Full Chisel Blog

September 25, 2008

Sawing with an Open Pit Saw

Filed under: Historical Material,Of Interest,Sawing,Uncategorized — Stephen Shepherd @ 6:16 am

After a recent post over on WoodCentral, I thought I would talk of my one and only opportunity to use a pit saw.  Back in the 1970′s Frog Tool Company in Chicago sold pit saws.  They were 6 feet long, I think and had one tooth per inch.  It had a decent tiller, it was an open pit saw (as opposed to a Frame Pit Saw, one contained in a sash frame, usually a thinner blade), but the pit handle (box) was a cheap welded strap iron thing that we found out didn’t work.

Open Pit Saw

A good friend wanted to saw up some lumber from a green pine log for a cabin he was building.  Now this was built in the city, so there was no real reason for using the pit saw, other than an exercise in history.  So I thought this would be a good opportunity to get some experience.

The pit saw came in a wooden crate, wrapped in paper and the grease was removed with turpentine, the tiller and pit handle assembled.  The log was readied on the ‘trestle’ that was hastily erected to support the log.  It was done over a depression in his property, so it wasn’t that high.  With skid poles and ropes, the log was easily moved from ground level to the top of the trestle. 

Prior to moving the log up we used spuds and a spade to remove the bark.  This saves the saw but makes the log slippery to handle and walk on.  First he snapped a number of parallel chalk lines along the bottom of the log, turned it over, took a plumb, then snapped corresponding lines on the top.  I don’t know if you need both, I didn’t look up much from the pit.  The important part was the plumb line and once the saw kerf was established straight, the saw tracked well.  Secured with log dogs (my friend was also a blacksmith) the log was ready to be rent asunder. 

Then the pit handle repeatedly failed to hold on to the blade, the metal distorted and the handle would not work.  A couple of hours later a new wooden handle (called a box) had been turned, then some more time with the kerf and slot for the wedge and everything was ready to go.  The new handle held tight and the daylight was fading.  He hosed down the log and covered it with a tarp.

Early the next day all was ready.  I being an assistant took to the pit and attached the handle.  Seeing the old pictures, I had on a broad brimmed hat, long sleeves and had my shirt buttoned all the way up.  I soon learned to keep my mouth shut while in the pit.  It wasn’t as bad as I had imagined, a lot of saw dust would fall but most of it was well in front of me.  The problem was the multiple cuts and saw dust would continually fall as the log was being cut up. 

The morning was good, but a wind picked up about noon and the sawdust was miserable.  One thing about the sawdust from green wood is that there is no static electricity so the dust does not cling, like it would if the wood was dry.  I don’t know if I can imagine how it would have felt in the pit in the Midwest with the temperature and humidity in the 90′s.

My friend had thought about this a lot before we started and had thought out the entire process.  He had dogged the log down with a few feet projecting over the end of the trestle.  We then started the 8 cuts that we were making, resulting in 9 planks.  The two slabs on the side were used for puncheon benches.  We began the cut and when we reached the cross piece of the trestle, we backed out and made the next cut.  We continued until all cuts were at the trestle, then the log was undogged, repositioned and dogged down again. 

With the kerfs enclosed it was necessary to remove the box and insert the blade into the kerf on each of the cuts.  We worked down several feet, then changed kerf until everything advanced to the same point.  I did get to spend some time at the tiller.  I didn’t like it as the log was not that easy to stand on and I had to lift the saw up for each cut, a whole new set of muscles to get sore.  It was not difficult at all to keep the lines straight, the only problem was pitch and pinch.  The first dispatched with turpentine and the second with wedges.

I was happy to be back in the pit, well under the trestle as all I had to do was pull the saw down and I had the help of gravity.  I am not sure how much different a framed pit saw would be, the much thinner blade has far less weight and the wooden frame probably makes things about equal.  I just know that lifting that saw was more work than pulling it down.

With the coarse teeth and large hooked gullets the work went fast after we had developed the sawing rhythm, and there definitely has to be some unison between the sawyers or you work each other to death.  It is important at the end of the stroke to let off pressure but keep the tip from whipping.  Then the timing to start the cut after the tiller-man has pulled it up, no need to burden them by starting the stroke too early.

I had the same experience on the other end of a bow saw, the initial cutting was rough until the rhythm and cadence was developed.  You develop a saw stroke memory and pull the saw down that much each time.  On top, the saw is pulled up as much as possible to get the maximum number of teeth involved in each cut.

The only other time the log needed to be moved was for the last couple of feet that were on the trestle.  Once it was repositioned with the still uncut end hanging over the trestle cross piece my friend attending the tiller made a few cuts and was standing on the end of the log.  He paused and said that the log was longer than necessary, so the end could be just cross cut off freeing the planks.

Here is when the young upstart apprentice opened his mouth, spitting a few wood chips.  I asked him why he couldn’t reverse the tiller handle on the top, to crank the other way and stand on the back side of the saw to finish out the cuts?  He looked at me, then looked at the tiller handle.  He popped out the fastener (but I think it had a square iron bolt with an iron wedge to secure it, like a tusk tenon), reversed the handle and stepped behind the saw.

