WO2021154202A1

WO2021154202A1 - Spreader supports comprising elevated wings

Info

Publication number: WO2021154202A1
Application number: PCT/US2020/015177
Authority: WO
Inventors: Daniel MOSHER; Kevin Bruce HULICK; Michael G. Monroe
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-01-27
Filing date: 2020-01-27
Publication date: 2021-08-05

Abstract

In some examples, an apparatus includes a spreader, and a support to which the spreader is mounted. The support carries the spreader that is moveable along a first direction to spread a powdered build material over a build bed. The support includes a base to contain the powdered build material within a boundary of the build bed, and a wing attached to the base, where a bottom surface of the wing is elevated by a distance from a bottom surface of the base, and the wing is to maintain a height of a portion of the powdered build material outside the boundary below a specified height.

Description

SPREADER SUPPORTS COMPRISING ELEVATED WINGS

Background

[0001] Additive manufacturing machines produce three-dimensional (3D) objects by building up layers of build material, including a layer-by-layer accumulation and solidification of the build material patterned from computer aided design (CAD) models or other digital representations of physical 3D objects to be formed. A type of an additive manufacturing machine is referred to as a 3D printing system. Each layer of the build material is patterned into a corresponding part (or parts) of the 3D object.

Brief Description of the Drawings

[0002] Some implementations of the present disclosure are described with respect to the following figures.

[0001] Fig. 1 is a schematic diagram of an additive manufacturing machine according to some examples.

[0002] Figs. 2A-2C are different views of a spreader assembly according to some examples.

[0003] Fig. 3 is a bottom perspective view of a support according to some examples.

[0004] Fig. 4 is a perspective view of a spreader assembly according to further examples.

[0005] Fig. 5 is a schematic diagram of an apparatus for an additive manufacturing machine, according to some examples.

[0006] Fig. 6 is a flow diagram of a process according to some examples.

[0007] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

Detailed Description

[0008] In the present disclosure, use of the term “a,” “an”, or “the” is intended to include the plural forms as well, unless the context clearly indicates otherwise. Also, the term “includes,” “including,” “comprises,” “comprising,” “have,” or “having” when used in this disclosure specifies the presence of the stated elements, but do not preclude the presence or addition of other elements.

[0009] In some examples, a build material used by an additive manufacturing machine such as a 3D printing system can include a powdered build material that is composed of particles in the form of fine powder or granules. The powdered build material can include metal particles, plastic particles, polymer particles, ceramic particles, or particles of other powder-like materials. In some examples, a build material powder may be formed from, or may include, short fibers that may, for example, have been cut into short lengths from long strands or threads of material.

[0010] In some examples of additive manufacturing machines, as part of the processing of each layer of build material, liquid agents can be dispensed by liquid agent dispensers (such as through a printhead or another fluid dispensing device) to a layer of build material. Examples of liquid agents include a fusing agent (which is a form of an energy absorbing agent) that absorbs heat energy emitted from an energy source used in the additive manufacturing process. For example, after a layer of build material is deposited onto a build platform (or onto a previously formed layer of build material) in the additive manufacturing machine, a fusing agent with a target pattern can be deposited on the layer of build material. The target pattern can be based on an object model (or more generally, a digital representation) of the physical 3D object that is to be built by the additive manufacturing machine.

[0011] According to an example, a fusing agent may include an ink-type formulation, such as, for example, the fusing agent formulation commercially referred to as the V1 Q60A “HP fusing agent” available from HP Inc. In further examples, a fusing agent may alternatively or additionally include an infrared light absorber, a near infrared light absorber, a visible light absorber, or an ultraviolet (UV) light absorber. Fusing agents can also refer to a chemical binding agent, such as used in a 3D printing system that forms objects using a metal or other type of build material.

[0012] Following the application of the fusing or binding agent, an energy source (e.g., including a heating lamp or multiple heating lamps that emit(s) energy) is activated to sinter, melt, fuse, bind, or otherwise coalesce the powder of the layer of build material underneath the fusing or binding agent. The patterned build material layer (i.e. , portions of the layer on which the fusing or binding agent was deposited) can solidify, for example after cooling, and form a part, or a cross-section, of the physical 3D object.

[0013] Next, a new layer of powder is deposited on top of the previously formed layer, and the process is re-iterated in the next additive manufacturing cycle to form 3D parts in the successive layers of build material. The 3D parts collectively form a 3D object (or multiple 3D objects) that is the target of the build operation.

