Gamma Progression 200 Racquet Stringer Stand
Intro: Gamma Progression 200 Racquet Stringer Stand
The choices for racquet stringing machines are wide and varied. The top end electric machines cost >$1000 and the middle range machines start at around $700. What these two upper-classes of machines have in common is they are floor standing machines. The low end machines, like I got, are only ~$180 but do not include a stand. Stringing a racquet on a table top is a bit cumbersome, and floor models are much more comfortable. Before this stand I would place my tabletop machine on some wood and a couple of saw horses. While this works, it is an inelegant solution. An Instructable was clearly calling out to me -- so here it is! I built my stand with fairly simple tools and spent around $80. I could have spent less, but I wanted to produce something with decent design margin and longevity.
STEP 1: Make the Base
The first task is to make a base for the machine itself. I decided to make a contoured base from oak. I chose oak because I didn't want the base to warp. But, honestly, if I were to do this over again, I would use a cheaper piece of wood and not cut a contoured shape, i.e., leave the base as a rectangle. I think a good piece of 3/4" birch plywood would suffice. Having a simple rectangular base is easier/faster to build and, if over-sized a little, creates space to store additional tools. Live and learn...
There are 4 screw holes on the bottom of the Gamma Progression 200 stringer base. These are 8mm (1.25mm thread pitch) holes. The task is to mark the relative location of these holes on the wood base. I had some short 5/16" carriage bolts, and I managed to get those to grab the first couple threads. I placed a small dab of poster tack material on the center of each carriage bolt and pressed the stringer bottom onto the wood base. You could also probably use a wax pencil or even lipstick (tool chest, 2nd drawer down on the right...). The tacky blobs eventually stuck to the wood, identifying the drill hole locations. Center punch these locations and drill ~10mm (11/32" if you mark the locations carefully, 3/8" if not) holes in 4 places.
Insert four 8mm bolts into the holes and temporarily attach the stringer bottom. Trace the outline of the bottom on the wood base and use a jig saw to cut a contoured base. Again a countoured base is nice, but I would leave the wood base rectangular if I had to do it over again. Use a plane and coarse sandpaper to take down the "high" spots around the perimeter of the base. Fine sand the entire base and add a couple coats of urethane.
STEP 2: Mounting the Post Flange
I knew I wanted to use a 2-1/2" galvanized post (made for chain link fences) as the stand riser, so I needed something to attach the post to. I found some chain link fence post floor flanges online for about $12 each. We need two.
Next we need to find the location to mount the flange on the wood base, and this location must be the Center of Gravity (CoG) of the entire stringing machine + wood base. Mount the stringer bottom onto the wood base using the 8mm bolts again and completely assemble the stringer top. The entire stringer mass and mass distribution needs to be used, since we want the post to be centered directly below this point. To find the CoG, balance the complete stringer + wood base assembly on the thin edge of a piece of scrap wood; I used a 1/2" wide piece of scrap wood. Mark with a little masking tape the two locations where the scrap wood extends to the wood base. Draw a light pencil line (or tape some string) between these two points to form a line. Rotate the scrap wood ~90 degrees and find the new balance position. Again mark the two locations where the scrap wood meets the edge of the wood base and connect the two points to form a second line. Where the two lines intersect is the approximate CoG. To test your CoG work, center the flange at the CoG and balance the entire stringer assembly + wood base on the flange; it should balance. You can short-cut this CoG process by using a "guess and check" method to hunt down the CoG: just keep moving the flange around until you find where the stringer assembly balances.
To mount the flange on the base I used 1/4" dia. x 1.25" long lag screws. The holes in the flange are huge: like 3/4", so I had to use two washers to cover the hole: 1/4" and 5/16", and I used a nylon spacer in the hole itself to center the lag screw. You probably can get away with not using nylon spacers, but they are only about 50 cents each. Drill the proper sized pilot holes for 1/4" lag screws for the wood type you used in your base.
STEP 3: Make the Cross Base
I used a 2"x3" piece of pine and cut two 30" lengths. Mark the centers and rabbet out a halving joint with a wood chisel. (There are instructional videos on YouTube on how to make a halving joint.) I planed-down and sanded the top edges of each piece of wood but only about 8" in from each end. This produced a rounded top part of the wood toward the outer edges. I added a couple coats of urethane. Do not urethane where the halving joints overlap -- these need to be glued.
Use wood glue to join the two pieces and form the cross base. Halving joints do not have much torsional strength, so I attached a couple 6" 'L' brackets with #12 wood screws for stability. Place the second 'L' bracket on the side opposite the first.
Test-fit the second post flange on the center of the cross base and mark the hole locations. Mount the flange with 1/4" lag screws, 1/4" & 5/16" washers, and nylon spacers (optional) as we did with the flange on the wood base. Again, drill the proper pilot holes, and do not over-tighten the lag screws, since they are in soft wood.
STEP 4: Cut Post to Length
The post is a 2-1/2" galvanized post made for chain link fences. I got a 6' length at my local home store and cut a 26" long piece with a hack saw. I am about 6' tall and this length places the racquet at a good height for me. The formula you can use to find the length of post you want is:
(Height you want the racquet to be) - (height from racquet mounting plane on stringer to bottom of wood base) - (height of wood used to make cross base)
If in doubt choose a slightly longer post length -- you can always shorten. :)
Insert the post into the flange on the cross base and then insert the entire top assembly onto the post. Snug up the bolts on each flange to keep things from rotating, and you're done! String away -- comfortably!