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Forum topic by mglmrgn posted 02-27-2013 08:36 AM 829 views 0 times favorited 16 replies Add to Favorites Watch
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mglmrgn

5 posts in 663 days


02-27-2013 08:36 AM

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16 replies so far

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bondogaposis

2749 posts in 1099 days


#1 posted 02-27-2013 01:25 PM

Handsaw the upper one and bandsaw the lower one.

-- Bondo Gaposis

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Kazooman

60 posts in 700 days


#2 posted 02-27-2013 01:28 PM

I agree with Bondo. I am curious about the design. What is the purpose of this unusual joinery?

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waho6o9

5286 posts in 1325 days


#3 posted 02-27-2013 04:09 PM

It looks like it slides out, like a drawer.

Welcome to LJ’s Miguel!

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mglmrgn

5 posts in 663 days


#4 posted 02-27-2013 05:20 PM

Thanks guys! Rick, I hadn’t actually thought about the grain too much. My plan is to have the top be free, and doweled in the front so that it can flip upward. Does that fix the expansion issues? I still have a week or so to finalize the design so I’m open to suggestions!

View RogerInColorado's profile

RogerInColorado

306 posts in 702 days


#5 posted 02-28-2013 12:18 AM

For the end, glue up an MDF template and pattern route the part, Clean up the inside curve with a chisel.

For the top, I can only come up with hogging it out with a saw and a chisel and work to get the fit you want. Think of it as a weird half dovetail.

View TCCcabinetmaker's profile

TCCcabinetmaker

925 posts in 1103 days


#6 posted 02-28-2013 12:23 AM

The real question is why are you cutting this angle? If it’s solid wood the way it’s oriented is going to give you some mechanical issues over time.

I would use a table saw, to cut the leg, then stop it before going all the way through, then come back with a jigsaw and finish out the cut, as for the other, I’d probably jig saw that cut or lay it out and use a multi-tool to cut it out.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

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thefrozenwoodworker

18 posts in 679 days


#7 posted 02-28-2013 01:10 AM

Agree with needing more info, but that said: the bottom is straightforward sawing, for the top strike your lines along the side and top, and depending on grain, use a handsaw and a chisel and pare down to your lines. If you know the angle, you can make a little block jig to help guide your chisel at the proper angle for the final cuts. . Can’t wait to see the solution you come up with and the finished project.

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mglmrgn

5 posts in 663 days


#8 posted 02-28-2013 02:52 AM

Hey guys, thanks so much for the feedback! I’m happy to give as many details as possible, but I’m not exactly sure what information to provide. What I’m going for is a table top that can hinge upward, almost like a drafting table. I’m trying to avoid metal hinges, though, so the plan was to have a pin inserted at the front. The image that I originally attached is the top and one of the sides. The funky looking joint is to allow the hinging motion, while still having the majority of the table top resting on the sides instead of between them. I’ll attach another image that will hopefully clarify that aspect.

TCC, it is going to be solid wood… can you explain why that will give mechanical issues and how I might fix them?

Rick, I’m totally open to suggestions… if there’s a simpler way, I’m all ears!

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Kazooman

60 posts in 700 days


#9 posted 02-28-2013 03:55 AM

Now I understand what you are trying to do. I do not really like the proposed joinery. I assume that the grain on the end piece will be running lengthwise. That would make the small portion that juts out to accept the dowel pretty weak. The sharp edge on the cut into the top will be a spot for wear down the road. You will also have an odd looking spot at each rear corner. All this to avoid a metal hinge?

What will the “back” side look like? That is the portion between the two end pieces and below the proposed dowel joint (to the right in your drawing). If there is to be a piece of wood across there then the best solution (in my opinion) would be to leave the top intact as a rectangle. Have the sides continue on straight with the back piece attached to them and use hinges. The entire top (both sides and the back) will be supported by the frame. That is as strong as you are going to get. You can use a simple piano hinge or get fancier with some positive stop hinges that will hold the top open at an angle just past perpendicular.

If you really must avoid a hinge, I would suggest making the sides straight and adding a small cleat to the bottom edge at the back of the top. That would accept the dowel at a lower position. You would need radius the corners of the side pieces to provide clearance as the top swings up. If there is a cross piece along the back then you would need to provide relief there as well. The hinge is the better way to go.

Finally, how do you plan to assemble the desk? Will the end of the dowels show on the side pieces? If not, then you will have to be able to assemble the desk while capturing the dowels in their holes. Also, if the desk top is to be opened a lot, then I would avoid wooden dowels. Metal pins would be more durable.

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mglmrgn

5 posts in 663 days


#10 posted 02-28-2013 05:36 AM

Thanks for the feedback! I tried to add some more details in the diagram, because I think you switched the front and back. I’m new to all of this, so please excuse my ignorance, but what is it about this set up that makes it weak? It’s been mentioned a couple of times and I just don’t understand where the issues will be and what will cause them. Any explanations would be greatly appreciated! With regard to the pin, I’d prefer it be hidden, but if it needs to be flush with the outside of the side board, that is fine. Thanks again!

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AttainableApex

338 posts in 1581 days


#11 posted 02-28-2013 07:00 AM

dunno if its been said but on the bottom part with the “ear” just glue that on then handsaw the top

-- Ben L

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Kazooman

60 posts in 700 days


#12 posted 02-28-2013 12:43 PM

I have altered your drawing to point out my areas of concern. From your drawing it appears that the amount of wood where the dowel will run through is less than an inch from front to back running along the grain. There shouldn’t be too much pressure on the dowel hinge, but if you let some kids at this they will figure out a way to apply some. Neither of these is a show stopper, but I would simply do it another way. To each his own.

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mglmrgn

5 posts in 663 days


#13 posted 02-28-2013 04:59 PM

Thanks Kazooman! Can you or someone else explain to me why the grain direction is a point of weakness?

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Kazooman

60 posts in 700 days


#14 posted 02-28-2013 08:24 PM

Wood tends to split easily along the direction of the grain. Layers of the wood that are the annual growth rings of the tree simply peel apart. You have undoubtedly experienced this when splitting firewood. The strength of the wood is along the long fibers (with the grain). With your joint if there is any upward pressure at the dowel the wood may split along the grain lines. I should note that you indicated hard maple and that is a pretty strong wood, but still…. Suppose the desk top is up and you toss something in it that is a bit too tall. You shut the lid and the stuff acts as a fulcrum and the top as a lever. A small downward pressure on the front lip of the top would be focussed on splitting your joint. Or if the desk is not against a wall and you flip open the top and lose your grip. The top would flop over the back until the sharp edge of your top piece contacted the end board and then all of that momentum would be transferred right onto your dowel joint.

The strength relative to the grain direction comes into play in many other situations. One of the most common is in a spline in a miter joint. To add strength to the miter joint you cut a groove in the mating faces of the pieces. You then cut a piece of wood (the spline) to fit the groove. You need to cut the spline so that the long grain is running across from piece to piece in the joint. If you were to have the grain running along the length of the groove, the spline would easily split along the grain and not add strength.

A similar instance is the use of “butterflies” to hold a crack together. The grain direction has to span the crack for strength.

In your situation, if the side board was just straight without the bump up and you fitted a dowel like you are planning you would have much more strength because it would not just be the inch or so, but the entire length of the board at work for you.

View TCCcabinetmaker's profile

TCCcabinetmaker

925 posts in 1103 days


#15 posted 02-28-2013 08:43 PM

James it wouldn’t open if you put the dowel there :/

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

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