panel cutting jig newb help, strait edges?

[phil]

So I finally have the time and all the tools to build my first set of speakers. I'm using a table saw for the first time also. I built a panel cutting jig and everything lines up with the blade using a square just fine on both sides, but after cutting a top and bottom, they don't match up at all. I've done 2 tops and 2 bottoms already and only have one completely strait top that hasn't been shaved down too small trying to get the edges strait.

Is there any kind of standard wood working procedure that I'm just not aware of that will make sure all my cuts are strait?

Thanks for any help. Must say it's been a little frustrating, and I feel like there's just something I don't know to make sure I'm starting with a strait edge or something.

[Tom Smit]

I built a panel cutting jig and everything lines up with the blade using a square just fine on both sides, but after cutting a top and bottom, they don't match up at all.

Is the push bar exactly square to the blade? I'm not sure I understand what you mean about square.

TomS

[djohnson573]

Is there any kind of standard wood working procedure that I'm just not aware of that will make sure all my cuts are strait?

By "strait", do you mean square? If so, step one is to get a big framing square and check the alignment of your panel cutting jig by butting one edge of the square against the push bar. The other arm of the square should line up exactly with the cut made by the saw blade in the jig base. Once you have this set perfectly, it will (may) require three cuts to get each panel exactly square. Place the panel with one edge firmly against the push bar (this becomes your reference edge) and make a cut that trims a tiny amount for the entire length of the cut (cut #1). Keeping the reference edge against the push bar, flip the panel over and cut to the desired width (cut #2). If you are cutting multiple panels of the same width, measure from the saw blade cut in your push bar and mark the desired width on the push bar. Align cut #1 with this mark to make cut #2. Finally, turn your panel 90 degrees and cut the panel to length (cut #3) making this cut on the edge opposite your reference edge. Again, if you have multiple cuts of the same length, it is faster to mark this length on your push bar (and align the reference edge with this mark) that to mark each board individually. Using this method, you should be able to rough cut all of the panels for a tuba/titan in under one hour and they will all be perfectly square and like sized panels with match perfectly.

While you are at it, take a smaller square and insure that your saw blade is exactly 90 degrees to the table (don't trust the angle indicator on the saw until you have checked that it is accurate.

Hope this helps.

[LelandCrooks]

Old test. Take a scrap, rip in half, invert one piece and put the cut edges together. If they don't match your jig is out of square. It will also show by the gap how far out you are.

[Tim A]

Actually, the first step is to get a big framing square and check it for square.

Put the short leg of the square on a factory edge of plywood and draw a line up the long leg. Flip the short leg over so it's facing the opposite direction and draw the line again in the exact same place as the first one.

Did you end up with one line, or do the lines separate? If they separate, the square isn't square. You can adjust it with a center punch and a hammer. If the right angle is too narrow, place the center punch on the interior of the square corner and smack it. If it's too wide, place the punch on the ouside of the corner. Re-check and repeat until it's square.

When checking for square against the blade, make sure you take into acount the toothset. On a saw blade, every other tooth faces the opposite direction. On a carbide tipped saw the teeth are wider than the blade. If you put your square on a tooth on one side and the blade itself on the other, it will be out of square. Make sure you check for square against the blade, not the teeth.

[djohnson573]

Actually, the first step is to get a big framing square and check it for square.

+1 Good call Tim. I got ahead of myself on that one.

[bgavin]

Square is directly related to the slot in the table.
The blade can be out of square, and result in a wider cut, and/or irregular cut.

If the jig backstop is not square with the guide block that follows the table slot, you will never get a square cut.

[phil]

Wow, you guys rule! Thank you for all the quick responses.

After building my panel jig, I used the square per the instructions to line up the push bar. It looked even from the one side, but after making the Piezo jig, and trying it out, it didn't flow smooth against the fence, and then when I actually cut a Piezo as a test, I noticed there was more of a mounting hole on one side than the other.

Once I noticed that, I got a 2nd square and lined it up on the other side of the blade (one square on each side of the blade) and saw that the angle was a little off.

I cut a strip of wood and lined it up with the 2 squares perfectly and brad nailed it down.

I remade my Piezo jig and did a test cut and everything was perfect.

I made my top and bottom and put them together and the cuts didn't line up on them.

