Cutting piezos and not your fingers.

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Harley
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Re: Cutting piezos and not your fingers.

#61 Post by Harley »

jswingchun wrote:I made one for my EZ track saw. You do have to flip the piezos upside down.
Isn't there a danger of all the swarf falling into the element by going upside down?
ImageSemi-retired: Former Australia and New Zealand Authorised BFM cab builder.

88h88
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Location: Coventry, UK

Re: Cutting piezos and not your fingers.

#62 Post by 88h88 »

Easily solved by using a healthy thick wedge of masking tape I'd imagine. That's what I'd do at least if that was the only way of cutting them.
4xOT12s, 2xT39s@22", TTLS@18", 2xT60@18"

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jswingchun
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Re: Cutting piezos and not your fingers.

#63 Post by jswingchun »

Harley wrote:Isn't there a danger of all the swarf falling into the element by going upside down?
The rail is over the top of the portion of the tweeter with the element. Only the part being cut off is visible. The swarf flies safely into the dust collector and around the garage.
Omni 10
Omni 10.5
OmniTop 12 x 4
Wedgehorn 8 x 3
XF212
T39 @ 18" x 2
T39 @ 20" x 2
T39 @ 28" x 2
Jack 110 x 5
Jack Lite 12
XF210
XF210 (Slant only, no crossfire)

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fender3x
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Re: Cutting piezos and not your fingers.

#64 Post by fender3x »

Been a while since I did this. When I did my last cab you needed to seal the piezos. I don't see a reference to that in my J12 plans so maybe it's not necessary on piezos that are externally mounted? Is that why folks don't just remove the screw before cutting?
One man's magic is another man's engineering. --Heinlein

1 x DR250
1 x T39
1 x Omni 10

Grant Bunter
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Re: Cutting piezos and not your fingers.

#65 Post by Grant Bunter »

fender3x wrote:Been a while since I did this. When I did my last cab you needed to seal the piezos. I don't see a reference to that in my J12 plans so maybe it's not necessary on piezos that are externally mounted? Is that why folks don't just remove the screw before cutting?
If you don't leave the screws in while cutting, you don't take a little slice off the screw head, and that means the piezo bodies will not sit flush to each other during assembly, making the whole array wider than it should be, and not fit. This is important in all those cabs that have full height arrays...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Tom Smit
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Re: Cutting piezos and not your fingers.

#66 Post by Tom Smit »

fender3x wrote:Been a while since I did this. When I did my last cab you needed to seal the piezos. I don't see a reference to that in my J12 plans so maybe it's not necessary on piezos that are externally mounted?
True. Sealing was only when the piezos were exposed to the internal cab pressures.
TomS

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fender3x
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Re: Cutting piezos and not your fingers.

#67 Post by fender3x »

So why not just take the screw out before cutting?
One man's magic is another man's engineering. --Heinlein

1 x DR250
1 x T39
1 x Omni 10

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David Carter
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Re: Cutting piezos and not your fingers.

#68 Post by David Carter »

I always remove the screws before cutting. Then, if needed, I use a Dremel with a grinder wheel to grind down one edge of the screw head. Why go to that trouble? Because the first project I worked on, I didn't do it, and I ended up taking a screw to the gut after the saw blade hit it, ripped it out of the piezo casing, and shot it back into my torso. Fortunately it was the head that hit me instead of the point. Left a nasty bruise even though I was wearing a loose shirt at the time.
Dave

Built:
- Omni 10 (S2010 + piezo array)
- 2 x DR250 (DL II 2510 + melded array)
- 2 x Titan 39 (BP102 - 14"W)
- 2 x Titan 39 (3012LF - 20"W)
- 4 x DR200 (Delta Pro 8B + melded array)

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Tom Smit
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Re: Cutting piezos and not your fingers.

#69 Post by Tom Smit »

I will have to point out that I use an abrasive blade in a mitre saw to cut the piezos, I don't use the sled on the table saw, so I guess that is why I don't have a problem.
TomS

Bruce Weldy
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Re: Cutting piezos and not your fingers.

#70 Post by Bruce Weldy »

Tom Smit wrote:I will have to point out that I use an abrasive blade in a mitre saw to cut the piezos, I don't use the sled on the table saw, so I guess that is why I don't have a problem.
I cut all of mine with the table saw.....the key is how much you are taking off and how fast you push it through. Nice and slow and it cuts right through the screw. In my case, I just nibbled the edge some.....

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

nola50
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Re: Cutting piezos and not your fingers.

#71 Post by nola50 »

Lots of great ideas on cutting Piezos. I'm researching and seeing which way get's the best results. I have chop and table saws.

I'm curious about Harley's post from way back when. The photos are missing. Anyone have that one stashed away?

Super resources, as usual.

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Tom Smit
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Re: Cutting piezos and not your fingers.

#72 Post by Tom Smit »

I think that you may be fortunate that I had copied the whole post when Harley first submitted it. i had to do some copying and pasting, saving images and loading images in order for the original post to appear as it was.
First page



OK, one side does the side trimming and has two set distances - one for the first trim and one for the second.

The other side of the jig when rotated 180 degrees, does the 45 degree cut - again two trim WIDTH sets,
Harley #1.jpg
Harley #2.jpg
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Harley #3.jpg
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This shows the first side trim you make
Harley #4.jpg
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Harley #5.jpg
Last edited by Tom Smit on Tue Oct 25, 2016 12:37 am, edited 1 time in total.
TomS

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Tom Smit
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Re: Cutting piezos and not your fingers.

#73 Post by Tom Smit »

Second page


Once you've done the first, load that into the second position for the second trim ( if required ) and put a new piezo in the first position - then cut the two at a time.
Harley #5.jpg
Harley #6.jpg
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Here's the 45 degree cut once you've turned the jig through 180 degrees. Note two positions to accomodate the two different width trims.

I had to shim the edges up until I got them right which took about 5 piezos to bin, then the result is perfect every-time and very very quick.

The little block houses to hold the aluminium locking bar again had to be shimmed in height until they were perfect. For the side trims, it has to be exact so you can pressurise each piezo when doing two at a time.

The push blocks are mandatory to keep your mits away from the saw blade.
TomS

David Raehn
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Re: Cutting piezos and not your fingers.

#74 Post by David Raehn »

Beautiful!

I think that design needs to be in the plans.

:fingers:

Well done.
BFM rig:
6 OT12
4 T48
4 WH8
Other:
56 box Electrotec LabQ rig
Way too many cables
:noob:

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