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Thread: Modern day cramps for clinker building.

  1. #1
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    Default Modern day cramps for clinker building.

    I may need a couple new cramps in the near future for a repair project. For holding the planks together when rest fitting and after steaming and while riveting. The need for grip width is minimal but the throat depth must be significant to reach across a wide plank.

    We all know the classic cramp model that has been used from the iron age up to our time. Two pieces of birch held together in the middle by a pair of iron (in earlier days wooden) straps and with a wedge driven in at the top to tighten. A rather awkward contraption.
    Then there is the new style from the early 20th century with the straps replaced by a screw with a huge wingnut or crank to tighten the cramp.

    Has any progress been made since then?
    Amateur living on the western coast of Finland

  2. #2
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    Default Re: Modern day cramps for clinker building.

    What width are you needing?


    I have about 20 Axminster Deep throat G clamps that do most of my moderate clamping. They’re about 120mm wide reach by 80mm thickness capacity. 13 each. Have some big g clamps for heavy lifting. Need to permanently glue some softwood to the pads rather than scraps.

    Wooden clamps like you describe are still very usefull and being able to make them means alot.

    Mortise and Tenon magazine 09 article shows how to make them to a ‘viking pattern’. They look like the quickest to use that I’ve seen/ very adjustable. I’d like half a dozen of these, hopefully once current project is done i can upgrade make my workshop. Metal free nothing to (try to) rust. Picture's enough to make one.

    Last edited by Edward Pearson; 10-06-2021 at 11:03 AM.

  3. #3
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    Default Re: Modern day cramps for clinker building.

    What you need was shown in an early article in WoodenBoat (probably no later than maybe WB40 or so) called the "Brenne Clamp". It was a wooden clamp with long curved jaws similar to the bottom clamp shown above, except the two pieces were hinged together at the aft end and the closing force was applied with a wooden cam with a small lever handle. It was made for lapstrake boatbuilding and the advantage was that it could be applied and tightened with only one hand.

    There are some variations of them shown here, though I remember the on in WoodenBoat looking a bit more elegant. In any case, they would be pretty easy to build.

    https://smallboatsmonthly.com/articl...brenne-clamps/

    This one is similar to the one shown in WB. The details are here:

    http://www.urbanoarsman.com/2020/03/...brenne-clamps/

    clamp.JPG

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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by Edward Pearson View Post
    ,,,,

    Tell us about the unorthodox plane - please
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

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    Default Re: Modern day cramps for clinker building.


  6. #6
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    Default Re: Modern day cramps for clinker building.

    Wooden boat #29 has the article

    ime, the wedge at the tail gives you more flexibility with jaw angle

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    Default Re: Modern day cramps for clinker building.

    Also, cam clamps.....an easy DIY project.

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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Tell us about the unorthodox plane - please
    Its a shot from Mortise and Tenon.

  9. #9
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    Default Re: Modern day cramps for clinker building.

    Thank you all.

    I have a couple of secondhand Brenne cramps which are said to come from a boatbuilding school. They don't work very well in practice. This may be because the cam should be harder and smoother than anything can be made from our local birch. I don't know.

    I want a 30 cm (12") throat at least.
    This leaves me with 4 options.
    -Fabricating my own 30cm throat G-cramps from scrap yard materials and threaded rod. Feasible.
    -Making traditional wooden cramps with bolts through the middle. Feasible
    -Making traditional wedged cramps...... Feasible but a bit oldfashioned for my taste.
    -Fabricating all metal brenne cramps. Feasible but a bit on the difficult side.

    I need to think
    Amateur living on the western coast of Finland

  10. #10
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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by heimlaga View Post
    ........I want a 30 cm (12") throat at least.
    This leaves me with 4 options.
    -Fabricating my own 30cm throat G-cramps from scrap yard materials and threaded rod. Feasible.
    -Making traditional wooden cramps with bolts through the middle. Feasible
    -Making traditional wedged cramps...... Feasible but a bit oldfashioned for my taste.
    -Fabricating all metal brenne cramps. Feasible but a bit on the difficult side.

    I need to think
    No, five. Cam cramps. They're a doddle. Paul Sellers long-winded version. They can be made with wooden shafts rather than steel or aluminium. (I'm MikeG from Woodhaven2.........hi again!!)
    Last edited by Mike-in-Suffolk; 10-07-2021 at 01:18 AM.

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    Default Re: Modern day cramps for clinker building.

    I made a set of "Crab Claw" clamps from WB magazine years ago for my brother inlaw. They worked well. The key as someone has already mentioned i that the cam has to be the hardest, slickest component of all.

    I used maple and mahogany as I recall.

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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by Mike-in-Suffolk View Post
    No, five. Cam cramps. They're a doddle. Paul Sellers long-winded version. They can be made with wooden shafts rather than steel or aluminium. (I'm MikeG from Woodhaven2.........hi again!!)
    they are something fun to make, but never the clamp you’ll reach for in the shop ime.
    -someone who has a box full of them he made

  13. #13
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    Default Re: Modern day cramps for clinker building.

