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How square is square?

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Forum topic by RichardDePetris posted 04-13-2014 01:35 AM 2193 views 2 times favorited 51 replies Add to Favorites Watch
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RichardDePetris

25 posts in 408 days


04-13-2014 01:35 AM

I am putting together some shop cabinets and it’s been driving me crazy. As a new woodworker, I am having the time of my life reading about woodworking from the armchair, but when I go into the shop, it’s a different story. What I thought I knew, turns out to be not enough or just plain wrong. It has been a very frustrating experience, especially getting straight cuts and squaring up pieces.

I was using (don’t laugh) my bandsaw to cut lumber and even plywood. Aside from the roughness, the edges looked straight, but there’s sometimes a slight dip or bow from lengthwise where you can see light when I hold a straight edge against it. I’ve tried everything in vain to fix or prevent the problem, including endless fiddling with the guides. I tried to check for blade drift and couldn’t find any.

Given to frustration, I purchased a Makita track saw (tablesaws are too dangerous, everyone I know has a story of a relative or friend who lost a finger) and I was amazed at the razor straight cuts. The problem is that when I stack the boards on top of each other and line them up, I find I am off square by 1/16” all the way up to 1/8”. I’ve gone back and tried to re-square them and made the problem worse.

Do I need to invest in one of those squares thingies for the tracksaw? The thought that I am being obsessive compulsive about it also has entered my mind. How square is square? Is 1/16 or 1/32 inch off square going to screw up the entire project. If you have to joint edges for proper glue up, then being that much off should be really bad, shouldn’t it? Do I have a machinist’s mentality that needs checking?

Any ideas? Thanks.


51 replies so far

View willie's profile

willie

465 posts in 1177 days


#1 posted 04-13-2014 02:08 AM

If each cabinet is 1/16” out of square, the problem will multiply with each cabinet. It’s either square or it’s not. I don’t know who has been telling you all the horror stories about tablesaws but I think they have been exaggerated a bit. Any cutting tool can be dangerous but with proper instruction and use, a tablesaw is no more dangerous than your track saw. A tablesaw allows you to duplicate cuts accurately and quickly. You still need an accurate square no matter how you cut your pieces.

The closer you are to being square and true, the easier the whole installation will go.

-- Every day above ground is a good day!!!

View rustfever's profile

rustfever

637 posts in 2033 days


#2 posted 04-13-2014 02:17 AM

All cabinets are installed into house/buildings that are not necessarily square. Good cabinet makers use the ‘scribe-to-fit’ system.
How does this work?
Allow a piece of material that can be scribed and trimed to and fitted to the irregular wall.

-- Rustfever, Central California

View waho6o9's profile

waho6o9

5201 posts in 1300 days


#3 posted 04-13-2014 02:19 AM

If your diagonal measurements are the same, then it’s
square.

View realcowtown_eric's profile

realcowtown_eric

367 posts in 660 days


#4 posted 04-13-2014 03:12 AM

I’ll re-iterate willies comments. make it as square as possible right from the start, as to be sure, errors will compound.

if 1/16th is acceptable on a first piece cut, what’s next…1/8. then 3/16

And diagonals may be a good check for a piece of flat stock, but for cabinets, it’s gotta be square front sides and back.

square is square, straight is straight, sloppy is sloppy. that’s about all there is to it.

Seek alignment with the universe….

Eric

-- Real_cowtown_eric

View RichardDePetris's profile

RichardDePetris

25 posts in 408 days


#5 posted 04-13-2014 03:16 AM

Thanks for the replies, but what’’s the tolerance? How off can I be when making a cabinet carcass for instance? The cabinets are standalone, as most of the stuff I do is. Surely, the ancient wood workers didn’t have the accuracy we have now, so there must be some acceptable margin of error, especially when considering wood movement.

Interestingly, my bandsaw cuts are often dead square for the first few inches on one corner, but can be a hair off on the other corners. Maybe there’s no hard fast rule and only experience will yield a better understanding, but there’s something very unsatsfying about that.

View paxorion's profile

paxorion

776 posts in 768 days


#6 posted 04-13-2014 03:26 AM

I tried an experiment to see if I could get away with woodworking project without using a table saw. I had a pain of a time trying to cut a few panels for a cabinet I am making with my circular saw + guide, and kept seeing how cumulative error really throws a wrench into the project. The harder part was making sure the operation was repeatable, which I find very difficult without the right stationary reference point. For example, Festool’s approach would be the MFT, and not just a square. Eventually, I got it “right enough”, but for the next round, I just went to the shop and cut everything on a table saw and a cross-cut sled. I didn’t even have to THINK, to get the cuts right because the table saw is very repeatable for those operations. That experiment taught me that for me, a properly tuned table saw, with the right accessories/jigs is an indispensable tool that improves the speed, quality, and repeatability of my work.

