You might have seen the Rockler Clamp-In Assembly Square before, a handy right angle fixture that can be used to assemble cabinets and other types of work. It’s rigid and made from high impact polycarbonate for strength, durability, and accuracy.
If you’re wondering how the Clamp-It is used, just consider the name. If you clamp two boards or panels to something that is nice and square, they will become nice and square to each other.
Now, there’s also the Rockler Clamp-It Corner Clamping Jig, which is a new add-on product to the Clamp-It Assembly square. While you can use Clamp-It squares with many different types of clamps, the Clamp-It Corner Clamping Jig is a quick and low-profile one-piece clamping solution.
The combination of a Clamp-It square and Clamp-It Corner Clamping Jig is meant to securely hold 2 panels or boards at a 90° so you can fasten them together, without the need for additional clamps or accessories.
The jig has two Acme-threaded clamping screws with soft non-marring pads. With the Clamp-It square in place, they combined fixture can handle material up to 1″ thick. Once nice touch is that the glass-filled polycarbonate base is raised 3/4″, so you can use a 1x dimensional scrap pieces for additional workpiece support.
I had already purchased one Clamp-It square back when Stuart sent me on a $200 shopping spree, and Rockler was kind enough to send over a Clamp-It Corner Clamping Jig to test out. In addition to 2 Clamp-It Corner Clamping Jigs, Rockler sent over two more Clamp-It Assembly Squares to use for the review.
Unboxing the Jig
First things first, I had to get rid of the annoying sticker applied to the base of the jig. It wasn’t just going to peel off, they stuck it on good. With a judicious application of heat to soften the sticker, it peeled right off. Then I just used a little isopropyl alcohol to remove any sticky residue left.
You don’t have to remove the decal, but I wanted to.
There were 2 screws protruded from the bottom of each base, and I wondered what they were for. The screw heads caused the clamping jigs to rock a little bit on a flat surface, forcing me to think about their purpose.
Before I removed the sticker, I first needed to remove the screws from the base. It was then that I realized that the base had threaded inserts. So I looked at the packaging, and sure enough the screws are intended to be used to secure the Clamp-It Assembly Square to the base, so it becomes a solid one-piece assembly.
When the screws are used properly to hold the Clamp-It Square in place, they don’t protrude from the bottom.
The only reason not to screw down a Clamp-It Square is if you want to move between the Clamping Jig and separate clamps very often.
Using the Clamp-It Corner Clamping Jig
Overhead Storage Project
I previously discussed building a storage rack above my bench in the Rockler Tapered Countersink review. I used the two Clamp-It Corner Clamping Jigs to assemble the rack before I hung it from the ceiling. I learned that, despite the implied ease of use, it can take a little bit of adjusting to get the boards clamped in place properly.
I found that if I’d try lining up and clamping both boards at the same time, the joint wouldn’t line up correctly. After practicing on a few corners, I discovered a procedure that seemed to work well:
First clamp the board being butted up against in place, and then bring the other board into place and clamp down. Finally, unclamp the first board and readjust it so the corner is flush.
I also found that it is important to make sure the boards rest flat on the base. Downward pressure helps to keep them there while you turned the screw clamps. If you don’t do this, the top and bottom of the joint might sometimes go out of line.
I may be making it sound like these clamps are difficult to use, but once you figure out the above techniques, it becomes second nature and the corner clamps actually make assembling corners much easier.
You don’t have to use the jig on a tabletop surface either, it works just as well unsupported, as you can see above where it’s holding a cross member in place while I drilled holes and drove some screws.
Little Library Project
I also used the corner clamping jigs to assemble the other project I mentioned in the Rockler countersink review, the unofficial Little Library.
I assembled the house in two steps, first I clamped it together so I could drill the countersunk holes, and then I re-clamped it so my daughter could glue and screw it together. While I could have just done it in one step, this allowed me to setup the project in the shop on my own time so that when my daughter came down to help, I could keep her busy assembling the house.
I tried a few different configurations to test the clamps. For drilling holes in the back, I attached both sides to the house with the corner clamping jigs and rested the assembly on the two sides so I could drill the holes downwards using the table. This only required one extra clamp to span the back and hold the tops of the sides in place.
To try something different, I stood the house upright and attached the two sides to the house on the bottom with the corner clamping jigs and I used my extra Clamp-It Assembly Square to secure one side on the top. The assembly was rigid enough that I only needed one small clamp to keep the second side in line.
There’s not much I could find to dislike about the Clamp-It Corner Clamping Jig, except maybe the price. One Rockler Clamp-It Assembly Square will run you $13 and one Clamp-It Corner Clamping Jig costs $28. So to just to clamp one corner you’re talking $41. That’s a lot of money for a specialty clamp, especially if you need four to form a complete square.
