Just starting out - quick question

[glynster]

I am brand new to this and intend to build an aluminium framed CNC router - I am a woodworker and a designer but know quite little of electronics and CNC specifically.

The unit I intend to build will be a slightly larger versions of one made by a guy called Benne at instructables - namely this: http://www.instructables.com/id/Buil...uter/?ALLSTEPS

My question, I note from his steps that he chose to make certain parts on another CNC router (small parts like mounts etc) and this seems very common on a lot of builds. Do you think it would be a smart move to buy a cheap small footprint router on ebay (the Chinese ones) for this purpose and then sell it again? I figure it wouldnt depreciate too much and I could at least learn how to use a CNC first. Or do you think it would be better to try and pay somebody to make them for me?

I did consider the Solsylva kits but I hated reading through the plans as there are no 3d models or proper drawings just bit by bit small drawings that are hard to conceptualise - plus I reckon the monite I'd built it I would only want to build another one. I also considered Joes Hybrid but I am not going to shell out $75 on more plans only to find out that they are incomplete or hard to follow.

[Wal]

My question, I note from his steps that he chose to make certain parts on another CNC router (small parts like mounts etc) and this seems very common on a lot of builds. Do you think it would be a smart move to buy a cheap small footprint router on ebay (the Chinese ones) for this purpose and then sell it again? I figure it wouldnt depreciate too much and I could at least learn how to use a CNC first. Or do you think it would be better to try and pay somebody to make them for me?

Personally speaking - I'd get it designed, work out what bits are needed and then have a machine shop fabricate 'em. Half the battle will be finding a shop that wants to take on a small job, but they're out there - you can always post a request on here too. Looking at the link you posted, a small cheap Chinese machine isn't going to be much help with your build and will likely cost you nearly as much as the fabrication involved. If you look at my build (pic attached) those plates cost me £200 to get drilled at a local shop. Top job, accurate and ready to assemble. You just need to plan ahead and get all the details right. A purist might say 'well, you haven't built it yerself..' - pff, I'd still be worrying about how accurately I could get the holes drilled. Sometimes you just need to pay the man and get the job done right!

Wal.

[glynster]

That's a hugely impressive looking bit of precision engineered aluminium. I have given up on the idea of buying a model machine to make parts - strikes me I could roughly make any parts out of MDF and then use the main machine to make better parts for itself later. Is that 15 or 20mm aluminium? Isnt that overkill?

[Wal]

Isnt that overkill?

Heh. No such thing..! Or to look at it another way - if you can't do the maths, make it as strong as you can afford to...

Yep, it's 20mm 6082 Ecocast plate from Aluminium Warehouse. This is to ensure maximum flatness across the faces that the hardware gets mounted to. Believe it or not, there can be a fair bit of variation across a large chunk of plate. Not what you want if things are going to line up as best they can.

While the holes are drilled accurately, if you look at the edges of the plate you can see saw marks. The plates themselves weren't milled to size, just machine sawn to ±1mm of the dimensions I needed. Profile milling the plate edges in relation to the holes would have been a better approach (easier to square the plates relative to each other with the right gear) but it would have cost a fair bit more. Squaring was reasonably straight forward as it happened and I didn't use any specialist equipment beyond engineers squares and dial guages. Sure, we're not talking aerospace tolerances, but for what I'm doing it's almost certainly as good as it needs to be.

Wal.