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kenk 04-09-2017 08:05 PM

Cabinet Carcass Back Rabbet
I was watching an online video of someone making a cabinet out of 3/4" plywood. Here is its URL:

He assembled the sides, top, and bottom using glue and countersunk screws driven from the outside (countersunk holes filled with wood filler later). Just butt joints - nothing fancy

Next was time to add a back.

Instead of cutting the rabbets before assembly, he used a router to cut a rabbet all around the back edges. Of course that left rounded edges in the rabbet at the corners.

I expected him to somehow cut the rabbet corners square, but instead he rounded off the corners of the 1/2" plywood he used as the back. I'd never seen that.

In the commentary he said that he didn't pre-cut rabbets before assembling because rabbets cut across the panels would show from the outside - makes sense. He also said that it was a difficult cut - that he kept his arms straight. Not sure what kind of bit he was using.

Of course using the stops on the SSRK, you could create "blind rabbets" (is that a real term?), but I can see that the post-assembly routing might be faster.

How did he figure out the exact radius (or whatever shape it is) to make the back fit nicely??

I'm curious what the cabinet makers here do. How do you prep the cabinet carcass for the cabinet back?

Thanks! -- Ken

philb 04-09-2017 09:40 PM

More than one way
There are several ways to make a cabinet back. If I am not going to have the back side exposed to people I use single strip ply cut to 3/4"X4" running along the top back side and a nailer or two running the same for fastening to the wall. Upper cabinets are where I have made the full back.

I switched to the Sommerfeld Cabinet method about three years ago. Love it and it is easier to do. More costly if you use their tooling but I have yet to make a cabinet or dresser that was out of square, or sub standard. Uses more glue but the product is sound.

this is a set of plans for a kitchen.

They have a YouTube channel and it is the same video in four parts. You can see what Sommerfeld tools do and what it takes.
Just an idea and I do not make cabinets every day so I need all the help I can get. I do need lots of help!

tomp913 04-10-2017 12:46 AM

5 Attachment(s)
I've done that before on smaller cabinets using a rabbeting bit, the trick is to clamp a support for the router to the outside of the cabinet - I use a piece of 2x4 that's been jointed to have adjacent square edges - and do the sides in order working around the cabinet. As far as the back, it's just a matter of using a corner radius template to suit the diameter of the rabbet bit - 5/8" in my case to suit the 1-1/4" diameter cutter. I've used that method for years to make quick doors for shop and utility cabinets.

Tracedfar 04-10-2017 02:14 AM

Maybe my approach is too simplistic. When a cabinet requires a full back, I usually just cut the back as an inset; no rabbet, no routing. I'll either glue and nail, if painting; or pocket screw the back, if staining. If the back will show, I use either veneer or door panels.

I've looked long and hard at Sommerfelds method. It sounds to me exactly as philb describes. Sommerfeld is a good teacher. One thing he doesn't emphasize is the need for quality plywood. Ever tried cutting a tongue in the cheap stuff? Another thing is to be careful with the glue because it won't take stain. In fact, I learned the hard way to stain my panels before assembly to avoid glue/stain problems. Anyway, what's​ kept me from using his system is the learning curve. If get a chance, I'd like to try it.

Gilad 01-01-2018 07:37 AM

Plywood for doors?
He used plywood for long doors. Will they not twist with time?

Tracedfar 01-01-2018 04:54 PM

Quality plywood (usually US or European) specifically intended for cabinetry will remain stable. I've seen cabinets from the'50's made from it with no more movement than solid wood

Of course, built and hung properly, most cabinets will last decades barring climate issues, insects and critters, shifting foundation,bad plumbing, playful toddlers, angry teenagers, etc.

Dino 01-01-2018 04:55 PM


Originally Posted by Gilad (Post 39593)
He used plywood for long doors. Will they not twist with time?

Yes, They will.
I made the same mistake using 5/8" edged glued maple.
Now I will redo them all using 3/4" ply with stiffeners inside.
Like a large x using 1x2" solid Oak strips. Strange looking but is mine and I like it easy. This is a summer project if I can make it.....


Tracedfar 01-01-2018 06:13 PM

I both agree and disagree with Dino. I'd use nothing less than 3/4" ply.

My uncle built his kitchen in the '70's from 3/4" hard maple ply and they're holding up fine. They were stained and finished but never painted. The doors are rabbeted for a 3/8" over lay, not edge banded. So I know it can be done, or could have in the past. I don't know where to get plywood like he used. It may not exist anymore.

Secondly, the 90+ year old house we now live in has some kind of hybrid cabinets that are both face frame and frameless. They're old and ugly but they are straight, including the plywood doors. They're painted but not edge banded so I can see the plies. Again, maybe they don't make that kind of plywood anymore but, obviously, at one time they did.

I used 3/4" domestic birch ply for my shop cabinets(carcasses, doors and drawers fronts) and finished with a few coats of poly. They're euro style but I didn't bother to edge band them. I only heat or cool my shop when I'm in it. This morning it was -3 and I'm not going out there. In the summer, it's been over 115. So far, I have had no issues going on 3 years. I also live in very dry climate.

Third, I made a cabinet a couple of years ago for a customer who supplied solid core 3/4" 3-ply with 1/8" mahogany veneer on both sides. He insisted I use it for everything, doors included. I don't know where he got it but it worked. However, unless he got it for free I can't believe he saved that much over solid wood.

Maybe these examples are the exception.

That said, I can't imagine recommending plywood doors to a paying customer.

Todd 01-02-2018 12:47 AM

I too used 3/4 birch plywood for my garage workshop cabinets. The cabinet boxes, doors and drawer fronts are all birch. The doors are all edge banded. The cabinets are two years old and I have had no issues. I am in Ontario, Canada and it has been in the -20's celcius. Fortunately I installed a 10' natural gas radiant tube heater a few years ago so I can use my workshop year round.

Dino 01-02-2018 08:20 AM


Originally Posted by kenk (Post 38781)
I was watching an online video of someone making a cabinet out of 3/4" plywood. Here is its URL:

I'm curious what the cabinet makers here do. How do you prep the cabinet carcass for the cabinet back?

Thanks! -- Ken

I only made 32mm cabinets..for few reasons.
Most important was the full overlap ( Better look )
and much easier to clean. No frames and hidden areas.

I ordered the plywood pre-finished but if not available I use a flat pad. 3-4 coats before cutting the parts. ( water-acrylic)

with a simple guide ( home-made) I did all dados. ( before cutting the parts)
I kept the sides of each cabinet as a pair and from each cut I had 4 wall sides.
For the bottom cab's I did the same but instead 34-1/2" I cut them 31"
That saved me the toe-kick and the work to cut it)
Now I had 3 base sides instead of 2.

The best part of my system was the leveling grid on the floor.
using 1x4's I started from the highest point and screwed the 1x4's #2 pine
all around the perimeter. On the end cabinets I stayed 3-1/2" from the end.
That give me a better look with all around recces toekick. ( custom look)

Doors was delivered ( finished) by door companies and life was easy.
I made the drawers ( dado) and all the rest...
Making cabinets is plenty of work and money for all.
If you try to do the end you lose money and time.
Imagine a $60K custom Cherry cabinet job been made in a garage?
3 guys-3 days was my start to 90 % finish. But we spend 2 more days for the details.
If the customer notice one small mistake...believe me...they will look for mistakes years after you are done.

happy new year

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