32mm Systems and Drawer Stretchers

      A discussion of the fine points of positioning and installing drawers stretchers (or "spreaders") in a 32mm Euro cab system. July 15, 2011

I'm new to the 32mm system and I'd really like to use it in some projects I've got coming up. My understanding is this system more or less allows for a common end panel and the doors and drawers are sized and located in increments of 32mm to allow the hinges and slides to land on common system holes - the shelf pin holes. Construction holes such as dowel holes and confirmat holes, once determined, can remain common from panel to panel as well.

My question comes with the horizontal spreaders that make a border between drawers over drawers or drawers over doors and how to fit them into the system. I can easily throw some construction holes in the end panels for dowels, confirmats, Rafix connectors, or whatever, but this leaves unique milling details in a 3 drawer vs. a 4 drawer vs. door/drawer end panel. Is there some hardware out there that I'm missing that allows these spreaders to attach using the system holes? What's the point of this whole 32mm system if in the end I still need a unique end panel for every configuration?

Forum Responses
(Cabinetmaking Forum)
From contributor A:
While we don't use dowels (we staple and screw cases together), we only have a middle stringer when there is a pair of doors under a drawer. This gives the top of the doors something to bump into.

On any single door cabinet with or without a drawer or drawer base, we use a stringer at the top of the case only, no intermediates.

This would cut down on the boring for most of your cases, then depending on how you are cutting, CNC or not, this could be tied into your program to only bore construction holes for a stringer if a cabinet is over a certain width.

From contributor L:
Blum used to have a publication that detailed what you are trying to do. It was the European standard and never much followed in the US. By using it you will need to figure your case and top height, then make a kick to make up the minor difference to come out 36" high. Best to work only in metric for the system you are trying.

From contributor M:
I strictly follow a 32mm system in my shop. It is not a simple thing to develop an intelligent boring pattern and integrate that into production.

One answer to your question is that drawers and doors are not necessarily sized to 32mm increments, but the reveals do fall on 32mm increments. If the reveals fall on the 32 increments then it becomes easier to locate items like stretchers and fixed shelves.

I have tried to use hardware pattern to locate the stretchers by dropping an 8mm bit in the head at the right place (we do not drill all the holes of the line bore, only the needed ones). It turned out to not be worth the trouble. It required that I use a 37mm setback for the first dowel hole in all my dowel patterns, and that caused problems with fixed shelves that have setbacks from the front of the case (also 32mm increments). Plus I still needed to drill a second hole (need at least two dowels for the stretcher). I would make the stretcher deep enough to reach the second line bore pattern, but that was ridiculous. In the end it is easier to bore the stretchers or fixed shelves separate from the line boring pattern.

We use our boring machines to drill the length or the width depending on the situation. Some hardware patterns are simpler to execute across the width of the board (in a base cabinet with 3 drawers for example). Sometimes it is easier to bore the length of "Y" axis of the panel (upper cabinets with adjustable shelves).

Your final question shows one of the big misconceptions of the 32mm system. All panels are not the same. This is true for 32mm cabs, dadoed cases, or any cabinets. Not even the low end generic closet companies have a "one pattern fits all" approach. The beauty of the 32mm system (or any logically devised set of production standards) is that everything is predictable. I do not need to know the measurement of the location of the drawer stretcher, only the drawer height. When setting up the machines in my shop we all know that everything falls on a 32mm number. The machines all have marks denoting the 32mm increments on the fences. It is predictable, therefore the setup is faster and less prone to mistake. I can take a guy off the street and have him running the boring machine in just 1 or 2 days.

The boring patterns are not the same, but the engineering behind them is consistent. This can work for any system. The only reason we use 32mm is that is the standard spacing on boring machines and CNC machines. People often do not realize how much faster their CNC can run if the boring patterns are on 32 increments.

From the original questioner:
This is cool... Sounds like I'm very much on the right path. I've got my cabinet cross sections engineered at this point with all system and construction holes on 32mm centers and, for this particular line of cabinets, all the end panels are identical with the exception of construction holes to attach the spreaders. My drawer and door heights, or rather the reveals, all land on 32mm increments. I do have a publication from Blum that I referenced to develop my boring pattern. This literature does address how to locate spreaders but not how to attach them. Here's a link:

Blum's Process 32 Manual

From contributor M:
If I wasn't clear, I dowel the stretchers. I use confirmats/dowels on tops and bottoms and fixed shelves in tall assemblies, but for the drawer stretchers I just use two dowels on each end. And I would say that you are on the right track. What are you using for software?

From contributor D:
"One answer to your question is that drawers and doors are not necessarily sized to 32mm increments, but the reveals do fall on 32mm increments."

I don't follow. For the face reveals to fall on 32mm increments the faces have to be sized in some increment of 32mm (32 x n - reveal). This is a primary element of the 32mm system.

For overlay faces I use 74mm deep stretchers with 2 holes 21/32/21. Depending on the layout, the mounting holes either straddle a system hole or the midpoint between two system holes. I use a drill bushing jig registered to system holes to drill the panel holes (the stretchers are bored on a flip-flop).

Click here for higher quality, full size image

From contributor M:
You are correct, most of the time the result of snapping reveals to 32mm results in n32-reveal sizes. There are situations such as odd top and bottom reveals or pattern offsets that can cause non-standard sizes. If a client insists on non-standard heights I will usually add the difference to the top of the case resulting in a non 32mm sized top drawer or door. But this has no effect on our process because all operations are referenced from the bottom.

My point is that instead of focusing in the drawer and door height, it is sometimes helpful to focus on the boring pattern first because that is what is driving everything else. Door sizes are 32mm increments because the reveals are snapped to the 32mm pattern, therefore it is the pattern that I focus on. I like your jig. Good thinking.

From contributor C:
For low cost operation use a 5 3/4" drawer front and a 24 1/4 door flushing the door at the bottom and leaving 1/8" between the door top and drawer front bottom. All drawer stretchers should fall about 5 1/16" from the bottom of the case shelf/stretcher to the top of the drawers stretcher. The drawer box can be 4" with dadoed in bottom. The end of all our cases are 30 1/2 by 23 3/4 deep. Our wall cabinets are 30" tall and 13" deep and the doors are less 1/4", always flushed at the bottom. See the pattern?

We drill only where the hardware goes and when we operated without a CNC we did that with custom made jigs. Rockler has a system that would save you loads of time.

We bore on ptp and lay holes only where we need and the majority of construction holes are the same. As the above posters have mentioned, 32mm system lends itself to great predictability. Develop a system that works for you with your budget.

From the original questioner:
Thanks for the help. I've got cabinets with varying heights, so my system holes all datum from the bottom. All parts will be CNC cut and drilled. My plan now is to make a standard cabinet end panel program for each cabinet height with all the system holes. I will leave construction holes for the spreaders out except for the one spreader between the upper drawer and the door, as this spreader will be on every cabinet. Other spreaders for 2, 3, and 4 drawer cabinets will be done with a drill fixture similar to what contributor D brought up. I thought real hard about leaving out system holes that won't be used for a particular cabinet and providing the construction holes (CNC cut) instead, but in the end I would have well over a dozen unique end panels. For our shop it would just be easier to slightly modify a standard part rather than have to store and manage multiple similar but different parts.

From contributor M:
I don't think there is any reason to have stretchers between all the drawers, just the top one.

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