Isn't the machine builder required to do a risk assessment and provide a safe machine to the buyer thus eliminating the need for the owner / buyer to do one?

 

Only the final end-user can do a full risk assessment, taking into account things like the environment where the equipment will be installed, the degree of training of the people who will be using it, the availability of the appropriate levels of maintenance ...

And from the legal viewpoint, when the thing goes bang, the manufacturer and the installer may not be readily available to drag off to the nearest courtroom.

 

Under the machinery Directive, which governs Machine safety in Europe, The machine manufacturer is required to do a risk assessment. However in the US there is no regulatory requirement for a risk assessment by the machine builder, as the responsibility for guarding falls on the end user.

If the machine carries the CE mark, the end user can reasonably assume that the risk assessment was done, but, again in the US, the end user is still responsible for ensuring that the machine is adequately guarded for his specific application.

 

Which country are you in?
Which country is the machine designer in?
Which country is the machine builder in?
Who designed the machine?
Who installed the machine?
Did anyone modify the machine?
How long has the machine been in operation?
Who trained your operators?
......
Your lawyer will probably ask a few more questions. You get the idea.

Your question has no simple answer. Ask your lawyer if you want a real opinion. In reality, everyone - including you - has a duty of responsibility.