dcf.cymru stimulus sheet · Design and Technology · Year 10

The desk tidy batch: CAM job folder dossier

The school, the pupils, the technician and every file on this sheet are invented. The file problems are real ones: every one of them happens in real school workshops and real factories.

1. The job

The team: Owen, Megan and Cai, three Year 10 Product Design pupils at Ysgol Cwm Glas, a fictional school in Rhondda Cynon Taf.
The product: a flat-pack desk tidy for the school’s charity sale. Batch production of 20.
The parts of one desk tidy:
- Body: a base and 4 side panels in 3 mm birch plywood, laser cut, joined with finger joints.
- Logo: the words “Ysgol Cwm Glas” laser engraved on the front panel.
- Pen clip: a small clip, 3D printed in PLA, that clips onto the side panel.
The machines: one laser cutter (bed 600 × 400 mm) and one 3D printer, both run by the technician, Mr Howells.

2. Mr Howells’s rules for CAM jobs

1	I only cut or print files that are in the Ready to cut folder. I do not go looking in other folders.
2	Laser cutter: DXF or SVG files only. Units must be millimetres. Cut lines are red hairlines. Engraving is black fill. All text must be converted to outlines (paths): my laser computer does not have your fonts, so live text comes out in a different font or not at all.
3	3D printer: STL files only, in millimetres. The printer software cannot open a CAD program’s own project file.
4	One file per part. The name must tell me which part, which version, and that it has been checked.
5	Share files with me from the shared D&T drive, with at least “Can view” permission. I cannot open files kept in your own personal storage.

3. The team’s folder: Desk Tidy Batch

This is what Mr Howells sees today. Dates are day/month. There is no Ready to cut folder yet.

#	Name	Type	Modified	By	What the preview shows
1	desk tidy.dxf	DXF drawing	02/10 14:12	Owen	Base and 4 sides. Slots 3.0 mm. 2 desk tidies per sheet.
2	desk tidy final.dxf	DXF drawing	05/10 10:30	Owen	Exactly the same drawing as file 1.
3	Copy of desk tidy final.dxf	DXF drawing	05/10 10:31	Owen	Exactly the same drawing as file 1.
4	DeskTidy_Body.dxf	DXF drawing, version history on	08/10 09:05	Cai	See the version history in section 4.
5	SidePanel_v3_Megan.dxf	DXF drawing	06/10 15:47	Megan	One side panel only. Slots 2.9 mm. Units: inches.
6	logo ysgol.svg	SVG drawing	03/10 11:20	Megan	The words “Ysgol Cwm Glas” as live text in a font.
7	logo_ysgol_outlined.svg	SVG drawing	06/10 16:02	Megan	The same words, converted to outlines (paths). Black fill.
8	penclip.stl	STL 3D model	01/10 13:40	Cai	Clip gap 2.6 mm.
9	penclip_v2.stl	STL 3D model	07/10 12:15	Cai	Clip gap 3.2 mm.
10	penclip_v2 (3D CAD project)	CAD program’s own file	07/10 12:10	Cai	The editable 3D model of the clip.
11	IMG_4471.jpg	JPEG photo	30/09 10:02	Owen	A photo of the first pencil sketch.
12	Untitled drawing.svg	SVG drawing	04/10 09:15	Megan	Empty. 1 KB.

4. Version history of DeskTidy_Body.dxf

The shared drive keeps every saved version of this file. Anyone in the team can open an old version or restore it, which makes it the current version again. The newer versions are kept too.

Version	Saved	By	Their note	What the preview shows
v1	03/10 09:40	Owen	“Body drawing uploaded: base and 4 sides with finger joints.”	Slots 3.0 mm. 2 desk tidies per sheet.
v2	06/10 15:30	Megan	“Test cut: joints were loose, because the laser burns away about 0.1 mm of wood along each cut (the kerf). Slots changed to 2.9 mm. Test piece fits tightly.”	Slots 2.9 mm. 2 desk tidies per sheet.
v3	08/10 09:05	Cai	“Moved the parts closer together so 3 desk tidies fit on one sheet. Tidied up some duplicate lines.”	Slots 2.9 mm. 3 desk tidies per sheet. The finger joints on the top edge of both long side panels are missing.

5. The team chat

Time	Who	Message
02/10 14:15	Owen	uploaded desk tidy.dxf, that’s the final one
05/10 10:32	Owen	made a proper final version, ignore the first one
06/10 15:50	Megan	test cut done. fixed the slots in the body file AND made SidePanel_v3 just in case. logo is done properly now too
07/10 12:20	Cai	pen clip v2 fits!! v1 snapped when I pushed it on
08/10 09:10	Cai	squeezed 3 on a sheet in the body file, saves wood
08/10 11:30	Mr Howells	I have a 45 minute slot on the laser on Thursday. Which files do I cut? Two problems: the link on your job sheet says “You need permission”, and the shortcut to your folder on the workshop computer says “Location not available”.
08/10 11:42	Owen	sorry sir, I moved the Desk Tidy Batch folder out of the shared D&T drive into my own storage last night to keep it tidy. The link is set to “Restricted: only people added” and I only added Megan and Cai

6. Time and cost: laser cutter or by hand?

	Laser cutter (CAM)	By hand (coping saw, files, hand-painted logo)
Setting up the job file on the machine	10 minutes, once for the whole batch	None
Loading and lining up each sheet of plywood	3 minutes per sheet	Included in the time below
Making one desk tidy body and logo	9 minutes (6 cutting, 3 engraving)	70 minutes (marking out, sawing, filing joints, painting the logo)
Desk tidies from one 600 × 400 mm sheet	3, using the close-together layout in v3	2, because saw cuts need wider gaps
Accuracy of a cut edge	about ±0.1 mm	about ±1 mm

One sheet of 3 mm birch plywood, 600 × 400 mm, costs £4.20. The 3D printer takes 18 minutes per pen clip and can run on its own while nobody is watching it.