Skid Loader Forks

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A couple of weeks ago, I posted pics of forks I was making for my skid loader.  Got em done last week, finally warm enough to "check 'em out".Now, I wanted these to use as backup to my TCI 525 4WD diesel forklift which is a bear to start in cold weather.  Designed them to be light duty as the capacity of my loader is 1200 lbs working capacity, 2400 lbs tipping cap.  No problem, I'm only going to be using them for light stuff.What do I chose to "test" it?  A log length (15') 30" diameter locust.  I figure if I can get the log a little off the ground, I've be good.  SNAP, one of my welds broke.  Actually pulled the channel I welded the angle brace on out of shape.  The weld had good penetration, just the log was too much weight for the design of my forks.  Going to cut the angle brace off, straighten the flat bar, reweld the angle back in place, and NEVER pick up that log again.  BTW, Sam, you ain't the only one with Orange paint.   Attached Images
Reply:Maybe wearing that orange paint just made it 'weak in the knees'!  BTW, what is the log for; making fenceposts?
Reply:Just in case you wanted to know that black locust log weighed 3534 lbs.
Reply:Thanks for posting up a failure, PA.It takes a real man to put pics up of something that broke. ( No offense welderwomn...)Sounds like a clear cut case of operator abuse.
Reply:I really like that shade of orange If I had pics to post of anything other than test fillet welds and broken test fillets, then I really would.No offense taken daddy
Reply:paweldor  Didn't I read a post somewhere that said you never welded anything?A butterfly without wings, is just an ugly bug
Reply:Pawelder.........  I wouldn't look at it as a total failure.  Look at it as a REAL GOOD LESSON.  The material isn't sutable for the job.  Mark8310 warned you about it.Nobody was hurt, so it wasn't such a bad day.  Could have been a lot worse.I think most forks are pretty exotic metal, and undergo some pretty important processes.A-36 ain't up to the load, and the weld can't support more than it was meant to support.  Doesn't mean it was a bad weld, just not enough for the load.Last edited by farmersamm; 02-25-2009 at 08:15 PM.Reason: "not enough""Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammPawelder.........  I wouldn't look at it as a total failure.  Look at it as a REAL GOOD LESSON.  The material isn't sutable for the job.  Mark8310 warned you about it.Nobody was hurt, so it wasn't such a bad day.  Could have been a lot worse.I think most forks are pretty exotic metal, and undergo some pretty important processes.A-36 ain't up to the load, and the weld can't support more than it was meant to support.  Doesn't mean it was a bad weld, just not enough for the load.
Reply:Originally Posted by Magnetic Mechanicpaweldor  Didn't I read a post somewhere that said you never welded anything?
Reply:Originally Posted by daddyThanks for posting up a failure, PA.It takes a real man to put pics up of something that broke. ( No offense welderwomn...)Sounds like a clear cut case of operator abuse.
Reply:I second guess everything I do.  It makes for sleepless nights sometimes.And after all that, I still don't get it right sometimes.WE AREN'T ENGINEERS.I still haven't figured out the limits of the material I work with.  I wish there was a simple calculator to do it.  The theory behind strength and stress and compression is great, but I wish there was a table/chart that distilled it into relatively simple terms.  I figure that it hasn't been published because of the liability involved.  There's so much I don't know  And I feel incompetent not knowing it"Any day above ground is a good day"http://www.farmersamm.com/
Reply:admitting   that you are incompetent is the first step to recovery Samm!... Aw, never mind... 'scuse me while I grab a cold one.
Reply:For the forks on my Ford/NewHolland 345D I used the forks off of an old broken down forklift.  I made some mounts on the back of the forks that allowed them to slip on the loader arms when the bucket was removed.  I have used them on my tractor to pickup my car hauler trailer which weighs 1895lbs. or logs I cut up in the woods, also used it for lifting roofing materials on that 1795 Farm House I am restoring.The forks I have from that old forklift are over 1" thick solid tempered steel. The metal in the pictures of that failure look like standard 1/4" angle ironLast edited by specter; 02-25-2009 at 09:49 PM.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:Originally Posted by daddyadmitting   that you are incompetent is the first step to recovery Samm!... Aw, never mind... 'scuse me while I grab a cold one.
Reply:Paweldor,Even for light work, The heel of the fork hanging below the carriage unsupported, puts a terrific cantilevered load on the fork's back. Another factor is dynamic load. Even a load that was easily lifted, may shift, or otherwise multiply it's forces, and try to "twist-out" the channel when moving on rough ground.A suggestion - Build a tough "foot" sort of a box or socket that the channel slides into about maybe 10" or so. Something like two parallel vertical plates boxed with a "floor"  or "sole."   Make the channel fork so it's easy to change, with just a weld or two, or even  bolts.Because...Channel won't lift diddley. Seriously, grab a length of 4" channel and try to us it as a prybar; it'll bend. And just a little twist goes a long way in bringing channel to yield. So it's just a matter of time until one little oversight bends the channel forks. When that happens, it'll be a simple swap to change the bent tine out of the heavy-duty "foot."If you stay with channel, then, keep an eye open for some heavy "ship channel."Or add a plate to the flange of the channel, even a thin plate would add a lot of strength. Or possibly "plate" the channel's bottom.Good LuckLast edited by denrep; 02-25-2009 at 09:51 PM.
