US MDF sheet dimensions

[greymann]

I was looking more closely at the process of using the lr32 system to make a custom sized holey top.  I found that the process I described earlier this week had some cumulative errors I couldn't find a way around, clever or not (thanks Paul).

I had always looked at a sheet of MDF as being a little over 49 inches wide, brainwashed as I am.  In looking more closely at the factory size of the MDF sheet I found that it is exactly 1248 mm wide.  A little math later I recognized that that is perfect 32.  This opens up a number of opportunities in jig making especially in making the first set of parallel rows needed to make a holey top.  If this observation holds up, I'll describe what I have in mind a little later.

The question to FOG is do you see the same across the country or is what I see just a fluke?

Thanks,

Dick Perry 

 

[peter halle]

U fortunately I don't believe that all mdf is oversized.  Usually that from a cabinet shop supplier will be to allow for an edge cleaning cut.  Big box stores may or may not have the oversized but usually in my area have 48 x 96.

Peter

 

[overanalyze]

My Menards carries the metric mdf. Its ok quality for the price.

 

[greymann]

Just a little more detail to egg this on.  All the MDF I buy is from Home Depot.  I don't have a full sheet of any thickness on hand right now so all I'm talking about is the width.  I do have partial sheets of 3/4 1/2 and 1/4 and all of them are 1248 mm in width.  I didn't expect or really wasn't looking for this given the variations you see in ply from the same store.  But there it is.

The other potentially useful thing I found is that the factory corners are square to CNC precision.

The use I'm hoping to make of this right now is to make tops for my 8020 workstations.  I'm going to try to make an external jig that the worktop blank cut to final size fits in.  Using the true 32 dimensions I think I can drill the first rows of holes needed in the process in the jig pieces.  Then when one is rotated relative to the other, the holes should line up as precisely as it is possible to achieve with the lr 32.  This becomes a template that once made will be reusable and future tops will take a fraction of the time to make.

I know pictures showing it will be better but that won't happen until later this week.

Comments are appreciated.

Dick Perry

 

[Wooden Skye]

The times I have bought MDF it measures 49" x 97", at least at Home Depot near me.

 

[greymann]

In the past I always thought of it as 49 inches wide too.  I think I knew it was really 49 plus a skosh.  It was only when I put the metric tape to it that I saw this. The bottom tape is a true 32 tape and inverted triangle a 1248 indicates it is a multiple of 32.

[attachimg=#]

After fooling with it a little I found it a true 32 with the endstops set at 32 up and out.

[attachimg=#]

[attachimg=#]

Since I am really interested in a true 96 for this application, with a little more fooling around I found that setting the endstops to 16 up and out gave me what I wanted.  Here the red dots are 96mm spacing.

[attachimg=#]

[attachimg=#]

Since I saw that on all thicknesses of MDF, I have a hard time attributing it to coincidence or accident. 

I will find several ways to use this in jigs and such and thought others might find it useful as well.

Dick Perry

 

[gkaiseril]

I suspect that with so much of the processed wood coming from outside the U.S. that the manufacturers decided to settle on the European sizes and drop the U.S. imperial sizes even if they had to appear to lose some profit. I think they make up for it in not having to run two different lines for different sizes or retool for different sizes.

 

[jimbouk]

Im pretty sure all uk sized mdf boards are 1220 mm x 2440mm