Hi Ian, Welcome

Quote Originally Posted by ian View Post
a budget of ±£3.5k or ideally less.

The machine will be used in my (small) office and will eventually be housed in an enclosure to reduce the noise.

The machine will mostly cut hard engineering plastic sheets (good finishing quality is essential) and some occasional aluminium for custom moulds or jigs.

I "inherited" some starting components

3. Should I use the heavyweight or lightweight profile? (from KJN)

1. What grade aluminium would be best?

Adjustability
I know it is important to have easy access to all the bolts/screw/nuts nd also to have adjustability so that the machine can be squared etc. However, I am unsure on which critical bits I need it and whether I should then just add oversized hole or slots in these areas? Any input here will also be appreciated.

Tapping
Where I connect motor mounts or bearing supports, I planned to tap the aluminium plate and not use a separate bolt - is this a good idea and how well does Ecocast tap?
Budget seems achievable. I don't envy you having this in your office; even with a watercooled spindle rather than a router don't expect to get much other work done without wearing ear protection. An enclosure will help... but...

The inherited components are never a good sign to be honest with you. They tend tie one hand around your back before you start. You've said you're cutting plastics primarily which tend to want higher feed rates, so 5mm pitch screws might not be ideal as they dictate your speeds somewhat. You may find you'll have to introduce some gearing to get the speeds you want. Having said that plenty of people on here build with 5mm pitch direct drive and it works for them.

I'd go with the beefyer profile every time. More rigidity, less vibrations.

As you've mentioned, the 'best' would be ground tooling plate.

Adjustability... This is a tough question.
  • Think about it from the spindle tramming perspective - What would you move to tilt the spindle left/right and forwards/backwards?
  • Think about it from an axis squaring perspective - How do I tilt Z to make it go vertical with respect to X, then wrt Y? How do I adjust the angle between X and Y?
  • Where you have components meeting that may have some positional variance from your CAD due to building errors or tolerances, how will you ensure they can mate appropriately? E.g. Ballnut connections - can you adjust in all three directions using slots/shimming?
  • Motor positioning - either direct drive (how can I line up the shafts precisely?) or pulleys (how do I tighten that belt?)
  • How do I adjust the ballscrew angle without modifying the linear motion components?


The list goes on an on. Oversized holes are one method, sure, but don't put them everywhere just because. Slots, shims, grub screws...

Tapping into ecocast is perfectly fine and works well.