SUPPORT BASE
In this post I'm going to detail the construction of a support base. The one described is the original or prototype model that was developed here. It is simple, strong and easy to build.
I offered some alternative ideas for supporting a swing frame earlier in this thread. Any of those ideas could be used as an alternative to this.
Tools
I'm a bit hesitant to recommend tools, since there are lots of ways to cut a board or drill a hole. People shouldn't think they need these particular tools in order to build this. But a miter saw can make things quicker and easier. If you have one, or if you know where to borrow or get one, it would be worth considering. The one I use is called a Compound Miter Saw, made by Craftsman (Sears).
(Compound Miter Saw)
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There also is a type of drill bit that works well for the larger holes that need to be drilled (1/2", 5/8" and 1"). I call it a paddle bit. It is also sometimes called a Speed-Bor bit, after the company that made them. I'll show a picture so that there is no confusion.
(Paddle Bit)
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This kind of bit scores the wood beforehand around where it will cut. This keeps the wood from splintering around the edge. It cuts a nice hole all the way through, but it is necessary to drill through and into another piece of wood beneath it, for the bottom of the hole not to splinter.
Construction
This support base is constructed primarily from 2 x 4 wood pieces, which should be easy to obtain. So long as the wood is straight and fairly dry it should work fine. Dryness of wood may be roughly determined from its weight. You may notice that two boards, that are the same size, may vary in their weight. When this is the case, the lighter piece is probably more dry.
The support blocks in the center are made from 2 x 2 wood of similar grade to the 2 x 4s used. A small piece of 1/2 inch plywood is used for the circle.
I now have a measurement diagram of the various wood pieces that are necessary to build the support base. It is shown below. I'll go over making the pieces individually.
(Base Parts)
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Verticals
Two pieces for the vertical supports are a good place to start. The two verticals are identical, except for one hole in the left one, used with the locking mechanism. It might be good to wait on drilling this hole until you are making the locking mechanism.
There is an easy way to mark the cutouts to be made at the top of each vertical. First, locate and mark a point that is centered on the side of the vertical, located one inch down from the top. Next, using a 45 degree guide such as a combination square, draw 45 degree criss-cross lines through this point. Then drill a 1/2 inch hole at the crossing point. Last, cut downward into the circle along the two 45 degree lines from the top. File the slight sharp points on the resulting hole and it's done.
I'd recommend using a paddle bit for the 1/2 inch holes. As mentioned earlier, back the vertical with a piece of scrap wood that you will drill slightly into, to keep the back side from splintering.
For the cuts, a band saw would be good, or a jigsaw, cleaning it up with a rasp. Even a hand saw will work.
The recesses for the lag screws can be made by drilling down about 3/8 inch with a paddle bit, following it up with a 1/4 inch hole all the way through. This will allow the head of the lag screw and a washer under it to remain below the surface of the wood.
The lower outside edge of each vertical is beveled to make it more comfortable for hands. This tends to be the place that one grabs the base when picking it up or moving it.
Foot (each side)
The two feet are cut to length, followed by a 45 degree cut on the front and the back of each. The two clearance holes in the middle of each foot should be marked from the vertical piece, just described above, and then re-measured to assure proper alignment of the lag screws before drilling.
Cross Member
The cross member has two small 45 degree cuts at the top of each side. Mark and pre-drill holes on the ends that will center the lag screws properly and will allow the cross member to sit about 1/2 inch above the bottom of the foot. This will allow 1/2 inch clearance under the cross piece when assembled. This clearance keeps the weight on the two feet. The cross member can't high-center.
Each end of the cross member has a treatment so slight that it is only shown in the enlarged illustration below. Essentially it's not flat, it's a point, a very slight one. The saw I used allows for other than 90 degree cuts. I adjusted it for two degrees off of square. I made two cuts, one from each side to the center of the end, between the two lag screws. Because of the slight point, the vertical may be positioned inward or outward by adjustment of the lag screws.
(Cross Member End)
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Assembly
The assembly of the right side of the base is shown below. Both sides are mirror images, so it should apply to the left side as well, but in reverse.
(Base Assembly)
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The support blocks and the circle used for standing the swing frame on end are shown in the illustration below. The blocks should be flush with the upper edge of the cross member and provide a solid, flat surface for the circle to rest on. Each support block is glued and screwed, using 2-1/2 inch drywall screws. The 5/8 inch downward hole through the cross member would be best made with a drill press, but a hand drill can be used if you are careful to keep the drill perpendicular both directions. The screws must be located to miss both the 5/8 inch hole and each other inside the cross member. I put the screws as far apart as I could on the support blocks, making the front screws higher up and the back ones lower, in order to avoid each other. The circle was cut using a hand jigsaw and is attached using four countersunk flathead screws.
(Support Blocks & Circle)
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All wood pieces were smoothed with a rasp as needed, then sanded smooth. The base was test assembled to assure that there wasn't any further sawing, drilling, filing or sanding to be done. With the prototype, several little things needed minor work. So don't be surprised if you find the same.
When finally done, the base was disassembled and given three coats of spray paint. The gray used for the prototype base is actually a primer, but very durable. It is Krylon 9183 Gray Primer. For the white circle, Krylon 8822 White Satin Paint/Primer was used. I got them at Walmart but Krylon is a common brand. Both of these dry very quickly and may be re-coated in as little as 10 or 15 minutes. After allowing 24 hours to completely dry, the base was reassembled and considered done.
Of course there is no reason you can't decide on different colors.
The next post will be about the locking mechanism that holds the swing frame and sewing machine in the position desired. I'll detail the one used in this prototype as well as explore some alternative ideas for locking mechanisms.
More soon ...
John