It was awkward at first for him, my job was the same.  The finishing cuts were a bit more vertical and the kerf split off the last inch or so.  The first time this happened my friend nearly fell off the trestle as it startled him.  He cut one more plank off with a bit more finesse.  The remaining kerfs were left a few inches from the end.  Removing any more planks completely left nothing to stand on.  We finished in the evening and after cleaning the saw I left and don’t know how he separated the planks, next time I was back there they were stacked to dry.

Speaking of that walking around on the top of a log that has been almost cut into boards, the kerfs in the log hold and release sawdust.  Pounding wedges into pinching kerfs also release the dust, still a good idea to keep your mouth shut.  But the worst was the dust in my eyes, even with glasses, the hat did help.

The pit saw continued even after sawmills were common and were used mainly by shipwrights to cut large knees for stem and stern posts and other large parts.  They were also common in underdeveloped countries.  In frontier conditions the pit saw provided the initial building material until sawmills could be instructed.  In July of 1847 the Mormon Pioneers entered the valley of the Great Salt Lake under the leadership of Brigham Young, himself a carpenter, painter and glazier.  The first wooden object built in the valley was made from a log from City Creek Canyon and it was rendered into planks with a pit saw and the boards used to construct a skiff to explore the Jordon River that flows through the valley and empties into the Great Salt Lake.

If one were to do this on a regular basis, digging a pit to work in, greatly reduces the log handling as they can just be rolled over the pit and dogged down.  Working on a trestle does require more work in log handling and positioning and its openness helps with ventilation.  In either case a peavey, cant hook, log tongs and pikes help in moving the heavy logs around.  Block and tackle or at least a couple of ropes to assist for trestle work are necessary.

Everyone should take their turn at a pit saw at least once in their life. Just make sure the logs you are going to saw are green, I would imagine pit sawing dry wood would not be pleasant.  To say that they have cut out a board from a log by hand gives a real connection to the past and a real appreciation for saw mills.

 

Stephen

15 Comments »

  1. Is there a distinctive pattern on lumber that has been cut this way? I’ve been studying some old houses that I believe have site-milled lumber and I’m wondering how to verify how it was cut.

    Comment by Joe Cottonwood — September 25, 2008 @ 11:39 am

  2. Joe,

    There will be score marks on the lumber. An Up and Down mill will leave similar marks. A couple ways to tell them apart is that the up and down mill will have score marks closer together and pretty much straight down through the lumber and fairly parallel to each other.

    A pit saw will have coarser marks, not all of them paralell to each other and at an angle (about 15 or a little more degrees from being straight through).

    And of course, a circular mill left circular score marks…but on smaller lumber cut on a large blade, the score marks can appear to emulate either type of saw. The larger the diameter of the blade, the less an arc appears in the score marks. Also, it matters where the cant was when they began slabbing the log. Lower down meant the score marks are more vertical than up higher. Sometimes you need to look on more than one side to see the arc.

    Take care, Mike

    Comment by Mike — September 25, 2008 @ 1:28 pm

  3. Joe,

    Mikes description is right on. Here is a graphic.

    Saw Marks

    Stephen

    Comment by Stephen Shepherd — September 25, 2008 @ 7:00 pm

  4. Okay, thanks Mike – and Stephen.

    Comment by Joe Cottonwood — September 26, 2008 @ 10:06 am

  5. If you know were I could get a pit saw I’d sure like to know!!!

    Ron

    Comment by Ron Westlake — September 29, 2008 @ 12:08 am

  6. Ron,

    I don’t know currently if they are available, there are a couple of saw makers talking about making them. So they may become available again, or maybe they are still available somewhere.

    Good Luck, I will look around myself.

    Stephen

    Comment by Stephen Shepherd — September 29, 2008 @ 5:24 am

  7. I have pretty much the same question as Joe Cottonwood, since I live in a 1773 post-and-beam in VT (gloat) we recently had renovated, regarding how to tell up-and-down water-power saw cuts from pit-sawn. I haven’t made a real close study of it, but so far all I’ve seen on original boards here, almost all of which are pine, meet the description you’ve offered for mechanical vs. pit-saw pretty well, namely the marks are vertical and consistently parallel to each other. However, I do see widely varying spaces between them, ranging say from 3/8″ to 1/2″ in close proximity on the same board. I attribute that variance to balky-ness in the mechanism that fed the log into the blade, or in the apprentices that did the feeding if that’s how it was done, but what do I know about it really? Not much. At least it’s easy to discern which were cut on circular saws by the curve of the marks, even on narrowish boards cut with huge blades, which would date materials to about 1840+ I believe. Such are mixed in here and there where renovations were undertaken in the 19th century. And to my eye at least I don’t see signs of band saw cuts at all, which I would think would not leave such definite and distinct saw marks since there would have been no up and down, stop and start cycle, but again, what do I know?

