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| Author: | Richard_N [ Wed Oct 18, 2006 12:45 am ] |
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I've just finished building a sidebender similar to the one shown in the jigs and techniques section. Fired her up this morning and the metal top-plate got up to about 105 ?C (about 220 ?F ). Presumeably this means I'm gonna have to change the two 200 Watt bulbs for something bigger - or will it get hotter once I've got the wood and aditional metal sheets clamped on top ? Your advice greatly apreciated. |
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| Author: | Pwoolson [ Wed Oct 18, 2006 12:51 am ] |
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Might try putting a third 200 w bulb in. Heating blankets will make all the difference but I'm not sure if you can get/use them in your area. |
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| Author: | tippie53 [ Wed Oct 18, 2006 12:54 am ] |
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Light bulbs are not that great of a heat source as you can't control heat like you can a blanket. For best results use this set up 200W at lower bout 150 at the waist and another 200 at the upper bout. You want them about 3-4 inches away to avoid scorching. also what are you using for a slat material? John Hall blues creek guitars |
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| Author: | Richard_N [ Wed Oct 18, 2006 1:20 am ] |
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John I'm using 0.5mm galvanised steel sheet (not slats but a continuous top ) |
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| Author: | JJ Donohue [ Wed Oct 18, 2006 1:52 am ] |
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Before going to the blanket on top I used light bulbs configured as John recommended. I line the inside of my forms with aluminum flashing to prevent scorching of the forms and as a heat reflector. I also painted the bottom of my bottom slat black to absorb heat. I tested this combination and it increased temperature a LOT faster. Now I have a heating blanket for the top as well as the bulbs below and it is so much more controllable. I highly recommend getting the blanket...I believe Blues Creek Guitars has them for your electrical system. |
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| Author: | Arnt Rian [ Wed Oct 18, 2006 2:01 am ] |
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JJ, I have the same set up as you, and I also like it a lot better than just the bulbs. I got my blanket from John Hall, so yes, he has them for 220/240V too. |
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| Author: | Colin S [ Wed Oct 18, 2006 2:19 am ] |
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John does do 220/240 volt blankets, I bought mine from John but I got the 110V version (with controller and some spring steel slats) and I run it with a site transformer, I also like to use 110V hand tools. In the UK on commercial sites 110V hand tools are a health & safety requirement, even though I'm just a hobby builder I like my health! Once you have bent using a blanket there is no way of going back, my advice would be to talk to John, he'll be more than happy to take your money  .
Colin |
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| Author: | old man [ Wed Oct 18, 2006 4:34 am ] |
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I plan to get a blanket, but so far I've bent everything for three guitars using three 150 watt bulbs. It gets plenty hot, but is pretty slow. Takes me about 30 minutes to bend a side.  I'm going to use three 200 watters on the next and see if it is enough faster to put off buying my blanket for awhile.
Ron |
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| Author: | Michael Dale Payne [ Wed Oct 18, 2006 5:21 am ] |
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If using bulbs I recommend 3 bulbs 200W CLEAR with reflector on inside of bender and mold. best if each bulb is set up on independent 600w dimmers. this makes it much easier to control the heat at the waist and upper bout. 3 150W or any glazed bulbs will not cut the mustard and without the ability to control the heat in the waist and upper bout scorching is a real possibility. Move to a blanket as soon as you can |
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| Author: | Marc [ Wed Oct 18, 2006 5:37 am ] |
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[QUOTE=MichaelP] ... If using bulbs I recommend 3 bulbs 200W CLEAR with reflector on inside of bender and mold. ... [/QUOTE] That's exactly what I use, I have them spaced and set up just like the plans from lmii. Reflective aluminum covers the entire inside. I would like to try a blanket but I can't justify it because everything seems to heat up quick and work fine. |
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| Author: | Michael Dale Payne [ Wed Oct 18, 2006 5:48 am ] |
