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-   -   Come join me in my shop for a Griffin build (http://www.diyaudio.com/forums/markaudio/187020-come-join-me-my-shop-griffin-build.html)

naturallmystic 13th April 2011 10:03 PM

Come join me in my shop for a Griffin build
 
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This community has been very helpful and welcoming in many ways so I thought I would give a little back by documenting a build of Jim Griffin's MLTL. We (you and I) will start with a single 5' x 5' sheet of true baltic birch plywood. I have been building furniture since I was a wee lad so I don't tend to do much by way of detailed drawing before turning on the saw. I did slow down enough to a a drawing to add to Jim's fine work that should be helpful to builders of this cabinet. I'll post as work progresses. Sadly I can't work on this everyday but will be able at least every other day so it should progress pretty quickly. Questions and comments are welcomed and encouraged. So are suggestions, but they may or may not be followed.:)

Picture 1: (the attached pdf file) are the plans Jim Griffin put together.
Picture 2: is the detail of the joinery I am using, that is a top view.
NOTE: I don't know if this was Jim's intention or not but I discovered that by using slightly modified (more on that later) 3/8" rabbets all four of the vertical pieces of each cabinet can be cut to 6 3/4". The photo (sorry for the quality) is a scale drawing done full size on graph paper.
Picture 3: is the balance of my "planning" work. I find it helps to write important numbers down else I might get confused while working.

Next: Rough Cuts...

naturallmystic 13th April 2011 10:28 PM

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Now for the rough cuts. As I don't have enough room in my shop to actually put a 5x5 sheet of anything up on my table saw I cut sheet goods down to a more manageable size outside. I didn't take pictures of this. Basically you put you 5x5 sheet of ply on a pair of saw horses, measure to the center, 30", draw a line straight down the center, check to be sure you did that right, then get out the trusty circular saw. I find that a new thin kerf blade really makes a difference when cutting baltic birch with a circular saw. I don't use a guide/fence but can follow a line with great accuracy. Since this is a rough cut it isn't critical that it be perfectly straight just stay within a 1/16" +/- of your line and you will be fine. After starting the cut about 12" in stop and clamp your kerf with a couple of wood cauls so that when the cut is finished the boards don't fall all over the place and get dinged up. There are a lot of different ways to deal with this problem but to each his own.

Once I had two more manageable halves I headed into the shop for the table saw. Before each project I pull out the Incra rules and calipers and double check the accuracy of the table saw fence to blade measurements and the blade runout. Most of the time there is no need for adjustment, but sometimes there is. There was today. Good thing I checked.

Picture 4: First I cut 8 pieces 60" long by 6 7/8" wide. That is what I call a rough cut. The cut itself is actually smooth.

Picture 5 & 6: Next it was time to cut to length. I like to use a miter saw for this kind of cut, it is safer, leaves a nice finish cut, and is very repeatable and accurate. As can be seen in the picture there is a stop set up to ensure the lengths are accurate and the same.

Picture 7: Then I set the fence to 6 3/4", put a magnetic hold down in place and did the final width cuts. This step gives you the opportunity to make minor adjustments if needed and the final shave also makes for a very clean cut. With a tuned saw and sharp blade no jointing and little to no sanding is needed.

Bas Horneman 13th April 2011 10:39 PM

Thanks for sharing! Love pictures of builds.

naturallmystic 13th April 2011 10:39 PM

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Joint Forming.

The rabbets on the edges can be formed using a table saw or a router. I find it easier and much messier to use a router, so that was my choice this time. As 3/4 baltic birch plywood is not actually a nominal 3/4" you have to make a minor adjustment to the bit depth. To get a really tight fitting joint set the 3/8" rabbet bit depth to 1/32" short/less (we say "shy" where I live) of 3/8". In other words don't set the bit depth a full 3/8" set it to 11/32". Wood work can be accurate down to about a 1/64", not much more though.

Picture 8: The old Bosch router loaded with a CMT rabbet bit. There are lots of ways to keep your wood from moving around on you, I like clamps.

Picture 9: Notice the rabbet goes around all four edges and the rabbet is on what will be the inside of the speaker cabinet, not the finish side.

Picture 10: Checking to be sure the fit is good. Though hard to tell it is indeed perfect.

naturallmystic 13th April 2011 10:47 PM

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I don't know how I managed to not include this but the whole center of this build in the MarkAudio Alpair 10.2 which just came to my door yesterday. I got to tell you guys that is one beautiful looking driver. Obviously excellent craftsmanship and design went into these drovers. I cannot wait to hear them!

That's all for today, will be back on Friday with more build...

Bedankt Bas Horneman, Blij dat u hier bent!

Jim Griffin 14th April 2011 12:14 AM

Great craftsmanship. You'll have a beautiful speaker in no time.

Yes, the 10.2 is a great looking driver. Just keep the training wheels on for the first 100 hours or so.

Jim

Bas Horneman 14th April 2011 01:00 PM

Quote:

Bedankt Bas Horneman, Blij dat u hier bent!
Blij hier te zijn! ;) Are you a dutchman living in the US of A?

naturallmystic 14th April 2011 01:25 PM

Geen Bas Horneman. :( Mijn dochter woonde in Amsterdam en leerde mij een beetje Nederlands. I have some Portuguese too as my spouse is Brazilian.

Hi Jim! I hope so, thanks to your efforts. I have a couple of surprises later on in the construction.

Well no build posts today, I have other things to do while the sun is shining. More tomorrow.

Bas Horneman 14th April 2011 01:27 PM

Quote:

Mijn dochter woonde in Amsterdam en leerde mij een beetje Nederlands
She did an excellent job. I can only say Obrigado in Portuguese. ;)

naturallmystic 15th April 2011 09:57 PM

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Did a little work today. It seemed to me that the next logical step would be to rout the speaker holes. It is easier, in my mind, to do this while still working with individual panels rather than an assembled box, especially routing the 45 degree chamfer on the backside of the speaker hole.

Picture 11: The tops and bottoms of the cabinets. The dimensions are 6" x 6 3/4". Test for fit was very tight so I trimmed about 1/32 of an inch as needed for a tight but not forced fit. Mmmmmm I love a great fit. :p

Picture 12: One of the front panels marked and ready to have a 1/4" hole drilled in the right spot. I like to use a 1/4" oak dowel as a pivot point. I have used nails in the past but just prefer the dowel.

Picture 13: This is the back side of the panel. I feel MDF does have it's place in cabinet building and this is it. By the time the hole is routed out for the speaker there won't be much wood left to hold the panel together. By adding this MDF brace I avoid what could be a tragic accident while routing and handling the front panels.


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