Official Luthiers Forum!
https://www.luthiersforum.com/forum/

Cracked Macassar Ebony sides.
https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=42483		 Page 1 of 1
Author:  fingerstyle1978 [ Fri Jan 17, 2014 6:36 pm ]
Post subject:  Cracked Macassar Ebony sides.
I attempted to start another build whilst waiting for coats of tung oil to dry on the current build. I had a beautiful set of Macassar Ebony that I figured I'd use before using some of my nicer stuff.

Admittedly I bent this stuff a little thick (0.095). Ironically, I thought it might help prevent cracking down the line. Well it didn't even make it out of the bender before cracking twice. I got it from the infamous Brock Poling and it's got some runout. So there's one large crack with the grain and then another massive crack across the grain at the bend between the waist and the head block.

So in order fix the issue I'm thinking I should do what I should have done in the first place and laminate it to some very thin mahogany sides (I'll have to mill) close the crack on the butt and use the other crack for a Florentine cutaway since it actually works out nicely.

However I have a couple questions.

1. Outside of the added weight, is there any issue with sides that will end up being 0.125 or possibly even larger depending on how thin I can get the mahogany?

2. In order to match the sapwood and grain at the cutaway is it advisable to flatten and re-bend the wood back the opposite way? or should I flip and rotate it and just deal with the grain inconsistencies?
Author:  Jim Kirby [ Fri Jan 17, 2014 8:16 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Unless you were trying to build ultra-light like a flamenco, I can't see that the extra side weight would hurt. The extra weight is even advocated in a number of circles as one means of trapping more energy in the top. Trevor Gore's approach, for example.

Sorry, can't help with the second question. I would probably try to match the grain.
Author:  fingerstyle1978 [ Fri Jan 17, 2014 8:21 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Imagei think the grain would match decently if I flip it and bind the tips of the florentine with a wider section of binding.

Imagehere is the crack at the butt. Should be an easy fix. There's another starting to develop on the other piece in the same spot. So lamination seems like a must.

Can anyone with experience laminating sides tell me if .03" is thick enough or should I go closer to .04-.05"?
Author:  J De Rocher [ Sat Jan 18, 2014 12:50 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
fingerstyle1978 wrote:
2. In order to match the sapwood and grain at the cutaway is it advisable to flatten and re-bend the wood back the opposite way? or should I flip and rotate it and just deal with the grain inconsistencies?


In case it's any help, I bent the Macassar ebony sides on the guitar below on a non-cutaway form in a bending machine and then reversed the bend on the upper bout on a hot pipe to make the cutaway. So the Macassar ebony, in this case, tolerated all that bending. The sides were 0.085 thick.

If it was my guitar, I would try to match grain across the tip of the cutaway. It would drive me crazy otherwise. Would the tip of your cutaway fall near the crack in the sapwood? I wonder if, after cutting off the section that you will use for the cutaway, you could thin it down some to help make the reverse bend easier.

Image
Author:  fingerstyle1978 [ Sat Jan 18, 2014 12:58 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
I can definitely thin it a bit because I am laminating the sides now. I ended up stopping with the mahogany at .050 because it's sooooo light. The final thickness should be .145 so theres plenty of room to thin the ebony, especially considering how rigid it is compared to Mahogany.
Author:  mkellyvrod [ Sat Jan 18, 2014 9:49 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
Joey, you sound like me - can't wait to get working on the next one before I've finished the one before.

I'm just a newbie, I know (only 7 sets of sides using a bending machine - all in the 0.08 to 0.09 range), but seems like the cracks that run horizonatally across the sides could be due to too little heat (i.e., not enough steaming) when bending. I've followed Todd's video on side bending with not a problem (knock on wood) - I begin around 250 F and generally end around 300 F. The long vertical crack running lengthwise, maybe just a problem with the wood to begin with?
Author:  fingerstyle1978 [ Sat Jan 18, 2014 4:37 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
There's definitely problems with the wood. I got it from Brock Poling so it was to be expected, not the like it's the first time the guy screwed me over. There's a lot more runout than one would like. If I had seen this wood first hand I never would have bought it.

I did go ahead with the lamination and it stiffened right up, no more cracks. I also cut the Florentine cutaway and I'm getting to bent the cutaway piece back the other way so that the grain matches. I don't think it was a heat problem at all, if anything I bent it too hot. I think I started around 280. It was pretty stiff though so I didn't finish until it was over 300. The sides were soaked for quite a while as well. I think the extra thickness and the runout was the culprit.
Author:  Herr Dalbergia [ Sat Jan 18, 2014 5:08 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
"The sides were soaked for quite a while as well"

.....soaked in Water? I do not use water on ebony. Once I used water and the side kind of exploded, exactly like on your pictures. Since this experience I bent ebony dry.
Author:  Clay S. [ Sat Jan 18, 2014 5:49 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Rather than rebend the cutaway I would flip it end for end (inside to outside) . That would keep the sapwood on the same side, and put the cracks to the inside.
A lot of back and side sets have some runout. Most are resawn from boards rather than billets so there is not a lot of thought given to "runout". Sometimes you do get a piece of wood with such terrible runout that bending is problematic, but usually it is the method rather than the material.
Author:  fingerstyle1978 [ Sat Jan 18, 2014 6:23 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Herr Dalbergia wrote:
"The sides were soaked for quite a while as well"

.....soaked in Water? I do not use water on ebony. Once I used water and the side kind of exploded, exactly like on your pictures. Since this experience I bent ebony dry.


