Make sure your saw blade is square!!

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fender3x
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Make sure your saw blade is square!!

#1 Post by fender3x »

I am not sure how this happened... I carefully used the clamping system that Bill recommends to get the top attached the the side. Square bar, clamps and screws. But I just did not get it quite sqare.... That's right! I have a problem after only the first two panels go together!

The top and side are not off by a lot--2-3 degrees (about 88/87 rather than 90 top-to-side). But it's very noticeable over the 19" of the top. I can easily square this by hand...but I am afraid the other panels might not go in square if I just try to sqeeze them in by hand. Would hate to have the finished cab lists like a drunken...well...me.

I am thinking that I will screw the back on (and maybe the front too?)--without gluing--as a way of squaring the top-and-side assembly before putting any of the horn plates or baffle in. I hope that will square it, while leaving the front and back removeable.

I also thought about using a couple of 2x4s as diagonal braces in the front and back?

Before doing any of that, I thought I'd see what the real craftsmen had to say about it...

I'll be grateful for any advice!!

Good thing I already have my driver, and the rest of my parts order went in already. I am committed (as the pig said about his role in the ham and eggs breakfast... )
Last edited by fender3x on Wed Dec 13, 2006 4:58 pm, edited 1 time in total.

joel
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#2 Post by joel »

Been there..... Don't continue with things out of square, it will just make everything else harder ( how do I know?-don't ask, please).

Did you take a square to each piece of wood to find out
where the angle is off? If you find it and it's little shy at one end you can use pl to correct it. Smear it on to an approximate thickness, let it dry overnight and re-cut it square. I've done it and it works.

Oh, by the way, use the square on everything, NOT your tape measure.
Hard, cold steel doesn't lie (much).
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Bill Fitzmaurice
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#3 Post by Bill Fitzmaurice »

The first thing to do is make sure your saw blade is square, that's the only explanation for the first two panels being that far out of whack. Once you add panel two you'll have a third plane, which will square things up a lot, but if all the parts edges are cut at a 2 or 3 degree angle it's going to make the entire build very difficult.

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fender3x
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#4 Post by fender3x »

I'll recheck everything. I use the metal square, and the sides are even. I checked the saw blade using a square as in the saw manual each time I change the pitch. Also initially when I made the panel jig (as per bill's instructions).

Still... I just checked it, and it looks like the blade may have been slightly off 90 degrees. It's hard to see when it is just a 1/2"...but at 19 you really see it.

That's it... Unfortunately, I have already cut all the 19" sides.... Will think about how to square them tomorrow.

Maybe I can use the "joel" method...but it's a lot of cuts...

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Bill Fitzmaurice
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#5 Post by Bill Fitzmaurice »

fender3x wrote: That's it... Unfortunately, I have already cut all the 19" sides.... Will think about how to square them tomorrow.
Maybe I can use the "joel" method...but it's a lot of cuts...
If they're identical I wouldn't be concerned, the PL will fill the gaps. Just be sure as each panel is added that it's square to both the side and the preceding panel it's attached to. If you're using a circuar saw look for a bent shoe, that could be the problem in squaring the blade.
Last edited by Bill Fitzmaurice on Wed Dec 13, 2006 9:43 am, edited 1 time in total.

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telecast
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#6 Post by telecast »

Make sure you're squaring your blade with it fully exposed, then set the depth of cut after it's square. The more blade you use to square, the more accurate it'll be.

Also, keep in mind the teeth have a set. They stick out slightly more than the blade itself. Always square between the teeth! Squaring against a tooth will make it a few degrees off.
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chad
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#7 Post by chad »

Bill Fitzmaurice wrote: the PL will fill the gaps.
+1

bgavin
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#8 Post by bgavin »

Moved to Tips & Techniques

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fender3x
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#9 Post by fender3x »

Thank God for PL! I will use good slatherings. All cuts were done on the table saw....

I checked with a big rafter square, with the blade fully extended, carefully placing it between the teeth. The blade was definitely a couple of degrees off. That's the culprit. I could have sworn that I had done this... and maybe I did. Which means I need to check it every once in a while to make sure that it is still square. In any case, that will help future cuts!

As to my current problem. I may have to rely on PL...but I have one thing left to ask about that I am considering trying. A Sears near me was closing recently, and I picked up something I was not sure I'd ever use: A 10" sanding wheel for use with a table saw.

http://www.sears.com/sr/javasr/product. ... Cookie=Yes

I have never used this thing before... Would it make sense to put it on the table saw (checking again to make sure we are at 90 degrees) and sand the edges of the 19" pieces? I am thinking that might flatten them, without removing much more than a mm or two from each end. I could do the same with the top piece since only one side is glued so far.

What do you guys think? Is that worth a try? Or am I better off just trying to keep things square and letting PL do its magic?

Thanks for all the advice. I have cleaned up the little green bricks I dropped last night and am pretty much ready to get back to work ;-)

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telecast
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#10 Post by telecast »

Sure. Give it a shot and see what happens. Cut a piece of scrap at the same angle as your pieces and then sand it flat. See how much it changes.
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telecast
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#11 Post by telecast »

"Advice so nice I said it twice!"

:lol: :lol:
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Bill Fitzmaurice
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#12 Post by Bill Fitzmaurice »

The sander would have to be very rigid not to flex itself. You could recut the parts 1/8 inch narrower, 1/16 off each side to square them, but I wouldn't bother, let the PL do its thing.

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fender3x
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#13 Post by fender3x »

I'll try that... I am pretty sure I have a piece of scrap cut at the same angle already... Thanks!

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fender3x
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#14 Post by fender3x »

Bill Fitzmaurice wrote:The sander would have to be very rigid not to flex itself. You could recut the parts 1/8 inch narrower, 1/16 off each side to square them, but I wouldn't bother, let the PL do its thing.
It's pretty rigid, but it may not be worth the trouble as you suggest. Got some long necked clamps and a bar level to use to square things up at HF today. Also got a clamp for the top that will do angles... Won't use the sanding approach unless the experiment goes perfectly. Hopefully all the extra clamps and extra care will be enough.

Thanks!

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#15 Post by bgavin »

fender3x wrote:Thank God for PL! I will use good slatherings.
As we say here in Kaleeforneeah, PL is muy bueno.

I never ceased to be impressed by how well PL does its job, nor how FAR it can span and maintain strength.

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