Repair a Feller Buncher Dipper Arm | Line boring & Liquid Nitrogen

Repair a Feller Buncher Dipper Arm | Line boring & Liquid Nitrogen

Show Video

good boy how you going guys Kurtis from cutting edge  engineering so today's job we have a dipper   arm off a forestry style machine in for some line  boring not 100 percent sure on what brand of machine this   is off from what i can gather of the look of  the arm it's some style of feller buncher or tree   harvesting or processing machine that end up there  would attach onto the boom that is attached to the   excavator or whatever machine it is and then this  end has got the attachment on it so whether it be   a feller bunching attachment or it be a saw or a  grab or a grapple that's mounted up at this end   judging by the size of the arm like what materials  it's been made out of and thicknesses i'm going to   assume this is going to be between a 25 and 30  ton machine so another thing that indicates what   this arm could be from or what style of machine  it is is the amount of pipe work that runs down   the right hand side of the dipper arm so we've  got eight pipes down there so that would be four   pipes in four pipes out which would indicate that  it would be a multi-function attachment that goes   on the end problem we've got with the dipper  arm at the moment is we've got some bushings   that have come apart in the end of the arm and has  actually done some damage to the bores the bush on   the right hand side is completely non-existent and  the bush on the left hand side three quarters of   it is missing judging by the state of everything  in there it looks like it's this end of the arm   cops a hell of a flogging typically on a linebore repair on say an excavator or something like this   we will bore out the damaged bearing surfaces we  would then bore weld them and then machine them   back to spec but in this case customer has told me  it's very difficult to find parts for this machine   so to make things a little bit easier for our  customer we're going to go with a standard   off-the-shelf generic bush to be fitted back into  the end of the dipper arm and it is an oversized   bush so we won't need to do any welding on the  id we're simply going to bore it out to suit the   generic bush one of the other things i did put  to the customer is that i did see that the bush   that is still in here has got a grease groove  through it and around it in multiple spots that   can be your best friend when it comes to greasing  the joint but when it comes to a very very high   impact or wear area like this one is it can be  your worst enemy because those grooves that have   been machined in there will also act like a dotted  line and when they do start to wear out they tend   to fracture through those grease grooves and then  the bush starts to come apart and then you've got   a mess on your hands to give you an idea on what  the standard style bushes look like on the inside   we do have this one here as an example it's not  off this machine it is off a totally different   machine in a completely different circumstance  of operation inside these bushes they have got   multiple machine surfaces to get grease around the  pin and throughout the bushings but as you can see   by the inside of this bush you do lose a lot of  surface area and you are essentially weakening   it and you're actually removing a lot of material  that really needs to be there in these high impact   areas the bush i have here is the generic bush we  are going to be fitting to the end of the dipper   arm the things that are different with this is  this has one grease port in to allow grease into   the bush it then has a center groove and two  holes in it to allow grease into the bush and   that is it there is no other material missing this  bush also has double the wall thickness which will   offer a great deal more support to the pin and the  joint than a standard one would so the other way   we could get around putting grease grooves inside  bushes is we could put grease through the pin and   run a solid bush with no grease grooves in it at  all that is not in my opinion an upgrade because   when you drill a hole through a pin and  then you drill a hole down through the pin   to allow grease through the grease channel that is  essentially a dotted line for a crack to form and   the pin to fail i have remanufactured hundreds of  pins since i've been here for customers that have   had machines with that particular upgrade that  have totally failed so the first thing i need   to do before i can start line boring this is  i need to get the remnants of that bearing out fractured through the center one so what i've done there is i used a welder to add material   to the bush and the reason for that was so  it would shrink after it had cooled down   so there are a handful of ways to remove a bush i  couldn't pull it out with say a press or a porta   power the other alternative is you super heat them  with sane oxy acetylene once it goes red hot you   let it cool and it will shrink down smaller than  what it was before you started they become easy   to remove welding does the exact same thing if you  weld a small area of the bush it will shrink after   it cools down and you can simply just knock them  out so if you are going to attempt the welding   method make