I had this idea about making a homemade bar clamp for a long time, the idea involved from making a homemade C clamp intro a homemade bar clamp from rebar, as i didn’t know if it would work i took it as an art project, if it works that’s great if it didn’t, i will hang it in in my workshop.
I have a lot of rusted rebar that i want to get rid of, i’m not going to throw it away but i will make more project with it.
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Ø10 Rebar, I used rusted one
M10 threaded rod, you can use a 140mm bolt
M10 coupling nut, i only used the halfe of it so tow normal nut would work fine
Ø30 washer, 2 of them with 7mm interior diameter
20mm angle iron, only 30mm is needed
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M6 bolt, And its screw
Cone nut, I took it from a bicycle axle set (a bushing would also work)
Spacer, I took it from an old HHD
Making of the homemade bar clamp:
I started with cutting the rebar intro pieces: 60cm ; 54cm ; 37cm ; 21cm ; 2.5cm then i cleaned them with cup brush in drill press.
I measured and marked 14cm on the 60cm piece and 12cm on the 54cm piece then i clamped the 60cm piece in the vise and i bent it to 90° and the 54cm piece past 90°.
I adjusted the angle of the 60cm so its ends meet the ends of the 54cm piece.
I put the two pieces on my welding table then i welded their ends.
Now we have what we will call the fixed jaw, so i clamped it in the vise to close the gapes then i welded it.
After that i grand off the sticking welds.
To make the sliding arm i marked the center of the 37cm piece and i aligned it with the M10 bolt i clamped in the vise, i heated it with the arc welder until it got red hot then i bent it.
I slid in the sliding arm i just bent in the fixed jaw, then i placed the 2.5cm piece (the clutch) next to it, and i held it with weight until i welded it in place.
I marked the center of the M10 coupling nut then i cut it with the hacksaw and removed the burr with a file.
I marked where it should be welded in the sliding arm, then i insert it in the sliding arm with a hammer and welded it in place (i screwed in the M10 bolt to prevent any threads deformation), i also trimmed the excess pieces.
I measured and marked 14cm on the M10 threaded rod, i held it in the vise between to pieces of wood and i cut it with the hacksaw.
I measured and marked 5mm from one end of the screw i just cut, then i made a shoulder with angle grinder i clamped in the vise.
The most thing i liked on this homemade bar clamp is how the swivel came out.
To make it, i first made the cone washer, so basically what i did is deform a washer with the help of the M6 bolt, spacer and a cone-nut to become a cone washer .
I screwed the screw in the sliding arm and i clamp it in the vise, then i put the cone washer and i welded on the shoulder to prevent the cone-washer from coming out.
I closed the hole of the second washer with welds (Tip: lower the amperage) then flatten it with the angle grinder.
I clamped the cone-washer with the second washer in the vise and i tack weld them, then i grand off the sticking welds.
To complete the movable jaw the handle must be made, so i did the same as for the sliding arm, i marked its center then heated it with the arc welder and bent it.
I screwed in the crew in the sliding arm and i inserted it in the handle with the vise, then i welded in place.
Now the movable jaw i done, i can make the pad for the fixed jaw, so i measured and marked 30mm on the 20mm angle iron and i cut it and chamfer it with the angle grinder.
I clamp it in it’s place then i welded it.
Now the homemade bar clamp is done!
I noticed that the sliding arm flex a little bit, a brace between the nut and the top of the clutch help a lot.
This Post Has 3 Comments
Very nice concept. I especially appreciate the beneficial use of salvage materials to create a useful tool. However, I do have a few comments on how to enhance the design with negligible outlay for additional materials and minor additional labor.
The stiffness of the fixed end of the clamp comprised of two bent bars could be enhanced by providing either a strut of rebar or, even better, a filler plate of 14 or 16 ga. sheet steel between the two bent rebars. In the present design the stiffness of the fixed end relies on a combination of the compressive stiffness and the bending stiffness of the two pieces of rebar. The bending stiffness is by far the weaker component.
As clamping force is applied to the anvil at the tip of the end member the upper bar in the curved section will tend to lift up and the lower bar will tend to pull down and straighten out. These two effects are restrained by the combined bending stiffness of the upper and lower bars and their tensile and compressive stiffnesses. In the absence of detailed calculations (which I do not propose to undertake), I cannot assess the relative importance of these two factors but intuition tells me that the bending stiffness is the weaker restraint on the flex of the anvil.
By filling the gap between the two sections of rebar with a relatively thin steel plate welded inside the curve, the reliance on the bending stiffness of the two sections of rebar is substantially eliminated because the two sections can no longer move apart, even microscopically. Technically speaking, you will have transformed the two independent sections of rebar into a beam having a high moment of inertia instead of two pieces of rebar acting somewhat independently. A short strut of rebar across the arc might accomplish the same thing.
Similarly, the strut extending down to the clamping screw is comprised of two pieces of rebar side-by-side. This configuration simply doubles the stiffness of the strut relative to a single piece of rebar. Relocating the second piece of rebar in that strut to be in line with the first piece (in the plane of the clamp body) would increase the stiffness of the clamp by increasing the moment of inertia of the strut. Since the moment of inertia of a beam is proportional to the square of the distance of the tensile and compressive elements from the neutral axis (in this case, the weld line), the effective stiffness of the strut is four times that of a single rebar, while the stiffness of two side-by side pieces is only two times that of a single bar. Note that, except for the slight added complexity of the attachments at the nut and the backbone, this enhanced rigidity of the clamp does not come at the expense of much additional material.
The effective stiffness of this strut could be increased even further by spacing the top ends of the two sections of rebar apart by, say, one bar diameter, creating a triangle. A triangle is a very strong structural element. because it does not rely on bending stiffness at all for its strength. In this location, addition of a filler plate between the two sections of rebar would have no particular benefit.
An additional benefit of the suggested revised placement of the second piece of rebar on the screw strut is that the increased distance between the point of application of the upward and downward forces on the clamp backbone substantially reduces the magnitude of those forces, possibly reducing the distortion of the relatively soft rebar and reducing indentation and wear.
I hope these comments do not come across as criticism of your basic concept, but rather as contributions to your design.
Thank you very much for your awesome comment and i really appreciate you took time to explain the improvements in details, and you are very right about them!
The two weak points of the design are in the sliding arm, it flex and it doesn’t align with the fixed jaw (it tends to drift from alignment as i tighten it up), it could be fixed by adding a second arm between the nut and the clutch to form a triangle.
As for the fixed jaw, it is stiff but the additional brace will make it very stiff.
Very innovative, I like the way you think.