Sprocket chain tension

[C.Lesco]

For intake we are using #25 sprocket chains off of vex and I was just wondering if there was a ratio of how much slack you needed for a chain.

[Billfred]

With #25, you want to keep it tight and aligned. This calculator was helpful for us in designing for exact number of chain links (protip: aim for an even number) and generally avoiding tensioners, but it should also help you get the chain run close in an existing system before adding any needed tensioners.

[Mechvet]

Now I'm curious if there's an actual tension/deflection number for #25 chain runs. I've always succeeded with "Good and Tight" while being careful to keep the sprockets as closely aligned as possible.

I'll see what I can find for objective numbers.

EDIT: Found something! http://www.diamondchain.com/frequent...-questions.php

About halfway down, under "How is proper chain tension measured, and why is it important?"

Also, this whole page is full of good stuff regarding chain.

[ASD20]

If you are looking for an easy tensioner, I designed a 10 tooth idler sprocket. It fits right on a 1/4" bolt and can be easily 3D printed.

https://grabcad.com/library/10-tooth...ith-1-4-bore-1

[Joe Johnson]

I almost always design in adjustment of one sprocket in the loop of the chain that can provide at least 2.5 links of overall chain length change (for #25 that is .625" of chain length change). This allows for having tight chain and no half links (blek, pew, yuke! we hates half links! don't make us use half links master...)

If my back is to a wall and I can't design in chain tensioning, I can get over it but I try very hard to get it tight by design (often designing the center distances to be a LITTLE too tight, then filing axle holes to be a little oval so that the chain can fit).

Whatever I do, even with good chain tensioning, I am sure to make sure that the wrap on all torque transferring sprockets is at least 120 degrees.

Good luck,
Dr. Joe J.