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[Rusty]

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[pat king]

Talk to Jim Lee. He has a section in the Vendors corner. He has done good work for me.

Pat

[Tim Wescott]

I need new rods made because I am building engines from parts.

Are you building brand new engines from scratch, or are you building old engines from a drawer full of old-engine parts (i.e. you have all the bits to make a BelchFire 53 except the rod)?

If it's the latter, ask Randy Smith -- he's got parts, at least going back to the 1960's, and may be able to dig something up for you.

[Richard Entwhistle 823412]

What size engine and maker?  I can make almost any sized machined rod.  I believe some rod may be forged and that is a different ball game.  What material do us want to use?  How much do you feel you can spend per rod? How many do you need?  When I fire up the mill I do not want to stand there for Walmart greeter pay.  A one off custom rod for ten bucks does not come from my house.  I know helping out fellow modelers is the correct thing to do but I am almost used up.  If the price is right I'm sure I can make it.

Later
Richard

[Tim Wescott]

I believe some rod may be forged ...

Just make it look like the original and pass it off as such; that qualifies as "forged".

... A one off custom rod for ten bucks does not come from my house ...

Jeeze Richard!

[Brett Buck]

Jeeze Richard!

   I am not sure what you are reacting to. If you took this job to a machine shop, they would probably quote you $200+, and there is a good chance it would not be any good. Modelers want to pay $15 like it came off the OS assembly line, that would amount to a charity donation.

     You can't fault someone for wanting to charge a reasonable fee for 2-ish hours of work to make a one-off part.

      Brett

[Tim Wescott]

     You can't fault someone for wanting to charge a reasonable fee for 2-ish hours of work to make a one-off part.

I can if they're a friend and I want to pull their leg!

Jeeze Brett!

[Richard Entwhistle 823412]

We still do not know what make of engine, what size or how many are  needed.  If you found someone to do it please say so.  My mill is cleaned up and the tooling is sharp and I have lots of 6061 t6 and new brass.  I am 80 so time is running out.

Later
Richard

[Lauri Malila]

How do they fail?

[Tim Wescott]

How do they fail?

And what are you doing that might make them fail?  And will you be more communicative with whoever you want to make the conrods?  you'll need to share with whoever does the job, or you're likely to get conrods no stronger than stock.

(And if the motor is well designed, don't be surprised if you find that you're breaking cranks or pistons next -- if the engine design is well done the conrod isn't that much weaker than the things it attaches to.  Without knowing the specifics of that engine, I'd expect you to start breaking cranks).

[Tim Wescott]

Richard used to engage is serious drag racing, and currently hot-rods model airplane engines for fun, so if you call him and take the radical step of actually sharing information about what you're doing and why, he should be able to help out -- but don't be surprised if he recommends modifications beyond just beefing up the conrod.

For that matter, Motorman does the same thing, only on the opposite coast.  And there's Randy Smith, and a bunch of others who I can't keep track of -- really, it's a target rich environment.  But you need to start by actually saying what's going on, and what you need.

[Tim Wescott]

I am attaching a picture of what happens to them. 

I love the slot down the center -- it's like Management went to Mechanical Engineering and said "please spend an extra man-month designing these things to split directly in half".  (OK, fine -- they did it do save weight, and accidentally put a stress riser in there -- and wow, what a stress riser).

[Dan McEntee]

    I do not know of anyone that can make the rod for you, but when you do find someone, have them duplicate the Davis Diesel unit exactly if you can. One thing you may try with the stock rods, and add to the after market rod is oiling holes drilled into the rod ends. I do not see any in either rod. That simple adding may make either rod last longer. It may be possible to have the existing Davis rods rebushed also at some savings.. I worked part time at a local hobby shop for 35  years and sold many Traxass products and the first word of caution to everyone was to break in the engine per instructions and to NOT run the engines to rich at the beginning, and to keep them cleaned out. The rod failure that you posted the picture of is typical of what can happen. If you have the exact dimensions of the Davis rod maybe you can cross reference with other manufacturers to see if their stock rods are any better.  These things run kind of like a light switch, on and off the throttle A LOT and almost never run at high RPMs for any duration. I would suspect that they aren't getting the engines up to a good operating and temp and keeping it there, and hard to do when on and off the RPM so frequently.. I can't remember if the 3.3 too hot or cold plugs but experimenting with different heat ranges may help, and maybe even cutting back on head cooling fins a bit. Traxxas has a pretty liberal trade in program where you can trade in an old engine for a new one pretty cheaply, so these are designed and built to be almost disposable. These guys want and need these engines to rev quickly, both up and down, and so they don'r run much oil, some times as little as 12% and maybe less, and that doesn't help the reliability and longevity issues.  Oiling holes in the rod ends would have to help I would think and certainly wouldn't hurt to try.
   Good luck with it,
  Dan McEntee