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Pergola post cap collar?

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Forum topic by logwolf posted 04-20-2017 04:28 PM 422 views 0 times favorited 17 replies Add to Favorites Watch
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logwolf

21 posts in 193 days


04-20-2017 04:28 PM

I built this main pergola-deck over 1 1/2 years ago. I need to finish it this year.)pic attached)
Here’s my dilemma. The pergola idea was taken from an idea from Ana White. In her instructions, she describes how to cut & wrap a post cap-collar over the 36” high post wrap(see attached drawing).
The 45 degree miter cuts are fine if you want to leave this cap flat. But I want it to have a slight bevel to allow rain/snow runoff. I have not added the wrap arounds yet, but I’ve included a picture of the spacers the wraps will go on.
I’m still learning , including combo cuts, etc.
I know the 9 1/2” outside measurement will change once I add a slight bevel to the end against the 4×4 post. Is there a simple formula to calculate this outside length of the 1×4 relative to the bevel angle? OR… Am I making this more complicated then I need to?


17 replies so far

View bandit571's profile

bandit571

16904 posts in 2344 days


#1 posted 04-20-2017 04:31 PM

Cut one piece a little bigger than needed, work it until it fits the way you want it…..and use it as a pattern to make the rest of the pieces.

-- A Planer? I'M the planer, this is what I use

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DirtyMike

626 posts in 563 days


#2 posted 04-20-2017 04:39 PM

ana white huh?

View builtinbkyn's profile

builtinbkyn

1210 posts in 601 days


#3 posted 04-20-2017 05:10 PM

Personally, I think it looks better without the base on the posts. And if I did, I’d make them lower that the window sills – maybe 12” lower. I would just trim off the posts at the bottom to close off the opening at the deck. But it’s your pergola, so obviously it’s your choice :)

-- Bill, Yo!......in Brooklyn :)

View jerryminer's profile

jerryminer

705 posts in 1102 days


#4 posted 04-20-2017 06:15 PM

Not sure I understand the question.

If the post wrap is 7 1/2” wide, and you want a 1” overhang on all sides of the cap, then the cap pieces will be 9 1/2” long, no matter what the slope of the cap.

Rather than calculating compound miter angles, I think the easy way to cut the cap would be to shim up one side and cut at 45 on the chop saw.

Be aware that you are creating the potential for moisture to get trapped between post and wrap. The cap miters will likely shrink, gaps may open and allow water to get in. Keep your eye on it and caulk as needed. Weep holes would also be a good idea.

-- Jerry, making sawdust professionally since 1976

View Smitty_Cabinetshop's profile (online now)

Smitty_Cabinetshop

14234 posts in 2279 days


#5 posted 04-20-2017 06:26 PM



ana white huh?

- DirtyMike

Love that arrogance…

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

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logwolf

21 posts in 193 days


#6 posted 04-20-2017 07:37 PM



ana white huh?

- DirtyMike

Dirty Mike…????

View logwolf's profile

logwolf

21 posts in 193 days


#7 posted 04-20-2017 07:49 PM



Personally, I think it looks better without the base on the posts. And if I did, I d make them lower that the window sills – maybe 12” lower. I would just trim off the posts at the bottom to close off the opening at the deck. But it s your pergola, so obviously it s your choice :)

- builtinbkyn

I think that picture may be misleading. I apologize for that. This is a detached deck with more distance between my windows and post then it appears. Not worried about water rolling off onto windows sills. There are no sills, just vinyl frame. That middle post sits exactly between the windows. The 1 x’s that I’ll be wrapping around those posts will be attached to those spacers, you see in the picture.. Those spacers will not be seen. The wrapped 1 x’s will sit about 3/8”-1/2” off the deck, maybe less, to allow for drainage.. The spacers will have holes from top to facilitate draining. Caulking will be done on top, after I install the cap collars.
Thank you for your feedback. I appreciate it.

View logwolf's profile

logwolf

21 posts in 193 days


#8 posted 04-20-2017 07:55 PM


Not sure I understand the question.

If the post wrap is 7 1/2” wide, and you want a 1” overhang on all sides of the cap, then the cap pieces will be 9 1/2” long, no matter what the slope of the cap.

Rather than calculating compound miter angles, I think the easy way to cut the cap would be to shim up one side and cut at 45 on the chop saw.

Be aware that you are creating the potential for moisture to get trapped between post and wrap. The cap miters will likely shrink, gaps may open and allow water to get in. Keep your eye on it and caulk as needed. Weep holes would also be a good idea.

- jerryminer

OK, that’s great, the outside length will still be 9 1/2”. But my miters will change after I angle the side of the cap facing the post, right? I think I’ll just experiment with the angle I want, and adjust from there.
Thank you for your feedback. Greatly appreciate it.

View Smitty_Cabinetshop's profile (online now)

Smitty_Cabinetshop

14234 posts in 2279 days


#9 posted 04-20-2017 08:02 PM

Log, I’m not sure but I think you’re overanalyzing. If the ‘back’ and ‘bottom’ of the pieces being mitred form a 90 degree angle, with long run being you sloped element, it won’t cut or join any different than square stock as long as that 90 degree corner is at the back of the mitre box.

Does that make sense, or am I missing something?

Also, thinking of adding a drip kerf to the underside?

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View jbay's profile

jbay

1389 posts in 560 days


#10 posted 04-20-2017 08:15 PM

I agree with Jerry.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

View tmasondarnell's profile (online now)

tmasondarnell

42 posts in 1450 days


#11 posted 04-20-2017 08:18 PM

Logwolf,

I think I understand your question.

If you have a table saw, as an alternative to trying to figure the compound miter angle, switch the material to 2x or larger. Cut the material with 45 degree miters just as if you were going to fit it as the drawing shows. Take it to the table saw and cut the angle to get the slope on the top of the material so it shed water.

View logwolf's profile

logwolf

21 posts in 193 days


#12 posted 04-20-2017 08:30 PM



Logwolf,

I think I understand your question.

If you have a table saw, as an alternative to trying to figure the compound miter angle, switch the material to 2x or larger. Cut the material with 45 degree miters just as if you were going to fit it as the drawing shows. Take it to the table saw and cut the angle to get the slope on the top of the material so it shed water.

- tmasondarnell

Yes, that’s the idea I’m trying to explain. However, don’t want to use 2 x’s. But I think I can accomplish this by sloping my bandsaw table down. It does not have to be a 45 degree angle. Thank you for giving that idea. Appreciate it.

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logwolf

21 posts in 193 days


#13 posted 04-20-2017 08:36 PM

Thank you everyone for your help. I looked on you tube and Google for weeks trying to come up with an idea for this. Now I have several options, Sorry I was not as clear on this as I tried.
Thank you again.

View canadianchips's profile

canadianchips

2579 posts in 2658 days


#14 posted 04-21-2017 12:32 PM

I would bevel the top cap to let water run away from post. Also I would cut a drip groove on underside of cap to let water fall down , similar to a window sill. Keep as much moisture away from the skirting

-- "My mission in life - make everyone smile !"

View Smitty_Cabinetshop's profile (online now)

Smitty_Cabinetshop

14234 posts in 2279 days


#15 posted 04-21-2017 01:17 PM

+1 to Chips, that’s exactly what I envisioned as well (and unsuccessfully tried to describe above).

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

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