Re: [CAD_CAM_EDM_DRO] Long Acme threaded rod

My Acme screw is about 5 feet long and it whips if I go too fast - luckily
for me at that speed my machine missed steps more often and so it's not the
only reason I have to slow down ;)

Jamie
Check out my CNC projects (and more) at http://www.backyardworkshop.com

On Mon, Jun 17, 2013 at 11:25 AM, Steve Greenfield <alienrelics@...>wrote:

> **
>
>
> Try not to laugh...
>
> I'm working on designing and building a CNC mill/engraver. I'd like it to
> have a cut volume of approximately 1000x1500x100mm (about 3ft by 5ft by 4
> inches) that can cut aluminum plate and hardwood, at most. I expect to take
> multiple passes to cut through an aluminum plate.
>
> I'm basing the design on the ShapeOko machine sized up, using 8020 in the
> 25mm size with Openrail hardcoat and grooved steel ball or delrin bearings
> rather than ground rods and linear bearings. The Y travel will have two
> steppers driving it.
>
> Something like this, except the Y rails will be fully supported by another
> piece of 8020 extrusion bolted alongside and the 8020 along the front and
> back will be raised so I can slide a longer sheet in:
> http://powercordlabs.com/1200mm-x-1200mm-shapeoko-build/
>
> Openrail:
> http://openbuildspartstore.com/openrail-hard-coat/
>
> The ShapeOko uses timing belts to move things, but for the size I want, I
> am worried about stretching. So I'm planning on using Acme rod. However,
> I'm worried about a 1500mm long Acme rod whipping. I already have some 6ft
> 1/2-10 and there are anti-backlash Delrin nuts available, but that seems
> thin for such a long rod.
>
> I have considered ballscrews, but the price is fairly high and it is
> cheaper to get a more powerful stepper to make up the power loss. Although
> if there will be a significant performance difference, I'll save a bit
> longer. I am not trying for 0.5 thou cut accuracy. I'll be cutting aluminum
> panels for equipment builds (slots for slide pots, holes for controls and
> buttons, holes for displays), and engraving/2-1/2D machining of plywood,
> hardwoods, machineable wax, plastics, etc. Probably the parts requiring the
> most accuracy will be wooden gears for clocks, driven by a stepper motor.
>
> Am I completely off track? There are also steel wire reinforced timing
> belts available.
>
> Steve Greenfield AE7HD
> http://www.linkedin.com/in/stevenjgreenfield
>
> [Non-text portions of this message have been removed]
>
>
>


[Non-text portions of this message have been removed]