A problem of squareness

[Ken Harding]

Hi all. I'm new to the forums and hoped I could get a little input on a common problem I have.

I build a lot of smaller chests with drawers and I often have a problem getting everything squared up. I use a typical side hung wood on wood drawer slide scheme with 1/4" dados in the draw sides and wooden runners. For the most part I assume that especially with tounge and groove joinery in the carcase not much can be too far out of whack if I make the cuts carefully. I check for squareness during glue-up with an engineer's square but haven't gone out of my way to do anything more fancy. However, I often have issues doing the final fit on drawers. The most common issue will be that I have a nice fit with the drawers closed or halfway open but as I pull the drawers further out I find a considerable amount of play side to side. Of course this means the drawers can skew and bind up while pushing them in.

I'm pretty sure that the drawers are winding up with a slightly wedged shape from front to back and I suspect I'm not getting the carcases quite square either. The drawers use commonplace joinery with lock rabbet joints on the fronts and the backs fitting into vertical dados on the insides of the sides. It would stand to reason that if my cuts are accurate and the drawer sides are square to the fronts that they shouldn't be off so much. Apparently I'm making a fatal error somewhere.

Ususally I just cut dados into the MDF sides of the chest and glue the runners into them. They seem to seat well but this method may introduce a little error. I cut the runners a bit wide so the drawers barely fit side to side and just remove a little material from the faces with a hand plane until the drawers move freely. The plane removes a pretty consistent amount of material so I dont think I'm introducing the problem during drawer fitting.

Even though everything seems square during glue-up I keep finding this issue. Apparently I need more accuracy in ensuring that the drawer sides are square to the carcase and the runner faces in the carcase are square to the drawer sides.

Any thoughts, tips and tricks that might help resolve this issue would be greatly appreciated.

[Todd Burch]

Welcome to the forum Ken!

Squareness starts with your stock, and then your cuts, and then your machining, and then glue up.

How are your preparing your stock? How are you machining dados? (Router? Tablesaw? Hand Plane?)

Do you organize your operations to leverage repeat cuts for needed lengths, so that they are all spot on (at least with each other)?

When I glue up drawers (I use box joints for drawers) I measure them diagonally and make sure they are dead flat when drying. I stack the first one on my tablesaw, and then all the others @ 90 degrees to each other, on top of the previous. If the first is flat, they will all be flat (assuming properly prepared stock, etc.) I use yellow glue, and once I've clamped a box tight and let it sit for a few minutes, I remove the clamps and put it in the saw (or stack) to cure. If the joinery is tight, it won't move before the glue dries.

Every case/box gets measured diagonally. I maintain a tolerance of 1/16" or less. The bigger the case, the more I allow up to 1/16".

Again, welcome!

Todd

[Andrew Hughes]

Hi, ken first thing that come to mind is make sure your engineer squ. Is accurate.I worked with a starred square that wasn't took me couple projects to figure it out.
I also check the drawer diagonally pretty much the same way Todd describes.
One more thing that come to mind is drawers that are wider than they are deep are fussy to slide.So a center slide helps.
Good luck Andrew

[Biff Johnson]

I'm definitely with Andrew, check all your measuring instruments first. When I'm teaching in the school woodshop I encourage the kids to use the same tape measure through the entire project. I was suprised to find out how much variance there is between brands of measures. Also making sure your squares are square.

Once that is done, then square all your equipment!

[pat warner]

"Any thoughts, tips and tricks that might help resolve this issue would be greatly appreciated."
************************************************** *****
My study: Accuracy, target and metrology.
You never state a number. A guess & x-golly here, a little off there etc.
You need to get some metrology tools and learn how to measure.
You have no idea where the errors are coming from because you can't measure and prove those numbers. Moreover, a diagonal measurement, should that be your standard of reference, is, in my view, as bad as it gets.
Routers, saws, drills etc. have a million ways to register from your work.
And, you maybe using secondary and tertiary references that you're not aware of.
For every reference frame from direct (the work itself as the reference, not a jig) there is a higher order of accuracy on the next.
The issue here is a systemic one.
Starting with your material. Is it flat, uniform in thickness, chopped square in 2 planes, parallel in width?
Can you answer all of those questions now? Or are you guessing.
Your router or saw will cut one way with edge A, another when referencing edge B.
Is your stuff (machinery and layout tools) calibrated and can you prove that it is?
Perfect material prep? Then there is a lot less dimensional heresy. But if your stock is, say, store bought-milled, you are guessing your way through this.
See the drilling setup (http://patwarner.com/images/close_drilling.jpg) for essence of this message. The principles here, apply to every step of your job except finishing.
Your question is a good one, not many folks care as much as you do about getting it precisely.
Get out the staple gun and getterdone is a more popular attitude.