[0014] In other examples, an additive manufacturing machine can be used as part of a sintering process. In the sintering process, as each layer of build material is deposited, and a binder (which is another type of liquid agent) is applied by a printhead or other fluid dispensing device to the layer of build material. Portions of the build material where the binder is applied are bound together by the binder. The binder can include an ultraviolet-curable binder, heat-curable binder, and so forth. After the layers of build material have been deposited and the binder applied to locations of each layer of build material, curing (based on heating) of the binder produces a so-called “green part.” The green part is de-powdered to remove any unbound build material powder. Afterwards, the green part can be transferred from the additive manufacturing machine to an oven, where the bound build material powder (e.g., metal particles, etc.) are sintered together to form a highly dense 3D object. [0015] Fig. 1 is a perspective view of a portion of an additive manufacturing machine 100, according to some examples. The additive manufacturing machine 100 includes a fluid dispensing device 102 (e.g., a printhead), that is able to dispense a liquid agent.

[0016] The fluid dispensing device 102 includes nozzles (not shown) to dispense the liquid agent generally in a downwardly direction (in the view shown in Fig. 1) to a layer of build material that is part of a build bed 104. Initially, before a 3D build operation has started, the build bed 104 includes the upper surface of a build platform 106. After build material layers have been spread over the build platform 106 and processed on a layer-by-layer basis, then the build bed 104 would include any previously formed part(s) of the 3D object based on the previously processed build material layer(s). More generally, a “build bed” refers to a structure onto which a build material layer can be spread for processing, where the structure can include just the upper surface of the build platform 106, or alternatively, can further include any previously formed part(s) of a 3D object.

[0017] In some examples, the fluid dispensing device 102 can be mounted to a moveable carriage (not shown) in the additive manufacturing machine 100. During a build process, the carriage can move back and forth to move the fluid dispensing device 102 along a scan axis 108, to dispense liquid agents to a layer of build material during a build operation. The fluid dispensing device 102 can move in each of the two opposite directions of the scan axis 108 when dispensing a liquid agent.

[0018] In other examples, the fluid dispensing device 102 can be moved along multiple different axes.

[0019] The additive manufacturing machine 100 also includes a spreader assembly 110 that is used to spread powdered build material across the build bed 104. The spreader assembly 110 is moveable in a spread direction (along a spread axis 112) to spread the powdered build material from a source pile of the powdered build material across the build bed 104. Note that the spreader assembly 110 can move in each of the two opposite directions along the spread axis 112 when spreading the powdered build material.

[0020] As shown in Fig. 1 , the direction of movement of the spreader assembly 110 (along the spread axis 112) is different from (or alternatively, the same as) the direction of movement of the fluid dispensing device 102 (along the scan axis 108). For example, the direction of movement of the fluid dispensing device 102 may be generally perpendicular to the direction of movement of the spreader assembly 110. The direction of movement of the fluid dispensing device 102 may be considered “generally perpendicular” to the direction of movement of the spreader assembly 110 if the direction of movement of the fluid dispensing device 102 has an angle with respect to the direction of movement of the spreader assembly 110 within a specified range, such as 85° to 95°, or 80° to 110°, or 265° to 275°, or 260° to 280°, or some other example range.

[0021] During a build process, it may be desirable to maintain a relatively small vertical spacing between the dispensing surface 103 of the fluid dispensing device 102 (the dispensing surface 103 can include the nozzles from which a liquid agent is dispensed) and the top surface of the layer of powdered build material spread across the build bed 104. For example, the spacing between the dispensing surface 103 of the fluid dispensing device 102 and the top surface of the powdered build material can be about 2 millimeters (mm) or some other relatively small spacing.

[0022] The spreader assembly 110 includes a spreader 114, which can be formed of a metal or another rigid material. In examples according to Fig. 1 , the spreader 114 is in the form of a blade. In other examples, the spreader 114 can be in the form of a roller. In further examples, the spreader 114 can have a different shape.

[0023] When the spreader assembly 110 spreads powdered build material as the spreader assembly 110 moves along a spread direction (along the spread axis 112), portions of the powdered build material at the end portions of a spreader 114 of the spreader assembly 110 may be pushed to the two opposite end edges 116-1 and 116-2 of the spreader 114.

