Apacheforge Posted September 1, 2020 Share Posted September 1, 2020 This is a shop built variation of the Da Vinci cam hammer. Its been about 18 years since my full time blacksmithing/fabricator days, and 17 years since i gave it all up to sail and live on a 30ft. boat. Four years back i settled in Western Washington. Bought a nice isolated little home with a nice shop space. Built a nice little woodshop/machineshop/ weldshop. Decided to add a smithy with a tiny trip hammer. I saw some on youtube and came up with my version. The posts are black locust 6x8 and the pillowblocks are lignum vitae. Its got a 20 hammer and the anvil can be changed out for dies. While i can hand forge certain things faster, for drawing out and planishing this is great. Link to comment Share on other sites More sharing options...
George N. M. Posted September 1, 2020 Share Posted September 1, 2020 Very cool. If I didn't already have a treadle hammer I would be thinking seriously about something similar. What part of the Puget sound area are you in? I have a good friend in Port Townsend. We were planning a trip out there this spring until Covid19 hit. "By hammer and hand all arts do stand." Link to comment Share on other sites More sharing options...
JHCC Posted September 1, 2020 Share Posted September 1, 2020 Fun fact: the US Navy used to use blocks of lignum vitae as bearings for the propeller shafts in nuclear submarines. Link to comment Share on other sites More sharing options...
Frosty Posted September 1, 2020 Share Posted September 1, 2020 Wow, that was quite a read, thanks for the link, John. According to the wiki article lignum vitae was used as rear shaft bearings in submarines including Nautilus the first nuke boat. But not later boats, a white metal bearing was developed and has been used since. Bear in mind that's WIKI and I'm always a little skeptical of WIKI though it's improved a lot. The white bearing metal is similar to babbitt though a different alloy. My older Brother was a caster on a sub tender and used to tell stories about casting new propeller shaft bearings in place. Yeah, sure Dennis. What kind of bearing is solid metal and an oil film? In a nuclear submarine? HAH pull the other leg! Even as a kid I KNEW what bearings are. Had it occurred to me I would've asked what the alloy was but he's gone now. It'd be kind of neat having a 100 YO power hammer with nuclear submarine bearings, wouldn't it? Frosty The Lucky. Link to comment Share on other sites More sharing options...
JHCC Posted September 1, 2020 Share Posted September 1, 2020 It would get glowing reviews! General observation: the problem with DaVinci/cam hammers is that since gravity is a constant, their impact is limited to by the weight of the hammer head and the distance it falls. Unlike a power hammer with a Dunlop linkage (such as a Little Giant) or a spring loaded helve (like a Bradley or an Abno) that actually transfers the force of the motor to the hammer, the motor in a DaVinci is only there to lift the hammer to the point where gravity takes over. Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 1, 2020 Share Posted September 1, 2020 I know of some armour makers who built a Da Vinci hammer, they said that the action was too slow using just gravity. If they sped up the drive the cam would be back into lifting position before the full down stroke was done. So not very useful for when you need a LOT of hammering! They helped get around the issue by adding a couple of screendoor springs to the helve in front of the cam to get better acceleration at the start of the down cycle. (Described over at armourarchive.org IIRC) Please remember: just because it was designed by Da Vinci doesn't mean it's a good design. Often it's just a good place to start innovating from! Link to comment Share on other sites More sharing options...
JHCC Posted September 1, 2020 Share Posted September 1, 2020 Worth noting that Leonardo's original design had the (hand-cranked) cam activating a pin rather than the length of the handle, making the release much faster. Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 1, 2020 Share Posted September 1, 2020 Still the acceleration of gravity is fairly slow. This is seen in old tilt hammers that often went to large mass for the top dies and a fairly short stroke so that the water powered drive could have numerous cams on it getting a number of short but heavy strikes per revolution. (Here is a 4 lobe cam example from the Sagus Ironworks which all us Americans are sure to be familiar with... https://www.youtube.com/watch?v=Jc5u9RcyQl0 There is a book on it that I happen to have: "Ironworks on the Sagus"...) Actually there was a SOFA member that once made a tilthammer using an old hay baler to provide the power source. He forged an anvil with it IIRC. Another example from the discussion back in 2007: https://www.iforgeiron.com/topic/3450-yoink/ Link to comment Share on other sites More sharing options...
