R-521
Hi Ron the R-521 is quite easy to use, but I admit at frist they seem abit scary, the one jig will lay out both stair stringers once you set one side and router it out you just flip it over and do the other side. The side of the jig that you use to set your angle of your stair is on your left when working from left to right and on your right when working from right to left, you use your square to set your first rise&run (left or right end of your material) then lay your jig with the tread side (that is the side with round noseing incerts faceing away from you, it would face the top of your stringer) line the top of the jig up with the pencel line you made with your square of the tread angle, keeping the round incert a inch. or so back from the top the stringer then slide the setting blocks down to the top of the stringer careful not to move the jig tighen them in place,then tighen the centre set screw to the back of the stringer now your set to router the tread and riser. To move to the next one you need mark your advance mark, ( at the very top of your jig you will see a small mark indicator, use it to lineup yout advance marks) the advance marks are layed out on the top of the stringer , say your tread is 10" & the rise is 7" the advance would be approxemitly 12"3/8th. of a inch. you would lay that advance figure along the top of the stringer for the number treads you need plus one extra,to match the rise at the top of your stairs. rember left to right for one stringer and right to left for the other stringer, so when you lay them out across from each other they match. I hope I have helped some, let me know how you make out useing the jig. I see in the picture that you have two r-521 I would like to buy one, I have always been interested in stair construction.