Reply:"Any day above ground is a good day"http://www.farmersamm.com/
Reply:The cat's outta the bag!!!!!!!!!Flange, or web.  Which does the work????Got my theories, y'all got yers."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Both, but in this case, more so the flange, by far.
Reply:Given that the flange is under stress in this application, is it an incremental step up to reinforce it, or would a deeper web be the answer??  And how about the compression side of the beam??We're airin' it out tonite folks..If you're interested in building stronger, this is the place to be"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Hey PA - I was just thinking, (I know - With what?  )  that pallet jacks get tossed by the gross.A junk pallet jack would give up almost everything needed for your fix.
Reply:Originally Posted by farmersammGiven that the flange is under stress in this application, is it an incremental step up to reinforce it, or would a deeper web be the answer?? . . .
Reply:Channel laying on it's side, the additional material on top would be benificial, but not really great.Channel laying on end, as it's supposed to be, the additional material on top would be greatly benificial.Does the additional material on top, in stress, make up for a deeper web??Top, and bottom.  Each flangeLast edited by farmersamm; 02-25-2009 at 10:34 PM.Reason: last sentance"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammI second guess everything I do.  It makes for sleepless nights sometimes.And after all that, I still don't get it right sometimes.WE AREN'T ENGINEERS.I still haven't figured out the limits of the material I work with.  I wish there was a simple calculator to do it.  The theory behind strength and stress and compression is great, but I wish there was a table/chart that distilled it into relatively simple terms.  I figure that it hasn't been published because of the liability involved.  There's so much I don't know  And I feel incompetent not knowing it
Reply:PA - Back to post #1, pic #3.Cut the angle iron off, and straighten what you have left.Add a plate to each side of the channel, extending from fork heel to the tube mount, and welded 100% to the vertical plate after straightening it.Attachment 29130That will save what you've already built. Just keep load limits in mind when using it.Good LuckLast edited by denrep; 08-24-2009 at 11:14 AM.
Reply:We're lookin' at a "floor" beam that's gonna be under a load from above.  In addition, it's a cantilever.  The reinforcements shown are how I've done it for years.  The leverage is to the right of the pic.The "spine"/"strongback" is a feature I've always used to deepen the web.  Am I wasting my money with the extra material??  It's always worked pretty wellThe front on pic is without the plate on the bottom of the tubing, but it's there. Attached Images"Any day above ground is a good day"http://www.farmersamm.com/This damn thing.Plate top and bottom to eualize heat, and strongback on top.Not a good pic, but it's middle of the nightDone it this way for years, but maybe done it wrong?? Attached Images"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by GLwelderI second what daddy says. Its nice to see someone else that isn't quite perfect (atleast on the first time around)I have a 3 point disk that I had to weld and add more bracing to about 1/2 dozen times before I could use it w/o something falling off it.
Reply:Originally Posted by farmersammI second guess everything I do.  It makes for sleepless nights sometimes.And after all that, I still don't get it right sometimes.WE AREN'T ENGINEERS.I still haven't figured out the limits of the material I work with.  I wish there was a simple calculator to do it.  The theory behind strength and stress and compression is great, but I wish there was a table/chart that distilled it into relatively simple terms.  I figure that it hasn't been published because of the liability involved.  There's so much I don't know  And I feel incompetent not knowing it
Reply:Thanks for all the replies folks.  They are all great suggestions, and appreciated.  When I started this project I was determined to use what materials I had left in my metal rack.  I would have liked to use a larger piece of 1/4" plate for the backboard, but what you see in the picture is what I had.  O.K. I think, how can I strengthen this?  Also, I would have preferred to use old forks from a scrapped forklift, but couldn't locate any (that I could afford).  Priced any of that stuff lately?.  As for pallet jacks, they really don't have "forks", mostly stamped steel.  I have been looking for forks for over a year now.  They're nuts what they want for them.  Also did lots of looking for those "clamp on the bucket" type forks.  Screw that.  Talk about cantilevering.  And, most of those are made from channel.About the channel.  I would have preferred to use 7.25 # channel, but only had enough for 1 fork.  I had plenty of 5.4 # channel, so I used that.  I can strengthen that by running a bar under the web, or 2 bars down the sides of the flanges.  However, because of the "heel" hanging down like it does, probably wouldn't matter.  With the amount of weight I attempted to "load test", something was gonna fail on the thing.  My fault entirely.Going to repair it today.  I'll take pics of the process.  Thanks again for all the responses.
