3-Way Panel Clamp System
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- Опубліковано 3 жов 2024
- Clamping panels, while not a difficult process can be cumbersome at times. In this video, I develop a way to combine all of the components of a good panel glue-up into one clamping system. Any suggestions for improvement? Let me know in the comments below...
00:07 Introduction
03:00 Build start
06:53 A word of warning on welding Zinc
10:00 Demonstration
Instagram: / thomaslightle
Facebook: / redbarnwoodworking
Twitter: / tnlightle
Website: www.redbarnwood...
Thanks for the post, great idea, I wonder if square nuts or spring nuts would have worked instead of welding nuts at the far end.(they sit in the channel)
A lot of people have asked this question and yes, I had considered it, but there were a few issues with using the spring nuts. First and foremost, the whole load would be placed on just the inner lip of the unistrut. I didn’t feel like that was strong enough for the application. Second, since I was placing a lateral clamping load on the piece, I was concerned about the spring but moving as I was tightening down the clamp. I was also concerned about warping the inner lip with the lateral clamping forces. Finally, if I used a spring nut, the threads of the bolt would dig in to the edge of the board I was clamping, leaving marks behind. They way I designed it, it bears the flattening load across the whole unistrut, it won’t move because the nuts are welded into fixed locations, and the bolts are long enough that the shoulder of the bolt is what interfaces with the panel, so the threads won’t mar the edge. This idea isn’t perfect. Someday I will release version 2.0, but for now it does the job. Thanks for your comment!
@@SouthpawWorkshop you can cut the springs off the nuts, you don’t really need them. There is no way the clamping force would bend the lips of the unistrut, most people tighten the clamps way too much, only a small amount of pressure is required. Great idea!
Really thoughtful engineering you have, regarding the use of welding instead of spring nuts. You raise extremely important engineering reasons for using the welded nuts. However, I do feel that if you're going to use Unistrut, then you absolutely have to use spring nuts, because spring nuts are part of the magic of Unistrut. The magic of spring nuts is the clean look, no welding, but most importantly--infinite adjustability. Spring nuts also allow nothing protruding from the bottom of the strut, so it would sit completely flat. The spring nuts won't deform the strut, as long as you use a standard thin washer on the bolt that tightens the two pieces together--the washer will deform visibly and will continue to deform, before the strut deforms.@@SouthpawWorkshop
That was one of the best ideas I saw regarding clamping panels. Thanks for the video.
Hello Thomas,
Go to a decent electrical contractor supply chain, get the taller 1-1/4" to 1-1/2" that has your same narrow width, it will not flex as much. Get the spring tube speed nuts by the box (come in different thread pitches), insert as many as you need in each tube, which looks like one to two to save all that fabricating time. That is why Uni-strut has all those holes/slots. Use regular speed nut and two 1" wedges opposing each other to put your side pressure. That way you don't need to use extra fabrication skills and steps. Industrial mechanics, electricians hvac and other tradesman use this stuff all the time for permanent or temporary projects. Ask electrical supply for one of their uni-strut accessory catalogs, might get other labor saving ideas.
I did watch a spanish woodcraftsman on y-t make something similar with a ripped 2x4 drilling five holes through the tall sides with 3/8" bolts, washers, wing nuts and wedges, did not mark the wood.
If you pause at 0:24, one clamp lines up perfectly with the red hand pallet (?) in the background that an optical illusion is formed. While the video plays, I thought that was part of some nice DIY clamp. Good video as usual, thanks for sharing.
Truly appreciate the safety issue on welding prep. 👍👍
Brilliant solution! Thank you so much! There's much glue-up hell in my foreseeable future bc I'm using a bunch of scraps and tree stumps to make my wood workbench top. Your idea is going help so much in ensuring my efforts to save some money doesn't go to waste.
Best clamp system, plan to use it with some modifications, like middle tightening for larg panels and flat head on the tightening bolt to increase pressure area.
Add wood inserts to the clamps where they contact the wood surface. This may also provide an alternate way to locate the nuts by locking them into the wood. No welding necessary. I am going to make a set and see how my idea works out. Thanks for a great idea.
The real danger is welding in a wood shop. Most men are not tidy and organized, and they won't stop to clean and vacuum everything before welding.
Welding galvanized isn't smart, but farmers have been welding it for decades (my agriculture shop teacher never warned us, he just said that you can "taste the zinc" when you're welding it).