That's good to know. I'm now terrified to bend ebony sides. I have some Malaysian and some Gabon that I plan to use later this year if all goes well on the current builds. Would you bend those dry as well? Also what thickness? I just may laminate both of those sets since ebony loves to crack so much.

I'd like to read Trevor Gore's book but I don't have an extra $245 laying around at the moment. Trying to square away my finances before I leave the Army in 10 months and return to the East Coast.
Author:  Alexandru Marian [ Sun Jan 19, 2014 9:19 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
I wouldn't bother to bend ANY wood at more than 0.08. With the more difficult ones, you are just asking for it. Mac, I only did one, just lightly damped surfaces, and it worked better than I expected. No problems, no distortion. Macassar is actually quite a tough and elastic wood (very unlike Black ebony) but sure when there is runout in a thick side, it will open up. Finding runout free tropicals is quite a lucky occurrence. Make it thinner next time.
Author:  Toonces [ Sun Jan 19, 2014 1:12 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Joey,
I highly recommend you start using double sides. For the record, I have been soaking my sides before bending and have been getting the best results I have ever gotten. I always had springback when I bent with lightly spritzed sides. Woods with oils (Cocobolo, Rosewood) tend to bend great without much water but dry woods like Ebony I find really need a noticeable amount of steam to bend. Unfortunately, thick sides and water can sometimes cause some warping/rippling.

The advantage with double sides is that the thickness decreases to the point where you will rarely break a side ever again. And the process of gluing flattens the surfaces so you get much better prepared sides.
Author:  fingerstyle1978 [ Sun Jan 19, 2014 2:08 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Toonces wrote:
Joey,
I highly recommend you start using double sides. For the record, I have been soaking my sides before bending and have been getting the best results I have ever gotten. I always had springback when I bent with lightly spritzed sides. Woods with oils (Cocobolo, Rosewood) tend to bend great without much water but dry woods like Ebony I find really need a noticeable amount of steam to bend. Unfortunately, thick sides and water can sometimes cause some warping/rippling.

The advantage with double sides is that the thickness decreases to the point where you will rarely break a side ever again. And the process of gluing flattens the surfaces so you get much better prepared sides.

I just laminated the sides and I like the way they feel (solid) and sound. They fit the mold better as well. Do you use mahogany to laminate or two thin sections of the same wood?
Author:  ZekeM [ Mon Jan 20, 2014 9:04 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
Joey,
I have no advice to give but do have a question. I saw your pic of laminating in another thread. Did you just put the two laminates in your mold and then use a rubber strip to hold them together when the glue dries? I've been wanting to try laminated sides but the rigs I've seen are a lot of work to build. Your method seems to be much simpler. I'd like to hear more about it and if you had any issues doing it this way.
Author:  Arnt Rian [ Mon Jan 20, 2014 10:00 am ]
Post subject:  Re: Cracked Macassar Ebony sides.
I've used it a bit, and I find it quite difficult to bend, at least compared to most rosewoods. Here are some things I have found helpful: No thicker than 2mm (.08"), thinner in sharp bends and cutaways. I use no water, as it tends to create ripples and unevenness. Instead, I use SuperSoft 2, which I spray on a day or so prior to bending. Also, check for hidden cracks before bending, and use thin CA glue to stabilize any suspicious looking spots or areas. Use higher temperatures than normal, and support the wood well while bending. Allow the wood the heat up thoroughly, then bend resolutely and quickly. Let it sit in the bender, and "cook" it a couple of more times, then cool off, before taking it out and placing it in the form. This usually gives good results, any spring back after this I can usually fix on the hot pipe. Luckily, it is not that hard to fix small errors in these dark woods...
Author:  fingerstyle1978 [ Mon Jan 20, 2014 12:18 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Zeke- yes I used a used truck tire tube that I picked up for free from a used tire lot per padma's advice. I wouldn't want to be without a tire ever again! I stuck another in the bender to see how that method worked as well but it ended up being more work to get an even clamp pressure. The set laminated with the tire came out perfectly and that is the method I will use from now on.
Author:  Pmaj7 [ Mon Jan 20, 2014 8:38 pm ]
Post subject:  Re: Cracked Macassar Ebony sides.
Truck tire laminating sounds interesting. Any pics?
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/