pic: Ultimate chain tool project

[Bryce2471]

Originally Posted by topgun

A couple of points:
1) Why not machine it out of 1018 steel? Tormach can handle steel.
2) Why do you want to push the pin out? I made one for my team and it's set to push the pin out enough so you can break the chain while leaving the pin in. Then you have a pin ready to push right back in. This is much more secure than any connecting link you would use.
3) I used an injector pin for the part that is actually pushing against the chain pin. These are very hard and won't mushroom out, plus you can get them sized to fit thru the pin hole.
4) Make sure you have enough leverage available on the handle to actually move the pin. We used a shcs so we can put a long allen wrench in it or even use a drill with a hex bit.

1. Because we have some 7075 to use, and who else can say they have a custom chain tool cut from aerospace grade aluminum?
2.Because, as stated in the description, this tool can be used to build chain (put the pin back in) if the pin is removed.
3. Thanks for the suggestion, I might look into that, but we have the all-thread and hardening compound on hand, so we'll probably start with that.
4. Good point. The handle is home made, so we could easily put a longer peace of rod in.

Originally Posted by MechEng83

Some additional comments I didn't see written:

I'd recommend you use fine thread rather than coarse thread. The screw will be easier to turn.

Are you machining the all thread down to the point? If I understood your description, it's case hardened, but that won't help you if you machine away the case. For our custom #35 chain tool (and the replacement we used for the #25 that broke) we used a hardened dowel pin inserted into the end of the screw.

The threads chosen were the finest threads of the correct size that we have a tap for.

Yes, I plan to machine the all-thread down to form the mandrel, but the case hardening will take place after that.

Originally Posted by Chris is me

I think the concern isn't with the difficulty of cutting the material, but with the strength of the threads tapped into the block. If these strip, a helicoil is the logical next step.

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I'm excited to see the development of not only an improved 25 chain break, but a 35 chain equivalent. Do you think instead of milling square protrusions, you could just press roll pins into the block to constrain the chain? This makes manufacturing much easier for you, and it avoids causing overconstraint by limiting the points of contact with the chain.

Both machining the block and the thread strength are a concern.

I think using roll pins is a great idea, but we don't have the size we would need on hand, so the first one will probably be cut as shown.