Hi Andy,
I (and a fair few others) use QCAD which is LibreCAD's older brother. QCAD also has a free community edition, plus a commercial version (about £30), that adds some worthwhile features. All three of them are competent 2D engineering drawing packages. QCAD is actively maintained. LibreCAD looks stalled at the moment: I couldn't download the latest stable version and the PPA site says it hasn't been updated for 166 weeks. That said, version 2.1.2 in the Ubuntu Repository looks in good shape. QCAD is my go-to tool for drawing single engineering objects, scale plans, templates etc – anything from back of an envelope to proper projection drawings with layers, dimensions, hatching and a version number! Simpler and easier to learn than Autosketch, which has too many unrelated bells and whistles for me.
I also use Fusion 360 which is a much more powerful 3D CAD tool. It comes into it's own for complex objects and especially Assemblies. For example, Fusion lets you model the individual parts of a machine and then model them together with approprate joints such that the machine can be animated. You can see if moving parts are going to collide without making a real one. Fusion can also produce rotatable photo realistic images, do stress analysis, produce 2D drawings, and output CAM instructions.
Although I find Fusion fairly intuitive, 3D CAD can be a steep learning curve, and the package has multiple capabilities. Getting to grips with it is a hefty investment of time and energy and you might have better things to do. MEW is running a course on Alibre at the moment; also very capable and well worth a look, but Alibre will eventually cost money.
Of concern is that Autodesk might change their minds about the free licence currently on offer. Draftsight was free for a long time before users got that nasty message. A pessimist might expect Autodesk to pull the same trick – get you hooked, and then demand money. For that reason I also keep up-to-date with FreeCAD, it's more obviously in development and whilst not in the same league as Fusion & Co functionally, it's genuinely free. An optimist might think Fusion a good bet because Autodesk are implementing a clever long term strategy: they don't intend ever charging hobbyists and students, the plan is to put loads of self-trained Fusion people on the job market, such that employers switch to Fusion to reduce their eye-watering training costs.
To keep life simple, it might make sense to choose the minimum the part-cutter will put up with. If he only needs properly scaled 2D plan drawings, LibreCAD/QCAD is easier to learn than Fusion.
Producing good engineering drawings can be quite hard; there are do's and don'ts. A basic book might help get you started.
Dave
Edited By SillyOldDuffer on 23/05/2019 19:11:21