[0024] Without elevated wings (discussed further below) of the spreader assembly 110 according to some implementations of the present disclosure, the portions of the powdered build material that are pushed to the two end edges 116-1 and 116-2 of the spreader 114 may build up in height as the spreader assembly 110 moves along the spread direction. As a result, the spread operation of the spreader assembly 110 can cause two general lines of powdered build material (that extend along respective boundary edges 118-1 and 118-2 of a boundary of the build bed 104) with elevated heights. In the ensuing discussion, these two general lines of powdered build material with elevated heights are referred to “elevated height powdered build material lines.”

[0025] The “boundary” of the build bed 104 refers to the outermost boundary of the build bed 104 onto which a layer of a powdered build material can be spread by the spreader assembly 110. The boundary defines the largest area of the build bed 104 onto which the fluid dispensing device 102 is able to dispense a liquid agent.

[0026] In some cases, the two elevated height powdered build material lines extending along the respective boundary edges 118-1 and 118-2 of the build bed boundary can rise in height to or above the height of the dispensing surface 103 of the fluid dispensing device 102. In an example where the target spacing between the dispensing surface 103 of the fluid dispensing device 102 and the top surface of the layer of build material is 2 mm, the two elevated height powdered build material lines can rise over the 2-mm gap between the dispensing surface 103 of the fluid dispensing device 102 and the top surface of the layer of build material.

[0027] As a result, when the fluid dispensing device 102 scans across the build bed 104 (along the scan axis 108) during a build operation, the dispensing surface of the fluid dispensing device 102 can collide with the elevated height powdered build material lines. Such collisions can cause powder of the build material to enter the nozzles of the fluid dispensing device 102, which can cause the nozzles to become plugged. Fluid agents cannot be effectively dispensed from the plugged nozzles, which can cause formation of sub-optimal 3D parts by the additive manufacturing machine 100.

[0028] In accordance with some implementations of the present disclosure, techniques or mechanisms are provided to reduce pile ups of portions of a powdered build material at the boundary edges 118-1 and 118-2 of the build bed boundary resulting from the spreading action of a spreader assembly 110.

[0029] As shown in Fig. 1 , the spreader assembly 110 according to some implementations of the present disclosure includes the spreader 114 and supports 122-1 and 122-2 to which the end edges 116-1 and 116-2, respectively, of the spreader 114 are mounted. The supports 122-1 and 122-2 carry the spreader 114 that is moveable along the spread axis 112 to spread a powdered build material over the build bed 104. In some examples, the supports 122-1 and 122-2 can be formed of a metal or other rigid material.

[0030] The support 122-1 includes a base 124-1 that is elongated along the spread axis 112. The support 122-2 similarly includes a base 124-2. The bases 124-1 and 124-2 act to contain the powdered build material within the boundary of the build bed 104.

[0031 ] During spreading due to movement of the spreader 114 in a spread direction, some portion of the powdered build material is pushed to the boundary edge 118-1 (and another portion of the powdered build material is pushed to the other boundary edge 118-1 ). To prevent the portion of the powdered build material at the boundary edge 118-1 from rising too high, the support 122-1 further includes an elevated wing 126-1 that is attached to the base 124-1.

[0032] The elevated wing 126-1 includes two winglets 126-11 and 126-12. The elevated wing 126-1 and the base 124-1 can be integrally connected to one another (i.e. , they can be part of an integral piece). Alternatively, the elevated wing 126-1 and the base 124-1 can be separate pieces that are attached to one another. [0033] The winglet 126-11 extends outwardly to be outside of the build bed boundary edge 118-1 (i.e. , the winglet 126-11 extends away from the build bed 104 past the boundary edge 118-1. The winglet 126-12 extends inwardly into the build bed boundary (i.e., the winglet 126-12 extends inwardly to be inside the build bed boundary edge 118-1).

[0034] A bottom surface 128-1 of the wing 126-1 is elevated by a distance D1 from the top surface of a layer of powdered build material spread by the spreader 114. For example, the distance D1 can be less than 2 mm in examples where the target spacing between the dispensing surface 103 of the fluid dispensing device 102 and the top surface of the layer of powdered build material is 2 mm. Similarly, a bottom surface 128-2 of the wing 126-2 is elevated by the distance D1 from the op surface of a layer of powdered build material spread by the spreader 114.

