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Old 18th April 2012, 06:10 AM   #11
AlanL is offline AlanL  United States
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Cool idea, buzzforb. I was going to try something like this
DIY Track Saw (comparable to Festool and Dewalt) - YouTube
but maybe like your design better, you could make a wider saw kerf to see the mark easier.
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Old 19th April 2012, 03:47 PM   #12
BFNY is offline BFNY  United States
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Quote:
Originally Posted by Fusion916 View Post
Using a circular saw, what tools do I need to cut perfectly straight for speaker boxes? Also, what circular saw do you recommend?
Where are you getting the wood? Most home improvement places like Lowes or Home depot will rip up 4 x 8 sheets for you at no charge. Helps getting it home. I usually do that for shelves.

For speakers, I would have them rip the sheets to the sizes needed but a little oversize, then use a table saw to do final cuts. Buy a used portable table saw, or get one on sale. I think it's a better investment than a circular saw for this sort of job, but it depends how big the speakers are, and how picky you are, long term plans in this area, etc.
I also use an aluminum metal edge clamped to the wood if I need to rip up a large plywood sheet.
Another option is to find a local woodworking club, and join it. They will usually have a facility with really nice tools for all members to use. Or you can find a member who will let you use his shop for good beer/single malt.

Once you use a decent cast iron table saw to do this, it's hard to go back.
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Old 19th April 2012, 07:52 PM   #13
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I don't mind using a sawboard at all. If I am lazy, I still get a bit of a wander from time to time on a good table with a good fence. It's bad Cal is what it boils down to. I must be more careful when I am using the board and clamps 'cause I can't remember the last time I had anything but a perfect cut with the circular saw. The only thing you can't do is repeat the cut so it may be straight but no two pieces will be the same length like they are with a fence. I find that kinda important when doing these sorta cuts.
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Old 19th April 2012, 08:09 PM   #14
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Now we can talk about blade set. I once bough a blister packed blade that was clearly on the bottom of a pile that had been bounced around. The set was reduced on one side. It would not cut straight in a table saw with the fence to the right of the blade. It would with the fence set to the left.

So if you are using a circular hand saw and it keeps drifting away from the guide, return the blade as damaged. Then find a better place to buy blades!
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Old 19th April 2012, 08:13 PM   #15
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All true and wonderful advice. I was suggesting mine as something that works in just about every situation. I must admit Cal's work is impressive. I just found a thread the other day with some speakers you made that looked to be about 10' tall. I would love to see the look on my wife's face.
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Old 25th April 2012, 07:15 AM   #16
dangus is offline dangus  Canada
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I cut oversize using a vintage Skilsaw, then do a final cut with a router. For a straightedge I often use the factory cut edge of a piece of MDF.
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Old 26th April 2012, 02:05 AM   #17
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I cut oversize using a vintage Skilsaw, then do a final cut with a router. For a straightedge I often use the factory cut edge of a piece of MDF.
That's my approach when I need to get things as closely matched as possible. For home projects the absolute tolerance usually isn't critical - plus or minus 1/16" or even 1/8" is good enough for things like a pair of speaker cabinets. It's generally more important to get dimensions that match as closely as practical.

In other words, if I want a panel that's (say) 20" wide and it comes out 19-15/16", that's nothing to get upset about as long as ALL of the 20" panels are 19-15/16" wide. And then some of them may want to be {20" + (1 material thickness)}, or {20" - (1 material thickness)} wide. That's where a decent router with piloted flush-trim bits comes in. A good router bit will cut a cleaner edge than any circular saw blade I've ever owned.

As already mentioned, using a shop-built straightedge to guide the router (or Skilsaw) baseplate is the key to success. Rather than trying to rip such a straightedge on a home-shop table saw, I'd go looking for one of those long aluminum T-squares used by drywall hangers, clamp it in position, and guide along its edge. Even cheaper than that - several years ago I picked up some pieces of extruded aluminum channels and angles at a scrapyard. This material has very straight edges - you can butt two edges against each other and verify this. (A friend uses some lengths of unistrut, but I don't know how he avoids errors due to the rolled, rather than square, edges.) Using these techniques you still have to measure very carefully to get good parallelism between edges, but a shop-built adjustable-offset router base can help you solve that problem, too.

Need a panel that's wider or narrower by a material thickness? Don't measure - place a scrap piece of the material (assuming that its thickness is uniform from piece to piece) against the straightedge to shift the cut by exactly one material thickness, or to mark the new location for the straightedge.

Even this method can produce a stack of panels with slightly different dimensions. Declare one panel - generally the narrowest - to be the "gauge" dimension. Use the flush-trim router bit to make them all the same dimension. My unsubstantiated eye-ball estimate is that a decent router, spinning trim bits with low runout pilot bearings, can track the reference edge within about 0.010". Are you tired of rectangular boxes, and want to get artsy with the shapes of your projects? Once you have a reference pattern to work from, the router can copy any non-rectangular or irregular shape with internal corner radii down to 1/4" (3/16" if you can find a good 3/8" pilot bit).

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Old 26th April 2012, 02:18 AM   #18
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Quote:
Originally Posted by Cal Weldon View Post
I don't mind using a sawboard at all. If I am lazy, I still get a bit of a wander from time to time on a good table with a good fence. It's bad Cal is what it boils down to. I must be more careful when I am using the board and clamps 'cause I can't remember the last time I had anything but a perfect cut with the circular saw. The only thing you can't do is repeat the cut so it may be straight but no two pieces will be the same length like they are with a fence. I find that kinda important when doing these sorta cuts.
Cal,

That is usually the result of the fence being out of parallel with the blade. Get a dial indicator & align the fence so that it's parallel to the mitre slot within 0.005". If you get that adjustment dead on the workpiece will track the fence and slide through the blade effortlessly.
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Old 26th April 2012, 02:43 AM   #19
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Originally Posted by kevinahcc20 View Post
That is usually the result of the fence being out of parallel with the blade. Get a dial indicator & align the fence so that it's parallel to the mitre slot within 0.005". If you get that adjustment dead on the workpiece will track the fence and slide through the blade effortlessly.
I was told that the out-feed end of the fence should be several thousandths wide of parallel, to avoid any tendency to bind the work between the fence and blade. (That stalls the blade if you're lucky; kicks back the work or breaks the blade if you're not.)

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Old 26th April 2012, 02:44 AM   #20
Pano is offline Pano  United States
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Thanks for the tips! I use a sawboard, but often have trouble with drift. A better guide should help.
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