Need help with a cut

[messmaker]

Building a ramp for a deck. I need to build it at my place and take it there for install. I know how to make the cut at location but am struggling to do it in the shop.
The rise on the deck end is 12.34"
The length of the deck will be 42"
How do I figure the bottom cut on the stringer? (where it will sit on the ground)
I realize I will finish with a plumb cut where stringer meets the deck.
Am I missing something?

[daddo]

Deck height= 12.75"
Deck length= 42" @ 90* horizontal?

The angle is 16.89*
Pretty steep ramp.

FYI;
For unassisted wheelchair or motored ramp you'd need a ramp 12.75 feet long.
For assisted ramp you need 7 feet.

[messmaker]

Thanks for your help. I was able to talk them into a step platform instead. I think they will be happier.

[mike4244]

Building a ramp for a deck. I need to build it at my place and take it there for install. I know how to make the cut at location but am struggling to do it in the shop.
The rise on the deck end is 12.34"
The length of the deck will be 42"
How do I figure the bottom cut on the stringer? (where it will sit on the ground)
I realize I will finish with a plumb cut where stringer meets the deck.
Am I missing something?

Both replies are correct, and I agree the ramp would be too steep. Next time you need to establish an angle cut try this method.
Take a framing square ,draw the rise and run on a board . Since your run is 42" and the square is 16" x 24" , then draw 1/2 the measurements. EG. 42"- 2 = 21"
EG. 12.34" - 2 = 6-3/16"
Draw the 90° , end at 6-3/16" at the tongue and 21" along the blade. Connect the lines and you have your angles.

mike

[MstrCarpenter]

Both replies are correct, and I agree the ramp would be too steep. Next time you need to establish an angle cut try this method.
Take a framing square ,draw the rise and run on a board . Since your run is 42" and the square is 16" x 24" , then draw 1/2 the measurements. EG. 42"- 2 = 21"
EG. 12.34" - 2 = 6-3/16"
Draw the 90° , end at 6-3/16" at the tongue and 21" along the blade. Connect the lines and you have your angles.

mike

Or you can put a stair guide at 6-3/16" and 21" to mark level and plumb. In this instance, you'll need to step it off once to get your full run. Personally, I think it's better to instruct how to determine rise per foot of run for ramps (12.34" / 3.5' ). However for a ramp this short I would just lay it out full size on a corner of plywood, lay the stringer on top and mark it on the bottom.