Baffle mounting question

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mlundy57

Baffle mounting question
« on: 30 Jan 2018, 02:36 am »
I am building a pair of Skiny 6s and a Flat 5.  I want to use solid wood for the baffles. There are two methods I can think of for attaching the baffles to the cabinets. I can glue them on or I can bolt them on.

If I glue them on I can get a good airtight seal but I worry about the risk of the baffle splitting over time. If I bolt them on I can avoid the splitting issue but I am unsure how to get a good airtight seal.

Any ideas?

Mike

Danny Richie

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Re: Baffle mounting question
« Reply #1 on: 30 Jan 2018, 03:08 pm »
For best results you can use a thinner layer of solid wood and bond it to a thin sheet of MDF.

mlundy57

Re: Baffle mounting question
« Reply #2 on: 30 Jan 2018, 03:39 pm »
What I’m trying to accomplish is using a thick enough piece of wood so the rounded over edges are completely in the wood. I would think that would mean for a 1/2” roundover I would need at least a 1/2” thick piece of wood and for a 3/4” roundover a 3/4” piece of wood.

In the past I have wrapped veneer around the edges but I had issues with that not working out all the time so I’m looking at trying a different approach.

Peter J

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Re: Baffle mounting question
« Reply #3 on: 30 Jan 2018, 04:54 pm »
Mike, I haven't done what you're describing exactly, so I'm coming from a theoretical view. In a lot of commercially made furniture, joints between composite panels and solid wood are somewhat hidden in what an old boss of mine called a "furniture joint". This is done so when they move differentially, it doesn't result in and abrupt or visible edge.  Typically a small groove or offset hides the actual joint. In the best of cabinet and furniture building, accommodation of wood movement is always a consideration.

I can see a couple of ways to do this. Will you have access from the back? As in back of cabinet mounted last?

jeffh

Re: Baffle mounting question
« Reply #4 on: 31 Jan 2018, 12:10 am »
Use veneer on the face and use a thick piece of matching hardwood for the edges. Then you can cut whatever profile you like into the edge. Something like this.
https://goo.gl/images/7rpJYg

You probably would not need to cut the v like this example. Google edge banding for more pictures.

cody69

Re: Baffle mounting question
« Reply #5 on: 31 Jan 2018, 12:19 am »
Quote
If I glue them on I can get a good airtight seal but I worry about the risk of the baffle splitting over time.
The theoretical part of me agrees and I'd search for a solution... the more practical side says with the very narrow baffles being used, doubt it would cause a problem.

Could use wood on the front and the back panel, so they expand & contract the same to eliminate chance of splitting.

May also consider Danny's suggestion to laminate a veneer over your substrate, and build-up the edges to carry the round over.

jeffh

Re: Baffle mounting question
« Reply #6 on: 31 Jan 2018, 12:29 am »
Here is another method. Build the box and then cut a dado into each corner. Then glue in matching hardwood. After that you can cut your edge profile. See an example here:

https://goo.gl/images/tyNxqP

mlundy57

Re: Baffle mounting question
« Reply #7 on: 4 Feb 2018, 05:58 am »
Thanks. I've seen the hardwood strip on the corner. veneering over that then cutting the roundovers. A viable option but the grain lines don't match well the the transition is visible.

I asked the furniture building instructor I have taken classes from and he doesn't think gluing the pieces on will cause a problem.

If I go with bolt on, as cody69 said just bolting them on may work fine. If I put a thin gasket behind the baffles that should definitely work. Any ideas about what type of material might work?

Peter, yes the back could be mounted last. There is access to most of the front but not the top of the Skinny 6s or the center of the Flat 5 because those compartments are sealed off by solid braces.

Captainhemo

Re: Baffle mounting question
« Reply #8 on: 4 Feb 2018, 07:03 am »
Mike,   what about gluing the baffle on with thickened epoxy, would that not give you an air tight seal ?  You  could also  run some  calk or  silicone   around the  inner seam   if you glued the  rear  baffle on last  (aside from the  2  areas you mention)

jay

degroot

Re: Baffle mounting question
« Reply #9 on: 14 Feb 2018, 10:59 pm »
I dado'd in my baffles on my last Flat 5 build. I only had to cut the baffles 1/8" over size and dado into the sides 1/16" each.  That was on 1/2" thick sides.  Rule of thumb is not to exceed about 1/3 of the side thickness with the dado.  I really liked how easy this made the assembly and will seal very well when glued. I posted a picture in the Flat 5 of Danny's awhile back to show what it looked like.  With my first AV-3S build I remember how frustrating it wa trying to glue in the baffles and keep them in place and perpendicular as well. I will use the dado method on all future builds if applicable. Hope this helps.

mlundy57

Re: Baffle mounting question
« Reply #10 on: 15 Feb 2018, 04:00 am »
Yes, gluing, regardless of the type of glue will seal fine. As long as the wood doesn't move enough with seasonal changes in humidity to crack gluing will work. A furniture maker I have taken some classes from said he didn't think gluing would cause a problem.