    For long-reach low-pressure work they seem a simple and effective solution. Cheap, too, which is always good. Mark Reuten, a pro boat builder, uses 20 or 30 of them for all his clinker planking.

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    Default Re: Modern day cramps for clinker building.

    Use some threaded rod, the nuts can be made up or just use them out ot the box and run them up with the cordless driver.


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    Default Re: Modern day cramps for clinker building.

    A plank braced against the floor pushing onto the strake, sometimes a block of wood nailed to the floor is needed to keep it in place.
    That is of course if you're building the boat right side up, but the same principle should be possible if you aren't.

    /Mats

    Diagnosed with autism. Sorry, not much I can do about it.

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    Default Re: Modern day cramps for clinker building.

    Seen a few variations based on a Quick Grip clamp pressed into service...



    I'd get rid of that end bit aft, and just countersink screws into the yellow clamp pads screwed into some hardwood. Then they'd slip on then slide it onto the bar through the mortise.

    There's a fair bit of weight at the opposite end to the clampy end, and that can make it a bit 'unstable' in the hold. I've had quick grips let go a bit overnight as well. If gluing I would only trust a G clamp now: the instigator of force is directly 'in line'.

    Faithfull tools sell a forged 10"/250mm one for 10.



    It'll be Chinese (5 on Alibaba) you might be a able to track back to the factory and see if they make bigger.
    Last edited by Edward Pearson; 10-08-2021 at 11:55 AM.

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    Default Re: Modern day cramps for clinker building.

    I made a bunch of 'F' clamps with 6" throats from 30x6mm flat bar. It would be very easy to do the same with heavier bar and a 12" throat. Not as elegant as those nice wood ones, but very quick to fabricate. For very long throats, T bar might be more stable. They could exert good pressure too, if needed.
    A2

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    Default Re: Modern day cramps for clinker building.

    The venerable hairpin & wedge clamp is quick to make and quick to apply. What’s not to like?
    3A9714D0-55F7-48F8-B9EA-1B55B3E9F0BE.jpg

    If you’re using a Tom Hill style setup, you can wedge the plank at the outboard ribband, too.
    I’d use thicker plywood than these.

    John Brooks, in his excellent book How To Build Glued Lapstrake wooden Boats, describes his method using battens, screws and blocks. Haven’t tried it, but I will on my next glued lap boat. There are many clever tricks in the book.

  19. #19
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    Default Re: Modern day cramps for clinker building.

    The best I have ever seen were made from some 2X1 that had been through the planer and reduced a bit.With the addition of three nails and two washers,you had cramp that could be picked up by the cam handle and applied single handed and being softwood it didn't leave a mark.On top of these advantages they were also light enough to minimise the risk of distortion that accompanies hanging a lot of hardware on a half built hull.

    screenshot.jpg

  20. #20
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    Default Re: Modern day cramps for clinker building.

    Now that is a good idea.

  21. #21
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    Default Re: Modern day cramps for clinker building.

    Some might say Jorgensen clamps are typical for lapstrake boat building.
    Attached Images Attached Images

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    Default Re: Modern day cramps for clinker building.

    One of the English forum members posted that one does not require much pressure of glueing with epoxy.
    So find some PVC pipe and chop it up.
    basil

  23. #23
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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by goodbasil View Post
    One of the English forum members posted that one does not require much pressure of glueing with epoxy.
    So find some PVC pipe and chop it up.

    The problem with that is the breadth of the strake. If you have, say, a 175mm wide strake, you'd need to find a pipe with an internal diameter of more than that, and they're not common or cheap. Such a clamp would also require 2 hands to apply.

  24. #24
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    Default Re: Modern day cramps for clinker building.

    According to Google. Pipe is available up to 12" diameter. (30.5cm.)
    basil

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    Default Re: Modern day cramps for clinker building.

    Of course it is, and larger. But I said common and cheap. Big enough pipes will be neither.

  26. #26
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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by John Meachen View Post
    The best I have ever seen were made from some 2X1 that had been through the planer and reduced a bit.With the addition of three nails and two washers,you had cramp that could be picked up by the cam handle and applied single handed and being softwood it didn't leave a mark.On top of these advantages they were also light enough to minimise the risk of distortion that accompanies hanging a lot of hardware on a half built hull.

    screenshot.jpg
    Now this may be the start of something great. With this concept I will have less stress on the cam than with a Brenne Cramp. I will post what I come up with (provided that it turned out usable).
    Amateur living on the western coast of Finland

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    Default Re: Modern day cramps for clinker building.

    I ended up making two Brenne cramps to see how they turn out. I changed the design a bit from all the Brenne cramps that I have seen to make better use of local birch timber. They are almost finished. If they work all right I will make more.
    Amateur living on the western coast of Finland

  28. #28
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    Default Re: Modern day cramps for clinker building.

