Side Bending Machine. Instructions for using Blues Creek Guitars universal bending machine.

CAUTION!
Please remember that all safety rules need to be followed when using the bending machine and the heating blanket: Check the heating blanket wiring for damage before each use. Never leave the machine unattended while the heating blanket is in use. The hearing blanket can attain 400F within a very short time and if not carefully monitored it can cause a fire!

Bending Pattern Assembly
The hole at the waist of the pattern is kept open for pinning the pattern into the machine as shown in the photo below.



The holes along the edges of the pattern will receive the half inch tubing. I use a hammer and gently tap one end of a section of tubing into each of the holes on one side of the pattern as shown in Photo 2.



I place this side (with the tubes facing up) on a flat surface and place the other side on top of the open ends of the tubing, as in this photo.



After carefully aligning the tubes with the holes on the upper side, I tap the side onto the tubing until each tube is flush with the outside of the side... and it's ready to use!

Using Bending Machine With A Heating Blanket
The first step in preparing the sides for bending is to identify the set's "show" sides and waist location. Use chalk to mark the outside of the set and the waist location. The waist reference is usually 12 inches from the neck joint.



This photo shows a figured set of wood and I use a different technique than with straight-grained wood. Figured woods are more easily bent using wet paper to help keep the wood moist (helping produce steam) during bending; with well quartered wood the paper isn't needed. Before bending, rough-shape the side set for the back radius. If you don't have a pattern for this you can make one from an existing guitar. Your side set should be a little bigger than needed so it can be trimmed to its final shape after bending. It is important to mark your set so you have the proper book match. The waist reference marks will be picked up though the slots of the machine frame. You do not need to be precise... just close. The final shape will be determined later during the build. At this point you are ready to set the machine up for the bend.



Place the pattern in the frame and pin it with the bolt (as shown in Photo 5). This will locate the pattern under the ram for the proper waist bend location. Next, set the wood up for the sandwich and bending. I will dampen the wood much like you would if you were cleaning a window: Spritz an even cover of water on both side and that is sufficient. Don't soak the sides because too much water may cause warping on straight- grained woods and "delamintation" of figured woods. With the wood damp, create a "sandwich" with the pattern on the bottom, then a metal bending slat, then one guitar side (if the wood is figured enclose the wood between moistened heavy brown paper, such as that used for grocery bags), then another metal bending slat, and last, the bending blanket on top. At this point, make sure the straight edge of the side (the soundboard edge) is parallel to the metal bending slats and perpendicular to the length of the pattern. Use spring clamps to hold all the pieces together and in position (shown in Photo 6), and place the thermometer between the blanket and upper slat (as shown in Photo 7). (If you place the probe directly on the wood it will leave a mark that is difficult to remove.) The waist caul is brought down onto the sandwich to apply friendly friction so you can align the wood into the machine and get the waist reference marks where they need to be.



Plug in the blanket and let it begin heating up. Remember, it will heat up quickly and to a very high temperature. Do not step away from the bending machine for any reason unless the blanket is disconnected and cooled to a safe temperature! Once the heat gets around 220F and the moisten side begin to sizzle, set the lower bout. Take about 20 seconds or so to "walk" the hold-down into position. Once the hold-down is in final position, check the waist reference mark and adjust as needed. Remember: you just need to be close. At this point check the wood at the upper bout and dampen if needed. To bend the upper bout, take 20 seconds or so to walk the hold down into position. The metal mending slats should be in full contact with the wood side. This is the secret to good bending. With both bouts bent it is time to bend the waist. Slowly crank the waist caul down until it is in full contact with the pattern. This will pull the side into the pattern for a good bend.



At this point the thermometer should read 250-300F. Once the wood is on the pattern let the heat build to 350F or so. Continue to heat the side for 4-5 minutes once it is fully pressed against the pattern. Unplug the blanket. As a general reference, total time with the blanket on will be about 10 minutes. Ideally, the whole assembly should be allowed to cool overnight to create a nice tight bend with little to any spring-back or warpage. If this is not possible, prop the side it in a mold to hold its shape (see Photo 7). Note the weight on the mold and how the set is placed on a bench. The weight will force the wood into the mold while it cools. The longer you keep the side in either the bending machine or the mold the better the results. Overnight is ideal.

Bending A Cutaway Side
With a cutaway side the bending isn't much different. The sequence is as follows: bend the lower bout, then the waist and then the cutaway. You are doing 2 bends at once with the cutaway so you need to pull up on the end as you push the ram into the pattern. This is a little tricky so you may want to practice with just the slats until you get a feel for the action. Once the ram catches the pattern you can set the ram home Photo 8 The key to successful bending is heat and moisture. I like to have a good steam going when bending the cutaway. Again remember safety! After you bend a few sets the process will become easier and easier.

Woods And Temperatures
Most woods bend well at 250-320F. Both mahogany and paduk have more spring back than most woods and require more heat for successful bending. For these woods, use 350F and leave them at this temperature for 4-5 minutes to help hold the shape and set the bends.

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