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| Author: | roby [ Wed Apr 22, 2009 5:25 am ] |
| Post subject: | Flat spots in sides |
Hello all ,got a problem with the sides on my first build.I've sanded in prep for binding,mostly ok apart from one section on the lower bout ,when i run my hand around it i can feel a couple of humps or flat spots that are quite noticable,i sanded all round the sides with a straight edge held from the top to the back but it seems to be just this one area giving me problems,anyone had similar problems.Ive tried sanding where it feels like the high spots are but not making much progress.Any advice would be appreciated.Thanks all Rob |
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| Author: | bluescreek [ Wed Apr 22, 2009 5:31 am ] |
| Post subject: | Re: Flat spots in sides |
what kind of wood is it? Some woods will flat spot during bending. You can try and sand it a bit more and you can also "finish fill " to help. |
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| Author: | roby [ Wed Apr 22, 2009 5:40 am ] |
| Post subject: | Re: Flat spots in sides |
Thanks for the reply John, the sides are indian rosewood,what do you mean by finish fill? |
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| Author: | Michael Dale Payne [ Wed Apr 22, 2009 9:27 am ] |
| Post subject: | Re: Flat spots in sides |
Typically these kinds of issues are low on the out side in the near middle of the rims (side) width and most happen in the lower bout area. This is often called cupping. This cause by moisture that was not cooked out during the bending and after cook if a Fox style bender was used. It can also be caused by insufficiently cured wood. As the rim dries after bending the moisture evaporates at a slower rate in the middle of the width than the edges this causing the wood to move. Some times this can be pretty bad but most often is little enough to sand or scrape out without getting too thin. If you used a Fox style bender I will suggest you cut back next time on the amount of added moisture. IRW bends like butter. Really no or very little added moisture is needed. |
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| Author: | roby [ Wed Apr 22, 2009 10:31 am ] |
| Post subject: | Re: Flat spots in sides |
Thanks Michael i think your'e right about using too much water when bending , i soaked the sides for about 20 mins and used a bending iron, what is the finish fill tecnique mentioned by John in the previous reply? Thanks again Rob |
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| Author: | Bill Hodge [ Wed Apr 22, 2009 10:38 am ] |
| Post subject: | Re: Flat spots in sides |
Howdy Roby, Not a good idea to soak your wood. Especially IRW! I generally spray a very quick light mist on each piece and don't even think that's necessary. In fact, I'm planning on trying Todd Stock's method of wetting the paper that I sandwich the sides in to bend rather than spraying the wood itself. As for sanding the sides, If you're using a rigid block with sandpaper that extends beyond both edges, I suppose that's fine but I typically use a wide cabinet scraper with excellent results. 
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| Author: | roby [ Wed Apr 22, 2009 11:07 am ] |
| Post subject: | Re: Flat spots in sides |
Thanks Bill i'll know better next time! Still want to know about this finish fill , anyone? |
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| Author: | bluescreek [ Wed Apr 22, 2009 2:35 pm ] |
| Post subject: | Re: Flat spots in sides |
Mahogany , rosewood and maple don't need much water. Black Imbya , you can't make wet enough. Some woods need water some don't. Some bend with low heat others darn near need to be set on fire. The first 1000 are the hardest to bend |
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| Author: | bluescreek [ Wed Apr 22, 2009 2:56 pm ] |
| Post subject: | Re: Flat spots in sides |
Finish Fill That is when you over coat an area to allow a transition area to help hide flat spots. Using an iron cause some issues until you learn the skills. Flat and riftsawn can also flat. Waterfall figure will usually flatten . I like to run the sides at .095 to allow some sanding shaping. These are the mistakes that teach you the most. Working wood is just that , making wood to do what you need it to do. |
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| Author: | roby [ Thu Apr 23, 2009 3:59 am ] |
| Post subject: | Re: Flat spots in sides |
Thanks John, i was planning to use french polish as a finish, is it possible to finish fill with shellac? Rob |
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