No problem digisoft, just a misunderstanding. :)
Unless you already have access to a workshop you will probably have to rig something up to grind a 45 degree angle in your supports like this guy has done:
Grinding a 45 degree angle for a linear rail with my CNC - YouTube
One problem with this approach is that you have to use v-groove bearings as wheels and the wheels will need frequent adjustment as the rail wears and your wheels become loose. The v-groove bearings are also really expensive and hard to get hold of.
It might be easier to use a piece of box section or square bar at 45 degrees as the rail like this:
That way you can use skate bearings (just the normal wheel bearings from skateboards) which are really cheap, it wears down slower so it requires less adjustment and it means a lot less work to setup.
OK if I have picked you up correctly you are going to make your own supported rail using the ally profile & chrome bar. First question would be what sort of equipment do you have access to because I would imagine you would really struggle to be able to drill & tap a length or round chromed hardened steel bar with DIY gear unless you already have your own workshop.
I calculated the Z part and ONLY the aluminum 20mm plates will weight 11Kg. It is not included, the rails, sliders, stepper etc etc, only the aluminum plates construction. Is that too much? Should I sue thinner plates?
A typical gantry will weigh in at 20 - 25kg. Without seeing a drawing of how your gantry is designed its impossible to say what the impact of making them thinner will be. Rigidity is key...
Going off advice given to my design, and the veiws i know others share I'd say it seems to have the right things in the right places pretty much.
Critisism: flip the stepper motor and mount it on the back then use a belt and pulley system. This will reduce resonance, as well as other things? (correct me)
Perhaps also mount the ball nut inline with the rails, might help give greater travel in x?
Finally, ignorance is getting the better of me, are you really from chernobyl?Hobgoblin.
Thank you for the help.
Can you tell me if the Y distance of the rails (vertical distance between the Y rails) is better to be 150mm or 200mm. Y will be 1140mm long
PS: I am still working on the Y boll-nut. I just put it like that, it is not in place.
PSS: I was also thinking about belt and pulley for the Z but I don't have those parts and it will complicate my design. What do you think? Is there that much difference?
All aluminum parts are 20mm tick.
I changed the design little so the Y distance between the two axis is 150mm
Do you think this is better?
Last edited by DigiSoft; 23-10-2012 at 09:31 PM.
Its always better to have the y-rails as far apart as you can and as low down to the bed as you can to improve torsional stiffness...
I think you could reduce the thickness to 12 or 15mm without undue effect...
What is the box section between the rails? material and dimensions?
BUILD LOG: New Build - For Your Amusement - MK-2 buildBy Karl in forum DIY Router Build LogsReplies: 11Last Post: 11-06-2012, 07:34 PM