    The thing I’m most puzzled by is why there’s so much shagginess to the surface of the 18th century period boards, the same surfaces that also show the straight saw cuts as described, but not on all such boards either. It looks kind of like they were run through a primitive planer in a wicked hurry, and it could be one of those was available at the same mill nearby I surmise, but I don’t see the usual telltale planer marks at all. Of course, where the boards were finished on one side for paneling, there’s good evidence of hand-planing, but the shagginess I’m referring to is not at all like that. I’ve never used a scrub plane, but I would think that would leave marks more like a spoon leaves when dragged across ice cream, as I do see here and there where things were clearly hand planed.

    Do the huge teeth, when combined with a rapid feed rate on up and down saws, perhaps especially when dull, leave such shaggy surfaces, almost as if it were riving almost as much as cutting? I would welcome any comments on this ranging from definite knowledge to rank speculation.

    And BTW, though, I mean if you were going to create a pen-name for your wooden prose, wouldn’ you pick something like “John Strong Oak” or “Frank Teakwether, as opposed to “Joe Cottonwood?” And if you really wanted to go in that direction anyway, why not go all the way, with something like say “Jo Tulipopple?”

    Comment by Ralph — September 29, 2008 @ 4:19 pm

  8. Ralph,

    Thanks for your comments and I will try and I will try and address your questions. It is not unusual to see boards cut on an up down saw and the edges dressed with a circular saw, a function that it does well.

    The roughness and unevenness can be a result of the particular log, the dullness of the teeth and the moisture content of the wood, but almost all wood was cut green. The unevenness that may look like planer marks may be shrinkage during drying and seasoning over the years.

    The carriage that holds and moves the log is generally operated by a rack gear mechanism, some had weight driven carriages, which would produce irregular marks, whereas the gear mechanism the spacing is much more uniform.

    Maybe others will add their comments.

    Stephen

    Comment by Stephen Shepherd — September 29, 2008 @ 5:26 pm

  9. A couple of years ago I tracked down a company in India that still made a variety of sizes and toothings of pitsaws.
    The only problem was they couldn’t ship a small order to the USA. I’d have to find an agent in India to get one or two from the factory and ship it. I was thinking one for hardwood and one for pine.

    I also tried to make a frame pitsaw using big bandsaw blades. The high-hook teeth were too aggressive for human power when I tested them in a temporary set up. I may still re-grind the teeth and try again.

    Tom Dowling

    Comment by T. Dowling — February 15, 2009 @ 10:32 pm

  10. Tom,

    Thanks for the comment, I will have to look into the India source as I would like to get a pit saw myself, and I don’t know why? As for the big bandsaw blade and the high hook tooth not being able to use human power to operate could also be a result of lack of weight in the frame.

    Also pit saws, open or framed were used for cutting green unseasoned logs, which cut much easier than dried and seasoned wood.

    Stephen

    Comment by Stephen Shepherd — February 16, 2009 @ 6:58 am

  11. I live near a hardware store that has that saw almost exactly. its on display. they won’t tell me how much the want for it. Its a Disston. I’d love to find one like it somewhere, but all my searching hasn’t turned one up so far.

    Comment by Trevor — April 16, 2009 @ 12:15 pm

  12. Trevor,

    Welcome and good luck in your search. If you find one or more let me know.

    Stephen

    Comment by Stephen Shepherd — April 16, 2009 @ 3:15 pm

  13. I have just received my pit saw, box and tiller from Frog tools http://www.frogwoodtools.com/ and it is likely the same saw described in this article. The saw will be found by clicking on the link in the side bar for log and timber framing tools. It was $300.00 even including shipping. the blade is made in Germany and although the tiller and box are nothing like the examples I have been fortunate enough to see in use at colonial Williamsburg, a recreation of such examples should be easily within the reach of the average metal smith. I intend to use it when re sawing is not an option with my 20 inch band saw and to produce lumber for more historic work. another option I had in mind (if you have a lot of time on your hands or are a saw sharpener) was to reshape the teeth and gullets on an old crosscut saw and make a tiller and box for it.

    This blade looks great although it is not properly sharpened and bears a logo of 3 crowns with the words “cast steel made in Germany” dose any one know what company this is? The man at Frog Tools did not know and I assume this saw may have been siting around frog tools storage facility for some time by the looks of the bird crap on the box.

    Comment by Nicholas — July 1, 2009 @ 6:18 pm

  14. Nicholas,

    I didn’t know Frog Tool Company was still in business! I have no idea who the maker is, but someone else may know.

    Good luck with your handles.

    Stephen

    Comment by Stephen Shepherd — July 2, 2009 @ 5:25 am

  15. Hi You can buy a pit saw at 815 288 3811. frog tool co. 2169 IL Rt 26 Dixon IL 61021

    Comment by Joe King — February 21, 2013 @ 1:30 pm

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