[0035] During spreading movement of the spreader assembly 110 along a direction 113 of the spread axis 112, the winglet 126-11 (and in particular the bottom surface 128-1 of the winglet 126-11 ) maintains a height of a portion of the powdered build material along and outside the boundary edge 118-1 below a specified height (i.e., a height that is lower than the height of the dispensing surface 103 of the fluid dispensing device 102 when crossing over the boundary edge 118-1.

[0036] The support 122-2 at the other end edge 116-2 of the spreader 114 similarly has an elevated wing 126-2 that includes winglets 126-21 and 126-22 (which are arranged similarly to the winglets 126-11 and 126-12 of the elevated wing 126-1).

[0037] During spreading movement of the spreader assembly 110 along a direction 113, the bases 124-1 and 124-2 and the inwardly extending winglets 126- 12 and 126-22 cooperate to keep the powdered build material confined as much as possible within the build bed boundary. [0038] Although not shown in Fig. 1 , each support 122-1 or 122-2 can further include another base and a connected elevated wing on the side of the support 122-1 or 122-2 opposite of the side with the base 124-1 or 124-2.

[0039] Fig. 2A shows a front elevational view of a spread assembly 200 according to further examples. The spreader assembly 200 includes a spreader 201 in the form of a blade.

[0040] Fig. 2B shows a top view of the spreader assembly 200, along 2B-2B shown in Fig. 2A. Fig. 2C is a sectional view of the spreader assembly 200, along 2C-2C shown in Fig. 2A. The following discussion refers to Figs. 2A-2C.

[0041] In the view of Fig. 2A, the left end edge 202-1 of the spreader 201 is mounted to a support 204-1 , which includes a base 206-1 and an elevated wing 208- 1 that is connected to the base 206-1. The elevated wing 208-1 includes an outwardly extending winglet 208-11 (that extends away from a build bed) and an inwardly extending winglet 208-12 (that extends into the build bed).

[0042] In the view of Fig. 2A, the right end edge 202-2 of the spreader 201 is mounted to a support 204-2, which has a similar arrangement as the support 204-1. The support 204-2 includes a base 206-2 and an elevated wing 208-1 , which are similar to the base 206-1 and the elevated wing 208-2, respectively. The elevated wing 208-2 includes an outwardly extending winglet 208-21 and an inwardly extending winglet 208-22.

[0043] In the view of Fig. 2B, the base 206-1 and the attached elevated wing 208-1 are on a first side 201-1 of the spreader 201. The support 204-1 further includes a base 206-3 and an attached elevated wing 208-3 on a second, opposite side 201 -2 of the spreader 201. The elevated wing 208-3 includes an outwardly extending winglet 208-31 and an inwardly extending winglet 208-32.

[0044] Similarly, in the support 204-2, the base 206-2 and the attached elevated wing 208-2 are on the first side 201 -1 of the spreader 201. The support 204-2 further includes a base 206-4 and an attached elevated wing 208-4 on the second, opposite side 201 -2 of the spreader 201. The elevated wing 208-4 includes an outwardly extending winglet 208-41 and an inwardly extending winglet 208-42.

[0045] As shown in Fig. 2C, a bottom surface of the winglet 208-11 or 208-31 is elevated by the distance D1 above a bottom surface of the base 206-1 or 206-3, respectively. This distance D1 allows the winglet 208-11 or 208-31 to rise above a target top surface of a layer of powdered build material by the distance D1. The bottom surface of the winglet 208-11 or 208-31 is generally parallel to the bottom surface of the base 206-1 or 206-3. One surface is “generally” parallel to another surface if the surfaces are parallel to one another to within manufacturing or assembly tolerances.

[0046] In operation, when the spreader assembly 200 is being moved in a spread direction 220 (Fig. 2B), the elevated wings 208-1 and 208-2 are behind the spreader 201 along the spread direction 220. As the spreader assembly 200 moves along the spread direction 220, the outwardly extending winglets 208-11 and 208-21 contact respective lines of the powdered build material along respective boundary edges (e.g., 118-1 and 118-2 in Fig. 1), to keep the height of the respective lines of the powdered build material below the height of the bottom surfaces of the winglets 208- 11 and 208-21.

