Jumpin' Jack!

admin

Greetings! Here's an interesting project I re-purposed an old tool for.  Definitely not a welding project.  "Earthmoving" but definitely not in Expat's or Specop's league!    I'm laying pavers for a patio and driveway.  The problem shows up in pic 1.  I bought a used plate compactor for the ABC courses.  Check out that HF Orange color!  It works well in the "larger" areas, but can't get into the corners or edges.  Need a "jumping jack" but they're $$$!!!  Now the welding part ... I have an old Makita demo hammer so thought I'd buy a foot square 1/2" plate and stick it on the end of the bull point bit.  A foot looked "too big" so I went for The BIG 10".   Used 1" sch 40 black pipe, "slitter wheeled" the side and welded on a couple drilled/tapped 3/8"x3/4"x6" straps to squeeze it to the 1" bull point bit. pic #2Then welded it to the plate.  pic #3I suppose we can all guess what happened after pic #3?    It turned into #4!    The wager was "how many lin feet did it compact?"  Answer: About 50' - all the patio edges - believe it or not!Welded it with the HH140, Lincoln flux core .035 (they sell at HD), Volts 4 (hi), Speed 40. It's alone on a 120v, 30A breaker with a 10-3 30' extension cord.  Since I consider 110v welders "HHot Glue Guns", I was rather surprised that the weld did NOT break.  It was the HAZ of the pipe right above the weld in pic #4Okay, now what?  Next post ... Attached ImagesLast edited by Fabn4Fun; 12-19-2012 at 11:43 PM.
Reply:Do over and brace it!  Welded a 3/8" thick hole saw drop to the plate so the bit point isn't trying to hammer thru it.  Pic #5Gapped the 1" sch 40 pipe 1/16" from the drop, tacked, then welded all around in that position, turning it with left hand.  Pic #6Thought it would be easier to miter 1/4"x1.5" strap than make a gusset.  (Didn't know at the time that IMS had 1/4x4x4 gussets for a buck!) Every joint was spaced 1/16" rather than bevelled.  Pic #7 is before wire wheel cleanup.Remarkably little splatter after a quick once over with a cup brush.  Pic #8Looks done!  Next post ... Attached Images
Reply:Started using it in the driveway, pic #9, and within a dozen feet or so, it popped the heads right off the three 5/16" grade 8 bolts!    Re-drilled and tapped for 3/8", and used Allen head cap (higher than Grade 8) screws.  They held!  To use it, I set the plate on damp ABC, stood on it, then pulled the trigger until the base course felt about as hard as the other plate compacted areas.  Got all the way around the perimeter of the driveway, about 100 ft or so, then it ripped.      Pic #10 & 11.  Again at the HAZ's, not the welds!  This surprised me, 110v welds NOT FAILING.    Any ideas why?  I suspect 70ksi weld steel vs 36ksi mild steel pipe & strap. More surprising was a) How fast the demolition hammer broke the steel; and b) How an old demo hammer like that doesn't just pound itself apart.  Those things are TOUGH!  A36 steel ain't.  Unfortunately, there is just NO way to measure the forces involved in a Jerry Rigged project like this! Am going to rebuild it when I need it again - will bump the thread when I do.   Attached ImagesLast edited by Fabn4Fun; 12-19-2012 at 11:46 PM.