sure you know where your bush starts  and your bush stops because i had a customer one   day that decided he was going to do a repair by  himself you could do what he did and he actually   welded the bushes into the end of the job and  it took a job that should have taken a couple of   hours and blew it out to over two days if you're  going to do it clean everything up and make sure   you know where things start and things stop so  you don't create yourself a hell of a nightmare righto guys we're about to start the boring  process we're not going to try and take out   massive amounts of material in a  single pass because the bar has   got no support through the center it is  about 800 mil between the bearing blocks   if i do try to take out a massive cut  it's just going to end up with chatter   vibration we're going to end up damaging tools  so we'll take a mill out per pass until we clean   it up and then we'll finish it to size and  we're using our 12mm tool holders with an ecgt   insert they seem to be the best thing that i  have found that works really well for line boring bit more to come out so will readjust that tool what's this one Homey oh my goodness his favorite [loud ducky squeaks] Homeless homeless the ball is all alone ready get it oh [giggle] slipping on his slobber [loud AF ducky squeaks] jesus [laughter] he's slipping over ahh Homeless just lay down lay down righto guys so all of the line boring is now completed we've bored the eye out to suit the bushes we're about to install the bushes we will  be using liquid nitrogen to do a shrink fit   at this stage the bore that we have machined is  0.1 of a mil smaller than the od of our bush so   using liquid nitrogen we're going to shrink  that down over 0.1 of a mil in order to get   that to be a slip fit when you're fitting these  there is a very fine line between things being   too tight and not tight enough so i'm going  to take a measurement of the bush as it stands   now in the current temperature after it's been  in the liquid nitrogen and everything's frozen   down we'll then take another measurement just to  show how much they do they actually can shrink this is what we store our liquid nitrogen in  it is a lab grade 30 liter dewar or vessel   it doesn't go out in the field so we don't  really need the big heavy duty one with the   big case and everything around it it comes  with a thermo blanket that just helps with   keeping everything nice and  cold and everything insulated if it is unopened it will hold and store liquid  oxygen for up to 260 days but we never ever   get anywhere near that sort of time frame we're  getting this filled every two to three weeks by our   local liquid nitrogen supplier and we do reuse our  old liquid nitrogen if we've got any left after   we've done a job we do tip it back into the vessel  for another use you wouldn't do that if you're   working in a lab or in a you know hospitality or  something like that because liquid nitrogen is   used in many different industries one of the other  cool things about liquid nitrogen dewars is they   are basically a tank suspended within a tank in  between the two tanks is a cavity they then pull   a vacuum on that seal that off and what that does  is that stops heat transfer going from the outside   atmospheric pressure into the tank and burning off  the liquid nitrogen that is my understanding of   how a dewar works something really important  to remember when it comes to liquid nitrogen   these vessels don't actually hold pressure they  have a venting lid in them the other vessels that   the guys who deliver our liquid nitrogen to us  they have pressure relief valves on their entire   system because when liquid nitrogen is stored  under pressure it can explode if you were to put   it in a bottle of some nature and try and take  some home for a lab experiment it's probably   going to blow your lunch box apart only use the  approved vessels for storage and the approved   vessels for transport so as you can see with the  vessel that is not a tight fitting lid that is a   self-venting lid it is made from styrofoam  and it doesn't fit tightly into the vessel   it just sits in there and stops the  liquid nitrogen from burning off so i'm going to give this a bit of a  preheat you don't want to get things too hot   when you're doing a preheat for bushings because  the hotter you get the job the quicker the cold is   pulled out of the bush you can create a thermal  crack in the bush not only that if you put too   much heat into the job you're trying to fit a  bush to the bush can then absorb that heat and   you will essentially shrink it and pretty  much destroy all the work you've just done   so you don't want them red hot you just  want them just the chill taken out of   the material it's a rule of thumb i've  followed for years and it's always worked righto guys so we just fitted the bushes  everything went exactly to plan we didn't   have anything bind up nothing locked didn't have  to hit anything with a hammer as you saw i shrunk   that bush 0.2 of a mill which is about 8 thou i  did have a 0.1 of a mil interference fit on the od   of the bush to the bore so we did shrink it well  beyond what i had machined it to because i could   shrink at 0.2 doesn't mean i would make it a 0.2  interference fit because the id of the bush has  

