I need a cheap frame that I can fold up fast and transport easily.
Prototype design. will update with adjustments.
Built as a horizontal design. Would work as vertical once strap is tightened.
This one calibrated well at 15 feet by 8 feet. Might adjust to be taller and wider.
Less than 80 dollars in 2025 and took less than an hour to make.
Very dangerous for fingers near the hinges
Hinges could be damaged by abrupt movements of the boards.
very stable once the strap is tightened. It can be lifted and moved or tipped up by one person.
Materials
4 2x8 by 8 foot lumber
45 feet of ratcheting tie down strap (pieces tied together)
6 sturdy door hinges 3 inch tall
36 1 1/4 inch construction screws
4 large screw hooks
4x8 foot sheet of oriented strand board for waste or stage board
in 2025 all of this cost about 80 dollars
Tools
Screwdriver or drill for screws.
1 inch drill and bit.
1/4 in drill bit for screw hook holes
Adjustable Wrench is helpful for putting in the screw hooks.
Four 2x8 by 8 foot boards are attached like a book using the hinges.
a 1inch hole is drilled about 1.5 feet from the other end of each board
Screw hooks are put into the top edge of each board.
Strap is looped through the hole in each board
Boards are unfolded into an x
Strap is tightened.
X is leveled if ground is wobbly
4x8 board is put on top. Can be screwed down but does not need to be
Ready to go
Future fixes.
Chains might be more stable than tie down straps but straps are more available and cheaper.
Bolts with hook heads seemed clever for something that the anchors can go over but not fall off. Might be nice with a different fixture? Door hinges worked well but stronger hinges might be better.
If one used chains or metal cables I think it would be exact each time. With the straps one could tack them in place and it would be close. Right now I am just happy to get it working and will calibrate each time
If one used chains or metal cables I think it would be exact each time. With
the straps one could tack them in place and it would be close. Right now I am
just happy to get it working and will calibrate each time
metal cables have more stretch than you expect, so I would try chains
that would also allow you to have just a single cable strap
Updated with chain and eyebolts instead of hinges. Worked really well was very stable. Good Fitness. Very easy to assemble and disassemble and carry. Four separate beams and one chain and the wasteboard. Today it was roughly 2600mm by 4200mm, that could change depending on how you set it up.
Hinges were dangerous and tied it all together so that I had to carry all four beams at once. Replaced them with eyebolts
Rope stretches and I want to try to get it in a place where I would not have to recalibrate. Replaced it with chains
Cost is now in 2025 roughly 100 USD in hardware and chains Plus 40 for lumber and then whatever you are using for a waste board.
Seems strong enough to use in a vertical position will try it leaning against a wall later.
My parents came by and asked what it was…. .I was cheeky and said BDSM thing. With all of the calibration troubleshooting I was not lying. They are 80 but still laughed after an uncomfortable pause.
4 2x8 by 8’ lumber
8 5/16’’ by 4’’ eyebolts with about an inch eye.
16 Washers for eyebolts
8 5/16’’ nuts
4 1/4’’ 6’’ bolts to hold the chains
4 screw hooks or something for anchors
1 large bolt that fits inside the eyebolt eyes 6’’ long and nut
35 feet of chain I used 155lb load chain and turnbuckle Chain has to be large enough so that the 6” bolts can pass through the links.
1 turnbuckle
1 4x8’ osb sheathing for wasteboard. Could be cut in half
5/16 inch drill bit
1/4 in drill bit 6 inches of cutting distance long
1 in drill bit
1 1/4 in drill bit
Adjustable wrench
Wood rasp to flatten one side of drilled holes.
Hammer to encourage bolts
Carpenter’s square
Pencil
Measuring tape
Lots of long straight drilling sideways, a drill guide might help
The hardest part was lining up the eyebolts in each board so that each set of two (four inches apart) was stepped down by 1/4 inch from the set before so that they all would fit together stacked in the center. Picture below
It is important to go through BOTH links when anchoring the corners for accuracy. Later I marked the links that I used with marker so that I could find them again.
this is a great solution. I currently don’t plan on moving my machine anywhere other than in the workshop on the ground, where I already have anchor points.. But if I wanted a change, this is the way to go. Wood would probably be the cheapest, but I might slap my wallet and try it with extruded aluminum profiles. It’s easy to assemble, fold, the weight won’t be too much either, seeing as it’s made of 4 bars.. and maybe it will be a stiffer frame in terms of flexibility.