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Back when I was on bulbs for my heat source, I could heat a covered mold to 300F in about 8 min. the problem with bulbs is the heat is uneven through out the mold. becase the waist and upper bouts are so close to the heat source, you have to be very carfull to avoid scorching. That is why I ended up while still on bulbs adding dimmers for each bulb.. Once the waist got near temp I would cut that dimmer back to maintain the temp but not gain in that area. Same on the upper bout. Typically the lowerbout stayed at full bore except on Om or smaller bodies. When pre heating It helps to have a slat clamped down to help keep the heat in. It disapates to the open air quickly. In fact all my old molds I used with bulbs i permenatly attached very thin stainless steel flashing material to the profile just for this reason. |
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| Author: | Marc [ Wed Oct 18, 2006 6:17 am ] |
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I don't even measure temp. I just clamp down the slats then sprits the slats until I get a sizzle, then release and take my time placing the side which is wrapped in paper and lightly sprayed with distalled water. I bend which takes about 3 or 4 minutes then leave on for 15 minutes then off for hours, completely cooled, no cycling, no reheating. It seems to work fine, I've bent EIR, honduras RW, Maple, sapale, all without any scorching, or breaking, and very little spring back except on sapale. BUT, I've only bent classical sides, perhaps the extra volume and greater bends on a SS would be a different story. |
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| Author: | MSpencer [ Wed Oct 18, 2006 6:31 am ] |
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I use 3 200W clear bulbs, my forms (Blues Creek) have hollow steel cross members so I place my pencil type thermometer inside the one furtherest from the bulbs, being the upper bout. I turn it on and wait about 15 minutes, spritz the sides with distilled water, wrap in foil, sandwich between two aluminum slats and place on the heat. In about 5 minutes I start cranking down on the waist and get it about 1/4" from seating and bend the upper bout, and secure, crank the waist to seat, and then the lower bout and secure. Like Ron, the process takes about 30 minutes per side, so when I am set up to bend I like to have 2-4 sides thicknessed and then make a day of bending whilst doing other things in the shop. Having good molds I found is important, since I ditched my homemade junk and went to the Blues Creek mold I have not had any problems bending since with the bulbs, just slow. Also bend all of my bindings for all during the same sitting. I made a few holding forms for my already bent sides to keep secure while waiting for mold time. Mike |
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| Author: | MSpencer [ Wed Oct 18, 2006 6:33 am ] |
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Correction, I use the BC molds, but I meant to say Bending Forms (also from BC) in the post above, Sorry Mike |
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| Author: | Richard_N [ Wed Oct 18, 2006 9:31 am ] |
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Thanks for the input guys. Undoubtably a blanket would be better but since this is my first build I have other priorities for my cash so I'll try and get the third bulb wired in tomorrow. Thanks for the descriptions of your methods too - that was gonna be my next question
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| Author: | Richard_N [ Fri Oct 20, 2006 1:47 am ] |
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OK so the 3rd bulbs in and it now gets up to temperature ( Ive tried offsetting the bulbs in an attempt to get an even temp at the bouts and waist ) Michael I've seen you post in another thread that galvanised can stain the wood. I'm planning to wrap my sides in paper and aluminium foil - will that prevent the staining ? Also I've seen people say they wrap the sides in craft paper - what type of paper is that ? Thanks |
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| Author: | Tom Armstrong [ Fri Oct 20, 2006 1:52 am ] |
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Kraft paper is the brown paper in grocery bags. It's also used to make corregated cardboard boxes. |
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| Author: | Richard_N [ Fri Oct 20, 2006 2:03 am ] |
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Thanks Tom |
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| Author: | Don Williams [ Fri Oct 20, 2006 2:06 am ] |
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I think we could all learn a lesson from Taylor Guitars on side bending. I would personally stay away from light bulbs. Funny things happen with them when they get real hot, or if oil from wood gets on them and heats up...like explosions.  I've also heard a lot of stories of folks not being able to control "hot spots" with bulbs.
Taylor's Factory Fridays has a great demonstration of what is probably the best way to bend sides. No, we can't afford to build benders like theirs, but we can use the same principles and apply them to our bending using blankets. |
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| Author: | russ [ Fri Oct 20, 2006 2:56 am ] |
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If you have a look at John How's site here: you can see he's put some of Taylor's principles to work in his bender...very nice! |
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