Princeton Reverb Cabinet - how to get the front angle right

[PRNDL]

How do you get the front angle of a Princeton Reverb Cabinet just right?

It appears to be a double angle - one for the speaker baffle, then another for the chassis.

Thanks!!

[punkykatt]

Princeston Reverb side panel :  height 16", width at bottom 9 1/2", angle for speaker baffle measure up from bottom 13 1/2" measure from panel back  8 1/2" to to front,  top angle measure from panel back top to front 7 3/8".  That will give the angles you are looking for.  Hope this helps.  Good  luck   Punky 8)

[PRNDL]

Thanks!

How do you cut that?

Do you make a 9-1/2" width cabinet, then draw lines and cut with a jig saw, perhaps with straight edge guide?

[punkykatt]

Yes , you could use a jig saw or a circular saw.  Make the box 20"w, 16"h, 9 1/2 d, mark the lines and cut. Be sure to maintain the angle on the top board. Can be done on a table saw before the box is built also. Take your time and go slow. Yes use straight guides. Measure twice and cut once.  Good luck  Punky

[jjasilli]

PRNDL:  Good question. With punkykatt's dimensions you can get the correct slant back angle on the side panels.  Might be good, if possible, to stack the wood and cut both side panels at the same time to get identical dimensions.  (Unless you have a real good table saw you can rely on to repeatedly make identical cuts.)

Then, the front-edge of the top panel needs to be cut to match that slant back angle.  I guess one way to do that would be to adjust the angle of a table saw blade right up against the angle of a side panel. 

Then you need to round over the top edge of the top panel.  This step is complicated by the fact that the front edge of the top panel is no longer perpendicular to the top surface.  So a typical rounding-bit won't work on that front edge.  Guess it can be done by eye with sandpaper.  But there must be a better way. 

[DummyLoad]

CNC machine.  :)

[sluckey]

Another idea... Build a 1/4" template for the odd shapped side pieces. Use the template to trace the outline onto your workpiece. Rough cut the workpiece with a bandsaw or jigsaw, cutting about 1/16" outside the line. Tack or screw the template to the rough cut workpiece. (Use double sided carpet tape if you don't want any nail holes in the workpiece, although this shouldn't be a factor if you're gonna apply tolex.) Use a router and flush trim bit to cut the workpiece to the exact shape of your template. Use a shaper instead of the router if you have one.

You'll end up with perfectly matched sides even if you're not very handy with a saw. The accuracy of the template is the key. The template method was used extensively for mass producing odd shapes long before computers entered the workshop.

[jjasilli]

The template idea is good especially to build more than one identical box.  But, because a rounding bit won't work on non-perpendicular surfaces, what's the best way to round-over the front edges of the top panel? 

[DummyLoad]

use CNC to make template...   :P

[jjasilli]

If PRNDL had a CNC, he'd probably be asking how to use that, instead of how to cut-out the box.   :D

(EDIT:  this comment is directed at CNC's not PRNDL!!!)

[punkykatt]

To build this style cabinet takes a lot of thought , planning and woodworking skills along with the proper tools and equipment. If you dont have the time and the right tools etc., I would suggest buy the cabinet. If you insist on building it yourself, practice on scrap wood.  Punky

[bbirling]

I build and sell these for $170.00 + shp.
Takes about 10 days to ship.

Bruce

[PRR]

> round over the top ... complicated by the fact that the front edge of the top panel is no longer perpendicular ... typical rounding-bit won't work ... by eye with sandpaper.  But there must be a better way.

In a furniture factory, such "complications" were everyday routine.

Routers are awful. A Shaper is an upside down router in a big table. Instead of those pilot-guides, you have a serious fence. This is how you PRODUCE.

For this part, you take a 1/4-round bit and grind your 13.7 degree slant tangent to the curve. Set the fence so the slant comes to the edge of the board. Now you can run boards a mile an hour.

A dual-spindle shaper was common. You load the other spindle with your plain 1/4-round. Now you can do all four edges zip-zip-zip-shift-zip.

All of Fender's total production would be just a few days work. He probably got killed with set-up charges because he couldn't take more than a few hundred at a time... an hour to set-up, an hour to run all that Leo could take, and then run danish-modern and french provincial coffee-tables and chairs for a month until Leo needed more.

[jjasilli]

Bingo!  Could probably use a shaper bit on a routing table with a fence. Then match the slant-back cut of the side panels to match the angle of the router bit.  Should be good enough so long as it's close enough to the slant back of the front panel of the chassis. 

[rob440]

I cut the long angle on my table saw using a tapering jig. This is done prior to the glue up. The second angle, the short angle I do after the cabinet is glued together with my table saw blade tilted to the proper angle. Accuracy with your cuts and assembly are critical for a nice job. To round over I usually use a router and then sand it the rest of the way as the router bit doesnt like the angle on the top. The bottom angle  is less than 90degrees and can be done on a router table using a fence. I am eventually going to grind a special cutter or make a sanding block for that angled radius.