[0047] In a different example, when the spreader assembly 200 is being moved in the opposite spread direction 222 (Fig. 2B), the elevated wings 208-3 and 208-4 are behind the spreader 201 along the spread direction 222. As the spreader assembly 200 moves along the spread direction 222, the outwardly extending winglets 208-31 and 208-41 contact respective lines of the powdered build material along respective boundary edges (e.g., 118-1 and 118-2 in Fig. 1), to keep the height of the respective lines of the powdered build material below the height of the bottom surfaces of the winglets 208-31 and 208-41.

[0048] Depending on the spread direction, the outwardly extending winglets 208- 11 and 208-21 or the outwardly extending winglets 208-31 and 208-41 are used to reduce the heights of respective lines of the powdered build material along respective boundary edges, for preventing collision between a fluid dispensing device (e.g., 102 in Fig. 1) with such lines of the powdered build material along respective boundary edges.

[0049] Fig. 3 is a bottom perspective view of another example support 300, which is similar to the support 122-1 or 122-2 of Fig. 1, or the support 204-1 , 204-2, 204-3, or 204-4 of Figs. 2A-2C). The support 300 includes a spreader retainer 302 attached above bases 304-1 and 304-2 of the support 300. The spreader retainer 302 includes a retainer slot 303 to receive an end edge portion of a spreader (e.g., 114 in Fig. 1 or 201 in Figs. 2A-2C). Once the end edge portion of the spreader is inserted into the retainer slot 303, attachment members (e.g., screws, bolts, etc.) can be inserted through retainer openings (310 shown in the view of Fig. 3) to secure the spreader against the spreader retainer 302.

[0050] The base 304-1 is attached to an elevated wing 306-1 , which has an outwardly extending winglet 306-11 and an inwardly extending winglet 306-12. The base 304-2 is attached to an elevated wing 306-2, which has an outwardly extending winglet 306-21 and an inwardly extending winglet 306-22.

[0051] The spreader retainer 302, the bases 304-1 and 304-2, and the elevated wings 306-1 and 306-2 can be integrally formed, or can be separate pieces attached to one another.

[0052] Fig. 4 is a perspective view of an alternative support 402 to support a different type of spreader 408. The spreader 408 is in the form of a roller that rolls when spreading a layer of powdered build material on a build bed. In the example of Fig. 4, the support 402 includes a spreader retainer 404 that has a generally circular receptacle 406 to receive the spreader 408.

[0053] The spreader retainer 404 is attached above a bases 408-1 and 408-2 of the support 402. The base 408-1 is attached to an elevated wing 410-1 , which has an outwardly extending winglet 410-11 and an inwardly extending winglet 410-12. [0054] The base 408-2 is attached to an elevated wing 410-2, which has an outwardly extending winglet 410-21 and an inwardly extending winglet (not visible in the view of Fig. 4).

[0055] The elevated wings 410-1 and 410-2 are arranged with respect to the respective bases 408-1 and 408-2 in similar fashion as discussed in connection with Figs. 1 , 2A-2C, and 3.

[0056] Fig. 5 is a schematic diagram of an apparatus 500 for an additive manufacturing machine, according to some implementations. The apparatus 500 includes a spreader 502. The apparatus 500 further includes a support 504 to which the spreader 502 is mounted. The support 504 carries the spreader 502 that is moveable along a first direction to spread a powdered build material over a build bed. The support 504 includes a base 506 to contain the powdered build material within a boundary of the build bed. The support 504 further includes a wing 508 attached to the base 506. A bottom surface 510 of the wing 508 is elevated by a distance D1 from a bottom surface 512 of the base 506. The wing 508 maintains a height of a portion of the powdered build material outside the boundary of the build bed below a specified height.

[0057] Fig. 6 is a flow diagram of a process forming a spreader assembly for an additive manufacturing machine. The process includes arranging (at 602) a first base in a first support, and a second base in a second support.

[0058] The process includes mounting (at 604) a first end portion of a spreader to the first support, and mounting a second end portion of the spreader to the second support, the first and second supports carrying the spreader that is moveable along a first direction to spread a powdered build material over a build bed, and where the first and second bases are to contain the powdered build material within a boundary of the build bed.

[0059] The process includes attaching (at 606) a first wing to the first base, and attaching a second wing to the second base, where a bottom surface of the first wing is elevated by a distance from a bottom surface of the first base, and a bottom surface of the second wing is elevated by a distance from a bottom surface of the second base, and where the first wing and the second wing are to maintain a height of portions of the powdered build material outside the boundary below a specified height.

