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How would I make this compound curve?

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Forum topic by Marcus posted 02-11-2011 10:26 AM 3777 views 0 times favorited 11 replies Add to Favorites Watch
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Marcus

7 posts in 2468 days


02-11-2011 10:26 AM

Topic tags/keywords: compound curve question

I’m helping a friend put 1”x8” base on this staircase, but don’t know how to make this tight curve look good. How would you guys do something like this?

Thanks!

-- Marcus, Minneapolis


11 replies so far

View Jack_T's profile

Jack_T

623 posts in 2498 days


#1 posted 02-11-2011 02:15 PM

You need to show use the base of the curve as it exists now. Additionally, please show a picture of a portion of the base that you have already modified. The photo that you have posted shows a staircase that is finished with carpet.

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

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Sawdust2

1467 posts in 3554 days


#2 posted 02-11-2011 02:44 PM

Can’t be too helpful with just this pic. But it looks like they used 2 pieces of 16/4 wood.
Draw the rough outline on all six surfaces of the square pieces. Cut with a bandsaw.
After you cut a piece tape it back on so that the wood is still somewhat uniform in size and then cut another curved section out. Tape that piece back etc.
Finish with a draw knife or lots of sanding.

You need to think in 3 dimensions.

Lee

-- No piece is cut too short. It was meant for a smaller project.

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Gregn

1642 posts in 2450 days


#3 posted 02-11-2011 03:32 PM

This is somewhat similar to David Marks Sculpted Elliptical Mirror.
http://www.diynetwork.com/diy/video/player/0,1000643,DIY_33170_8201_39621-39682,00.html
While not quite the same as the handrail I think this video will help you to see how its done and answer some of your questions. I think it will give you a good idea as to how to go about cutting the compound angle needed. This video deals with cutting angles and should help to know how to cut the compound angle needed for the handrail. While David doesn’t do a compound miter in the project it should give you an idea of what your trying to do. As to the degree of angle needed I can’t say but will give you a good example of how to basically go about accomplishing the curve and making the compound angle needed to make the joint. I hope this helps.

-- I don't make mistakes, I have great learning lessons, Greg

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crank49

3981 posts in 2438 days


#4 posted 02-11-2011 03:48 PM

Gregn, what does making a laminated veneer chessboard have to do with the OP’s question?

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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CampD

1475 posts in 2953 days


#5 posted 02-11-2011 04:06 PM

First, I gather that your intentions are to put a baseboard or skirt as it’s called on stairs.
Second, there is no quick and easy way around it.

Now, 1st pieces should be the stair skirts, both upper and lower sets of stairs.
this gives you what your base trim size will be.
Now, I would use MDF (easier to sand) and back skarf it every 1/8” (with a curve that tight) about 3/4s of the piece deep.
From the pic it looks like you could use the wall as the template, bending the piece around the curve and attach it with nails or screws, I would also use construction adhesive.
Next, sand the radius smooth using either a belt or plam sander (remember, not to remove to much material)
If the piece is to be painted, just fill and smooth, if you want a finished wood, glue a piece of veneer to it.
If attaching basecap, you can find some pieces in a stair parts catalog (look under landing step)or steam bend it.
Be prepared, it make take more then one to get it right.

-- Doug...

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crank49

3981 posts in 2438 days


#6 posted 02-11-2011 04:41 PM

First, let me say that I have never tried to make something like this in wood. I have done it with steel, for spiral stairs, but not wood, so I’m just trying to offer some suggestions that may help; or not.

+1 to what CampD said about being preparred to make more than one to get it right.

The problem, as I see it, is this is a compound curve. The back scarfing has to run at an angle so the piece can run at an angle and be bent at the same time. Then the top edge is going to reveal all those cuts which can be covered with a cove mold or what ever profile you need to match the rest of the stairs. The top mold can be steam bent to fit. Or, if this is just going to be painted, you might be able to get creative with putty or filler to hide those back cuts.

I would probably use some plywood strips to make some prototypes. Might even use plywood for the finished product, depending on how well it worked. It would have to be good quality plywood without voids and plugs.

There are some insanely expensive wood products out there that are processed to have very high moisture content and compressed. You can take this stuff out of its plastic bag packaging and form it into what ever shape you need, tie it in a knot if you want to. Then as it dries out while held in the shape you want, it stabalizes. I think it is called “comp wood” or something similar. Comes from Denmark I think.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View Gregn's profile

Gregn

1642 posts in 2450 days


#7 posted 02-11-2011 06:05 PM

Crank, There is a video of a Sculpted Elliptical Mirror that relates to the thread. Sorry if you just seen the chess board. I may have gotten the link wrong.

-- I don't make mistakes, I have great learning lessons, Greg

View Gregn's profile

Gregn

1642 posts in 2450 days


#8 posted 02-11-2011 06:22 PM

I checked the link again and the video is right below the player just click on the Sculpted Elliptical Mirror box. Sorry for not clarifying where to see the video better.

-- I don't make mistakes, I have great learning lessons, Greg

View Marcus's profile

Marcus

7 posts in 2468 days


#9 posted 02-12-2011 05:03 AM

Thanks so much for all of the helpful hints guys…

However, I mistakenly wrote base, but what we are really trying to do is replace the curved handrail with a 1×8 wall cap.

My question is how to make/create a 1×8 wall cap in Cherry that can go around those super tight compound curves. It will need to be able to be stained when completed.

Here is a similar curve on the same stairs to help understand the problem

-- Marcus, Minneapolis

View Jack_T's profile

Jack_T

623 posts in 2498 days


#10 posted 02-12-2011 05:28 AM

I would do it exactly as in Gregn’s post #3 the video appears below the main screen. Remove the handrail and trace the curve. Make a template of the curve and make the cap in the same manner.

However, before you do anything, you need to check the local building code. Builiding codes are very explicit with regard to size and location of handrails. An 8” wide cap might violate the local code.

Good luck

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

View Bernie's profile

Bernie

416 posts in 2304 days


#11 posted 02-12-2011 06:02 AM

I just finished rebuilding all the molding around my staircase. I had removed the rail to sand the the stairs and rather then trying to refinish the molding, 98% of it was straight cuts and 45 miter cuts. The bottom step was a different story. It’s molding ran a 225 circle and then a 45* convex. The original molding was mostly missing except for one short piece, but I was able to figure how it had been put together. Basically, it was in pieces so the grain of the wood followed the curves. I ended with 5 pieces. I used the original piece to get the radius of that piece. Then I used a Home Depot tool which is a bunch of pins in a holder and you can push the pins onto a curved surface to get a copy of the profile. I transferred the profile on my piece of oak, cut the outer shape on a 4X4 oak, and routed the edge profile before cutting the finished product off my slab. Granted, this is a bottom under the step edge piece so only folks getting down on their knees will see the minor flaws. In your case, test out a sawdust wood+glue combo with stain-ability. or cut a thin cap or read other posts!

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

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