Love the design! And I think it's a very good use of Unistrut; it should be utilized more in woodworking; your design is the best homemade panel clamp system I've seen so far.
I like your ingenuity, your persistence and a sneak preview of what I think will eventually be a real asset to woodworkers! Please keep on with it and end up with the kinks out. I am looking forward to it! Thanks!
Ive made a set but used the 2" unistrut. I build some very large tables from reclaim lumber or just pine or fur. I need to weld the nuts to mine. Good idea. I use clamps to pull the boards together but the panel clamps to make it flat. Awesome 👍
this is magical
Amazing.. you just solve my problem i was thinking of the whole week...
Brilliant,Excellent clamping system
Thomas, I love your concept. I might follow your lead on this one. Thank you.
Thanks!
I think it is a good idea. Gonna build me some. To prevent the unistrut from digging into the wood, I would cut strips of pine or other soft wood to match the length and just a little bit wider than the width of the unistrut for better load distribution and cut a channel in the middle of the wood for the bolts to pass through and then attach the wood to the unistrut with screws and washers making sure the screws don't go all the way through the wood and gouge the panel. You wouldn't need to have the screws to go any further than where your most inner clamping bolt starts. The other screws will keep it lined up and attached plenty good enough. I'm also going to cut out some round slugs from some 1/8" plate and weld them to the ends of the lateral clamping bolts. If that doesn't work like I want, I'll fabricate some swivel cups for the ends of the bolts instead.
nice clamps and an ingenious build. the first thought that came to mind was just strips of 1/4 attached to the beams to avoid marking
Great idea. I’m making a set. Thanks a bunch
Awesome idea, i will be making some, thanks for posting.
Thanks!
these are best i ever seen, nice one bro for butchers block counter top
I like your clamping system a lot! It has inspired me to make something similar, maybe using wood cleats and wedges, but using your design outright. Thank you for sharing your design and creativity.
Thanks!
Great idea. I will have to make some. You might weld washers on to the 1/2 in bolts that tight the side clamping to give the contact to the sacrificial boards. Thanks for sharing.
Nice video ..put some piece of wood in the middle of wood and metal and i think you will not have none of problem..but i like it..nice idea..hello from Greece..
Great Job... I Made some of these out of Red Oak Scrap and Carriage Bolts and Wing Nuts. Rather than using your "Horizontal pressure through Bolts". I just used some of my aluminium bar clamps to pressure my Work pieces together. When I used my Scrap 3/4" red oak cross bars Made the centers taller in the middle than either end to help keep these pieces from Flexing...
Either end was 1-1/4" and the centers were 2". One side(the part that touched my joining work pieces)was perfectly Flatwhile The Outside edges were arched.
My sandwich clamps will accommodate up to 30"...
I hope you understand my description... Again I Like your Design... Whatever Works Right... I did subscribe to your channel... 👍👌👏
Thanks! I think I understand what you were describing. Thanks for the sub!
Wedges are a great idea. My goal was to try to come up with an all-in-one type system, so wedges may have made it more complicated. Or at least, more pieces to keep track of. Still a great idea, though.
We have tons of Unistrut and fittings around the shop at work rhat we use for all kinds of sruff. Square "U" bolts (you can get rhem any length) works to clamp the ends. Two peaces threaded rod running the length of the Unistrut gives side clamping pressure. Use a piece of bar stock at each end with double nuts counter tightened on the end inside the Unistrut, and the other end a piece of flat steel covering the ends. Your system has fewer bolts to tighten. Mine has 6 for each clamp. Also, I won't take the time to cut the strut, so I use awkward 10 foot clamps.
very excellent idea, maybe one tip, to weld a small handle to the front nuts so you would not have to use the wrench, and in stead of 2 pieces of scrap wood you could always slide in a few pieces of your uni strut kind regards Hans
great idea and it was a great starting point, we all seem to expand on each others ideas in this community keep up the good work.
Yours look more efficient than Rocklers, well done.
Nice idea just a few tweaks and that will be a awesome set of clue clamps I'll be making some for my shop maybe Evan built on the wall so I can clamp up boards and keep working but thanks for the idea
Very good,I was looking for something just like this, will be making it, thanks
Good luck!
Really nice idea.
Looks good. You can remove or reduce the dents with steam or maybe hot water. Wax the clamps or apply packing tape to reduce staining.
