A Good Day in the Shop - Melded Array Jigs

[DaveK]

I was apprehensive about tackling melded arrays, but these jigs actually make it fun. This is my take on the cutting jig.

Piezo Cutting Sled

And the glue-up jig

Piezo Glue Jig

And the result

Wired Piezo Array

(Edited to replace stale image links)

[LelandCrooks]

I was apprehensive about tackling melded arrays, but these jigs actually make it fun.

You just haven't cut enough of these things yet.

[AntonZ]

Dave, I just started making jigs for piezo's and other small stuff this morning. Nothing as elegant and practical as what you're showing. Please post any new jigs one day earlier from now on

[bgavin]

You just haven't cut enough of these things yet.

Yeah, but he is just about finished with a whole herd of T36... I dunno which is more the PIA...

The fun is seeing the jigs work properly. The actual building is just work.

[DaveK]

Please post any new jigs one day earlier from now on

DR brace cutting jig. The jury is still out on this one. I snapped a router bit on the second cut and haven't gotten to the store yet for a replacement.

DR Brace Cutting Jig

[Bill Fitzmaurice]

Please post any new jigs one day earlier from now on

DR brace cutting jig. The jury is still out on this one. I snapped a router bit on the second cut and haven't gotten to the store yet for a replacement.

Get a 1/4" spiral downcut. I use a similar rig on DR braces and it's slicker than snake snot.

[DaveK]

The bit I broke was a spiral upcut. Does up vs. down matter for this application? Also, is the feed direction the same for both? I think it broke because I was cutting in the wrong direction and the bit grabbed. I was moving the router counter-clockwise across the work.

[wb2]

Also, is the feed direction the same for both?

Yes.

An upcut bit would normally be used when the router is upside down, eg. when using a router table. The idea is to exhaust the chips away from your face and work. I like to use 1/2 shank router bits, a lot beefier.

[bgavin]

Interesting.
I'm using upspirals on my Jasper Jig to cut baffle holes. My line of thinking was removing the cuttings from the work as I progress around the circle. I make about 3 passes and increase the plunge depth at each pass, to avoid stressing the bit. My router takes 1/2" shank bits (expensive) but they are much less likely to break.

[wb2]

My line of thinking was removing the cuttings from the work as I progress around the circle. I make about 3 passes and increase the plunge depth at each pass, to avoid stressing the bit.

I use an up cup bit, mostly because I can't find my down cut bit. I guess the only place a down cut bit makes sense is if you make the cut in one pass, which I normally don't do. When routing, I'm resigned to the fact that's it's messy, no matter what you do.

[bgavin]

Bill suggested I use the spiral cutting bits.. very good advice indeed. Makes my baffle and general cutting chores a LOT easier.

[Tim A]

Downcut if you're making one pass, upcut if not. I don't even bother purchasing downcut for that reason.

1/2" shank bits help stop the shank from breaking, but a 1/4" cutting diameter is 1/4" cutting diameter regardless of the shank size. Almost every time I've broken a bit it's been the cutter. Which is why I make cuts in a couple of passes, hence, no downcut bits.

[wb2]

I just cut the DR200 butt cheeks, both panels together (BB), in one pass with a spiral upcut. 1/2" shank and cutter.

[SoundInMotionDJ]

And the result

Whoever posted several months ago with the suggestion to put some of the offcuts from the piezos in the ABS cement - that is awesome!!! I just finished two crossfiring melded arrays and the matching cement makes them look a lot better than the first batch I did.

--Stan Graves

[Tim A]

I just cut the DR200 butt cheeks, both panels together (BB), in one pass with a spiral upcut. 1/2" shank and cutter.

I always make that cut with the same diameter bit as the material being installed. Example: The butt cheeks are made of 1/8" ply, so a 1/8" bit is used for the cut. That ensures an exact fit when installing the top and bottom extension pieces on the back of the cheeks because you're replacing the same amount of material as was removed.

When you think about it, you have a radius on the panel of 4-11/16". You add 1/8" material to the entire radius, making it 1/4" wider on the outside dimension side to side, or 4-13/16". But, the cut-out area on the extension piece is a full 5-11/16" wide due to the bit diameter. In other words, the convex radius of your cut is 4-11/16", and the concave radius is 5-3/16".

Also, note that the cut is well shy of where the butt cheek panels will meet. That needs to be cut out with a jigsaw. After installing the extension piece, it'll need to be filled. Using a 1/8" bit eliminates that.