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Advice re cutting LaScala doghouse angles


longdrive03

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Building a pair of LS now  - doing the hard part - doghouse.  Using 1" BB ply throughout.

 

I did a test cut on the roof top (toe end) of the doghouse and the front toe joint isn't meeting properly.  I measured and there is a "bow" in joint where the two pieces meet.  Towards the middle of the front joint the boards are "narrower" than than at the top and bottom of the joint.

 

All the test parts  are square and I used a slid jig I built (which is square)  and made sure the piece was vertical on my tablesaw before clamping to the heavy jig which was flush with my rip fence.  I've attached a few pics below.    The "1 BB isn't easy to cut and I took it slow (maybe not slow enough and pushed the jig all the way through the blade.  

 

I'm probably not describing this well and will take a pic tonight of the rooftop joint.  

 

I just looked at the photo and noticed there may be a slight tilt toward the blade because the orange blade cover insert isn't flush with the table top.  Not sure that would make the scoop, but could increase slightly increase the cut angle if at the beginning and end of the cut when the jig isn't straddling the blade insert?   I will flush the blade insert tonight with the table top and see if that helps as well as making a preliminary cut then second final cut. 

 

Anyone have this problem and know about a fix??   I'm thinking maybe I should an initial cut then make s second cut where I only slice of 1/8"-1/4" to hopefull get smoother straight rooftop edges.  All responses are appreciated.  

 

 

IMG_6472.JPG

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Thanks for the response done.   Don, hope that is it.  The 1" ply (18 plys) ain't easy to cut.  At the 60 degree angle the ply is nearly 1.5" thick

 

In theory this should work like clockwork.  But this is woodworking and there are usually issues.

 

I  think I'll  also build a redesigned jig to have a flat bottom with a longer base that will prevent any tipping of the jig at the blade insert area.

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2 hours ago, longdrive03 said:

Never mind.  Figure it out that Andy is HDRbuilder and sent him PM.

Why are you using 1" Baltic Birch for the doghouse roof?  It should be 3/4"...and it really does NOT need to be any thicker than 3/4", nor does it NEED to be Baltic birch.  If your saw blade is too thin (and/or too dull!), then the density of that Baltic Birch will splay the blade AWAY from the fence in the middle of the cut (your ears should be telling you this as you try to make that cut)).  Now using the 1" stuff for the SIDES of the bass bin is fine, and will add stiffness, which is WHY they went to 1" MDF on the current LaScala version, which (for aesthetic reasons) REQUIRED them to use 1" for the top and bottom panels. also.  Just go with the original plans (which I posted on here YEARS ago), but use the thicker material as needed for the sides (and top and bottom, if desired).  The thicker material does NOT NEED to be used in the doghouse portion of the bass bin at all.  The flexing issues are due to the Mouth end of the sides, and have nothing to do with the doghouse, itself...since the basic construction of the doghouse design has stiffening incorporated into its construction.

If you use 1" material for the roof panels, you will need to adjust the plans pushing the sides outwards, then pushing the dimensions for the rear panel outwards to the left and right), along with changing the wings between the motorboard and the rear panel...because if you let the EXCESS wood of the thicker panels run to the INSIDE of the doghouse, instead of outwards, you reduce the interior horizontal dimensions making it almost impossible to get the woofer FRAME to fit inside of the doghouse, much less being able to mount it in there easily by limiting the ability to work with it once the woofer is in it.

 

I would advise using NON-BALTIC birch high grade 3/4" plywood for all things involved in the doghouse, except the splitter and wings...use the Baltic birch for the wings (3/4"), and a piece of clear poplar for the splitter.  Keep in mind that TOLERANCES for these parts is 1/64" OR LESS...yep...you gotta split the 1/32" lines on your tape measure!  LOL!

 

Oh, and BTW...do NOT set your saw to 30 degrees for the cut...or the "toes" of the roof panels will not mate correctly...1/2 to 1 degree off of that reduces heel push and allows for the toes of the miter cut to meet properly on such a long miter joint....so 29.0-29.5 degrees should be what the blade is running off the fence face.