[Steve Jenkins]

As said check diagonal measurements on drawers and also on the carcass. Even though things are cut perfectly square and straight you can pull things a long way from square when you clamp and glue.

[Ken Harding]

Thanks all. Some good points made.

I think that the feedback here points out the a fundamental issue. I don't do enough measuring. I'll measure when I set up for a cut and stand there fretting over fractions with a set of calipers but if the first cut is ok I'll run the rest with very little checking. I rarely make just one of anything so that could be many of the same cuts. Even though I know I have accuracy problems I think it's a cumulative thing. My tolerances are too loose. Off by a 64th here and a 32nd there and when it comes to assembly the draw may bow in a hair while the carcase is out a bit and I'm really not checking by how much to go back and correct the root problems.

I'm always in so much of a hurry to try and make a buck that I let too many things slide too long. I do need to check machinery and tooling as well as correct a lot of small issues in my procesess'.

[Andrew Pitonyak]

I'm pretty sure that the drawers are winding up with a slightly wedged shape from front to back and I suspect I'm not getting the carcases quite square either. The drawers use commonplace joinery with lock rabbet joints on the fronts and the backs fitting into vertical dados on the insides of the sides. It would stand to reason that if my cuts are accurate and the drawer sides are square to the fronts that they shouldn't be off so much. Apparently I'm making a fatal error somewhere.

The thing that bothers most about this statement is that you state that you think that things are not square..... With the tips provided here, have you done anything to check to see if they are square?

If things are not square, what part is not square? Is it the drawer, or the place where you put the drawer?

It helps a lot to figure out which piece is not correct if you want to prevent it in the future.

I assembled a drawer that was not square.... I had to make a new one. Oops...

I do like these:

http://www.woodpeck.com/boxclamp.html

Before I bought those, I used clamping squares. I have these under the Woodcraft name brand:

http://www.woodpeck.com/clampingsquare6.html

Note that many people make their own clamping squares, especially for larger glue-ups, not too difficult to make from plywood.


The most common issue will be that I have a nice fit with the drawers closed or halfway open but as I pull the drawers further out I find a considerable amount of play side to side. Of course this means the drawers can skew and bind up while pushing them in.

Also, make sure that the problem is that things are out of square. it is possible that the drawer is pulled side ways so that it binds. You might fix things a bit by waxing the sides so that they do not bind.

[Jim Rimmer]

What great information! I love SMC. :D
And, Ken, welcome to the Creek. Do you think you have $6 worth of info yet? Become a contributor. :)

[Jeff Duncan]

It's tough to give decent advice without being able to see the piece in person. Measuring is fine and good, but many places you could go wrong can be checked simply without even pulling a tape out. For instance, you mention you think the drawers may be wedge shaped....simply placing the front and back, or 2 sides together and ensuring they're the exact same length before glue-up should rule this out. Same with carcass parts, using a tape to check measurements is OK, but simply putting two cabinet sides on top of each other is quick and easy to ensure they're the exact same. Running a tape corner to corner will take care of square.

As far as drawers binding it could be several things. First you may be trying to get too tight a fit? You need to have a little wiggle room for a drawer to function correctly over time. If you make it too tight and get it to work it could be still be problematic with seasonal changes. If the drawers are wedge shaped you'll have to make new one's, or if it's really minor you may be able to true them up? If the drawers are parallel but out of square it should not make any difference in their operation. Only problem is the face will not seat flush to the frame. This could potentially be remedied again if small enough by truing up after the fact. And lastly as mentioned a little wax helps properly fit drawers slide easily.


good luck,
JeffD

[Andrew Hughes]

Due to my low sense of self lately.I value my input at 1$ and 17cents.

[Mel Fulks]

I think there is good chance you have too much play between the sides of the drawers and the drawer guides.It is quite common,even a little wear will do it. Before changing any thing big,do something easy. Put some layers of tape on the guides to see if that keeps the drawer in a straighter path. If it does you can adjust the guides or shim .Which ever is easier. To me oak always slides the best. Give woodworking another shot before moving to meteorology. Just because nobody can do that well is no reason for you to try it.

[Richard Wagner]

You have said that the parts are cut correctly and I believe that. I'd also believe that a dry fit is likely to check square. I suspect that you are introducing the error during clamping. I say this because I believe I have the same problem. If clamps are not positioned correctly, it takes very little pressure to kick the assembly out of square.