Clever stuff! 2 little suggestions you've probably already thought of... a piece of waste wood between the top of the piece and the clamp to prevent the clamp from marring the surface and also possibly putting hardwood shoes or metal shoes on the horizontal bolts to spread the clamping pressure and spare you having to use a sacrificial hardwood piece each time.
Thanks for sharing! I'm going to have to make some!!
Thanks for watching!
Metal strip instead of sacrificial wood strip will not only stand up to many uses against the clamping bolts but will give a beter spread on clamping pressure! Strips of anti slip fabric (like for use in car dash) might help reduce dents from over/uneven bolt tightening ! Just one or two idea to help but a great system well done !!!
Great ideas. Thanks!
Fill the void in the unistrut with some hardwood to displace the clamping force
Great idea you had there. I think there are possibly a few minor improvements that can be done although the overall concept and idea is great. Thank you. I plan on building two sets of these. One extra large to do 60” wide by 80” long glue ups. And one to do standers size stuff maybe 32” x 48”
Glad you liked it. If you try any improvements and they work out good, let me know!
Nice job I like this very much
You did awesome!
Love it, im gonna make a bunch. have some variations i think would work awesome with what you have already done. rubber feet on some sort of t slide bolt( keep the dents away), maybe a steel block welded to the front of the cross pressure bolt. Great video thou.
Great ideas!
excellent design i like it
Definitely planning to build some of these. Thanks so much! Loved this video.
great idea
Very innovative.
This size Unistrut is a bit of flimsy on its own. I have found it still twists and bends but doubling it back to back up would be very rigid if you need it. A piece of 1/4 in thick steel from the hardware store between back to back doubled unistruts will make it very strong and resist bending even better. They have a larger size but its really not much stronger in one direction. The size you have is good if used right for more narrow panels. Also you can get some tap sockets and you can drive 2 flute taps snd some 4 flute ones with a socket wrench or impact. Spiral taps for blind holes. Right now I have 2 x2 inch Aluminum bars but I like this idea of yours but Im going to try turning them 90 degrees double them back to back with a 1/4 bar between them for wider panels I can see yours bending where the clamp bolts go thhrough and that dents the wood.
Here is an idea I might try on your design. Try fitting a piece of hardwood the length of the unistrut that will fit snugly inside the channel of both top and bottom bars and high enough to keep the hard metal off the softer wood and drill a hole in the wood at every opening in the unistrut. Again, use a wax substance on the wood to keep it from sticking together.
Many have suggested that and it is a good idea. The only issue I see is that the wood strips would have to change length every time you wanted to glue up a different width board. I have some ideas for a 2nd generation of this idea. Just don’t have any time to develop it. Thanks for watching!
1) use metal strips instead of sacrificial wood strips. 2) put metal panels on each side of the panel boards. Make it so the bolts and the unistrut only bear against metal, and let that metal spread the load for you. It's a nice concept - well done!
Put wax paper down before the clamping. Thanks nice idea 💡👍
Great job Thomas, definitely a thumbs up from me!
Спасибо, крутая идея !
Pretty awesome build, I was wondering about soldering galvanize material so this was also good information as well.
It probably would not have left dents if you had flipped them over onto the flat side. Just a bit more surface area. Very cool I am considering doing this too
Good idea! I was about to make something like your design and make it out of steel. I'm glad you don't feel like it has to be made out of wood entirety. There are spring captive nuts made for those rails. Did you try them? An angled wall mount would be my choice. Good job.
I did consider the spring nuts, but I wanted the pressure to be applied across the whole piece of unistrut, not just on the rails. Hope that makes sense.
Thats brilliant
Strut have connectors so ready made for it; using those would save you the welding and time, and they would be plenty strong enough.
Excelente ideia
Tom you're almost there I would recommend planed hard wood between the unistrut and your work
Good ideal !!!!!!!
I thought of a similar idea years ago but yours is much more thought out. I like the simplicity and ease of use. I've used more Uni-Stut than I care to remember working in the HVAC/R field, mainly for supporting refrigeration lines and hanging unit heaters. In regards to he fears of welding on galvanized, they also make a painted version as well as specialized nuts (I've always just called them cone nuts) and with a little ingenuity one might eliminate the need for welding.
