CNC Design and advice

[irving2008]

MP,

Dont buy ready made nuts, they are expensive. buy an extra 100mm of the rod and make a tap as Jonathan has suggested and cut the threads in some delrin (engineering plastic). It will do for what you want. You don't need to harden the tap for plastic.

As to the steel frame, its massive overkill for a first tryout machine. Also those motors/driver wont be up to the job. My recommendation is keep it small and simple, you can do a lot on a small simple machine as long as you plan carefully and dont expect miracles.

[GeorgeD]

As to the steel frame, its massive overkill for a first tryout machine.

I don't understand the logicinthat statement,Iriving.

I'm assuming you're stating.....build it in MDF then find out the pitfalls and gather some experience from the MDF build then apply it to a more sturdy material in the future?

Isn't that a more expensive way of looking at it than doing it in a more sturdy material from the start? I myself looked and thought about the material I was going to use first,MDF didn't even get a look in and so it was either Perspex,Aluminium or MS box section.

Perspex was not suitable so that left Ally or MS,Ally was far too expensive on a budget so MS was the deciding material for me.

[irving2008]

I don't understand the logicinthat statement,Iriving.

I'm assuming you're stating.....build it in MDF then find out the pitfalls and gather some experience from the MDF build then apply it to a more sturdy material in the future?

Isn't that a more expensive way of looking at it than doing it in a more sturdy material from the start? I myself looked and thought about the material I was going to use first,MDF didn't even get a look in and so it was either Perspex,Aluminium or MS box section.

Perspex was not suitable so that left Ally or MS,Ally was far too expensive on a budget so MS was the deciding material for me.

George, you're missing the point... he's already got small motors, and the overall size of that machine is maybe 400 x 400mm. Its too small to justify/need a steel construction and MDF will be quite sturdy enough for his needs of PCB milling/drilling. Plus to do a steel frame needs much more complex equipment than MDF and MP already discussed with me elsewhere about the difficulty of accurately cutting MDF with the tools to hand so I am making a fair assumption that steel is beyond his capabilities right now. Unlike you George it would appear MP isnt in a position to go out an buy a lathe, welder, etc. as you did, so lets get him up and running as simply as possible.... so lets get this back on topic as regards MPs design for an MDF-based machine OK?