I think the danger with a table saw comes from user behavior (i.e. knowing what to do and making sure you’re fully capable of doing that operation at that moment…like making sure you don’t work when you’re tired, rushed, or any other condition when you are not in the right state of (sober) mind), using the right safety fixtures and accessories (e.g. guards, featherboards, push sticks/blocks, etc) for the operation, and to make sure your tool is properly alignment to ensure a predictable operation.

-- paxorion

View Paul's profile

Paul

566 posts in 288 days


#7 posted 04-13-2014 03:30 AM

A band saw blade can “wander” If your trying to build cabinets with one my guess is you will be very unhappy. I personally don’t consider 1/32th of an error acceptable in cabinet making. Interestingly enough I left my shop like this today.

cabinet carcase parts all over the place!

2 tools come to mind as a must, at least for me to make cabinets square. A Table saw, or more time consuming a track saw.

I wouldn’t even try to use my band saw to make cabinets.

Paul

View woodchuckerNJ's profile

woodchuckerNJ

892 posts in 357 days


#8 posted 04-13-2014 03:51 AM

A band saw can indeed rip boards to width, but will need a plane to clean up.
The band saw can not easily do large sheet goods, the table isn’t big enough. You would have to build outriggers, and outfeed, and possibly an infeed.. then learn to properly push through at the right feed rate.

A tablesaw or track saw has a better chance of doing the cut. Even a handsaw after practice.
1/32 may not seem like a lot, but the errors add up over time. But if it is rough stuff you are building, you are in the learning process. In order to build with a track saw, you must learn to reference one straight edge to begin with, don’t start using another reference. You can stack cut the parts to exact size after rough cutting.. That will ensure 2 like side, but not square.

If you are using a framing square for your first 90, have you checked your framing square. Make sure it is accurate. Put it on a sheet, draw a line, then flip the square over using the same edge, and draw a line right next to the one you drew.. Are they parallel??? If not, you need to adjust your framing square.. do a google search on how..

One of the tricks you might want to learn is to not use the tape measure, but to use a story stick. You can use the tape for the first measure, but then set that mark on a story stick and use it to set the other end of the track.. and verify both ends… Or make it like a story stick with a hooked end..like a hooked end ruler.. it will keep you lined up…
BTW a compass can be used to draw a 90 degree line.. So you can check your squares line that way too.

-- Jeff NJ

View Paul's profile

Paul

566 posts in 288 days


#9 posted 04-13-2014 04:04 AM

woodchucker,

“A band saw can indeed rip boards to width, but will need a plane to clean up.”

100% true, but the OP is talking cabinet panel cutting. I wouldn’t recommend using a plane to clean up a plywood cut.

This is shop project he’s talking about so I assume he’s using ply.

Paul

View MT_Stringer's profile

MT_Stringer

2069 posts in 1954 days


#10 posted 04-13-2014 04:27 AM

It comes down to this. Your cabinet parts need to be cut accurately. If they are, the cabinet will go together nicely and it will be square. I measured the last one I built. Both diagonal measurements were 35 5/8 inches. That is good enough for me.

If you can’t make accurate cuts, you might as well stop now. Frustration can be a bad thing.

-- Handcrafted by Mike Henderson - Channelview, Texas

View GarageWoodworks's profile

GarageWoodworks

446 posts in 879 days


#11 posted 04-13-2014 04:45 AM

@waho6o9 That’s not always true and can lead you down the wrong path.

If X is shorter than Y (or vise versa), A can still equal B in distance, but your piece will not be square.

-- Subscribe on YouTube: http://www.youtube.com/user/GarageWoodworks?feature=guide

View guitchess's profile

guitchess

82 posts in 2431 days


#12 posted 04-13-2014 06:20 AM

I have built dozens of feet of cabinet with nothing more than a circ saw and straight edge jigs. It seems to me that the real issue is your layout technique/tools. Everything from a dull pencil leaving an over size line to the fact that plywood is routinely out of square from the start can cause the described issues. My tips include a sharp/mechanical pencil or perhaps a marking knife, getting very comfortable with Pythagoras’s Theorem/3 4 5 method, and making sure the ply panel is fully supported during all marking/cutting operations. I will go into further explanation of these tips if needed.

