Installing folded backs...troubleshooting?

Discussion in 'Saw Makers Forum' started by mattsworld, Feb 27, 2012.

  1. mattsworld

    mattsworld Member

    Messages:
    23
    Greetings fellow saw makers...

    I have been doing a lot of work with backsaws over the past year and would like your thoughts on installing folded backs. I often straighten saw plates for customers and re-install backs to straighten toothlines on vintage saws, and I also teach saw building at two local woodworking schools in CT and RI.

    My questions are:

    1) I use saw plates punched on a Foley. Do any of you smith the plates true before installing the back? Or do you smith them after installation? I have done both.

    2) Do you have any other approaches to truing the toothline after the back is installed?

    3) I have found the process of straightening the toothline after back and tote installation to be just too daunting for students in class and am considering milled backs, but I have never worked with them before as my work is always on old saws. Any tips?

    Thanks in advance,

    Matt Cianci
    www.thesawblog.com
     
  2. TraditionalToolworks

    TraditionalToolworks Most Valued Member

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    181
    I do whatever I need to do. I have a small saw maker's anvil that I use on my workbench with a small ball pen hammer. I always lusted for a large saw maker's anvils, but they seem less practical than a traditional London Pattern Anvil.

    Several years ago I bought this little saw maker's anvil from a guy I bought some other equipment from. No maker's mark, so not sure what type it is.

    (As a drive-by, an old Beardshaw that Sir BarleyS brought over to this side of the pond...:p It has the biggest honkin' brass back you have ever seen on a handsaw...it is a monster piece of brass. Simon did send another saw nut since.

    For new plates I would like to have a roller, but don't. That would help flatten them out. I just kinda bend 'em, work them around until they are flat, and do that before I assemble. I want the plate as flat as possible, and also the backs. Brass especially is so soft it bends easily. Most of the plate ships in rolls, so like 25' or 50' of it ships in a coil. Because of such it is slightly curved. I bend 'em and wiggle them around to get them as flat as I can. I use a snips to cut it, so file those edges also. The hardest part is getting the blue off and getting them shinny. I do that before I put the back on.

    The whole mess with the saw back, removing them, putting them back on, etc...it's a mess, IMO. Make it flat, clean the edges up, put it in the back with some loctite or epoxy. I've never had one come apart yet. And I have dropped them.
     

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  3. mattsworld

    mattsworld Member

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    23
    Alan

    Awesome...just the kind of stuff I'm looking for. Now lets see who else weighs in....

    The most interesting thing about saw building is that since there doesn't seen to be much info to formally educate us, we are forced to rediscover the paths once well worn and now overgrown and hidden in the the forest of hand tool history.

    I love it!!!
     
  4. TraditionalToolworks

    TraditionalToolworks Most Valued Member

    Messages:
    181
    Matt,

    Just for clarity, I don't use loctite/epoxy on folded backs, just slotted of course. I have never had a slotted back come out yet.

    As I mentioned in the other thread, I have had a newer Wenzloff saw have it's back pulled up, and fixed it with a mallet. That wouldn't have happened with a slotted back.
     
  5. o_lucas_o

    o_lucas_o New Member

    Messages:
    2
    Making folded backs the history and present poin of view.

    Hi!

    I'm new to this forum and this is my first post, so I'd like to state an official: "nice to meet You!" to everyone :)

    I have a question upon the folded backs subject. How were they manufactured on a larger scale in the past and how are they made now? I'd like to make some replicas of older W. Tyzack saws, especially the steel backed ones. I tried the vise method of bending 3mm cold bent steel angle, but the result was poor. Recently I found a machinist company and asked them to bend the angle. They used a hydraulic press with 60 tons (ca. 120 thousand pounds) of pressure, but the results weren't much better. There still is bow and some twist in the elements, the opening is not even and the 1" on either end is worth only cutting off.

    As I spoke to one of the engineers over there, he suggested, that to achieve a predictable, straight fold etc. one must use a force high enough to override the Young elastic module of the steel. Otherwise it is to dependent on the spring back action of the material, which is hard to calculate. Unfortunately, they don't have a press like that.

    Do You have any knowledge upon this topic? Did Tyzack, Disston, Buck, Groves and others use super folding presses or where there other methods of creating descent backs (rolling)? I don't think they had an army of smiths who where hammering the backs straight all day long :) How is it done nowadays?

    I know about the folded and slotted back discussion and I'm aware of all the advantages of the slot...I'm just kind of charmed by the look of steel backs and didn't see anyone make slotted steel backs...yet :)

    Take care,
    Lukasz.
     
