RotoBoss JR Tensioner Relocation Modification

1 min read·Updated Jul 2026
Quick
answer

Instructions for relocating the tensioner on Thunder Laser RotoBoss JR devices with acrylic plates to reduce strain and mount it more perpendicular to the belt.

Applies toAll machinesTopicRotary
THIS ARTICLE IS FOR THUNDER SPECIFIC ROTOBOSS JR DEVICES WITH ACRYLIC PLATES ONLY

Is your tensioner mounted like this?

Tensioner mounted at extreme angle

If so it is at an extreme angle and under pressure.

There is a modification for this version that needs to be done to your rotary that will need to be done.

If you have aluminum plates there are extra holes to mount the tensioner much more perpendicular to the belt. This relieves the strain on the tensioner. If your tensioner is already mounted this way you can disregard this article:

Tensioner mounted perpendicular on aluminum plates

If you have acrylic plates you simply drill a hole and relocate the tensioner so it is parallel. The red dot is an approximation of this hole location but verify for yourself to be sure. You will need some hardware to fasten it as the tensioner is currently using motor mounting hardware:

Acrylic plate with red dot showing approximate new hole location for tensioner relocation

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