 

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 Thanks  Andy for all the helpful information. I'm building a shed for friend and he wants it to be 1 inch Baltic Birch all the way around. I've had to calculate changes to the height and the width based on the 1 inch material. 

 

 I've built a new jig tonight after I made sure my blade install panel was flush with the table saw top and it is much better. I recut the test panel and everything squared up nicely. You're right about the Baltic Birch being hard to cut. I've got a fairly new blade on the tablesaw but I might go with a slightly wider blade to cut down on flex. I will also make an initial cut and then slice I thin cut off of that to reduce any binding of the blade. Thanks a bunch for all the information.

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I made a glue and clamp jig for my LaScala doghouse "roofs"...it had the joint facing downwards, so that any glue squeeze-out dripped onto the newspaper underneath from the toe-end of the joint, and what did NOT drip could be easily removed after the glue had set-up...plus it kept any glue off of anything which was not the toe of the joint itself.  The "Clamp" part was actually two panels cut to fit to the INSIDE of the "roof" with the points of them squared-off so that they did NOT get into any of the glue on the inside of the miter joint.  This kept me from needing to use any fasteners on that part of the assembly, which meant no nail holes to show whether puttied or not.   I just squared up the ends and put a couple of staples into the plys so that they would be unseen on the final product, but would hold the ends together while I tapped the panels from the inside to align the rest of the  joint.  The wedges on the inside of the joint forced the toes of the joint together making an excellent toe joint...very tight!

 

In the pic below you can see the staples into the plys of the joint of the roof of the doghouse, as mentioned above.  This doghouse is sanded and ready for urethane finish everywhere EXCEPT where glue will be applied.  By doing it this way, any squeeze-out of glue during assembly will be on TOP of the urethane finish and easily wiped up, WITHOUT leaving any glue lines in the grain of the wood under the finish.  These are oak veneer, so it would be a major problem, since oak is more "pithy" fiber than something like walnut or rosewood, both of which are denser and have more oils in the wood to keep the glue from being absorbed into the surface fibers quickly.

completed LaScala doghouse assembly.jpg

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21 hours ago, longdrive03 said:

 You're right about the Baltic Birch being hard to cut. I've got a fairly new blade on the tablesaw but I might go with a slightly wider blade to cut down on flex. I will also make an initial cut and then slice I thin cut off of that to reduce any binding of the blade. Thanks a bunch for all the information.

Baltic birch is so HARD to cut because of all of the layers of urea-formaldehyde glue between the plys...the more plys, the more glue between them...it eats up blades and router bits like crazy!  BTW, here is the PAIR of book-matched oak doghouses just before I put the finish on them.

doghousepairI.jpg

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My plan is to use my planer/jointer for these particular cuts, after getting them "close", once I get my shop set up after retirement (TWO MORE YEARS!...counting the days!)  It is the pits seeing all my stuff sitting there still new in boxes/crates, while waiting for retirement to happen!

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Andy them thar is some good  looking dog houses. Hey we need to take a picture and put it on the wall. It's a work of art. 

 

 Glad to see people are excited about this build. I spent most of today cleaning up my shop and final rubbing the belle bass bins  so I could get them out of the shop to work on the La Scala's. Had to do a little rehab work on by a rigid tablesaw because the  wrench won't secure the arbor because it has rounded over. And a care cut a pair of slip joint pliers down so I could grab it and hold it to change blades. It's always something. 

 

OK I've decided to go with the old three-quarter inch ply on the doghouse roof. Put on a new blade and have learned to make an initial cut then the final cut. Hope to get the doghouse drive for tomorrow and get both of them bill so I can start the veneering. Thanks for everyone's help.