  6. fred0325

    fred0325 Most Valued Member

    Messages:
    1,084
    Hi Lucasz,

    I am not a saw maker but I do have an interest in things technical even if the ability is lacking.

    Because we have the convenient tools to work steel cold, ( ie. hydaulic presses as opposed to monsters driven by steam), I think that we may do it more than was done in the past. I think that I asked the question in another "Topic" (I forget which one now) "Did they do it hot or cold"? I've just remembered - cutting saw plate - for what it is worth!!

    And so with this. It would surely be a lot easier to fold the steel at red heat and then press, hammer or roll it to its final form. This, I assume would overcome all the problems re distortion/elasticity etc.

    Simon would probably know but he has been absent from the site for a while, having other things at the moment to keep him busy.

    As I said, I have no idea really, but if you know a blacksmith, it may be an idea to ask him or to let him have a go at doing it to see how the final product turns out. Particularly if he started out as the Victorians/Pre Victorians would have done with flat bar and not angle iron.

    Fred
     
  7. TraditionalToolworks

    TraditionalToolworks Most Valued Member

    Messages:
    181
    Welcome Lucas,

    I think for the most part, most of us over think this stuff. In the old days there were brakes, and there were similar devices used for wagon tires, which were steel. Blacksmiths did have tools to do much of that stuff, and working it hot and forming it is tedious also.

    I think it was bent cold. You must use Alloy 260, it's much different than the brass used to mill which is Alloy 360 in most cases. There are many varieties of brass, and steel backs were used as well.

    Diarco brakes are some of the more well known brakes that are capable of doing this type of work. A good brake will run in the neighborhood of $1k-$.1.5 on the used market, depending on size.

    Harbor Freight sells one for about $300 that could be beefed up to work, and some folks (Leif Hansen) have made them and folded their own. I think Mike Wenzloff uses a beefed up Harbor Freight brake.
     
  8. pedder

    pedder Active Member

    Messages:
    38

    Hi Matt,

    The Foley curve: I think most of the curves vanishes after the teeth are filed a few strokes. So I punch, file install the spine, install the handle and nuts, Sharpen, and corewct the curve when it is there after all.

    The main reason for curve in our (Klaus + mine) experience is the slotes for the blade and the spine are not 100% parallel. A good tip we got from George Wilson over at saw mill creek is to turn the spine a little to correct that.

    Cheers
    Pedder
     
  9. mattsworld

    mattsworld Member

    Messages:
    23
    Hi Peddar

    I appreciate your response...I have experienced this as well, but not consistently. My process right now is actually the same as yours. But I def still have saws that retain the warp.

    Matt
     
  10. need2boat

    need2boat Most Valued Member

    Messages:
    65
    Just so I follow what your saying:

    You run it thru the Foley

    file the teeth

    install the back and handle

    Then Sharpen, touch up any bends, and adjust for set.

    As per the foley Bend. I hear a lot of people on many of the lists talk about using them but not a lot of people really seem to talk about set up and use. There is a LOT of adjustment in the dies and I've yet to buy or look at one that is perfect. In my experience if your finding the Foley is putting a bend then something is not correct. a sharp die and punch should easily cut backsaw plate.020-.032 plate. In the past I've mostly cut older saws but not that I've worked with some of the newer plate I've found it's slightly easier to deal with.

    Joe
     
    Last edited: Mar 30, 2012
  11. ilges71

    ilges71 Member

    Messages:
    22
    Something not mentioned in the posts so far is the grain of the metal for the back. Cold rolled sheet will have a grain to it so it will bend one way better than the other, of course for most purposes it does not matter, but when bending it could make a difference. Strip rolled as bar will have the grain running along the length, there could be a tendency for it to split on bending. If the strip is cut from a sheet of metal, the grain will usually run in the direction of the longest measurement. You could therefore cut a strip so the grain goes across the bar. this might make it more stable.

    The other issue that does not seem to be mentioned is annealing before bending. This would make the metal more ductile, take less force to bend and wiould not spring so much. This would apply to steel or brass.

    I would have thought that a brass back could be bent with a the brass clamped between two strips of steel using a mallet or hammer to get a right angle then closed on the bench. Remember the guys who made these in Victorian times would have been making many saws each week, so using a hammer to bend the back they would not have bruised the metal with miss hits!!

    If you read the book about how wooden spoke shaves were made up to the 1960's completely by hand, you realise just how much british industry had not invested in machines.

    Just a few thoughts.

    Graham