Reply:I like the clamp type mounting idea.If you are serious about how to "fix" it, I'd say gussets. My guess from running jumping jacks and jack hammers is that the failure was due to the fact the plate wasn't staying flat, but was flexing as the ground gave under the base unevenly. I've used air tampers in the past as well. Same idea, but usually just like the round end on a digging bar, but air powered. We used to have one for our 90 lb hammer we'd use to fill in tight areas around tanks we'd set. Smaller area, but the base tapered up to the shaft for support.Honestly 10" sq was probably still too big IMHO. I'd have gone maybe as small as 6x6" myself. Then again I prefer a jumping jack for really compacting material compared to a plate tamper. The tamper does win for getting a surface flat for pavers etc.Remember your paver patio is only as good as it's base layer. If the base settles at all, your pavers will move. From experience, ground around a building will always settle as it is almost never well compacted. It's even worse if you have a basement. Many times we'd dig all the way down to the footings and fill and compact to try and rectify existing issues. If you hit the ground with areal jumping jack and the ground drops more than 12", you probably need to take it all out and start from scratch. I stunned a buddy of mine one time when I compacted under a 2nd floor deck next to a house, and we needed 3 triaxles of modified to fill the depression I made with the jumping jack. He was just going to toss down 4" of stone and hit it with the plate.I'd take the blunt end of a digging bar to the sub grade and give it a full power hit as hard as you can. If you can put dents in the modified deeper than 1", it's not compacted enough for me. We only ever had one paver patio with settlement issues. That one settled 1" in one corner maybe over a 10 sq ft area. We had almost 6 feet of fill there however that we had to put in on that corner because of the way the grade dropped off..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Edit: you posted up the other picts while I was typing. As far as pipe failure. If it's home store pipe, that doesn't surprise me. Most of that stuff is trash, brittle and full of crap.Your welds I see don't look like material failure in the HAZ. Looks like poor fusion between the base material and the weld.In both the circled areas it looks like the weld material tore out of the base material right at the surface. About what I'd expect from cold welds with an underpowered machine. If the base material had failed in the HAZ, I'd expect to see the flat torn straight thru. That's not what I believe I'm seeing here. Better close ups would help. Cold welds, torque caused by a moment arm, vibration, possibly stress risers... all combined to fail these welds..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:The reason it broke the second time is cause u clamped the bit down and the pressure of the bit pushed it apart till it snapped.I forgot how to change this.
Reply:Nice try, you can learn a lot from things that don't work out.  Why not make a hand tamper for the tight spots, or even buy one, I think HD sells them for about $30.Years ago I had a jumping jack compactor I bought at an auction, but didn't yet own a vibe plate compactor. (I was looking for a good used one and I would rent one as needed).Anyway a neighbour knew I had that jumping jack compactor and asked to borrow it to pack his driveway before he installed interlocking paver stones.  He packed his driveway and sand with it and brought it back.  He then laid his paver stones, all was good, he then borrowed it again to set the pavers.  I told him I didn't think it was a good idea, but he didn't want to drive to town to rent a vibe plate.  (He was an engineer to boot)Well he tried it, broke about 25 pavers before he got it stopped. I told him at the time I thought it wasn't a good idea but thanks to him I now know it wasn't a good idea.  We both got a good laugh out of it, his driveway turned out great in the end."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:Fabn4Fun  -  Great effort, but no surprise.There never was a prize behind Door #1.Door # 2 was Door # 1, but taller - so the absence of the prize is bigger, but it still doesn't exist.Structurally [welding] you are chasing your tail, and you will never win because of the tool you are trying to adapt.A soil compacter is a refined, balanced, governed, reciprocating devise,and built with/for conservation of weight.  A jack-hammer is an impact-recoil-charge-repeat tool; the heavier thebetter.Compactors are specifically designed for reciprocating mass.Jack Hammer are designed for one way delivery and welcome the biggest spader, or bull-prick you can handle.  You will always lose this battle.  Apply your welding efforts to discovering failures - instead of proven failures.Opus
Reply:A valent effort. seems to me that your failures have all accured primarily in the Sch 40 pipe. Obviously to light for the task at hand. Yes, the tools you're using aren't exactly right for the job. welder doesn't have the power for the material, Jack hammer not ment for compacting soil. but hey, it's a fun project.get sch 80 or heavy wall round tubing. Also  do some hardening on the area where the tip of the bit rest. I think your failure accured because it wasn't bottomed out on the plate and the pipe was supporting the impact of each and every hit. I'm not sure you need 6" of clamping surface. The only reason for the clamp is to keep the plate attached to the bit meaning there is minimal weight that needs to be secured. I'd say 2" of clamping area and two bolts. This will reduce the height of your tube, and allow you to bottom out the bit better.There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:Nice effort and persistence...good luck
Reply:better success will be had with your cap screws if they are properly tensioned as well.http://www.engineershandbook.com/Tables/torque.htmnot sure what is higher than Grade 8, but tensioning to grade 8 specs would be a pretty good start.  This gives the bolt the best chance to resist shearing.i LOVE this project ....  run what ya' brung ... my kinda guy!  I'd probably use a smaller plate and some X-tra strong pipe, as short as reasonably possible to reduce the side loads imparted on the pipe section.love it!