When I say some kind of procedure, I mean like "shave off small piece before 1st cut, make 1st cut, flip clockwise, make 2nd cut, flip again clockwise and...."

Should I maybe like, if I need to cut it down 3 inches, should I cut 1 1/2" off one side and flip it and take 1 1/2 off the other to make sure both sides are cut strait, doing the same for horizontal and vertical ending up with 4 cuts per piece?

Thanks again.

[bgavin]

Pay close attention to Tim's advice. He is the master woodworker here, also Leland.
There is no substitute for "been there, done that."

[phil]

Old test. Take a scrap, rip in half, invert one piece and put the cut edges together. If they don't match your jig is out of square. It will also show by the gap how far out you are.

I tried this and I'm not real sure how to do it. I tried it and the edges lined up. I also tried it purposely making the angle a little off, and inverted and put them together and they fit together just fine.

I know it's simple and I'm just not getting it. I think I'll be ok once I get through this minor learning curve .

[LelandCrooks]

Pay close attention to Tim's advice. He is the master woodworker here, also Leland.

Not in the same league. I 'm at best a AA player, Tim's in the big show.

[phil]

Old test. Take a scrap, rip in half, invert one piece and put the cut edges together. If they don't match your jig is out of square. It will also show by the gap how far out you are.

I tried this and I'm not real sure how to do it. I tried it and the edges lined up. I also tried it purposely making the angle a little off, and inverted and put them together and they fit together just fine.

I know it's simple and I'm just not getting it. I think I'll be ok once I get through this minor learning curve .

I think I got it. With the edges placed against the bar you'll see a difference ....Duh phil.

So I'm perfectly square. I tried making an uneven cut by placing a small piece of wood between the scrap and the bar before cutting and it showed up huge when I did what you said. When I just use the bar and make the cut, it lines up perfectly when inverted.

So I'm square, I'm just somehow not making sure all the edges are good.

The way I'm making my cuts is...

I'll shave 1/4" or so off what will be the finished end to make sure it's straight, and then make the finish cut. Then I'll flip the wood to the finished cut I just made and do the same thing for the other cut, shaving a small piece off and then make the final cut.

I have to be missing something.

[phil]

Is there any kind of standard wood working procedure that I'm just not aware of that will make sure all my cuts are strait?

By "strait", do you mean square? If so, step one is to get a big framing square and check the alignment of your panel cutting jig by butting one edge of the square against the push bar. The other arm of the square should line up exactly with the cut made by the saw blade in the jig base. Once you have this set perfectly, it will (may) require three cuts to get each panel exactly square. Place the panel with one edge firmly against the push bar (this becomes your reference edge) and make a cut that trims a tiny amount for the entire length of the cut (cut #1). Keeping the reference edge against the push bar, flip the panel over and cut to the desired width (cut #2). If you are cutting multiple panels of the same width, measure from the saw blade cut in your push bar and mark the desired width on the push bar. Align cut #1 with this mark to make cut #2. Finally, turn your panel 90 degrees and cut the panel to length (cut #3) making this cut on the edge opposite your reference edge. Again, if you have multiple cuts of the same length, it is faster to mark this length on your push bar (and align the reference edge with this mark) that to mark each board individually. Using this method, you should be able to rough cut all of the panels for a tuba/titan in under one hour and they will all be perfectly square and like sized panels with match perfectly.

While you are at it, take a smaller square and insure that your saw blade is exactly 90 degrees to the table (don't trust the angle indicator on the saw until you have checked that it is accurate.

Hope this helps.

Man, for some reason I only read the beginning of your post initially. This is exactly what I'm looking for!

Thanks a bunch djohnson and everyone else! Hopefully next time you guys hear from me it will be a review! Maybe I'm being a little optimistic .

[djohnson573]

Man, for some reason I only read the beginning of your post initially. This is exactly what I'm looking for!

Thanks a bunch djohnson and everyone else! Hopefully next time you guys hear from me it will be a review! Maybe I'm being a little optimistic .

You're quite welcome. Glad I could help since apparently I'm not even in the minor leagues.

[LelandCrooks]

You're quite welcome. Glad I could help since apparently I'm not even in the minor leagues.

I've first hand familiarity with Tim's mad skills. No offense meant.