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Connecting Rod Balance pic's???

Discussion in 'Shop - Engine' started by atomicjoe23, Dec 3, 2010.

  1. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    Could any of you guys that own connecting rod balacers (to weigh the big and small end of the rods for balancing the rotating assembly) post up pictures of them.

    I'm a Tool & Die Maker apprentice and right now I get to work on some of my own projects just to gain experience with tool design and machining; a connecting rod balancer is on my list (along with a lot of other stuff) and I was hoping to see some pic's of some different models to see what they looked like.

    So far the only pic I have seen is the one from ProForm Tools (the one that you use with a scale, not the cheesey on that you use two rods to see if the rods are balanced to each other).

    Thanks!
     
  2. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    Here's the pic of the ProForm one. . .it's a good pic, but it doesn't show me how it really works.

    [​IMG]

    I don't need dim's I can figuire that out myself, it would be really helpful to see some pictures of one in use with the rod installed and the scale in place (two pic's, one illustrating the big end and one illustrating the small end) as well as a short explanation of how it works would be really helpful.

    I'll post SW's pic's of my design once I get it done (assuming I can get my computer to run it again. . .I need a new computer so bad!!!)

    Thanks!
     
  3. idealer

    idealer Active Member

    Joined:
    Jul 22, 2007
    Location:
    Costa Mesa, CA
    Most performance rods are pre balanced I just have my stuff done by the machine shop while they balance the complete rotating assembly.
     
  4. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    True, but if I have the capability to do the work myself then why not. . .

    . . .cost of material isn't an issue as I can get material rather inexpensively, I'm getting paid for my time so I might as well make stuff that I can use (or will use in the future) rather than just make throw-away exerises that go straight into the recycle bin once they pass inspection. . .

    . . .even though the rods may come "pre-balanced" they should always be checked prior to assembly, most manufacturers even state this in their literature.

    Point being. . .if I'm getting paid to design and machine parts/tools and the material is free then I'm WAY ahead if I make my own tools rather than pay for them. . .especially if they want ~$230 for the connecting rod balancer.

    Here's a list of some of the other parts/tools that I'm gonna make:

    -delrin (or nylon) piston istallation tool (would cost $55). . .I bought a stick of 1 1/4" x 48" delrin rod for body mounts for $30 and I have about 18" left, so that will b free

    -aluminum cylinder head/engine block handles. . .probably make these out of 7075 and then heat treat them (free vs. $40)

    -magnetic deck bridge (to check piston-to-deck clearance). . .only thing I will pay for will be the magnets and the most expensive magnets of the appropriate size that I could find were $15 each, but most are only $5-$6 so ~$12-$30 vs. ~$50

    -camshaft installation handle (free vs. $30-$50. . .I'm thinking about using a MX/ATV handle bar grip and I already have several spares of these so that won't cost any extra and wll be more comfortable than just a bare metal handle)

    -TDC locator (for use when the heads are off). . .once again free vs. ~$20, not a lot of savings for this one, but it's still $20 that won't be coming out of my pocket so it's still a savings.

    Just with these relatively simple tools I can save around $400. .that's pretty good considering I'll be doing this while I'm at work and not on my own time!!!
     
    Last edited: Dec 3, 2010
  5. idealer

    idealer Active Member

    Joined:
    Jul 22, 2007
    Location:
    Costa Mesa, CA
    I here ya... Are you going to balance the crank? If your not going to do that your self you might as we get it all don't at the machine shop... just sayin...

    PS I dont think you will need the cam handle I have never used one.
     
  6. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    Yeah. . .but only to the extent of matching the rod/piston/ring/pin weights to the crankshaft bob weights. . .which is why I will need a rod balancing jig, to weigh the big and small ends of the rod(s) separately. I won't be doing any computer balancing or drilling the counterweights and pressing in mallory metal though; I don't know enough about the balancing process and I think that requires a special type of balancer with sensors. . .the fancy digital balancer may not be necessary to balance that way, but it's probably way faster and the way most shops do it now.

    Maybe not, but it won't cost me anything and then I can play with the indexing head on the mill some more. . .Yeah!!! So far the only thing I have made for myself is 316SS threaded blind sleeve to go in our sailboats keel. . .the old sleeve pulled out so I needed to replace it.
     
  7. joe1369

    joe1369 Member

    Joined:
    Mar 16, 2008
    Location:
    northridge, Ca.
    Sorry if this is way off base, but I was under the impression that the crankshaft, balancer, and flywheel were balanced as an assy, and the rods were weighed and all were set to be the same weight, the pistons were then set to be the same weight, and the weight of the rod and piston assy, calculated into the formula to balance the crank, flywheel, and balancer. I was unaware that they weighed the different ends of the rods????
     
  8. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    OK. . .here goes. . .part of the connecting rod is reciprocating weight (the small end) and part is rotating weight (big end and the rod bearing).

    Rotating weight includes: big end of the connecting rod and the rod bearing.

