pic: Ultimate chain tool project
 

Re: pic: Ultimate chain tool project
 

Some things to consider:
Deep pockets with fairly small area need a lot of consideration paid to chip clearing.
Chain breakers put a substantial load on the threads. If using 6061, you may want to think about designing it for a Helicoil.
To run this on your Tormach, you will be using fairly small dia. end mills. To keep your chip load proper, this part will take a lot of time to process.

This is a really good training exercize. It will teach you a lot about setting up and milling small parts.

Re: pic: Ultimate chain tool project
 

True. Should be a good test for rout planing and coolant systems.
We've got some 7075 we're planning to use but if it's too tough to machine, helicoil is a good suggestion.
Very true.
That's good I hope they learn a lot.

Re: pic: Ultimate chain tool project
 

7075 machines like a dream. Honestly I would say it machines much better than 6061, pity that it's so expensive.

Re: pic: Ultimate chain tool project
 

+1, on both comments.

Re: pic: Ultimate chain tool project
 

I would consider the next step up for re-usable fasteners - a keyed insert. The brand name I know is Keensert. These are much more robust inserts, but do require some specialty tooling. I would see if a local machine shop would lend the tooling to you. This was our standard insert for aluminum vibration tooling to allow easy install of control accelerometers. We found that using tanged or tangless helicoils over and over again was a bad idea and once we switched to Keenserts the problem went away.

-matto-

Re: pic: Ultimate chain tool project
 

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.

Re: pic: Ultimate chain tool project
 

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.

Re: pic: Ultimate chain tool project
 

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.

Re: pic: Ultimate chain tool project
 

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.
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.
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.

Re: pic: Ultimate chain tool project
 

The Dark Soul chain tools are made out of 7075. I have never seen the threads wear or strip out. I have seen the pushing pins fail, the screws get lost, and the groove where it pushes the pin through wear and deform. The dark soul tool does use dowel pins for the pusher screw and roll pins for the chain indexing.

Re: pic: Ultimate chain tool project
 

We had to replace a Dark Soul when a student somehow cross threaded it and then started wrenching down hard on it after it started to get stuck. We had a long conversation about when to ask for help.

We tried a variety of repairs, but ultimately had to buy a new one. If you can make your own new tool when something like this happens because you own a CNC, material may not be a concern. Dark Souls were on a 2 week back order at the time so we were in a bit of a panic.

-matto-

Re: pic: Ultimate chain tool project
 

I believe they meant sizing the pocket such that you can only press the pin out enough to have a little bit left over. That way, you never push the pin out all the way and subsequently be unable to push it back in, which is the most common failure that people seem to have with these.
Also, for rebuilding, I know that the Dark Soul tool has a very wide mandrel for pushing the pins back in. Have you thought about incorporating that rather than relying on the same pin to reassemble?

Re: pic: Ultimate chain tool project
 

I don't know if you already got this or not, but this tool is hopefully designed such that it can press a pin back into place after it has been entirely removed.
Are you suggesting that it would be better to design for pushing a pin in that has only been partially removed? Maybe that would be easier.
Yes, I have thought about this. Testing should show if it is helpful or not.

Re: pic: Ultimate chain tool project
 

Yup, the DarkSoul tool is sized such that there is a pocket that generates a hard stop when the pin is hanging in just the outer link. This frees the chain to separate, and the pin stays stuck in the outer link.

It can be a little tricky otherwise to align the pin back into the hole for the outer link such that when you apply force it goes in, versus binding up slightly crooked. Leaving the pin in the link makes this a non-issue.