@Tvzblaze Ggg To respond to the question of using spring nuts: The reason I did not use the spring nuts has to do with how those nuts interface with the Unistrut. There is a small lip on the inner channel of the unistrut that catches these nuts and all of the clamping pressure is applied to that narrow lip. In normal pluming and structural unistrut applications, the nut and lip are always pressing against something say, a pipe, a piece of structural steel, or another piece of unistrut. In this application, there is nothing backing up the nut and the tendency will be for the lip to bend outward away from the inner channel of the strut. I am using the full thickness of the unistrut to behave like clamping cauls, so the bolt and nut needs to press equally from the outside of the unistrut, using the rigidity of the strut as the caul action while the bolt provides the clamping action. With a spring nut in use, my belief is that only 1 side would provide the caul action and the nut side would just fail over time because of the pressure being applied to the inner retaining lip. I sure hope that book I just wrote gives you some insight to how I was thinking when I approached this project. I did consider using spring nuts at one time, but decided against it for the reasons stated above. Thanks for your input, guys!
Muito obrigado pelo trabalho
Good idea! I have 60 raised panels to make, and the thought of all those glue-ups is quite daunting. I think I will make multiple sets of these. This material is available from Home Depot/Lowes?
Yes, everything is available at the big box stores. The unistrut will be a little pricey, but still cheaper than any panel clamping products out there.
If you will die from welding galvanized steel I would have been dead before you were born,,,,,and at 77 years old. I'm still welding the crap today. (When I am forced, anyway) The way to take away the sickness after you get done lies in a Black Velvet and Budweiser. +++++++
Next time get 1.5" Uni-Strut instead of 0.75", it's MUCH stiffer.
Use wood wedges instead of the end bolts, (no chance of damage), then hammer them tight behind the bolts.
There's really no need to weld-on nuts, just use loose nuts with washers.
You really don't want to be forcing a board straight, and then hope the glue will keep it straight,
you're just asking for a big mess.
Your boards need to be straight FIRST.
This whole thing looks somewhat "iffy"......
I would prefer to have a known, checked, flat work bench,
then lay down a sheet of Vis-Queen (polyethylene film) on the work bench,
then drill holes in the bench that are ~1" wider than the work-piece, to accept 3/8" All-Thread,
then use 1.5" Uni-Strut to hold the boards down to the bench.
Then use standard bar clamps to squeeze out the glue.
You should only need 3 Uni-Strut bars max, if your wood is already straight.
And, be careful tightening down the Uni-Strut, there's no need to bend it,
and consequently, put indentations in your work-piece that will have to be fixed later.
Strips of cardboard can be used to protect the work-piece from the Uni-Strut.
So at this point, why not just use some cheap 2X4's and some 3" Drywall Screws to screw it to the workbench ??
Use #8 flat washers under the Drywall Screw heads to prevent burying them into the soft 2X4's.
If they bother you, you can fill the screw holes in the bench later with wood putty.
.
.
Very good idea. You could try to steam out the clamp dents with a damp cloth and an iron.
Madts.
You need to turn your unistruts over so they have the flat surface on your wood. I did something similar and maybe one day I will post a video or share with some of my youtubers so they can make some and pass on. But I will try to describe the best I can...
I use the same size unistrut but unaltered other than cut to length. I took some 2 1/2 in 1/4 angle and cut them around 2 inches long. One side I cut the angle down so it is just under 3/4"x2 1/2" the long side I drilled 2 holes I think 5/16ths the same distance as the center of slots of the unistrut. The then I took 5/16th (or 1/4 don't remember) carriage bolts in the holes so the bolt head only sticks up the thickness of the unistrut material. I used my belt grinder and took of just a little bit of the square shank that keeps a carriage bolt from turning in order to get the right height. Then placed the bolts with the head sticking up that distance on the flat side opposite of my shortened angle. Then cut the back of the bolts off flush and welded them down solid to the angle. Now I made two for each set of clamps. then take the grinder and flat just enough off sides of the two sides of the carriage bolt heads so they fit inside the ovals. So now you can drop them in the strut on flat side opposed the U on the strut and slide them down in the slot and they will lock onto it. Now you just made the foot of essentially a pipe clamp that uses the strut instead of pipe. You use one just like so. The other one centered it the short side of the angle that is 3/4 drill a 3/8 hole. You can weld a nut on to it on the inside the angle or you could drill it a bit smaller and tap the hole for 3/8 thread. I then take 3/8 all thread and cut it around 4 inches or a bit more. Now I took hardwood and turned handles I threaded and epoxied onto my all thread but you could use a 3/8 bolt or weld a nut on it so you can tighten with a wrench. They just screw into it to push the board together like a pipe clamp does. I also made me some little feet that swivel on the end of my all thread that has a little wedge of hardwood attached. You could put some flatthen bar stock in place of the pine that you used to sacrifice when tightening down or hardwood. I hope this is as clear as mud for you. LOL... if so you can see you have made a bar clamp you can use with any size length of strut just cut to length.