    Reciprocating weight is comprised of: pistons, rings, wrist pin, locks, small end of the rod and a few extra grams for oil on the small end of the rod (depending on the balancing shop).

    Crankshaft manufacturers usually include a figure with their crankshaft specifications that is called bob weight; bob weight is the amount of weight that the crankshaft can support on one rod journal (i.e. two piston and rod assemblies). . .you calculate your actual bobweight by adding 100% of the rotating weight and 50% of the reciprocating weight.

    If your actual bob weight is less than the crankshaft bob weight then the balancer drills a hole in the counterweight to lighten it to match the actual bob weight, but if your actual bob weight is more than the crankshaft bob weight there are two options. The first and more desirable route is to lighten your actual bob weight by using lightweight wrist pins and/or removing material from the piston and connecting rod balance pads. . .this is only possible if the difference between the two weights is not very great. If the difference in weight is too large then you are stuck with the second less desirable route which is to drill the counterweights and then machine mallory metal slugs and press them into the counterweight to increase the weight. This is considerably more expensive because there is a LOT more labor and time involved and the fact that mallory metal is pretty pricey (I don't know how much exactly, I couldn't find a current price for it).

    Mallory is a tungsten alloy (90% tungsten with the rest comprised of nickel and iron which is why it's heavy and expensive) and is approximately twice the weight of steel. Here's a link to a data sheet on Mallory Metal:

    http://www.mallory.com/pdf/DATA SHEET - 1300.534.pdf
     
  9. joe1369

    joe1369 Member

    Joined:
    Mar 16, 2008
    Location:
    northridge, Ca.
    Thanks for the interesting information, got to love RDC.
     
  10. mfs

    mfs Member

    Joined:
    Dec 18, 2003
    Location:
    ramona, Ca.
    I went to a school and got to do engeine building blue printing and balancing. I just wanted to add U also weight the big and small ends of the rod find the lightest one and sand off metal making all the big ends and small ends weigh the same as well and have the total weigh be the same. The jig just holds the rod horizontally so the scale only weighs one end at a time. I could try and draw how it looks if u want.


    Sent from my iPhone using Tapatalk
     
  11. mfs

    mfs Member

    Joined:
    Dec 18, 2003
    Location:
    ramona, Ca.
    Btw Want to make a press brake die for me? ;)


    Sent from my iPhone using Tapatalk
     
  12. tcrperformance

    tcrperformance Member

    Joined:
    Jul 10, 2009
    Location:
    Tucson, Arizona
    The construction of a C. rod balancing fixture is a good idea, it would provide the means to verify the quality of the machine shop anyone uses. Rarely is their a race engine component that you can wash and install without some massaging that would improve the component. The possible down fall of prepping your own rods for V-6 / 8 applications would be you would need to establish a really good relationship with your machine shop.
    I would suggest you look into building your own electric precision piston ring grinder, you will use it far more and with better engine building results. The *^+ form products are really entry level at best and have no place in a quality engine build. + or - .001" has no place in a race engine, just like a 1/4 gram is not good enough!
     
  13. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    If you don't mind drawing one I would love to see what the ones you used looked like!

    Sounds like a good idea. . .who does make a quality ring end grinder???

    Depends. . .what do you need and what kind of size are we talking about here. . .if it's not somethig that is too big or requies CNC'ing I probably could. They won't let us touch a CNC machine until our second or third year. . .if it's small enough I can do it as a personal project, but I wouldn't be able to do the heat treat for you. We have a heat treat oven in our shop and we can heat treat stuff, but we have to be able to justify it for our own personal stuff. . .so far I only have a grinidng arbor, a jig pin, and a set of 30-60-90 angle plates that I will be able to heat treat.
     
  14. Mean Dean

    Mean Dean Member

    Joined:
    May 8, 2008
    Location:
    San Felipe, Baja California, Mexico
    I balance my own rods end-to-end and over-all and I don't use a jig. First - I weigh all the rods and set aside the lightest one as my standard. Second - I weigh my standard (lightest) rod by placing each end, standing on the side, one end at a time on the scale and the other end on a level even with the scale. The weights of the two ends added together will equal the overall weight of the standard rod - this verifies that the weight is correct. Thirdly - I remove weight to get the remaining three rods to weigh the same end-to-end (and overall). My method may not be as accurate as using an expensive jig; however, it is repeatable because no matter how many times I weigh a rod I get the exact same result on my scale.
     
  15. atomicjoe23

    atomicjoe23 Well-Known Member

    Joined:
    Feb 2, 2008
    Location:
    Silverdale, WA
    The level surface is your jig. . .as far as accuracy goes. . .what's your level of precision (i.e. how many decimal places are you going out to). . .and I only ask this as a matter of personal interest, not because I'm questioning your method.

    I don't know the level of precision that is achieved when you have a shop balance your rod's anyway. . .if I were to balance my own rods I would probably end up going too far overboard on the precision. . .a fortunate side effect of my career as a toolmaker.
     
  16. baja619

    baja619 Well-Known Member

    Joined:
    Aug 7, 2004
    Location:
    Corona / San Diego

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