As to the question of how much accuracy is required, it depends on your goals and build methods. Considering you’re talking about shop cabinets, I would assume you are not building them like a piece of furniture. As far as modern production cabinet construction, the carcasses could be 1/2” out of square with very little issue(not that I think it’s ok to build that way). The face frames, doors, and drawers are where accuracy is required. If you do want to build it furniture grade, then every 64th counts, and I would venture to say that it is almost impossible to do without a tablesaw. You will at very least double the project time.

Just my $.02

P.S. I just wanted to say that in the time it takes to learn how circumvent the table saw with the necessary accuracy, you could learn how to use a table saw in a safe manner, which would open up a world of possibilities. Despite what the inventor of the Sawstop would have us believe, it is possible to use a table saw for a lifetime without replicating his injury.

View Whiskers's profile

Whiskers

389 posts in 750 days


#13 posted 04-13-2014 01:04 PM

First I want to reiterate the squareing of your plywood stock. I’m amazed at how out of square it can be.

2nd, If these are standalone shop cabinets, a little out of square is not going to hurt that much. I know that none of the mobile stands I have built are 100 percent square, cause I used a circular saw and ordinary lumber as a straight edge for most of the cuts. Generally what I did was cut the top and bottom as square as possible using a circular saw slightly larger than the minimum size I wanted, than I select which sides will be top and bottom etc and clamp the top and bottom together. Invariably they were off a little bit. Sometimes more than I will admit. To “square” them up to each other I used my router and a pattern bit to trim whatever side down to match the other. Flip the 2 pieces and do the other size, that way the top and bottom are now “square” to each other. Than I set about measuring and pieceing the face frames around the pieces. Even if the edges are a little bowed in or out the 1×2 stock has plenty of give to make a good edge. One would not know how imperfectly square my cabinets are.

Of course this is for the shop, not furniture grade. I needed to make my tools usable before I could attempt making furniture.

View bbc557ci's profile

bbc557ci

543 posts in 797 days


#14 posted 04-13-2014 02:40 PM

Thanks for the replies, but what’’s the tolerance? How off can I be when making a cabinet carcass for instance? The cabinets are standalone, as most of the stuff I do is. Surely, the ancient wood workers didn’t have the accuracy we have now, so there must be some acceptable margin of error, especially when considering wood movement.

Interestingly, my bandsaw cuts are often dead square for the first few inches on one corner, but can be a hair off on the other corners. Maybe there’s no hard fast rule and only experience will yield a better understanding, but there’s something very unsatsfying about that.

In wood working a perfect 90 or attaining a perfectly square piece can be challenging, at least. Take your time though and you can get damn close with a good strait edge, cic saw, and measuring tool/s.

For, or of myself, I expect very close tolerances…yeah, some times I drive myself nutz… but that’s just me. And I’ve found that getting accurate repeat cuts is allot easier with a table saw than with a strait edge and circular saw.

Man up and get a decent table saw ;o) If you’re afraid of the blade you have two choices. Get a Saw Stop, or use a rubber blade :o)

-- Bill, central NY...no where near the "big apple"

View guitchess's profile

guitchess

82 posts in 2431 days


#15 posted 04-13-2014 04:28 PM

“Maybe there’s no hard fast rule and only experience will yield a better understanding,”

You’ve hit the nail on the head. There are as many different acceptable tolerances as there are woodworkers. You are going to have to find you own balance of project quality and build time. Unfortunately, this is my greatest weakness. After being in the production carpentry industry for 23 years, it’s hard for me to slow down and try to make something flawless. There is something ingrained in me that makes it hard to spend days on a box or step stool. That’s why everything in my projects list was built in 8 hours or less, including finish.

For me, the tolerance depends on the size of the build. The smaller the build the smaller the tolerance.

For example, if the carcass of a 12’ bank of shop cabs were within 1/8”, I would call it good. Doors, drawers, and face frames would have to be a quarter of that at 1/32”. As far as cutting the bulkheads, it is quite easy to fudge 1/16” out if you take certain steps. For instance, aligning the panel’s out of squareness, under-sizing the carcass to allow for shimming, and adjusting the carcass after assembly. Of course, more initial accuracy dramatically reduces the time it takes for these steps.

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