So to use Glue up just like any other pipe clamp and run the claps hand snug. Then you just use bolts to pull another piece of strut down against it to prevent the cupping and tighten. I weld a piece of flat into a all thread to make like a T bolt and use a washer on top with knob so it is all done with hand to wrenches needed. Like I said it is probably about as clear as mud but if you read it enough times maybe you can understand the just of it. Now if you clamp something thinner than 3/4 you have to lay a spacer board down the width of the panel or the foot of the clamps will keep the other strut from clamping it together. The do work very well though.
I really debated patenting them but here I am giving away my golden goose.
I think you had gotten better results if you had used square pipes and drill yourself spaced holes. For the rest of the procedure your idea is great and I give you a like.
I think that’s gonna leave indentation lines from them metal bars I think it might be better to turn them around.not sure that what I’m seeing wrong if you ask me...great work good idea 💡
Would you not use the unistrut spring nuts (zebbs) then there is no need to weld.
Tackweld a nut to a small piece of flat metal for the cross bolt that applies pressure to the edge grain or sacrificial piece.
Good Job
Do like people have suggested and turn your strut over and use 1/2" spring nuts. Full size strut is power coated so staining should be minimized if not eleminated
I designed something like this and put it on 3D warehouse to share if anyone needs it. It’s under jtl1274, not trying to take away from this build! Just would like to share.
How does someone get to your design??
Great job looks fantastic thanks for sharing love the idea. 🍺🍺👍👍👍👍👍👍
Nice idea! Maybe use the unistrut with the flat side against the wood with a threaded piece of steel that slides in the channel.
This is a genius idea. I will definitely implement it, you could weld small handles onto the side pressure bolts to feel out how tight you are clamping, versus the drill method, or you can just set the torque setting on the drill to a known tightness. I was a little worried about the twenty minute video but your explanation was extremely concise and very thorough.
Thanks! I know my videos can be long, but I try to keep the filler to a minimum. I like the idea of setting the torque on a drill to control the tension. I’ll try that out next time. Cheers!
Thanks! Great video and great clamps! 👍👍👍
Thanks!
thats a great setup. I found unistrut for $50 for 10' plus shipping. Probly by square tubing for the same or cheaper and thicker. Everything is so expensive now. sucks.
I hear you. High prices slowing me down too.
I love this idea, and I'm looking forward to expanding upon it. I make a lot of heavy duty tables and have been looking into other methods for clamping. I have looked into the industrial clamp racks / tables and not only are they pricey, but they are usually rather large. I would definitely like to collaborate with you - or at least brainstorm a little. Great Idea and Thank You for sharing this approach.
I would suggest going with deep unistrut for rigidity, I'd REALLY like to see what you come up with. I use a set of 4' pieces and just nut and bolt thru them as cauls but use conventional clamps to join the boards.
If you are goin to use that little bit of glue on one bd. Coat the other🔨🔨
You can get a thick square washer that is designed to be used with Unistrut. You can buy them from the Unistrut dealer or any industrial electrical supply.
Hey Dale, here is the response about spring nuts that I wrote to others that suggested the same thing: The reason I did not use the spring nuts has to do with how those nuts interface with the Unistrut. There is a small lip on the inner channel of the unistrut that catches these nuts and all of the clamping pressure is applied to that narrow lip. In normal pluming and structural unistrut applications, the nut and lip are always pressing against something say, a pipe, a piece of structural steel, or another piece of unistrut. In this application, there is nothing backing up the nut and the tendency will be for the lip to bend outward away from the inner channel of the strut. I am using the full thickness of the unistrut to behave like clamping cauls, so the bolt and nut needs to press equally from the outside of the unistrut, using the rigidity of the strut as the caul action while the bolt provides the clamping action. With a spring nut in use, my belief is that only 1 side would provide the caul action and the nut side would just fail over time because of the pressure being applied to the inner retaining lip. I sure hope that book I just wrote gives you some insight to how I was thinking when I approached this project. I did consider using spring nuts at one time, but decided against it for the reasons stated above. Thanks for your input, guys!
