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'been there, done that. see here: http://www.cnczone.com/forums/showth...227#post708227Originally Posted by RiseUp
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I've been lurking around for a little over two years now,and after drooling over others' builds, I've decided to FINALLY build my own. Simple and cheap for the first go around,then use it to build the next.
I was browsing through Lowe's, had two hours to kill before Avatar in 3D started (AMAZING movie) and came across some drawer slides. I picked one 18 incher up,took it out of its packaging to see how much wiggle room it had,and much to my surprise,there was none. I extended it fully, and it flexed, at MOST, 1/16" with me pulling on it. The label said Light Duty, and it said it had a weight limit of 35lbs, but I applied probably about 50lbs of force, and it flexed only vertically. Horizontally there was absolutely NO movement. It was only $4.98,so I grabbed four. I made sure the other three had the same tolerances,and surprisingly,they did.
I came home,spent 15 minutes in SketchUp, and came up with this design.
Moving gantry, made from 3/4" MDF, table is two layers both for rigidity and to allow enough wood for the drawer slides to be mounted. 15 3/4" of travel X and Y, 4" Z. Any ideas,comments,suggestions,etc are much appreciated.
RiseUp
Nanite CNC V2 under construction! :D
'been there, done that. see here: http://www.cnczone.com/forums/showth...227#post708227
I think you'll see far more flex than you think. But there is a method to using drawer slides that'll work better. Use 2 pairs of slides, mounted in opposite directions, so that as one set extends (where there's more flex), the other set is retracting.
Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I plan on keeping the gantry sides supported at all times,so I'm not TOO worried about flex. I just plan on using it as a beginner/fun/learner's machine.
Picked up some spare wood from a friend today,so I'll probably just slap something together to play with for now. Once I'm more familiar with the actual CNC process(CAD to GCode),I'll be able to decide if I want to invest more time and money into it. Until then, a learner's CNC for $50 sounds great to me!
Nanite CNC V2 under construction! :D
They probably would do better with a moving table in a mill type setup rather than in a moving gantry.
Probably, but then the travel would be cut in half. I know it's a dumb argument, travel vs rigidity, but since it's strictly to learn on, I figure its alright for now. If i like it,I can always build another one or rebuild this one:P
Nanite CNC V2 under construction! :D
Yea but if your going to put some work into something, it may as well be something you could get some good use out of.
Good point. Ill go with a fixed gantry instead. I really like this design. Simple,effective.
Nanite CNC V2 under construction! :D
I wonder if anyone has mounted the drawer sides at 90degree angles to each other, in pairs.: / \ / \ Seems like it might give acceptable rigidity, especially if the pairs were mounted so they traveled in opposite directions.
Hey everyone!
I built a router using heavy duty drawer slides and baltic birch ply this past fall. The travel (x, y, z) of the 3 axis is just under 28" x 24" x 10"
I used 4 slides per axis, in the perpendicular configuration mentioned above.
I got the Y axis very stiff this way.
The gantry's center of mass is quite far behind the mounting point on the X axis slides, and as a result, the entire gantry does lean a couple degrees rearward. This was quite a surprise to me, since the gantry isn't more than 25 or so pounds, and each pair of slides is rated at 100 pounds. Oh well. Because of all this, the anti-backlash nut and X acme shaft aren't aligned, so I've had to run the thing with no bearing on the non-drive end of the shaft. Otherwise, the bend in the shaft becomes so great at the ends of travel, the machine binds and loses steps.
The Z axis has a fair bit of deflection to it, as well. I'll be redesigning that at some point.
I would also recommend a fixed gantry that houses the Y and Z directions of travel, and a moving bed for X travel. This keeps the mass of the gantry off the X axis, and will increase precision and stability significantly.
Can drawer slides be used effectively? Definitely! They just have their own limitations that you must account for in your design.
Im attempting using them now on my first build
My build thread.. that NOBODY has comented on yet lol
http://www.cnczone.com/forums/showth...797#post748797
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