Saw blade question

[10range]

I am preparing to build my first horn with the meld array and have a saw blade question. In my Omni 10.5 builds, I used the 4 tweeter setup and was able to trim the sides with my fine tooth blade on my panel jig and table saw. I would like to use the table saw to trim the piezos for the meld array but it appears from the dimensions that I will be cutting partially into the the screw heads. I have also seen mention of abrasive blades but in my limited knowledge of table saw blades, I was unaware of a 10" abrasive blade for a table saw. Can someone point me in the right direction on this or straighten me out? Thanks

[David Carter]

When I did the piezos for my DR250 melded arrays, I bought an abrasive blade which I used in a borrowed table saw, but I can't remember if it was a 10" blade or if I used a smaller 7 1/4" blade. Either way, it mounted in the table saw with no problem and did the trick.

As for the screw heads, they were indeed in the way on mine. At first I thought that the blade would grind the edge off the screw heads and everything would be fine, but I soon found that every time the blade came into contact with the screw head, it ripped the screw out of its place and fired it straight back at me. Fortunately, it hit me with the head side and not the tip because it left a welt a couple of inches to the left of my belly button. What I ended up doing was taking out all the screws with a screwdriver, cutting the piezos on the table saw, and then replacing the screws. Time consuming, but it worked and was much safer.

[LelandCrooks]

At first I thought that the blade would grind the edge off the screw heads and everything would be fine, but I soon found that every time the blade came into contact with the screw head, it ripped the screw out of its place and fired it straight back at me.

+1

I cut them on the table saw, then go to the bench grinder and grind the sides off the screws and screw mounts. On a DR array, you have to grind some off of the head.

[David Carter]

At first I thought that the blade would grind the edge off the screw heads and everything would be fine, but I soon found that every time the blade came into contact with the screw head, it ripped the screw out of its place and fired it straight back at me.

+1

I cut them on the table saw, then go to the bench grinder and grind the sides off the screws and screw mounts. On a DR array, you have to grind some off of the head.

Oh yeah, I had forgotten about that last step. After putting the screws back in, I used my Dremel to grind down the edges of the screw heads that would have otherwise bumped into each other when the two sides of the array were put together.

[10range]

Thanks for the help. The grinder option sounds like the safest way so I will do that. With my luck, one of the screws would end up smacking me in the jaw!

[Les Webb]

I totally removed all the screws after putting strips of abs cement in two or three places to hold the back in place. Works well and if you have to replace any elements it's a fairly easy process with a sharp knife. This also allows you to cut the tweeters significantly narrower to fit more in the array

[gdougherty]

Alternate the orientation of the tweeter elements and the screw mounts need no trimming. I trim them flush up to the horn body with the blade down lower. It produces a reduced risk of losing a finger, or worse. Using this method I was able to trim them down to about 1-15/16" which gave me enough clearance to fit 14 elements in a melded array for an OT12. I file down a little bit of the rear housing so it's even with anything the saw blade takes off. I did have to use a low spacer between my fence and the element so the screws on the second cut weren't throwing everything out of whack as they stick out once you've cut them that tight to the horn body.
Nice trick from the old DR280 plans I had when building the 12 element straight array.

[Tom Smit]

I was able to use someones miter saw-12". I went to the chop saw in the shop and removed the blade and installed it in the miter saw...perfect fit. On one set I cut slowly, and found that the screws warmed up and slightly melted the head contact surface. On the next set, I just went whammo!, and everything was OK.

TomS

[LelandCrooks]

IAlternate the orientation of the tweeter elements and the screw mounts need no trimming.

True. I keep forgetting that in the new plans there is more room than the older design. If you did that before the latest revs it wouldn't fit. Doesn't look very nice from the back, though.

I trim them flush up to the horn body with the blade down lower. It produces a reduced risk of losing a finger, or worse.

Exactly. I mount the tweeter jig in my panel jig.

I totally removed all the screws after putting strips of abs cement in two or three places to hold the back in place. Works well and if you have to replace any elements it's a fairly easy process with a sharp knife. This also allows you to cut the tweeters significantly narrower to fit more in the array

Pic please.

[10range]

My only thought on having the screws lined rather than alternating is that it would give the array more strength and support on the back side.