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I've been toying with the idea of building a Davinci style power hammer for some time.  Having spent most of the year fighting tendonitis in my right wrist, I decided that it's time to pull the trigger.  The other day I stumbled across the drive mechanism for a self propelled snow blower and thought it might work perfectly.  I did a temporary mount of a 1/2hp/3450rpm motor to it today to try things out.20201003_202037.jpg

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A rough trial looks like I'll be able to vary the bpm from 40ish up to around 240 or so.  I'm not 100% sure that it will transfer enough power to run the hammer, but if it works it'll be a convenient way to engage/disengage, as well as provide the variable bpm.  Time will tell as I work my way through it.

Edited by Alex Middleton
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I like the idea of a Da Vinci hammer more than I like the implementations I've seen.  They tend to be low power unless you make them huge.  That said, any powered hammer is better than nothing.  A big anvil will help, but some sort of treadle hammer with some whip in the arms will be way more bang for your buck.

https://www.iforgeiron.com/topic/17543-treadle-hammer-you39re-probably-not-surprised-i-have-my-own-ideas/

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Perhaps the rotary trip mechanism as illustrated in the Da Vinci hammer, could be used to trip the treadle allowing such a spring set up which would support a heavier hammer to anvil. I like the treadle hammer design as Grant Sarver shows in his video however it’s the depth of pressing the treadle that would wear me out over time. Just some thoughts ....... (prior hip replacements).

Gary LT

 

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ive been thinking about a cam activated drop hammer that has a preload spring so you can get more power in the drop. it would be something like a treadle hammer but the cam that moves the hammer up and down keeps the hammer up until its time to drop so you can put variable force on the spring through the treadle, the treadle could also be an on/off switch so the thing isnt just running and mashing your anvil when you dont need it.

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24 minutes ago, steven smith said:

ive been thinking about a cam activated drop hammer that has a preload spring so you can get more power in the drop.

This is kind of where my mind is going as well.  Probably not a true Davinci style, but still similar in spirit.  I'm going to sketch up my thoughts before I get too much farther.

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Cam-activated hammers need to be huge to do any meaningful work.  That's why the old waterwheel-powered hammers were 300-700lb heads mounted to foot-diameter logs ten or twelve feet long.  In theory a really heavy spring preload might work, though.  Keep in mind the smaller the hammer die, the more metal it will move for a given weight/drop speed.  That is, narrow flat dies will work better on this than big honkin' square flat dies.  

 

I do like to watch people play with these ideas!

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That's a good point Alan.  I've only played with damascus a few times, but it's been enough to know that I want to keep doing it, and doing it by hand is a royal PITA.  As good of a time as I had hanging out with @Jeremy Blohm and using Smurfette, it's a bit of a hike to make every time I want to draw out a billet :D.  As long as I can get it to hit at least as hard as I do with a 2lb crosspien, I'll consider it a win.  Plus, I'll have a one of a kind hammer which is worth the trouble of building it all in itself!

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  • 2 weeks later...

I hired a couple of local high school kids to come in this past weekend and clean out one of my mothers' old flower gardens.  She has an "eccentric" taste in garden styles and we've been dealing with cleaning them up since we bought the house from them 4 years ago.  I told the boys that they would most likely stumble across some interesting finds that would have them scratching their heads.  As I was checking up on them Saturday, I noticed them struggling with some sort of massive square metal frame.  When I went out to give them hand, they had uncovered an old driveway drag made from 2-8' sections of railroad track welded together with 6' long 3" x 3/8" angle iron cross members.  Damn thing must weigh upwards of 500 pounds.  I'm thinking I've found a portion of the frame for my Frankenhammer.  The bad news is that I don't currently have a good way to cut it apart.  The good news is that I now have an excuse to go a buy an Oxy-Acetylene torch.:D  It might be more trouble than it's worth to use it, but it'll definitely increase the sentimental value of the build. 

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  • 2 weeks later...

I managed to finish up the rough design for the hammer shaft (tup?) and it's carriage.  The whole thing will be made from 1/4" steel plate, with the shaft itself being 2" sq. x 1/4" wall tubing.  The holes in the end will be to attach different tooling when I get that far. I saved a bunch of springs from the kids' old trampoline and I think they'll be a perfect fit to start out with.  The idea is to have a Davinci style cam lift up on both sides of the lower crossbar, it's set for a 3" stroke.  The shaft is actually in two different pieces with the thought of being able to isolate them from one another and have both a heavy and light hitting mode.  It will most likely fail gloriously, but it will be a whole lot of fun at the same time!

Hammer Assembly.JPG

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This is the puny hammer I built for about 65$. Strange thing is, for the simple construction it works quite well for small billets. It was mostly just fun to build, needing only a little from the hardware store. This is unfinished stage. I added a foot lever, belt, and railroad track hold down. The only difficult part was the cam geometry. There are 2 springs kinda hidden between the uprights by the hammer head.

Tom

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Pretty slick.  That's essentially what my original idea was, but then I found that speed control gearbox and went off on a different tangent.  What size motor do you have powering your hammer?

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I believe it's a 1.5 horse. Ill take a look for sure. I had it up in the barn for years so it got elected. Geared down as it is, it seems to have no issues, but again, only for small work. Just saves the arm.

Tom

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Thanks T.  Motor size is the biggest unknown on this whole project.  I'm sure theres a way to calculate it, but what fun would that be?:D

In the end, all I'm looking to do is replace my arm when drawing out normal sized billets.  Tendonitis kept me sidelined for several months this year, it's not something I really want to repeat.

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Sorry for the delay alex, the tag on the motor apparently was made when Moby dick was a minnow, but the best I can tell is its a 1/6 hsp with 1720 rpm. Pretty small but it moves the cam around with ease.  The wheel riding on the cam helps with friction. I even have 2 very heavy springs pulling down. Probly could add more. Hope this helps You!

Tom

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Most definitely, thank you.  The current motor I have set aside is a 1/2 hp 3450 and I'm worried that it won't quite be big enough.  I guess time will tell.

Edited by Alex Middleton
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