[0060] In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.

Claims

What is claimed is:

1. An apparatus for an additive manufacturing machine, comprising: a spreader; and a support to which the spreader is mounted, the support carrying the spreader that is moveable along a first direction to spread a powdered build material over a build bed, the support comprising: a base to contain the powdered build material within a boundary of the build bed, and a wing attached to the base, a bottom surface of the wing being elevated by a distance from a bottom surface of the base, and the wing to maintain a height of a portion of the powdered build material outside the boundary below a specified height.

2. The apparatus of claim 1 , wherein an end portion of the spreader is mounted to the support.

3. The apparatus of claim 2, wherein a winglet of the wing is to extend outwardly from the boundary of the build bed, wherein a bottom surface of the winglet is elevated by the distance from the bottom surface of the base.

4. The apparatus of claim 3, wherein the support is a first support, the base is a first base, and the wing is a first wing, the apparatus further comprising: a second support, wherein a first end portion of the spreader is mounted to the first support, and a second end portion of the spreader is mounted to the second support, the second support further comprising: a second base, and a second wing attached to the second base, wherein a bottom surface of the second wing is elevated by the distance from the bottom surface of the second base, and wherein the first wing and the second wing are to maintain heights of respective portions of the powdered build material outside the boundary below the specified height.

5. The apparatus of claim 4, wherein the first wing and the second wing are behind the spreader along the first direction.

6. The apparatus of claim 5, wherein the first support further comprises a third base and a third wing attached to the third base, wherein a bottom surface of the third wing is elevated by the distance from a bottom surface of the third base, wherein the second support further comprises a fourth base and a fourth wing attached to the fourth base, wherein a bottom surface of the fourth wing is elevated by the distance from a bottom surface of the fourth base, wherein the third wing and the fourth wing are in front of the spreader along the first direction.

7. The apparatus of claim 6, wherein the spreader is further moveable along a second direction opposite the first direction, and wherein the third wing and the fourth wing are behind the spreader along the second direction.

8. The apparatus of claim 3, wherein a further winglet of the wing is to extend inwardly from the boundary toward the build bed, wherein a bottom surface of the further winglet is elevated by the distance from the bottom surface of the base.

9. The apparatus of claim 1 , wherein the spreader comprises a blade or a roller.

10. The apparatus of claim 1 , wherein the bottom surface of the wing is generally parallel to the bottom surface of the base.

11. An additive manufacturing machine comprising: a fluid dispensing device moveable along a first direction to dispense a fluid during a build operation; and a spreader assembly comprising: a spreader; and a support to which the spreader is mounted, the support carrying the spreader that is moveable along a second direction to spread a powdered build material over a build bed, wherein the second direction is different from the first direction, and wherein the support comprises: a base to contain the powdered build material within a boundary of the build bed, and a wing attached to the base, a bottom surface of the wing being elevated by a distance from a bottom surface of the base, and the wing to maintain a height of a portion of the powdered build material outside the boundary below a specified height.

12. The additive manufacturing machine of claim 11 , wherein the bottom surface of the wing is generally parallel to the bottom surface of the base.

13. The additive manufacturing machine of claim 11 , wherein a winglet of the wing is to extend outwardly from the boundary of the build bed, wherein a bottom surface of the winglet is elevated by the distance from the bottom surface of the base.

14. A method of forming a spreader assembly for an additive manufacturing machine, comprising: arranging a first base in a first support, and a second base in a second support; mounting a first end portion of a spreader to the first support, and mounting a second end portion of the spreader to the second support, the first and second supports carrying the spreader that is moveable along a first direction to spread a powdered build material over a build bed, and wherein the first and second bases are to contain the powdered build material within a boundary of the build bed; and attaching a first wing to the first base, and attaching a second wing to the second base, wherein a bottom surface of the first wing is elevated by a distance from a bottom surface of the first base, and a bottom surface of the second wing is elevated by a distance from a bottom surface of the second base, and wherein the first wing and the second wing are to maintain a height of portions of the powdered build material outside the boundary below a specified height.

15. The method of claim 14, wherein each of the first wing and the second wing includes a winglet that extends outwardly from the boundary away from the build bed, and a winglet that extends inwardly from the boundary toward the build bed.