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19 hours ago, longdrive03 said:

Andy do you have any photos of the jig that you referenced above? I'm not really following the narrative and photos would be great. Sounds like a great setup

No pics of the jig, sorry...it is currently in storage in FT Smith.  It is completely made out of Baltic Birch in the metric equivalent to 3/4".Here is a drawing below of the plans for the jig, but no dimensions are given because it is in storage...should be easy to figure out, though:

 

Just look at figure 1:  I cut three panels out of 3/4" Baltic birch, all indentical in outside dimensions.  First I made my measurements and markings for everything on all three of the panels.

 

     The notches were the first cuts...both sides...for the attachment of the strips (also 3/4" Baltic Birch, and shown in GREEN in the bottom two figures below.

 

     Only ONE of the three panels got notched for the "T" assembly, because that assembly free-floated THROUGH the "T" notch in the center panel but was BUTTED against the end panels...the "T" assembly is ACTUALLY a reinforced strait-edge to center up on the center-lines of the two end panels.

 

     Finally, I made the cut for the removal of the isosceles traingles, which were IDENTICALLY marked on all three panels with  both the cut line for the 60 degree equilateral triangle, and ALSO for a second triangle WITHIN the first...but inside the original marking about a half inch.  I then cut out the triangles using a bandsaw BETWEEN the two lines (this is the dotted line on figure 1).

 

Now for Fig. 2:  After cutting out the triangles, I put a Forstner bit in the drill press and cut a hole as you see marked in figure 2.  This is so that the glue dripping out of the toe of the miter joints will have someplace to drip to DOWNWARD and AWAY FROM the miter joint itself.

 

    Next I took EACH panel, in turn, and went over to my disc sander, and used its table (set at 90 degrees from the disc) to sand the INSIDE edges of the triangular cuts made in the panels to the SOLID INNER LINE (see figure 1).  By already having the HOLE in the panels from the Forstner bit, this allowed me to get perfect edges along the triangle lines without needing to worry (as much) abouit getting the disc caught or jammed at point of the triangle.

 

Now for Fig. 3:  The triangles I had removed from the panel were then taken over to the disc sander and the edges were sanded down to the remaining line, and were checked by fitting them into the already-sanded-panels..."looking for light" coming through the fit.  These will be the wedges which will hold the glued-up doghouse roof panels into the jig, one for each of the panels they were sawn out of.  The liast thing I did to each of the wedges, was to cut off the downward. points for the same reason as I made the holes in all three of the panels.

 

Looking at the SIDE view, keep this in mind:  The ENTIRE thing has to be assembled PERFECTLY square...and mounted on a base to KEEP it square!  The overall length of the side view is LESS than the overall length of the doghouse roof panels, by a total length difference of 1.5 ".  There will be a stand-off at only ONE of the end panels, which consists of two half-inch blocks, one on either side of the "V" cut-out, about half way down towards the point.  to these blocks will be attached  a small "T" assembly so that the top of the "T" is facing inwards toward the jig.  This is to get a basic alignment of the TOE joints of the glued panels by butting the edge of the panels to the stand-off "T" block, then aligning the end of the toe joint at THAT end of the jig, and shooting two shallow wire staples into the plies of that joint, at that end to hold the toe there in place...then doing the same to the joint at the other end of the jig.

 

Following that, you just put the wedges in and tap from the inside or the outside of the toe joint as the joint aligns itself at the toe and once that is done, finish gently tapping the wedges to fit as you work from one end of the jig to the other.  NO TAPE IS NEEDED FOR CLAMPING PURPOSES, BUT... I always use some masking tape on the sanded edges of where the triangles were cut out of the panels, just because it gives more "traction" for gripping the panels.

 

I hope this explains the jig pretty much!

 

LaScala doghouse roof jig.jpg

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Andy,

 

Outstanding post and pics.

 

Now could you come cut these for me!!!!??

 

This helps tremendously and I now get what you explained previously - duh

 

Very efficient jig.  

 

Here's a few pics of my progress.  I'm going to cut out the woofers entry hole in the chamber bottom and see if i have room for installing the  crites 15C woofer.  I've widened the motorboard to 15.5" wide and I think it will fit using the 1" ply. 

IMG_6505.JPG

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