Perpendicular threaded tightening bolts!!!!!!!!!
Nice solution and good engineering 2way or 90degree bolt is what comes to my mind I was happy you mentioned Not calling it the cross threaded bolt due to that was my first thought when you used the term as my father used to tell me when we worked on projects together don’t go and cross thread that bolt or as a a teenager I very often Tightened something untill I broke the bolt or stud Giving the old man hours of extra work fixing my screw up ! Typical rookie mistake and it pissed Pops off evertime as usually it was Something like a manifold bolt or ? That was a bear to get to and required work like pulling the entire engine from a car or truck Pissing off the old man wasn’t fun as a teenager but I guess it’s how I learned How not to do things
I like 2-way bolt or cross bolt
Great idea, I might try mounting the unistrut upside down with the nuts inside. That way, I would have a larger surface area on the wood panel and reduce denting. Also on the panel tightening bolt, I want to try putting a 10-32 bolt or threaded rod through a hole to use as a T handle. A couple of cap nuts would finish the handle. That way I don’t put too much pressure on the panel by using a drill or impact. Again, great idea!
Flange nuts w/o the serrations would very well. If U can't find them U can grind off the serrations. GOD'S BLESSINGS ✝️⚾🙃
Outstanding. I’m a woodworker, so I was thinking about using JB weld to fit the nuts and bolts. After all they are to just keep things in place.
I would totally build these if I knew how to weld! Great idea
It is a nice job and a great idea incorporating the cross-body bolt into the top/bottom struts.
I like the use of an impact or drill into the system, certainly makes it easier to clamp down and over.
You could use a piece of angle iron or flat bar as protection for the Cross-body bolt.
Clever design. I am going to try and make it with some kiln dried hickory stock (Holds threads decently well). Since I don't even have basic metal working tools.
do they make a two way bolt like you fabricated, and one with a pad on the end of the bolt? Just curious
Not that I know of. That is why I ended up making my own
The first morning I welded galvanized metal, I was sick to my stomach in no time. I was informed at lunch that drinking a glass of milk before welding galvanized will help coat my stomach and help keep me from getting sick. Worked like a charm. Used it for years since and when coupled with good ventilation and it has never failed me.
Great Idea I will be making a few of them 2,4,6,8ft ones form free c channel from work they are always getting rid of for table tops and doors
Use some flat aluminum or polish that unistrut, maybe or put a smooth pipe inside the strut to stop marring. What's everyone think about those? They do make a lot of configurations of unistrut or other competitors versions. Things like half or full slots even no slots, painted galv zinc coated. I'm not sure about no coating. Food for thought.
Nice concept.... seems to work good. If you get the dented wood and need to use that section... Just dab a finger in water and put on the dent, it will swell grain out and then when you sand, it will disappear.
Good idea, not sure about the impact wrench, it seems you lost a little bit the feeling screw tightening. also, the profile was bowing too, hence the marks.
Good idea and information. I will probably try epoxy to hold the parts you welded.
Great idea!
If you dent the wood...wet a paper towel and put a hot iron on it for a couple seconds. The wood will absorb the water and swell. It will take a major portion of the dent out.
Put something in the ends of the bolt threads to spread out the force a bit. Walk into the hardware aisle and I'm sure you find a dozen options
Excellent idea. I've 3 recommendations for improvements.
1. Deep well socket for your impact gun.
2. Turn the unistrut over to help avoid denting the wood.
3. For added strength, get the 1 1/2" deep unistrut.
You can get bolts, nuts and washers that will go inside the strut and make it quicker and more streamlined.
Great idea and execution.
Great suggestions. I think there are a lot of ways this can be tackled. I hope others try it out with their own improvements.
What if you bolt a pine strip to the inner surface of each clamp, (countersunk bolts of course)? That might help prevent the clamp from digging in.
Doug Sholly And the strip could be tapered down to the ends so that the pressure would be even across the width (notice the dents are on the outside edges, showing the caul pressure is not even across the width)
this just a thought. Can you flip the uni-strut upside down from the way you have it? That way the flat side would be against the wood. It may keep the edges from digging into the wood when you clamp it down. Like I said, just a thought. Great clamps!!!
I had considered it. It probably would work, but I'm not sure how well the nuts, bolts, and washers would seat or fit in the open side of the unistrut.
Nice DIY Clamps! These look like they will come in really good handy!