I'm still not sure I want to take the chance. Other than a bead of silicone, is there any other type of gasket material I could use to create a seal when bolting the baffles on?

Captainhemo

Re: Baffle mounting question
« Reply #11 on: 15 Feb 2018, 04:33 am »
Well yeah, you  could  physically make a  gasket.  Gasket material is available in sheets in  varying  thickness at most  auto  parts stores.    But, that's not going to  give you  a seamless  edge

Personally,  I'd  use the epoxy and then  seal up the entire   cabiinet , inside and out with epoxy if it's got you  worried

jay

mlundy57

Re: Baffle mounting question
« Reply #12 on: 15 Feb 2018, 05:16 am »
Well yeah, you  could  physically make a  gasket.  Gasket material is available in sheets in  varying  thickness at most  auto  parts stores.    But, that's not going to  give you  a seamless  edge

Personally,  I'd  use the epoxy and then  seal up the entire   cabiinet , inside and out with epoxy if it's got you  worried

jay

Jay,

Epoxy is just another type of glue. Gluing will create the seal with a solid wood baffle just like it would if I made the baffle out of MDF. I'm trying to have my cake and eat it too. I've seen it done before, I just don't know how it was done.

Mike

fishboat

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Re: Baffle mounting question
« Reply #13 on: 15 Feb 2018, 07:29 pm »
I'm still not sure I want to take the chance. Other than a bead of silicone, is there any other type of gasket material I could use to create a seal when bolting the baffles on?

I too think you'd be fine with gluing solid wood and not have splitting issues.  Splitting (not allowing for wood expansion/contraction) is typically worrisome when panels get wide..say a foot-ish or more.  I haven't seen the dimensions of the Skiny 6's, but they look narrow enough that I wouldn't worry about gluing a solid wood baffle to them.  It would be a good idea to finish the baffles exactly the same on both sides though.

As for something besides a bead of silicone (anything silicone in a woodshop is not a good idea)..you might look into 3M 5200.  It'll stick to anything, stays flexible, and lasts..forever.  It comes in white and black.  Just let it cure the recommended amount of time.  To shape a bead of it after it's laid down, a finger(gloved or not) dipped-wetted in xylenes(xylol) can be used..it won't stick to your finger as you form/smooth it and xylenes won't dissolve the 5200.  Of course, this isn't much different than gluing up the box and skipping the bolts.

A stiffer closed cell foam could be used for a removable gasket(google closed cell foam sheets or check ebay).  The foam-ropes may be an option too..look in a home-supply store in the door-window seal area.  Foam rope comes in 1/4-ish to 3/4 inch diameter.  It'll stay flattened if compressed long enough, but I'd think it could provide a air-tight seal if pinched between two panels.

fishboat

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Re: Baffle mounting question
« Reply #14 on: 17 Feb 2018, 12:48 pm »
Mike..thought about this some more & looked up the Skinny 6 dimensions..wow..they are skinny.  At 4.5 inches wide at the baffle, I'd see no issues with using a solid wood baffle.  That's really narrow to be suffering from expansion/contraction & splitting issues.

You can calculate, or at least get a ballpark estimate of wood contraction/expansion by wood specie, with the Shrinkulator(link below)..using (unfinished)Sapele at 4.5 inches wide and a wood-moisture content change of 4%, it looks like 3-4 hundredths of a inch change in width..not much.
http://www.woodbin.com/calcs/shrinkulator/

But..even if there was a more significant change in width with the seasons, there's a tried and true option that is sometimes used with table tops having breadboard ends.  The narrow baffle width would allow this to work well I think.  You can hard-attach (glue or, in your case, bolt) on the baffle centerline-only (not edges) and ignore any expansion issues.  The center doesn't move(even in wide tabletops).  With a hard centerline attachment the board is still allowed to expand and contract as it will with no ill effects.  Given how narrow the baffle is, I think a centerline attachment in multiple places off the braces, would be plenty to hold the loaded baffle in place.

A couple ideas(rough sketches, but you'll get the idea):







The foam gasket could be something like this:
https://www.amazon.com/Density-Adhesive-Weather-Stripping-Insulation/dp/B06XCK65QM

Check Ebay, Amazon, Thomas Registry(thomasnet.com), McMaster Catalog..there's a foam strip out there somewhere with the right dimensions.  I'd make sure the strip is closed cell foam though. Open cell doesn't have much 'body' to it.

THROWBACK

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Re: Baffle mounting question
« Reply #15 on: 17 Feb 2018, 01:40 pm »
FISHBOAT
Leonardo da Vinci would have been envious of your "rough sketches."

Danny Richie

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Re: Baffle mounting question
« Reply #16 on: 17 Feb 2018, 03:47 pm »
FISHBOAT
Leonardo da Vinci would have been envious of your "rough sketches."

That's what I was just thinking.

fishboat

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Re: Baffle mounting question
« Reply #17 on: 17 Feb 2018, 05:18 pm »
:)  Sketchup is a beautiful thing..and free.  It makes so many things so much easier..particularly in woodworking.