a 0.15 clearance on it something that needs to  be remembered when doing such things like this   always measure the id of your bush and make sure  you don't make the od too tight because you will   then make the id too tight and it will have to  be honed or machined to size a general rule of   thumb that i have followed forever if i have  to machine out a hundred millimeter od bush   i will give it point one of a mil interference  fit which is one thou per inch across the   face of the bush one thou per inch is a  good rule of thumb for something like this   it's never let me down something else we're  going to do while we've got the liquid nitrogen   out i've got a brass bush i use for another job  we're going to throw that into liquid nitrogen   so we'll get an od measurement we'll freeze it  down and then we'll take a measurement of that righto guys so you just saw how much the  brass shrank it shrank point three of a mil   so the brass generally shrinks 1.5 times  the rate of steel so if you would like to   put a lot more crush on brass you can but there  are a lot of other materials used as bushings   and bearings that can also be shrank even more  than brass and steel generally aluminium will   shrink about three times the rate of steel it's  because it is a softer material and it seems to   disperse heat and cold very very differently  and there are a lot of materials you shouldn't   freeze down like sintered bearings which are a  self-lubricated bearing they don't like it and   it does actually ruin them this is the result of  something that has been frozen in liquid nitrogen   and then left out in the atmosphere so it will  create little icicles on it that you can just   skin skim off the top once this bushing thaws  out we can put it back on the shelf and use   it on another job don't really want to do this  too many times because you can actually mess up   the structure of the material if you freeze it  then heat it freeze it and heat it there's one   more thing i i need to do i haven't done it for  a lot of years i'm going to freeze a banana and   attempt to hammer a nail in with it i have a  broken pallet here i'm going to try and repair oh no [laughter] poor banana it's still good can you use that much the banana was too frozen right oh so i left my hammer i mean banana in my  liquid nitrogen for a little bit too long and it   actually shattered when i started to use it as  a hammer i would not recommend what i'm doing   here although i have used this stuff for years  and i do use the proper gloves which have got   a woolen inner and they are pretty impervious  to liquid nitrogen freezing them and hurting   you or hurting your fingers i do wear safety  glasses so it's quite a safe environment here   it is a little bit of fun but liquid nitrogen  is no joke if you get a drop of that in your   eye it will freeze any moisture it comes in  contact to and it can blind you it's one of   those chemicals you shouldn't play with so don't  try this at home righto guys so the job's done   everything went to plan so we're gonna get this  one back to our customer and thanks for watching my hat on straight yeah okay go are you ready  yep am i too close i don't know i think so  [giggle]  this could be a feller buncher style uh [ __ ] i've lost it [giggle] whew down through the surface of the material down  through the surface of the down through the [ __ ] [snort] [ __ ] [ __ ] oh [ __ ] oh [ __ ] [ __ ] in my opinion that is the worst idea man has  ever come up with terrible idea stop doing it yeah [giggle] right what was it starting with and judging by  oh and judging by so the other thing that indicates   okay indicates that's a great word okay thank you yup for multiple for multiple what well i don't know what a freaking fellow buncher thing is that can be your best friend when it comes to greasing is it under that pile nooo it's a [ __ ] ruler ghost [ __ ] rulers grown legs and [ __ ] off it is dangerous [ __ ] it might explode in there   exploding banana i think the banana's having a bad time [giggle] um it's a hang on shush crow oh shut up trains it does have a thermal uh a thermal blanket  on it to keep everything a little bit cold uh der [giggle] it's uh [ __ ] right so we hmm [giggle] right ready no okay uh pff uhmm ahuuuhh [giggle] come on train and come and interrupt this so i can stop [Laughter] [sigh] it's not funny this isn't funny [giggle] right so that is my understanding of how a dewar works   i'm not a rocket surgeon i have never cut one  apart to see what actually happens inside them   so until i break this one i'm just going to leave  it alone so that's how a dewar works i think [ __ ] slobber i think he's dribbling  yeah he is he's dribbling must kill ducky poor ball [more loud AF ducky sounds] [Laughter] oh my gawd jesus [ducky crying out for help] poor [ __ ] duck poor ducky getting a flogging

2022-03-04 10:11

Show Video

Other news