Trying to pre-plan a project and having mental problems

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Forum topic by cassady posted 09-02-2012 03:55 AM 1071 views 0 times favorited 8 replies Add to Favorites Watch
View cassady's profile


16 posts in 2402 days

09-02-2012 03:55 AM

I am trying to plan a project that will eventually be an octagonally-shaped cart for my air compressor. I have the plan in my head but I apparently lack the brainpower necessary to figure out how to join the pieces of wood AND also figure out the angle I will need to cut the wood at to form the octagon. Picture an octogon about 2 feet across. If anyone has a tip for figuring angles and then also knows a good way to clamp angled joints, feel free to school me!

Thank you!

-- Cassady in Denver, CO

8 replies so far

View DIYaholic's profile


19618 posts in 2669 days

#1 posted 09-02-2012 04:44 AM

Doing the math for the angles wood hurt my brain right now…...
Clamping could be accomplished with a band clamp. Like this one on sale at Rockler.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View Ryan Haasen's profile

Ryan Haasen

385 posts in 2395 days

#2 posted 09-02-2012 04:46 AM

Matthias Wandel has a video about how to calculate the angles for a polygon (10 sides). While that part may not be such a great help, he also shows how he glues the angles joints together. Here’s the link, hope it helps:

-- Ryan

View casual1carpenter's profile


354 posts in 2469 days

#3 posted 09-02-2012 05:18 AM

cassady, this might help if I have the tolerances set right lol.

View tomd's profile


2155 posts in 3764 days

#4 posted 09-02-2012 05:26 AM

Just do a Google search for a segmented angle chart. An 8 sided ring will need and angle of 22.5 degrees on the end of every piece. To clamp them, form the ring with all sides in their place, glue then rap a band aroung it making sure its flat an in an even octogon shape, I use a large rubber band or belt clamp. After it dries screws or splines can reinforce the joints.

-- Tom D

View Howie's profile


2656 posts in 2917 days

#5 posted 09-02-2012 11:29 AM

360 degree circle-divide by 8 = 45-divide by 2 = 22.5 like tomd said. Key is dividing the circle by the number of sides.
I would use bisquits for alignment and a good glue along with a strap clamp or some type of rubber band. I buy surgical tubing at Lowes and it works great for rubber banding odd shapes.

-- Life is good.

View helluvawreck's profile


31027 posts in 2861 days

#6 posted 09-02-2012 12:26 PM

A really good program for a woodworker to have is a CAD program. It makes anything like this easy. A really good affordable CAD program is Turbocad.

helluvawreck aka Charles

-- helluvawreck aka Charles,

View cassady's profile


16 posts in 2402 days

#7 posted 09-02-2012 01:43 PM

Thanks for the info everyone! Appreciate the sharing

-- Cassady in Denver, CO

View Monte Pittman's profile

Monte Pittman

29216 posts in 2332 days

#8 posted 09-03-2012 11:17 AM

8 pieces (obviously). Diameter X π (3.14) divided by 8 that’s the length of the pieces. All angles are 22.5 degrees. I build a lot of octogons.

-- Nature created it, I just assemble it.

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