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So I was looking at some guitar porn (Suhr Guitars) and I was curious.

The Suhr guitars have a 3/16" figured maple top which is straight forward, but how do they have this thick top and still have the forearm contour? I noticed Jackson Phil Collin signature models and some higher end Ibby's have the same feature.

I think it looks awesome and would like to put this kind of top on a build soon.

Here are some photos to explain what I am after...











Thanks for any advice in advance.

Rick

I dont know for sure but Im guessing they shape the back wood and just use ALOT of clamps to make the top curve across the contours

Water, heat, and a press.

Thanks for the replies


I was thinking this was well. Would this method work.

1 - Plane the book matched maple down to 3/16inch
2 - Glue and mount the lower half and let set for a few days
3 - Heat with Steam the upper half of the maple for about 1/2 hour
4 - Glue and mount the upper half
5 - Place a few small screws in the un-routed neck pocket, and 2 pick-up routes (this should help the maple top from shifting.
6 - Use clamps and sand bags to bend the upper maple top into position (while wet with Steam) and hold until the glue sets

Any suggestions?

If you have the option, why not go thinner? It would make bending it much easier. Not saying you necessarily should, just wondering what the advantage is.

Use a hot pipe, just the same as bending sides. No need to soak the timber just spray with water as the pipe heats up. Spray again as the water steams off, both sides. Don't try to do the whole bend at once, work the entire bend. use the shaped body as a drying form.

I've done this 3 times for a mate who makes guitar basses. As your pics show it's a great look.

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Regards from RangeView, Bill

BTW the species was always swamp ash. I don't know the exact th. , but much thicker than guitar sides.

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Regards from RangeView, Bill

Thanks Bill, I started to research bending sides and don't want to buy a bending iron. Can you recommend a DIY method/jig to heat up a pipe?

Could I use a torch to heat the pipe clamped in a vise?

Just thinking out loud, but I would think you'd want it at least as thick as the radius of the rounded edge, or if doing a faux binding you'd want it as least as thick as the faux binding. Otherwise I suspect a veneer and a vacuum press would be easiest.

Rick, homemade, gas fired is fine. The one we used was 2in. dia. x 14 in. , the one I used for my db. We needed 7-8in. free to do the arm rest. I saw one recently that was heated with a heat gun in a fitting that directed all the air into the pipe. Eventually I want to get a heat blanket.

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Regards from RangeView, Bill

Andrew,

I was checking out a a trans-finished USA Jackson Soloist at a music store this afternoon. The maple cap was about 1/8 inch and I think they used an 1/8 inch edge radius. This one was trans-red and they darkened the burst to obscure the transition. Here is a photo I found on line.



Like Lex said, the look that I am after is to use the edge of the maple as a type of binding. This is most commonly associated with PRS guitars, which is straight forward on carve tops without a forearm contour.



Here is a photo in the Ibanez Premium with this feature. Its a flat top with the forearm contour.

There are a couple ways to achieve that bend.
1 Use a hot iron to bend it and then glue with clamps and formss.
2. use a vacuum pressa after bending with the iron.
3. Hot sand to bend then glue with hide glue and hot sand.

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Ken

Hey guys, newbie here after lurking for awhile. Drop tops are usually done by kerfing the underside of the top, as verhoevenc mentioned above. A good example of this can be seen in the Tom Anderson factory tour.

http://www.youtube.com/watch?v=xPwkZEOA_s4

This is shown at 3:50 into the video. The top is bent and glued in place by vacuum clamping. Probably the majority of builders do it this way. With this method, no heat or water (other than what's in the glue) are needed. Just a healthy vacuum pump!

Thanks BMac!

I think I would still try to just put a bend in with an iron. It seems easier than routing all the kerfs and leaving a hard line so the kerfs don't show. (by the way kerfs is not in the spell checker )

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Ken

Thanks Bmac and Ken,

You have both been super helpful. I ended up putting in some kerfs but found it still very stiff to bend. I probably did not make them deep enough. I was concerned about sanding through when I finish sanding. So I used heat and steam also and I am using the guitar as a form. Here are a few picks. I have not glued yet. I thought I would let it dry up and repeat to ensure I did not break the top.







How long should I let the top sit like this before repeating and gluing. Also, I was planning to use regular Titebond, should I use something different?