JHCC Posted September 1, 2020 Share Posted September 1, 2020 I agree about the speed, but at least both Leonardo's original design and hammers such as the one at Sagaus release the hammer completely right after the cam reaches its highest point. Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 1, 2020 Share Posted September 1, 2020 Now if he just figured away out to increase the gravitational pull...hmm neutronium lower die perhaps? I have seen a tilt hammer somewhere that used a "spring board" to start the acceleration at the top of the stroke. Link to comment Share on other sites More sharing options...
Apacheforge Posted September 2, 2020 Author Share Posted September 2, 2020 I found that the rpm of the cam was too high so after some calculations came up with a pulley combination that gave me about 80 strokes a minute. The cam was made from two inch thick sections of fir sandwiched between plywood. I notice friction wear was occurring and added a 2 inch wide strip of heavy gauge sheet brass as a bearing surface. While yes, i could have built a much refined version, i just wanted to bodger up a machine from material laying around my boatshed. Built mostly for fun as i really don’t have a need for this to make a living. It is a fun toy to make other fun toys. Link to comment Share on other sites More sharing options...
pnut Posted September 2, 2020 Share Posted September 2, 2020 I wonder how it would perform with a downward spring assist to add a bit more force to the blow? Pnut Link to comment Share on other sites More sharing options...
Apacheforge Posted September 2, 2020 Author Share Posted September 2, 2020 There have been examples cited for just such a spring. Looking at my system, i can see how such a spring can be fitted. I think a greater horse power of motor will be needed to push against the added load. Experimentation will proceed. Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 2, 2020 Share Posted September 2, 2020 With all the gearing down you may not need an increase in hp. I was wondering about a HDPE "wear plate" though... Link to comment Share on other sites More sharing options...
Frosty Posted September 2, 2020 Share Posted September 2, 2020 HDPE is wonderful dry bearing material. I pick up cheapy plastic cutting boards at Wallyworld when I run short. Frosty The Lucky. Link to comment Share on other sites More sharing options...
arftist Posted September 11, 2020 Share Posted September 11, 2020 JHCC DuPont linkage. Link to comment Share on other sites More sharing options...
JHCC Posted September 11, 2020 Share Posted September 11, 2020 You're quite right. I must have been reverting to my days selling mattresses and explaining the difference between Dunlop-process and Talalay-process latex foam. Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 11, 2020 Share Posted September 11, 2020 Hmmm, Memo to Self: when they talk about going to the mattresses; listen to John's input! (cue "the Godfather" theme...) Link to comment Share on other sites More sharing options...
JHCC Posted September 11, 2020 Share Posted September 11, 2020 I'll make you an offer you can't refuse! Link to comment Share on other sites More sharing options...
Michael Posted September 11, 2020 Share Posted September 11, 2020 (edited) there's an Italian paper model artist (Paperpino) who has devised plans for a sand powered paper model of Da Vinci's hammer. A free download though it is a rather involved paper model. He has a handcranked version as well. This model would last all of about 10 seconds in a a shop setting, being cardstock and all. Considering a hard material version at some still toy sized scale. No affilliation etc. I've built a half dozen of the paper models from the free .pdf downloads. Edited September 11, 2020 by Michael to add contact info Link to comment Share on other sites More sharing options...
Frosty Posted September 18, 2020 Share Posted September 18, 2020 Cool model, thanks for the look. Leo would've loved it. Frosty The Lucky. Link to comment Share on other sites More sharing options...
eseemann Posted September 25, 2020 Share Posted September 25, 2020 I have a "TuffShed" building that has steel floor joist 12 inches on center with a plywood floor so I know I can do a power hammer but I wonder if I can do a Da Vinci cam hammer or a treadle hammer? Anyone have any idea how these work on a plywood floor? Link to comment Share on other sites More sharing options...
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