Sunday, 1 November 2020

CAD assembly for the Colchester Bantam in Fusion 360 - bed, saddle and cross slide

Modelling the Bantam:

Yes, I'm still talking to Fusion, despite our recent misunderstanding. I'm not the kind of guy to attempt a CNC conversion without spending weeks designing everything in CAD. Rightly or wrongly, I prefer to model up the base machine, then design and import the new components to make it work. Ideally I'd be able to import stuff like the fasteners, pulleys, bearings, leadscrews etc from places like Misumi, Traceparts, McMaster Carr etc but I won't find a Bantam CAD model anywhere, so I need to model it up myself.

This bit takes forever and doesn't really achieve much in itself but with a bit of focus, a half decent model can be crafted up in a few days, around all the other stuff that needs to be done in this world. It doesn't need to be photo realistic but I want to be able to create parts that can be CAMed up and made without having to redesign them - or find they don't actually fit once I've made them.

This is basically an imperial machine, albeit with metric cross slide and top slide leadscrews (the gearbox and leadscrew are imperial, natch), so the dimensions are all made in inches and the fasteners are all UNC / UNF threads etc. Luckily I have the manual in PDF for reference, showing all the "standard" parts and the exploded views.

Bed casting:

Rear view:


Rear view:

Cross slide:

And a quick idea of where the 10t and 32t pulleys might fit:

Still quite a bit to do to both the model and the concept itself but it's a start...

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