    I suppose some already knew it....... but Brenne cramps are a hoax. Even with significantly less excentricity than there is on the most widespread drawings the excenter has no holding power what so ever. It just unwinds itself as there is no ratchet mechanism to lock it. The maximum excentricity that is self locking seems to be around 3mm on an 80mm diametre disc which would make around 5mm of jaw movement at the very most.

    The word "brenne" gives associations to firewood and now I know why. I have wasted a very valuable workday making firewood and I still need boat cramps. Now I must lenghten my week further from the ordinary 10-12 hours 6-7 days a week to make up the loss. I am angry to say the least. When living on the edge of both burnout and bankrupcy practical jokes aren't fun at all.
    IMG_4712.jpg
    Amateur living on the western coast of Finland

  29. #29
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    Default Re: Modern day cramps for clinker building.

    Excuse me. My temper flooded over. Too much stress and too little sleep.

    Anyway we figured out the flaw. Birch is a more slippery wood than the ash which you southerners probably use for Brenne cramps.

    I will make a ratchet mechanism for mine. As soon as I find some time.
    Amateur living on the western coast of Finland

  30. #30
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    Default Re: Modern day cramps for clinker building.

    Harbor Freight does have a 12" C clamp they sell for about $10.00 if you only need one or two.
    https://www.harborfreight.com/12-inc...amp-45919.html

  31. #31
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    Default Modern day cramps for clinker building.

    Quote Originally Posted by heimlaga View Post
    Excuse me. My temper flooded over. Too much stress and too little sleep.

    Anyway we figured out the flaw. Birch is a more slippery wood than the ash which you southerners probably use for Brenne cramps.

    I will make a ratchet mechanism for mine. As soon as I find some time.


    No problem, Heimlaga. I am sure we all have our moments.

    I made a bunch of the pvc pipe clamps mentioned above. They are cheap and easy to make, but not one-handed to use. Also, they do, or can, leave a mark.

    Kevin


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    There are two kinds of boaters: those who have run aground, and those who lie about it.

  32. #32
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    Default Re: Modern day cramps for clinker building.

    I made up a few clamps this week. Very simple.

    _DSF2405.jpg_DSF2407.jpg

    I glued little feet on front and back and use a carriage bolt and wingnut to tighten them down. A bit of string on the back end keeps them from flopping all over the place when they're loose. And I made a simple little handle that I use to harden up the wingnuts the last turn or so.

  33. #33
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    Default Re: Modern day cramps for clinker building.

    Intriguing hint on a boat build. It would be nice to have the weather to build outside.

    I don't give that handle long. The tip will break off.

  34. #34
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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by heimlaga View Post
    Excuse me. My temper flooded over. Too much stress and too little sleep.

    Anyway we figured out the flaw. Birch is a more slippery wood than the ash which you southerners probably use for Brenne cramps.

    I will make a ratchet mechanism for mine. As soon as I find some time.
    I have been looking for the reply I got from someone who either was a student, or perhaps instructor at the Saltdal Boatbuilding School in Northern Norway. He sent me a simple drawing of the Brenne Clamp, which I had never seen or heard of whee I was boatbuilding in Western Norway.

    The one detail I remember was that the diameter of the hole in the top finger was slightly smaller than the diameter cut in the moving cam arm, supposedly to make it stay put wherever the position of the arm was in its travel. I had a good collection of homemade deep reach clamps using an acme threaded rod so I never made a Brenne clamp. It is a bit of a dance bending up a new plank and getting a clamp in position and tightening the clamp and grabbing the shore that pushes out from the overhead beam to the upper edge of the plank being bent...ahh, I miss building without molds.

    You may be able to use a rotary sanding drum to deepen the cutout on the upper finger to make the cam arm bear only at the edges, as I recall the difference in diameters was on a millimeter or two.

  35. #35
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    Default Re: Modern day cramps for clinker building.

    Quote Originally Posted by Paul Schweiss View Post
    I have been looking for the reply I got from someone who either was a student, or perhaps instructor at the Saltdal Boatbuilding School in Northern Norway. He sent me a simple drawing of the Brenne Clamp, which I had never seen or heard of whee I was boatbuilding in Western Norway.

    The one detail I remember was that the diameter of the hole in the top finger was slightly smaller than the diameter cut in the moving cam arm, supposedly to make it stay put wherever the position of the arm was in its travel. I had a good collection of homemade deep reach clamps using an acme threaded rod so I never made a Brenne clamp. It is a bit of a dance bending up a new plank and getting a clamp in position and tightening the clamp and grabbing the shore that pushes out from the overhead beam to the upper edge of the plank being bent...ahh, I miss building without molds.

    You may be able to use a rotary sanding drum to deepen the cutout on the upper finger to make the cam arm bear only at the edges, as I recall the difference in diameters was on a millimeter or two.
    That sounds like a logical explanation why my Brenne cramps didn't work. I tried to make the excenter fit into the hole as precisely as I could.
    Amateur living on the western coast of Finland

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