequently badly scarring the surface we are trying to sell. Frequently the iron nails will break off making them impossible to pull out. Of course when you hit the nail it can destroy the band and more importantly screw up the cut. In a dayís cutting I can destroy 10 or 15 normal carbon bands.
I am looking for a better solution. I don't mind if the sawing is slow. I am open to just about anything to help to the productivity and improve the quality of the product. Would the carbide tips of a swing blade do better than the bands on my Woodmizer? Is there some other blade insert that would work better than carbide? The kerf of the cut doesn't mean anything to me for this situation. Is there some other sawing technology that could handle the nails?
(Sawing and Drying Forum)
From contributor D:
Carbide on the swingblade is not the answer. It is hard but brittle. The first nail will break your teeth off and possibly wreck the seats in the blade as well.
My best cutting in dry timbers is with 4 degree 0.055 blades from WM. Pulling nails is the best and one of the reasons reclaimed timber lumber cost so much. Dirt in the checks is another cause of blade wear and not much you can do about it.
I did try the pneumatic punch idea. I need to grind down my punch to a small diameter but for most of the nails it works pretty well as long as they are driven in close to straight. The depth of the surface I am cutting is 1 1/4" ->1 1/2" so I drive them in approx 1 3/4". Itís pretty easy to do and the best part is the scar is hardly noticeable.
The other thing I experimented with was the speed of the cut. I reduced my speed down to a crawl - approximately two plus minutes per cut compared to my normal 30 or 45 seconds. This makes a huge difference especially on iron nails. Instead of the nail breaking off a few teeth, the band grinds the nail more evenly across all of the teeth. The slow speed also prevents the band from dipping after you hit a nail.
As an experiment I tried stacking two old pine 4x6 beams on the sawmill to be cut at the same time. Both were loaded with iron nails - approx 8d in size. I crawled through the timbers with a regular carbon band. I cut 38 nails in the first beam and 14 in the second beam all in one pass. I couldn't believe it - the band survived! The band was dinged up but still cutting straight and relatively smooth. The cut took about three minutes. I consider that light speed when you compared it to pulling 50 plus nails by hand and scarring the surface to boot.