I finally have the time and most of the parts to contemplate building the my CNC router. I stacked up most of the parts last night to get an idea of the thing. The motors are the cheap Clifton servos as per the "my cheap servos" thread. The z axis are THK NSR20TBC that I got for a song on ebay. They are 640mm (25"). The y-axis is a thomson superslide with a 5mm lead ballscrew. The screws for the x-axis are IKO rolled units, two start 10mm lead, both will be coupled with belts, I have bearing blocks for these also. The z axis is a Aerotech with 5" of travel, has a ground ballscrew with 2mm lead. That will probably be stepper driven, not too sure.
For noise I am adding a 900W Kress router, they are really nice and not too loud.
I'll add pictures as I do stuff however progress may be slow as I have run out of cash at just the same time having some time to do the work.
That is a good question. I have some large pieces of extruded ali for the two uprights, this stuff is 80mmX160mm and has internal webbing and a thick wall. I'll add an aluminium doubler for mounting the rails on. I can get these milled true with respect to the base on the mega sized milling machine in the department .
For the base I am still thinking, I really liked the egg box torsion style contruction but not sure how to go about it, this is one idea I had attached Not eggbox but I think it would work OK I think, the sides might be 80mmX40mm extruded ali and the cross-pieces 40X40mm. There would be a top and a bottom, the former t-slotted. Not sure I am getting much stiffness for the weight, I can't make it too heavy, my workshop is in the attic with a horrible little spiral staircase up to it. I would really like the webbing of the base to be made from say 5mm sheet upright and welded into a criss-cross but the welding is the problem in that I can't do it and the access to the joint lines would be limited anyway.
Other things I am stuck on is the gear ratio to the screws. Thanks to the new FAQ I can do the calcs and Mariss from gecko also posted info on matching these motors to a ballscrew however I am leaning towards accuracy so encoder choice and pulse rates all come into it, I am also not sure what I want. Then I wonder if I am really going to acheive any more accuracy than most due to the rolled screws.
The use of the machine other than general routing in wood and ali is mouldmaking and 3D milling jobs. I make propellers and such things and would like a good degree of accuracy so things can be made to fit together.
Generally confused but I now have time to work through the confusion.
p.s. Reason I have no cash is the 25W CO2 laser sat on my bench, another reason to finish the router!
great start graham and welcome to the wonderfull world of pulling out your hair,oops i mean cnc.no realy it will all come together and you will be gladly missed everytime you run for the work shop.like my wife says,the only time i see you is when your hungry or when your hungry for it.L.O.L. cheers.
This is my first router but I'm not new to the hair pulling
I don't live in the US so I am not sure 8020 means much over here. The slots are slots so you can always bolt a rail over them I just think a doubler should be used to ensure a flat surface and full contact area, I'll also mill it so it has an edge so I can have a reference slide as per the THK recommendations.
"Maximum overkill" may be the name of my router I suspect.
Sounds good graham cant,t wait to see what your router will do.Just talked to a chap who knows of you and he said you you are very knowledgable.I think I,m going to try 24 volt setup as you described and see what comes about .If you don,t mind me asking ,where in the UK are you situated.My wife is from there,other side of the Mersey from Liverpool.Sure miss the place.Anyhoot post pics as you can .Cheers,Corrie.
Picture1: The old config showing the large overhang from x carriages to tool.
Picture2: Flip the slide vertical and it is reduced. I have removed bearing blocks from the ends of the thompson rail, these will be built in to 1" thick gantry ends. This ties it all together much better but involves boring which is not only boring but I find easy to mess up. Still it builds character.