Don't trust the factory edge!

dusty · Post by **dusty** » Tue Feb 21, 2012 8:07 am

I just learned the hard way that the factory edge on a piece of MDF is not necessily square to the surface. Maybe I always knew that but I learned again the hard way yesterday.

I ended up with very visible gaps where there should have been none.

The good news - my cuts were all dead on. The factory edge was off at least 1/64". Close but not good enough especially when mated with another factory edge.

Lesson Learned: If wanting or needing a precise joint mill your work pieces. The precut dimensions are not necessarily as advertised or expected.

If you mill your own - you have only yourself to blame for inaccuracies.

mbcabinetmaker · Post by **mbcabinetmaker** » Tue Feb 21, 2012 8:11 am

A good rule of thumb is to always trim the factory edges on any sheet goods. I usually take off 1/4" unless there is some visible damage that requires more.

dusty · Post by **dusty** » Tue Feb 21, 2012 8:49 am

Yup! Sure wish I had been a disciplined craftsman.

The results were bad enough that I had to retrim many of the edges not done in the beginning. As a result, the finished project does not meet the original plans. She will probably never know but I DO!:(

robinson46176 · Post by **robinson46176** » Tue Feb 21, 2012 10:13 am

Here is an option:
http://www.fine-tools.com/hobelzubehoer.html

Here is another option. Notice the knob to hold the fence tight to the material:
http://www.hiwtc.com/products/electric- ... -11566.htm

Jointer plane.
http://lumberjocks.com/projects/2814

Here is a quick way.
[ATTACH]16341[/ATTACH]

I really liked this one.
[ATTACH]16342[/ATTACH]

JPG · Post by **JPG** » Tue Feb 21, 2012 12:04 pm

Way back in the 'dark' ages, sheet goods were always square and correctly dimensioned(a 3/4" sheet was 48" x 96" x 3/4"). If an edge was damaged, it was not sold(at the 'regular' price).

Even structural lumber was square and dimensioned correctly(length). Even further back 'dimension' lumber was 'bigger'(nominally)!;)

Only since 'external' sources came along do we have these 'quality' problems!:(

dusty · Post by **dusty** » Tue Feb 21, 2012 1:19 pm

Okay, now you have confused me!

Dimensioned lumber vs Finished Lumber vs Rough Cut Lumber.

Using a 2x4 as the example:

I though a rough cut 2x4 measured 2x4 and had not been surface planed at all.

I also thought that finished lumber had been surface planed according to its description - S4S as an exampled surfaced on 4 sides but not dimensioned to specific size.

I further thought that a finished 2x4, as the example, was finished four sides but actually measures 1 5/8 x 3 5/8 (this being a standard). Being called a 2x4 because that was its unfinshed dimension.

If I go to Lowes to get a 1x6, I will come back with something that is close to 3/4x6 and will be s2s and may or may not have saw marks on the edge but it will measure 6".

Please set me straight; just in case I decide to buy something other than rough cut again someday.

Hmmm Maybe there is no standard for what one gets when one buys from a box store.

JPG · Post by **JPG** » Tue Feb 21, 2012 1:57 pm

A '2x4' is what that part of the tree measured prior to being sawn.

Rough cut lumber is smaller than 2x4 by the saw kerf.

Finished 2x4 used to be 1 5/8 x 3 5/8 an a specified moisture content(do not ask-I do not know the number).

A few decades back, that became 1 1/2 x 3 1/2. (corrected)

2,4 6,8 10,12 became 1 1/2, 3 1/2, 5 1/2, 7 1/4, 9 1/4, 11 1/4. Not sure of the '1/2 to 1/4' boundary nor the reason. Charlese will probably correct/elaborate on this.
http://en.wikipedia.org/wiki/Lumber Scroll down to dimensional chart

S2S applies to more exotic lumber(hardwoods etc.). http://wiki.woodmagazine.com/page/S2S

S1ES one edge ripped straight etc.

S3S === S2S + S1ES

dusty · Post by **dusty** » Tue Feb 21, 2012 2:46 pm

Wow. I was confused when I started but this simple explanation made me more so.

mbcabinetmaker · Post by **mbcabinetmaker** » Tue Feb 21, 2012 3:01 pm

robinson46176 wrote:Here is an option:
http://www.fine-tools.com/hobelzubehoer.html

Here is another option. Notice the knob to hold the fence tight to the material:
http://www.hiwtc.com/products/electric- ... -11566.htm

Jointer plane.
http://lumberjocks.com/projects/2814

Here is a quick way.
[ATTACH]16341[/ATTACH]

I really liked this one.
[ATTACH]16342[/ATTACH]

Farmer remember we were talking about MDF board. I don't like to sharpen hand planes that well.

JPG · Post by **JPG** » Tue Feb 21, 2012 3:07 pm

dusty wrote:Wow. I was confused when I started but this simple explanation made me more so.

An 'excellent' example of why it(board ft) confuses so many! Their 'technical advisor' is a rambling idiot. That is why explaining by 'example' is usually doomed to failure.

Cubic inches it totally irrelevant. What it measures at the lumber yard after planing is irrelevant. Only thing that counts is the size it was rough cut from the log and the final length.

Yes hardwoods are handled differently and somewhat looser(caused by randomness of sizes). Not sure I unnerstand all I read about that today!;)