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Larger Format Machine

Discussion in 'CNC Mills/Routers' started by Finnigan, Jan 12, 2014.

  1. Rocco Ross

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    I just ran into this thread because I have this same question. How do I get a 4'x8' work area with the Ox style build? I know there haven't been posts in awhile. So, I am not sure if this was addressed anywhere else, but, what if I use 2 sets of Chris Laidlaw's brackets that he sells?http://pages.ebay.com/link/?nav=item.view&alt=web&id=261855927419&globalID=EBAY-US
    I figured 2 sets because obviously one set is for the standard 1500mm build. They are pricey, but from what I have read, he does some great work on his pieces.
    Put a snug fitting rod in each of the butting holes for alignment and fasten two of the brackets close to each end of the joints for deflection. All brackets are in turn fastened to my mdf torsion box.
    Any thoughts?
     
  2. nomenclature

    Builder

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    This seems like a good place to ask... I live in Australia, and luckily enough for us one of our local suppliers stocks/sells v-slot in lengths of up to 2.4m... Which got me thinking, would it be possible to do an OX with dimensions of 2.4x1.2m (mabe 1.4 to allow full width cutting), with the gantry spanning the width of the machine, without getting too much flex or other issues? Thanks
     
  3. Serge E.

    Serge E. Journeyman
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    You could use standard 1500mm length of V-slot for your X axis to get 4+ feet of width. Some bolt these into single piece for extra 'strength' but mostly to control deflection as your router (and the forces involved in cut) reach towards the centre of that span. The use of C-beam (basically 40x80) would be better, but it is limited, currently, to 1000mm lengths which doesn't allow for a 4' work width after accounting for the carriage wheel base.

    I am thinking of a different style of gantry / bridge to bring the centre of gravity (router et al) beneath gantry instead of way out to one side which adds torsional forces ...

    As for the Y axis, since it can be supported in various ways along its length, it could be just about any length - joining standard lengths as needed - ex: allow cutting 8+' without having to slide the work piece as done in a PhlatPrinter (rollers pinch the material and move it back and forth beneath the router/spindle).

    As I looked at having longer and larger profile made closer to home, some of the issues are as stated in some previous posts : tolerances become a pain (read : mostly harder to control, leading to increase of waste and a substantial rise in cost). OBPS walks far enough from that line to keep costs quite reasonable. It then comes down to finding ways to properly aligning joined lengths of extrusion. Our use of lighter structures will make this a bit tougher than for heavy industrial machines using their mass and volume to their advantage.

    If you have access to 2-3 m length of "V-slot", use them for your Y axis and make sure they are parallel along entire length (and very straight since two curves can be parallel - equidistant along their full length !)

    Do not forget that handling those extra long lengths of extrusion also adds to the headaches (and wallet pain) from the shippers possibly mishandling those lengths (throwing them off tolerance) or wanting more money, through simply moving those lengths around at your end without flexing / bending them out of whack.

    At this point, I'm looking at some form of extruded / formed support 'beam' for the Y, mostly to get rid of the spacer lengths (along X axis) to gain some Z. Right now, most OX type machines use 20x40 lengths plus the thickness of the spoil board, ... That's about 2" of wasted Z... If one wants to use a 4" extra long end mill, the extra 2" of Z would be most welcomed.

    Probably the best thing about building our own machines is that we can adapt them to our needs with what is readily available within our budgets ...
     
    Jestah and Rocco Ross like this.
  4. ANDRESCAMPA

    Builder

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    Hello friend, I am in a design with 1600 oz Nema 34 or 115kg torque motors, weighing approximately 5Kg each + 0.7 of a nema23 motor for the Z axis, and a 2.2Kw spindle that weighs 5.5Kg + 2Kg from other parts in the X axis In total an approximate of 24Kg in the car X counting the 2 plates with motors in the Y axis ... Do you have any table on the maximum weight for profiles 20x80 of length of 1500mm?, what do you think about of my project?... This is my desing
     

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