Corner Assembly Clamp Blocks

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Project by ratchet posted 05-05-2010 04:11 PM 9773 views 41 times favorited 12 comments Add to Favorites Watch

These are more of a set of assembly jigs than a WW project, but I think these are going to help me greatly. I am fairly confident in preparing frames and casework, but seem to come up short in ASSEMBLY.

As I’m planning some upcoming cabinet projects I went looking for commercial corner clamps to help with that. Whoa…they can be pricey epsecially when you might need a dozen or more of them! I took a look in the scrap bin for some 3/4 Birch ply and came up with these pictured. I doubled the ply for a wider clamping surface. There are 3 sizes. Notice the 45 degree center spot to clamp at the center if needed (as such they will need to be used on the inside of corners instead of the outside).

I was carefully when these were cut out on the TS to get the 90 very close. Finished each 90 on the wide belt sander and 12” disk sander checking frequently till the machinists square showed no light and were spot on the 90. Note the square in the second pic.

Finished with several coats of shellac and spray acrylic to keep any glue from sticking on assembly.

Hope you like them. Please offer your comments.

12 comments so far

View patron's profile


13640 posts in 3540 days

#1 posted 05-05-2010 04:16 PM

these are great ,
very good idea !

but tell me ,

how are the rich guys

supposed to make any money ?

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Raymond's profile


676 posts in 3927 days

#2 posted 05-05-2010 06:35 PM

You know I was going to buy some corner blocks just the other day. Great idea…

-- Ray

View redryder's profile


2393 posts in 3301 days

#3 posted 05-05-2010 08:59 PM

Your right! These little units cost way too much in the stores. Yours look great!

-- mike...............

View jack1's profile


2117 posts in 4226 days

#4 posted 05-05-2010 09:36 PM

good idea

-- jack -- ...measure once, curse twice!

View Dusty56's profile


11822 posts in 3887 days

#5 posted 05-05-2010 09:39 PM

Very nice job : )

-- I'm absolutely positive that I couldn't be more uncertain!

View wch's profile


45 posts in 3157 days

#6 posted 05-05-2010 09:44 PM

These are excellent – the ones from Rockler are pretty expensive and the surfaces aren’t quite flat – they’re a little wavy, but probably fine for woodworking. They are very rigid, though.

One nice thing about the Rockler clamping squares is that they can be used on the outside of a corner. Have you considered making squares that can be used that way? You’d have to cut away the angle brace area on your current design and drill a little hole at the corner for relief. That might affect the rigidity, although they look pretty beefy to begin with.

View ratchet's profile


1391 posts in 3986 days

#7 posted 05-06-2010 02:43 PM

Thank you all for your comments. When I can easily make a jig or tool instead of buying them it allows purchases of the things I can’t make…like saw blades,etc.

WCH, agreed these corner blocks can only be used to clamp on the inside of a corner. I don’t see the downside there though. Time will tell if I need to pull some more 3/4 plywood scrap from the cutoff bin to make some outside corner clamps.

View Jamie Speirs's profile

Jamie Speirs

4168 posts in 3056 days

#8 posted 10-04-2010 10:40 AM

That is a super idea.

-- Who is the happiest of men? He who values the merits of others, and in their pleasure takes joy, even as though 'twere his own. --Johann Wolfgang von Goethe

View Roger's profile


20952 posts in 3003 days

#9 posted 10-20-2010 03:47 AM

yup. grrrrreat idea. there are far too many “gizmos” on the market such as this that cost way way too much money…. I’m sure it doesn’t cost these companies (not mentioning any names, but they know who they are) THAT much to make things such as this…... Very great idea, and simple….Thanks for sharing

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed.

View a1Jim's profile


117328 posts in 3776 days

#10 posted 10-20-2010 03:52 AM

I’ve been using these for a number of years they work great.

-- wood crafting & woodworking classes

View PineInTheAsh's profile


404 posts in 3467 days

#11 posted 02-07-2011 01:03 AM

It’s been some time since this has been up; this just came through on rotation and thought it deserved renewed currency.

Ratchet’s excellent post is a wonderful time- and money-saving project for LJs everywhere.

By doubling up on the ply gives a greater clamping area and makes for an easier to handle block when fumbling with getting those “just right” corner alignments. To my knowledge, this one gives a wider surface area than any commercial clamp block currently available. I like it.

It ain’t as easy as one would think making a precise corner block. I’ve tinkered with various assembly blocks, coming away with a mixed bag. An accurately cut square of 3/4 MDF with holes to accept clamp heads remains a good user. Right now on the work table: a 4” steel L bracket carefully screwed to pcs. of milled flat oak with a thin layer of cork for a cushiony friction grip holds promise.

In all the years roaming through the hardware cafeterias of HD and Lowe’s, I’ve never seen one. And, you would think HF would jump their discount feet into offering something like this, but, no!

Perhaps it’s time for a clever consortium of LJs to offer a select catalog of quality wood jigs, fixtures and work aids priced right. (??)


View Ben Simms's profile

Ben Simms

191 posts in 2491 days

#12 posted 09-28-2012 02:19 PM

Simple and effective! is there anything else to look for in a jig?
I have the same HF clamps you do, there not bad at all.

-- I played with Legos as a kid and I never had the part I thought I needed, so I learned to improvise. Now I'm an engineer with a woodworking hobby.

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