Looking back at it I wanted to clarify five design assumptions I made that may not be obvious.
Tall beams. I used 2x8 beams for stiffness in the z direction I based this on engineering standard practice for houses and decks about the same size as the frame. I did not calculate anything, just felt right. It worked well. Not sure what optimal would be.
Moving the chain down the beam towards the center. Putting the chain at the ends of the beams would maximize stiffness. I moved it down because I liked it aesthetically and to greatly reduce expensive chain and weight. Not sure where the optimal place would be. Felt like two feet canteliever at the ends would still be stiff enough.
Centering the chain holes internally on the beams. One could bolt the chains to the tops or bottoms of the beams for easier use and construction I felt that it would twist the frame and get in the way of the belts. Again partly aesthetic, I did not try the simpler design. It might work
Spacing the eyebolt pairs wide apart in the center. This is pretty important for the stiffness of the frame. In the z direction the frame is pretty thin. The stability in this direction is entirely dependent on how widely spaced the connections are between the beams. I am not entirely satisfied with eyebolts spaced 4.5 in apart. I considered one sided strap hinges with a removable pin but could not fit eight of them on a 2x8 and they were more expensive. They would fit on a 2x10. And would be easier to make. I would be interested in other designs for the center. It occurs to me that flat metal plates or bars might work really well and stack nicely.
Chain gauge and strength. You could probably go with a lot lighter chain saving weight and cost. I have no idea what would be optimal here. I chose these because the bolts I wanted to use fit through the links and because I wanted it to be strong on a human scale as I tossed the frame around. Chain was a LOT stiffer immediately than the ratchet straps. Tight ropes of any sort would work well, be cheap and accessible and light, but I think you would have to recalibrate on each set up. One can also count chain links to ensure rectangularity.
I really like the simplicity of this frame. What about staying with hinges, but instead use ones with removable pins for easier transport. Like a standard door hinge.
I really like the simplicity of this frame. What about staying with hinges,
but instead use ones with removable pins for easier transport. Like a
standard door hinge.
usually you have to drive the pin out of the hinge from the other side, with two
hinges above each other, it’s hard to get in between them to do that.
since it’s pre-tensioned, it may be that one hinge is stable enough,
experimenttion needed.
I think this idea has caught a few peoples imagination @wouldchuck
I have been pondering how to do a really big frame to test out a few things, and a few calculations make me think 3m (10ft) legs would give me the ability to do a ~4500*4000 (or ~4200 square, or similar) frame that gives nice clearance for full sheet cutting.
And I think similar to @Dano is thinking, a square/rectangle inner re-enforcement under the edges of the spoil board might solve a couple of issue at once, with chain / rope outer square close to the actual attachment points to give the full effect
(Might require trying belt extensions though, it’s on the limits of the belts)
I’m wondering if you could have some reference points. Here you would either measure between the reference points or use something like a string. The idea is that these would not be in tension at all and are only used to ensure that the dimensions are the same as when you did the calibration as @dlang indicated.
You need some way to check that the frame is as you last set it up.
In the same way, are you marking the chains where they interface with the wooden frame? I saw that you have a tensioner, which is a bit of a source of inconsistency. Perhaps you need something that applies enough tension so that you can link the end of the chain to the beginning and then release once the connection is made. (you always have to over-tension to make a connection under tension.
I hope that’s clear. It’s a bit hard to explain but really simple if you’re looking at it.
I think that marking the chains and then tightening the tensioner to a marked place should be pretty good but we will find out. Hopefully some time to try some cuts using the frame this week. I will also try setting it up and tearing it down a few times and compare calibrations.
Hi, I don’t know if you’re unnecessarily straying from the idea.
If it’s supposed to be a mobile frame that can be quickly folded and unfolded, then the process of finding the anchor points should be so fast and accurate that it should be done after each new frame assembly.
I don’t really believe that it will always be possible to fold it to 1mm. But if it is, it can’t have a big impact on the final cutting.
It depends on how accurate you are at 2m length. For me, 1mm is generally enough. I probably wouldn’t achieve that kind of accuracy by hand anyway, and Maslow helps me so much.