Reply:I tried to quote parts of everybody's replies like castweld, but it got too bunglesome!  So I'll just ramble ...DSW - forget the clamp idea!  If I'd given more thought to the nature of jackhammers, I would have simply let the bit float in the pipe and put a shaft collar on the bit between the "gussets".  That would probably have lasted until the end.  The pipe was drops from some industrial contractor job - simple "black iron" gas pipe.  Or maybe sprinkler pipe.  Interestingly, the pipe could NOT grip the bit tight enough to prevent rotation, therefore it could not have gripped it tight enough to try to jack the plate off.  Looks like "lateral forces" may have started the rips.  Probably when I was standing on it and it was not perfectly plumb.   After all, it is crowned 1/8"+!The only other "close up" I have is the other side, Pic #1.  It's dated early May 2012.  If I'd thought I was going to post this, I would have got more, closer.  Which is a laugh because the original idea of the thread was "Destructive Testing".  Then I realized it wasn't, because I had no test protocol!    10" square - that's the hand tamper size, and it just seemed right.  Over most of the drive, the HF compacter did well enough that a Nissan Frontier with a 1500# load of sand barely left tire prints.  And when barefoot, I "felt" a certain "give" with my heel.  And the ABC compacted with the jumping jack "felt" the same.  Since this wasn't a municipal road project, that was "good enough" for me!  Turned out like Pic #3.Found a hand tamper on CL for $15 (plus $10 gas to get there and back (Phx is big)) and wish I had one.  However, it won't easily reach under the 4" overhang at the patio at the edge of the house.  So ... just happened to have a demo hammer just sitting in the shed, along with everything else except the plate ($17!). AND, most of all, I really would enjoy a little more "seat time"!  My HH140 turned seven years old on Thanksgiving, and I haven't quite finished my 2nd 10# spool of wire!  So why not build something?  I thought that the welds failed at the HAZ because the break followed the edge of the bead instead of cracking or ripping thru the bead.  The bead is on both faces of 1/4" strap and I  could see the puddle "digging in".  That's why I thought HAZ.Lawson and Opus were right.  The thing was inadvertently "non-designed" to self destruct!    Opus, you have a way with words!  This project was simply a "consumable" to accomplish another job.  It did the job, well enough, and got me some "seat time", and new knowledge.  And when I torched it apart, about 5-10 lbs of steel went into the recycle.  Kept the plate.    That said, I still want to do it well, and post mistakes for others to laugh while they learn. Conclusion?  So even when we are certain we have a good 110v weld ... think again?  On the rebuild, I'll fire up the PA-3A, CO2 & .045 and have at it!    And "start / stop" in the center of the side welds.  And get some torch time cutting the gussets and relief.  And go buy a collar for the bit!  Pic #2. Attached ImagesLast edited by Fabn4Fun; 12-21-2012 at 01:04 AM.
Reply:I think ya done good and it gives me a few ideas too!Thanks for posting.
Reply:I like your brickwork!  What part of Phx. are you in?  I'm in Scottsdale---No good deed goes unpunished---
Reply:Originally Posted by mebuilditI like your brickwork!  What part of Phx. are you in?  I'm in Scottsdale