Ratio Plates
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When you need a ratio other than 1:1, Ratio Plates (Product Family Page) make it easy to position sprockets and pulleys at the perfect center-to-center distance for the given ratio and length of #25 chain or RT25 belt.
Each ratio plate is designed for the indicated sprocket or pulley combination and a loop of chain or belt that is the indicated length. For example, 56PL equates to a 56 link loop of #25 chain or a 56 tooth RT25 belt.
Alignment Markings show the intended direction for the run of chain/belt to have the correct spacing needed for the ratio.
The ½ in Pitch Grid allows the Ratio Plate to match up with the desired MAXTube pattern used for the connected structure
The shifted area marked by the white box allows for the mounting of a motor or bearing and the shaft setup at the denoted ratio spacing
Standard MAXSpline, present in the MAX Pattern and MAX Tube, has 2in center to center spacing. This is designed for very convenient 1:1 ratios using #25 chain or RT25 belts which have a 0.25in pitch.
If you want to have more specific ratios on pitch (down the tube) you may run into issues due to belt or chain lengths being too loose or too tight due to the correct center to center distance not being a multiple of 2in. To allow for a few specific ratios that teams may want to use, Ratio Plates are designed to give you that very specific spacing while still mounting to the MAX Pattern of MAX Tube!
To determine roller chain pitch/link count: Each pin equals a pitch, so count the links and multiply by 2 OR count each individual pin
Designed for a 2:1 ratio using a 12T and a 24T sprocket/pulley
The pitch needed for the belt or roller chain is 56 pitches (56 tooth RT25 belt, or roller chain with 28 links)
Designed for a 3:1 ratio using a 16T and a 48T sprocket/pulley
The pitch needed for the belt or roller chain is 72 pitches (72 tooth RT25 belt, or roller chain with 36 links)
Designed for a 4:1 ratio using a 16T and a 64T sprocket/pulley
The pitch needed for the belt or roller chain is 80 pitches (80 tooth RT25 belt, or roller chain with 40 links)
Ratio Plate used with sprocket and chain
Ratio plate used with pulley belt
As seen in the Onshape example, generally three standoffs are used to mount the ratio plate to the MAXTube. One is in the middle towards the alignment markings pointing for direction and the remaining two stand on the opposite side to support the plate and allow clearance for the belts/chain.