Rick

After you bend it with heat it should stay pretty much bent to proper shape. I bend double bass backs that are actually thicker than that with an iron and it works fine (pliage). Since your are going across the grain a little just be careful not to crack it. When you remove those clamps if it stays pretty close then I think you will be fine and you can glue it down. I personally would use UF glue DAP brand Plastic Resin for that. When you clamp it to glue it to the substrate, I would use a caul over it to help distribute clamping pressure better. A sheet of thin plywood will work probably, 1/4 inch luan seems about right.

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Ken

Newbie mistake, cracked it. . I went to check everything and tightened one of the clamps and snap.

Starting over,

I rewatched the Anderson video and noticed the kerf's they put in extended well beyond the stress area. This would have helped. If the top is about 3/16th thick how deep would you recommend the kerfs go? I will go with sand bags for weight next time as a vacuum press is a bit much for me.

Finally, would you recommend that I join the book match first, then bring the thickness down to 3/16th? Looks like this is how they are doing in the Anderson video. I found that the heat and moisture must have swelled the one side of the book match and the seam was no long tight. So even if it did not crack,
I would be reworking the seam.

Thanks again for everyones help.

Rick

Cutting kerfs into the bottom. Brilliant. I'm just getting ready to build a drop top and I was scratching my head figuring out how to do it. I don't think I ever would have thought to simply cut kerfs.

If you freeze it at 4:03, it looks like they're using a V bit to make the slots. I wonder if that makes any practical difference.

I believe the kerfs are cut with a small flat end router bit (maybe 1/8"?). Depth being possibly 2/3's of the thickness of the top or deeper. This technique has been used for a long time in furniture building.

http://www.allwoodwork.com/article/wood ... g_wood.htm

The idea is to create sections of veneer thickness to enable the bend.

Rick, I'd go with a glued top so the bend can be positioned in relation to the entire top.

Bob

Well, FWIW I did mine tonight. I only put maybe 5 or 6 kerfs in the neighborhood of the bend. I roughed out the angle on the body on the bandsaw, cleaned it up with a #5 and sanded it a bit to break the sharp corner at the bend. It's gluing up now, but it looks fine and the whole thing went off without any drama. If I make anymore of these, I think I will add a vacuum bag solution to my shop....I should do that anyway, actually.

Anyhow, thanks everyone for the great ideas.

John,

Can I ask, did you put the Kerfs 2/3 of the depth? I would love to see a few pics.

Rick

You know, I didn't think to take any pictures. I realized that I should have about 15 clamps into the glue up. LOL. Sorry.

I think I used a 1/16" router bit to make the kerfs. At first I tried a V bit I had....with extremely poor results. If anyone ever X-Rays this guitar, they're going to find a mess under the top! I went about 2/3rds down, but I just eyeballed it. I only made about 5 or 6 cuts right around where the curve was. When I did the glue up, I set it up with two screws through the pickup location to keep things from squirming around.

A trick with the screws if you only have flat heads kicking around is to use a washer with the screw. That will keep the screw from going into the hole. If you allow it to go into the hole, the screw needs to be absolutely perfectly located because the it will cause the top to center on the screw as it countersinks into the top. The washer allows you to position the top and then cinch it down wherever you want. Pan heads would be better, actually.

Anyhow, I'll post a picture of the end result at least.

OK, the second attempt went way better. Thanks to everyone for sharing your knowledge.

This time I glued the 2 pieces of Maple together and used a 1/8 bit to create the kerfs along the back similar to the Suhr video. The piece still felt a little stiff so I used my iron to steam and heat things up. I still do not have a vacuum press so I used various clamps and weights to glue the top. I am really pleased with the way it turned out. A few small issues that I think I can repair. If any one has any suggestions please let me know. I am planing a light blue top to show off the figure and a black or dark brown base, scrape binding.

Here are a few photos after a quick rough sanding.









I was unable to clamp one area correctly and after removing the clamps I can see that I rounded the forearm contour too much and need to fill a small piece. Any ideas?



Lastly, I noticed a small crack in the same area? It feels really solid, so I think it is more cosmetic at this point. I just want to ensure it does not continue to split. Let me know if you have any ideas.


Again, thanks for all the help,

Rick

looks like a lot of trouble....i'm sure Suhr only does it to save money on figured wood. if you are not mass producing, why not just use a thicker maple cap...? or for that matter, a much thinner veneer top....?