Reply:Got them repaired.  I straightened the 3/8" x 4" flat, cold.  Used a large C clamp and my short handled "gravity accelerator".  Then rewelded the angle back in place.  I decided to stick with my original design, and slap myself up side my head if I ever pull a "load test" stunt like that again.  I discovered that I was actuall picking up 2 logs when it snapped.   I designed it for up to a max of 1000 lbs, and I'll stick to that. One pic shows the flat straightened, one pic shows a weld, other pic shows the back with steps. Attached Images
Reply:Your workmanship  looks excellent, just be sure to strictly respect the design's capacity.Or to greatly increase capacity, the heel could be boxed.Because. . .What's happening here is that a load on the fork creates a terrific leverage between the angle and carriage. Probably with a ratio, -I'm guessing- of around 48/4 or 12 to 1. The angle, beyond a limited very small capacity, no longer adds strength, but instead, becomes a pivot point.  The fork is now a high-ratio lever. This multiplied force is transmitted as compressive force to the vertical flat plate. Unfortunately, unrestrained flat plate can not resist much compressive edge-loading.Not trying to condemn the job, just giving an experience-based opinion.You probably wouldn't put it out here if you weren't inviting opinions. And my opinion is that without reinforcement,  the flat plate will yield again, with very little load on the fork tip. However, boxing the heel would add plate that is in tension. Plate in tension would raise the heel's strength to the steel's yield point, at least in 40,000 psi range.Good LuckLast edited by denrep; 02-26-2009 at 03:30 PM.
Reply:Yup, box the 'heel' as denrep said.Or big, thick gussets from the 'fork' to the 'heel'.Or both.Because as denrep mentioned, the current flat plate strips are pretty much going to bend and buckle with the long cantilever forks and the leverage that the forks trying to lift a load will put onto those flat plate strips.Box out the bottom of the fork channel too.  Too get 'fancy', you can run intermediate 'bulkhead' gussets inside the channel before you fully box it closed.  Plug weld the box plate to the 'bulkheads'.Maybe take the piece(s) of heavy channel that weren't long enough for your desired fork length and use THAT to box-out the thin skinny (in pretty much every dimension that matters here) flat plate that the entire fork is relying on to lift and support the complex loading from the 'forks'.I'd say (without running the numbers and such), that you would even be better off taking that angle iron and cutting it off from where you currently have it and instead move it so that it is flat against the flat plate.  Weld the angle fully to the flat plate and to the fork channel and to the top hangers.  Generally, 'closed' shapes are better than 'open' shapes for resisting bending and twisting.  So use tube instead of plate, tube instead of channel, tube instead of angle, etc.  And not getting 'funky' (strength-wise) when a shape starts to twist or distort under load is often VERY important.  Because as soon as the open shape starts to bend or twist or otherwise distort, the loading changes and suddenly the shape that should have been OK strength-wise fails.Oh, and the general design criteria for most lifting designs is a MINIMUM 3 or 5 times safety factor, aerospace and highly engineered (and inspected) applications not withstanding.  If people are involved over/under or as part of the load, the minimum 'overdesign' usually jumps to 5x or 10x.  ie: You want to lift a 1000 lb load, you design for a 3000-5000 lb load.And never EVER try to lift that 3500 lb log (times 2!!!!) with the home-made 1000 lb MAX forks.  Hey, I admire your creativity and such, but as denrep said, not trying to condemn but just to make it better (We can rebuild him, we have the technology, ... better, stronger, faster ...  Name that show. ).  Better and safer.  The best laid schemes ... Gang oft agley ...
Reply:I can definitely relate to the problems associated with using what you have on hand. Sometimes it is really hard to build something that you are satisfied with.Hindsight being 20/20 and all, I wonder if you had simply exchanged the locations of the flat plate and the angle, if you would have been better off. The angle is better at resisting compressive loading than the flat plate, and the plate does not provide the failure initiation "point", (literally), that the angle does.I don't know if it makes much of a difference when you have your machine set hot enough, but especially with wire, I always try to end the weld where I think it will see the most tension, or even better, weld around the corner if possible. Those notorious "cold" mig starts can bite you in the a$$.
Reply:Hey PawelderI just received a really good tutorial on flanges, and stuffDenrep is 100% on the moneyI believe you can also greatly increase the strength of the forks by adding a bottom flange.  In other words, box the bottom part of the channel.  You add a compression member."Any day above ground is a good day"http://www.farmersamm.com/
Reply:back to the drawing board.....My skid is rated at 1000 lb load, I made some forks from a old battery operated fork lift, I paid $15 bucks for it, These were the fixed forks (cheaper) I just took my Plasma and cut off the  back plate, welded that to a 1/4" plate cut to match my quick hitch on the skid....works great, i lifted a 1100 lb. ATM with it, the back wheels of the skid were off the ground. but it held up nice.....
Reply:Would be easier to go find a junk pallet jack or some old forks off a forklift. The set of forks I have only cost me $50 each fork. All I did is weld 1/2" plate steel onto the fork where the tractors bucket arm are then cut only some 1 1/4" holes for the bucket pins to go through. If I was up on my farm I wwould send you a couple of pictures. When made the forks on my tractors can lift a car. I use them for harvesting huge black walnut logs. I sell the logs to gun companies to make stocks, furniture companies for furniture, trophy shops, flooring companies.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:All good responses, and really appreciated.  Modifications will be forth coming.