Another option is to use just a pair of these Clamp-It Squares and Corner Clamping Jigs. Clamps always seem to work better in pairs.
It comes down to whether you clamp enough assemblies to justify the cost. While these Rockler Clap-It squares and Clamping Jig do make assembling boxes much easier, there might be better ways to spend the same money, such as on good parallel jaw clamps.
But if you already have a well-stocked clamp rack, and the budget, there is just one another reason why you might not want to buy this, and that’s if you mostly work with stock that’s more than 1-inch thick.
Buy Now (Clamp-It Corner Clamping Jig)
Buy Now (Clamp-It Assembly Square)
Thank you to Rockler for providing the review samples unconditionally.
I’d be interested in seeing a head to head comparison of these versus something like the Bessey WS-3 angle clamps. The Rockler clamps look like they’re more stable, but they also take up a lot more space, which may make them difficult to use on smaller projects.
The WS-3’s seem to cost about half the price (I’ve bought them for about half of Amazon’s current $30 price http://www.amazon.com/Bessey-WS-3-Angle-Clamp/dp/B000022454), so you could pick up a pair for the cost of a single Rockler clamp.
Just how square are these? They look like they would be great for anything not requiring too much precision, but my jevon 3d squares are far more precise (though they cost me a pretty penny too)
That’s a fair point. I didn’t think of testing how square the Assembly Squares were, I just trusted they were square enough.
I just took out my Crown Tools square, placed it against the outside of the Assembly square and held it up to the light. On the whole it looks pretty close, but I can see light under the blade of the square because right at the corner the assembly square it’s raised slightly. It’s not a burr, it is on both sides of the Assembly square and I tested another Assembly square and saw the same thing.
I can barely get a piece of printer paper underneath the square so the gap is not huge.
Hmmm. I’m seeing the same thing on the inside of the square at the first point of contact from the corner. I’m wondering if this is designed into the mold or if it has something to do with the way the plastic cools as it comes out of the mold.
The projects I clamped with the ClampIts came out square, that’s what matters to me.
Before Rockler (and other purveyors of jigs) came along, most of us fabricated out own jigs from plywood and scraps of hardwood. I’m not sure they were any cheaper if you factor in the labor and cost of materials – especially if you need to buy the wood specifically for the jigs. For corner squaring on some projects –plywood triangles with oak or maple glued and screwed on was my solution 30+ years ago. They still work with 4 small F-Clamps to hold each in place. BTW – using F-Clamps with the Rockler plastic “L”s would seem to allow them to be used with 5/4 or thicker stock – maybe not as conveniently.
Now if you want an even more expensive solution to corner clamping – you might look at Jevons (as John S posted) or Woodpeckers :
There is also the Bessey WS-3 (as David says), its bigger brother WS-6 and WSM-9 (welder’s clamp). There are also look alike ones like the MLCS (Merle) Can-Do clamp, The Stanley 83-122, Irwin 226410. Then there is the Pony 9133 or Stanley 83-121 and Wolfcraft 3415405 (more useful for moldings.
Lee Valley also sells plastic assembly clamps 50K38.01 – more holder-helpers than squaring fixtures – but certainly cheaper than Woodpecker’s BC4. Kreg makes their KHC-90DCC which also sells for about $30 each. And while we are on the subject of clamps to keep corners together two of my favorites are the Gross Stabil MCX system, and the Chestnut Tool Co. (not the Lee Valley low cost China-Made brand) Clam Clamp for pulling together window and door casings.
At the expense of being even more long winded – I’ll add that one of Benjamin’s pictures shows him assembling a box by screwing into the end-grain. While this was probably fine for the purpose being illustrated, even with glue – this can result in a bit of a weak connection. While it is a bit more work and requiring more tooling, making the connection with pocket screws would have been stronger.
Kinda bizarre they didn’t counter sink the securing screw holes for thr jig to make it flush when attached. If they’re sticking out like that it be pretty annoying quick when laying on the jig and on the table. At first glance I thought those threaded holes would be cool to use to secure to a table or better yet secure to a t-track.
Hmm… I wasn’t clear enough and something was lost in editing.
The bolts ship screwed into the bottom like the picture, but when you use the bolts to secure the square into place they come through the top of the square, through the square and into the threaded inserts. They don’t protrude through the bottom at that point.
Sorry for the confusion.
Does anyone make something like this out of metal, for holding things square for welding? I have the 90 and 45 degree magnets, but often I need something with more holding power.
(need to add an edit button to comment)
See John S’s link to Jevon.
We used these:
and the smaller WSM-9
Thanks a lot, that’s what I was looking for.
I bought 8 of these and within a short time the tightening screw handles had broke. they are not solid and will break very easy.
Won’t fit at 90 degree, why?
Maybe it’s defective? If so, Rockler should be able to help with that.