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Discussion in 'CNC Mills/Routers' started by sgspenceley, Feb 13, 2015.
Discussion in 'CNC Mills/Routers' started by sgspenceley, Feb 13, 2015.
A CNC build using linear rails & lead screws.
PS. What made you decide to move away from rack and pinion ?
I know it's been a while, but can you run through the math with us on this one?
I'm coming up with different figures.
somewhere near 110N of force at the ball nut at hold.
its a little xls. sheet. Unfortunately i do not know how to post the results..
well anyway that is just a quick calc... of course that assumes that friction and all other factors really are
what you type in and of course it assumes a real ballscrew with 80% efficiency.
If i change that to trapezoidial screw than figures will change dramatically. Your 110 N sound to me like that.
screwlenth.. motor inertia friction ....onandon....
so if you change a few factors you will see dramatically different figures.
Can you post the spreadsheet?
fragen zu Berechnungen
unfortunately in German only.
Thanks. I'll take a look at it later.
I really like the gold version of this build (on page 4). I found some stainless steel 1/4" angle stock that is 4 inches x 4 inches for $1.50/lb (1000mm length was around $33) that seemed like a possible candidate for the frame. Was thinking about a 1500 x 1000 build with that. On the 1000mm side I was thinking of making the L face down, and the 1500mm side, flip it upside down so I could put the linear rail on top and the ballscrew on the underside.
Big Thanks to everyone who has been contributing to the wealth of information on this thread! Can't wait to see how your machine come together, as I too and looking at ways to upgrade my Ox.
Again, many thanks!
Just thought i would post my video log of the machine i've ended up building as i took inspiration from this thread.
Great looking machine @MartinTurner !
Cheers Mark. Do you think there is a market for a kit ?
There should be a market for them, I would think depending on the cost. I really like the sign cut out at the end with the aluminum letters too. Do you have any of the project files you could share I would like to make one as well.
Well it was done in Artcam. Do you have that? Sketchucam doesen't do v carving.
What size linear rails did you use there? Looks great!
Thanks. 20mm rails on the Long axis and 15mm on the gantry. I was originally planning to use 15mm all round, but I coulden't get the 15mm long ones so easily.
I would probably go for 20's all round if I was building it again..
Hmmm ... if you are not doing changes in depth, why not use SketchUP with SketchUcam and your V-bit to trace a line (your letters) rather than an outline ? The effect will be a V groove of even depth and width . Of course, true V carving allows for a variable depth of cut to create the variable width of the V groove. But your sign looks like it doesn't need this, does it ?
Just thinking out loud (again) ...
It looks like it did change depth Serge.
F-engrave works good for vcarving.
Also, fusion360 does vcarving now.
Martin, very nice build!
Did you post a build log here on OB, or just the video seen in this thread? Would you be willing to share the SketchUp file for this design? Also, can you post your sources for hardware such as linear rails, ball screws....thanks in advance.
This thread was pretty great. Did we lose the OP?
It kicked off some ideas in my head for another, larger CNC machine (already built the Plate Maker). Thanks for sharing.
Nice thread...lots of great info...I have been using my Ox clone (1000x750mm) for a few months and am going thru the plans to strengthen/upgrade...
Here are the planned upgrades, in somewhat order...
TinyG -> Gecko 540 - Waiting on cables, will build a nice enclosure
Increase Z height - Making new end plates to gain 3" Z clearance
Strengthen X rail - The main flex in the machine seems to be in the X cross beams, have ordered a CBeam to replace the 20X60, so I will make new Carriage plates and spread out the wheels for the Z axis
Linear rails - Have received a used linear rail setup from E-Bay....very cool, very strong/stiff, very expensive! Will redo the Z and X first, probably use the linear rail with current belt setup (I have pretty good repeatability with the belts)...the next step will be ball screws if needed...
Then maybe replace the long Y rails with CBeam and linear rails and ball screws!
Will it never end! Upgrading and redesign is almost as fun as cutting parts!
Thanks to all of you for posting your experiences...
Hey , It's very nice work.
Is there any new development? I look forward to .
a beautiful work more! @MartinTurner
Can i ask, what the differences of this one(except that the open source) Because i want to make a new cnc and I want to use linear rails.
GrabCAD - CAD library
Hello! I really like your cnc, it's amazing!
I would like to build my own cnc, based on your structure. Could you tell me please what is that thing, that holds cross extrusion (in hole)? May be a link on ebay?
2016-06-11_18-32-37 by Bartik226 posted Jun 11, 2016 at 7:28 PM
2016-06-11_18-32-30 by Bartik226 posted Jun 11, 2016 at 7:28 PM
This will be my next build!
I will still use my OX but need this BadBoy!
Very Nice Build!
I read your comments on this forum, you seem to have a good grasp about the construction and the mathematics of a cnc machine.
Do you have any documentation about spindle power needed to cut say 4140 steel or 7075 aluminum?
I am trying to find the right spindle for such application as well as the right stepper motors.
no i do not have any docs at hand but you should be able to get that online anyway ( i am german anyway so....). Try getting something like a "formular book" for school purposes.
I happen to have 3 buddies working on professional cnc centers and my work tents to circle around machinery of all types...
anyway, back on topic:
I do not cut steel at all but aluminum which is considered soft anyway.
With our hobby cnc it does not make sense to by a big heavy and slow spindle and plug in a say 15 mm bit. Our cnc simply are to flimsy for them. If you really fancy a 5-7mm deep cut with big bits you better get one of the old heavy mills and convert them to cnc. (surprisingly cheap if you can fit it in your place) look for a machine 1 Ton and bigger
If not continue with our gantry style cnc there is just one sensible solution: High rev and therefore huge feed but shallow passes ( little on Z)
Now you only have to decide if going 0,8 1,5 or 2,2 Kw
Most people i know take the 2.2 one for the sole reason of ER 20 Collets to take up to 12 mm bits in wood. In Alu again the stiffness of the cnc dedicates your cut.
I have used a 0,8 kw for more than 2 years and never used all 800 watts of it...My mill weights about 140 kg...
for steppers it gets more complicated.. Voltage, desired dynamic, tpi of your ball-screws, cutting forces of course and weight lifted around (though far less than you`d think).
I posted a link ( in german) above to calculate , just play with the numbers a little to get a grasp.. you will understand it once playing with it.
I have been away a long time due to health issues, But it's really great to read I inspired a few people with this thread.
I decided to create a new build thread for the machine I'm building. As things worked out, I come across some heavy duty 15 series aluminium, so decided to bolt laser cut steel & aluminium plates to the 8020 frame. If I find the machine needs heavy steel construction then it will be easy replace the 8020 at a later stage.
15 Series CNC