took the JD..B rods to local machine shop in coshocton to have turned out for inserts, left the inserts with them for fitment. when i got them home they were under size by 7 thousands, took them back and was told they couldn't turn that small amount that it would ruin there tooling ! never heard of such a thing but i'm no machinist. all i know is i'll be looking for another machine shop to do my work. sorry for the rant but do feel better......LOL
- Thread starter ohiojim
- Start date
dr sportster
Well-known Member
I've been a hobby machinist for along time now and never heard of small cuts affecting tooling. There are speeds and feeds for all surfaces.
I know I recommend Center Automotive to a few people on this forum lately for this rod procedure. .007" they should be able to get that out with a power hone. Tell them to make them right or give you your money back so you can go another place. Maybe anyone with a Bridgeport mill could get them finished up for you ?
Steve@Advance
Well-known Member
It is difficult to cut a small amount of material. The tool tends to deflect and ride over, or dig in and take too much.
But if they are trying to size rods with a cutting tool, best get them back and take them to a shop that knows what they are doing!
Sizing rods is a very precise operation that requires shaving the cap and rod mating surfaces, thus undersizing the hole. It is then power honed to size within .0002" tolerance. It must also be in parallel with the side thrust surfaces and the wrist pin hole.
They are not ruined, they just need to be done by the right shop. Anything else they did, check it or have it checked by a 3rd party. Bet you'll find more surprises!
But if they are trying to size rods with a cutting tool, best get them back and take them to a shop that knows what they are doing!
Sizing rods is a very precise operation that requires shaving the cap and rod mating surfaces, thus undersizing the hole. It is then power honed to size within .0002" tolerance. It must also be in parallel with the side thrust surfaces and the wrist pin hole.
They are not ruined, they just need to be done by the right shop. Anything else they did, check it or have it checked by a 3rd party. Bet you'll find more surprises!
Steve@Advance
Well-known Member
One more thing, when looking for a shop to fix the rods, ask if they can "recondition rods".
Steve@Advance
Well-known Member
And one more thing... LOL
If you bolted the .007 undersize rods down on the bearing inserts, they are probably crushed to the point they will be loose in the correct size rods. Proceed with caution, but I would replace them.
If you bolted the .007 undersize rods down on the bearing inserts, they are probably crushed to the point they will be loose in the correct size rods. Proceed with caution, but I would replace them.
Mike(NEOhio)
Well-known Member
- Location
- Newbury, Ohio
I've been following this and have a question. Are you altering the original babbitted rods to take shell inserts like the 50s?
Mike(NEOhio)
Well-known Member
- Location
- Newbury, Ohio
Steve has it right. Rods are honed, not bored, to a very precise ID. And yes, some steels are resistant to light cuts but it can be done to as little as .0005" I've had rods reconditioned and they were honed. The bores also need to be square to the face and parallel to the wrist pin bore. Take them to an engine rebuilder.
Mike(NEOhio)
Well-known Member
- Location
- Newbury, Ohio
Second that.
Had my own mold building tool shop for over 40 years and if I couldn't make precision light cuts I would have been in a heap of trouble. Not cutting with the proper set up you can cause the surface to harden in some steels. If you have enough to remove after hardening the surface you are going to ID or OD grind to save a round part or start over. I have never reworked rods but I don't think they will surface harden with a mill cutter. When my mold tool makers surface hardened a piece of steel it was on a lathe not on a mill. Can be done on both though. We worked with a lot of prehard steel so I didn't have to send it out for heat treat.
dr sportster
Well-known Member
Cmon over to my house I have a nice Sunnen hone you can use free.
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