The modular frames in this system are constructed using only one component, repeated and assembled in a variety of configurations attached using nuts, bolts, and washers. These frames assemble quickly, intuitively, and squarely in all dimensions and on uneven surfaces, under water, or in zero gravity. Frame members are easily manufactured from renewable and widely available raw materials such as trees, square steel, aluminum, and other metal tube, even bamboo and recycled thermoplastics. Aluminum frame members retain perfect interchangeability and reusability after years of intense sun exposure, submersion in water, etc. Wood frame members retain near-perfect interchangeability and reusability across lifetimes when stored in a home, or other controlled environment.
Most projects require a physical structure. Sizes, shapes, and configurations vary widely. Welding requires special skills and equipment. Aluminum extrusion, widely used, can be frustrating to insert nuts into channels in already assembled frames, and the infinite adjustability of the extruded channel requires measurement tools at assembly time and great care and attention to detail.
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Construct projects using a standardized space frame kit optimized for local production. Unlike Isaacs or Jergensen frames, Replimat uses only lengths that are multiples of 5 segments: 200 mm or approximately 7.5 inches. Frames of two, three, and four segment lengths are included to allow for the construction of additional joints and assemblies. <gallery> Perforatedtube.jpg| Flat pack frame.jpg| Delivery.jpg| Frame delivery.jpg| Flat pack frame2.jpg|Flat pack frame by Ian Willey </gallery>
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Replimat frames are constructed using standard lengths of material with a square profile or cross-section. Frame sections may be solid or hollow, constructed from a single piece, laminated, or joined. All Replimat frame sections share the same 40mm width. Frames of larger or smaller widths may be produced, and work with all of the construction techniques found here. Frames of evenly divisible widths interoperate.
Spaceframes constructed similarly are possible using other profiles. Hexagonal profile frame may be capable of building sections of Weaire–Phelan structures.
Holes are centered on each face of the frame and spaced regularly in a repeating pattern at a distance equal to the width of the frame. This geometrical arrangement allows the frame members to reliably produce rigid joints in three dimensions.
Frames of larger cross section require fewer holes than frames of smaller cross section that are the same length. And fewer saw cuts when working from lumber or sheets. Counterintuitively, thicker frame is sometimes faster or less expensive to produce than thinner frame. Thicker frame also creates stronger tri joints and requires fewer nuts and bolts to create frames of equivalent size and strength as compared to frame of reduced width. Thinner frame can allow accurate and reproducible model building before final assembly at larger scale. Thinner frame also allows for a finer resolution in the hole pattern, easing complex mounting problems.
Replimat uses frame lengths of 2, 3, 4, 5, 10, 15, 20, 25, and 30 holes per side. These lengths have been chosen to allow for the creation of all necessary joint configurations as well as to allow for lengths with a center hole and lengths which are evenly divisible by two. Reducing the set of lengths allows for improved reuse from project to project, easier identification in photographs and diagrams, and simpler production, handling, and shipping. Projects in this wiki make use of only these 9 lengths and rely on trusses, splicing frames, stacked washers, and adapter plates to reach arbitrary positions.
{| class=“wikitable”
! 8mm width !! 20mm width !! 25.4mm width !! 38.1mm width !! 40mm width !! 50mm width !! 60mm width
| 8mm | |||||||||||
| 16mm | |||||||||||
| 24mm | 25.4mm | ||||||||||
| 32mm | |||||||||||
| 40mm | 40mm | 40mm | |||||||||
| 48mm | 50.8mm | 50mm | |||||||||
| 56mm | |||||||||||
| 64mm | |||||||||||
| 72mm | |||||||||||
| 80mm | 80mm | 76.2mm | 76.2mm | 80mm | |||||||
| 88mm | |||||||||||
| 96mm | |||||||||||
| 104mm | 101.2mm | 100mm | |||||||||
| 112mm | 114.3 | ||||||||||
| 120mm | 120mm | 120mm | |||||||||
| 128mm | 126.6mm | ||||||||||
| 136mm | |||||||||||
| 144mm | |||||||||||
| 152mm | 152.4mm | 152mm | 150mm | ||||||||
| 160mm | 160mm | 160mm | |||||||||
| 168mm | |||||||||||
| 176mm | 177.4mm | ||||||||||
| 184mm | |||||||||||
| 192mm | 190.5 | ||||||||||
| 200mm | 200mm | 202.8mm | 200mm | 200mm | |||||||
| 208mm | |||||||||||
| 216mm | |||||||||||
| 224mm | 220mm | 228.6 | 228.6 | ||||||||
<gallery> Frame-2.png|2 hole frame - smallest frame useful for making tri joints Frame-3.png|3 hole frame - often useful to create spurs, mount points, and clevis fasteners, smallest of the frames with center holes Frame-4.png|4 hole frame - sometimes required for linkages and structural elements Frame-5.png|5 hole frame - count by fives which have center holes and can accommodate two tri joints each Frame-10.png|10 hole frame - “a ten” Frame-15.png|15 hole frame - this size works great for larger pivoting mechanisms thanks to it's center hole Frame-20.png|20 hole frame - desk or counter top height Frame-25.png|25 hole frame - the largest of the frames with center holes Frame-30.png|30 hole frame - makes great shelves </gallery>
In the imperial version, popular hole sizes are 21/64 inch and popular bolt sizes are 5/16 inch. For the metric frames, we can use a 6 mm bolt and 7-8 mm holes for the 25 mm frame; a 12 mm bolt and holes for the 40 mm frame and 13-14 mm holes for the 50 mm frame.
Wikibooks: robot building materials implies that cardboard (!) is best for quick prototypes; for functional robots, “wood is probably the best material to start with.”; where wood isn't quite durable enough, aluminum is the best metal – better than steel for most robots.
<sbailard_> VikOlliver, steel and aluminum box section down in NZ, is it metric, or '25.4 mm'? <VikOlliver> Strangley it's in approx 25mm increments... * sbailard_ is beside himself in surprise. <VikOlliver> It's sold as 25x50mm box section but you know what they mean...
In North America, wood which is called '1×1' or '2×2' is actually smaller than 1 inch or 2 inches in cross section. This is unfortunate but legal. Speak to a lumber yard or other supplier about getting 'wood which is actually sized 1 inch by 1 inch or 2 inches by 2 inches'. They will be able to help you, possibly by setting up a small order correctly sized material with a local mill, which may be a quick job. (If you are a woodworker, this paragraph is obvious, and we apologize. And you have a table saw.)
A common so-called “two-by-four” (38 mm x 89 mm, 1.5 inch x 3.5 inch) can be ripped and planed into two separate grid beams (each 38 mm square). Does it make any sense to do slightly less work, converting that so-called “2×4 board” into one beam that acts like those 2 grid beams permanently attached to each other, 38 mm x 76 (1.5“ x 3.0”) with a double row of holes on the 3.0“ wide side?
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