Gina

Printed the new Z carriage then added the V groove wheels with eccentric spacers in the larger holes so that any slack can be taken up.  Set it up on a V groove rail and adjusted out the slack then I tested for possible wobble and couldn't find any at all.  I think these Z carriages are going to work well but we'll see.

Here's a photo of the eccentric spacer used to take the slack out.

Simplified version of Z carriage.

This part of the CAD model shows the LH Y rail and rear support bracket plus Y carriage and X rail.  I think the Y rail will want to be shorter to allow for the motor at the front (unless the motor goes outside the box).

Alternative corner bracket.

Bottom box brackets.

Top rear bracket to hold box panels together plus Y rail and the rear pulleys.

That's considerably cheaper!!

This printer will be bigger than I thought and yes, very heavy.  I thought I might be able to store it under the table but no, it's far too high.  Printers other than my Giant have been assembled on the living room table but Concorde is going to be heavier than the Giant and will also have to be assembled on the floor.  I was able to move the Giant out and into another room without wheels but not Concorde!!  My original thought was to have something like 50mm square internal corner blocks of wood to stiffen the box but this would add yet more weight so I think it will be 3D printed angle brackets.  Top rear brackets will also accommodate the Y rails and rear pulleys.  Bottom rear can be simple corner pieces bolted to the plywood panels.  Top front will be brackets to hold the XY motors and bottom front can be similar to the bottom rear.

Thanks Dave.  Yes, a 12v regulator would eliminate the buck converter - I too have both 24v and 12v devices.  I wonder if any of the extra I/O would be useful.  I'll see how thing go it's always an option for the future.

I have no plans for an enclosed box - I do not plan to print ABS or other filament needing a heated chamber.

Since you ask I'll cover the bed now.  Or at least my initial thoughts.

A frame made of 20mm x 20mm aluminium extrusion 500mm x 500mm outside will have an aluminium plate on top 500mm x 500mm x 2mm.  On the underside of this will be a self-adhesive silicone heater pad rated at 1200W at 240v.  On top of the aluminium plate a glass plate will form the printing surface.  Here's a CAD model viewed from the underside.

The X and Y axes will be driven by the usual NEMA17 stepper motors with timing pulleys and belts in CoreXY configuration with one motor accounting for X+Y and the other X-Y.  This simplifies the construction and uses two motors at the front and four pulleys at the back of the box with two pulleys on each Y carriage.  The ends of the timing belts are attached to the X carriage.

This is my initial Y carriage design.  The X rail fits in the square slot (held with screw into the end) and ball bearing pulleys in the top and bottom slots.

As I recall Dave the Z carriages had rather closely spaced wheels - my Z carriages have the wheels spaced 150mm apart giving much better control.  But the proof of the pudding...

3 hours ago, tekkydave said:

I would strongly recommend having 3 leadscrews each driven by it's own motor. I use this method on my D-Bot and the bed is rock solid. If you are planning on using the Duet then get the Duex2 Or Duex5 expansion board to give you sufficient drivers.

You can also make the bed self-level itself

https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors.

Yes, I remember that you did that Dave and if I find the bed is not held level enough I may go for your solution.  And yes, I shall be using a Duet control board.  I was originally planning on using 3 Z drive rods but with belt drive.  Decided it was too complicated and experiments with 4 rods on my Giant printer proved disastrous.  Three motors means an expensive add-on to the Duet so if I can get away with two motors I can save money.

EDIT :- For @tekkydaveChecked cost of Duex2 - £74-34.  This seems an inordinate cost just to add two stepper drivers.  Actually, really adding only one as the second extruder driver could be used for one of the Z drives.  If only Duet had provided 6 drivers instead of 5 it would have been covered.  Considering TMC2100 drivers cost about £8, spending £74 to obtain the same result does seem excessive.  I wonder if there's an alternative.  I can see the advantage of three Z motors.  I wonder if one could connect three motor coils in series like we do for two.

Since the printer box will be on wheels, there will be space available underneath the base of the box.  This has enabled me to mount the Z drive motors below the base and not only simplify the construction but add a bit to the available printing height (I might as well get as much as practical).   As can be seen in the CAD model, the Z drive uses the standard threaded rods and a pair of stepper motors.  The substantial Z carriages keep the bed level.  The threaded rods are 8mm 1-start trapezoidal thread-form x 500mm.

The printing capacity of this printer would appear to be more than I originally intended.  The increase in box size from 500mm to 610mm has resulted in a corresponding increase in the size of bed that will fit in and the available printing area.  So the 300mm x 300mm bed of the Titan is replaced by a 500mm x 500mm bed size and printing area of 400mm x 400mm.  By various means I think I can provide a printing height of approaching 400mm.  I can't say if I shall actually get these printing dimensions until I have worked out the design of all the parts.

This printer will indeed be very heavy - I shall be fitting it with wheels (heavy-duty casters)!  I guess I shall be building it in my living room but where it will end up eventually remains to be seen. 

Regarding ventilation, I shall not be printing ABS on it as that has been superseded by more user and environmentally friendly filament types.

These photos show the "V" rail arrangement.  The printer carriages use four wheels, two each side of the rail and separated along the rail to provide an accurately running carriage, constrained in all but the longitudinal dimension.  The 2nd photo shows a "Mini" carriage (gantry plate).  The carriages used in the 3D printer have the wheels much more widely spaced and the plates are 3D printed in thermoplastic (PETG).   In the CAD model above, the wheels are represented by cylinders on the Z carriages and are 150mm apart to keep the bed as accurately level as possible over the Z range.

The box will be built from high quality hardwood plywood panels 18mm x 610mm x 610mm (2ft x 2ft).  The Titan box was built from 500mm square acrylic panels with printed corners connecting the panels except for the base and back which were plywood, so I searched for ready cut pieces of plywood this size or larger and came up with the 2ft square sheets (a bit bigger than I really wanted but not by much).

This CAD model gives an idea of the arrangement of some of the parts within the box.  X and Y rails are aluminium extrusion "V" rail with the carriages running on them with matching ball bearing wheels.  The Z axis also uses "V" rail vertical pieces with 3D printed Z carriages running on them and supporting the print bed.  The Z carriages hold the bed level with any remaining deviation from truly level being compensated for in the firmware using Z probing immediately prior to printing.  I'll say more about the "V" rail system later.

Filament reel support added.  This shows a 4.5Kg reel of filament.

Here is a diagram of how the parts are to be laid out on the top of the printer.

Key :-

1. Filament Reel (4.5Kg) - Black
2. Fume Fan - Red
3. Water Reservoir - Blue
4. Control Box = Yellow
5. PSU - Green

Now looking at the location of other parts - PSU, control box/board, water reservoir & pump and fume vent/fan.  Checked up on the Duet 2 WiFi control board that I'm using for mounting and cooling advice.

Quote

Cooling

The PCB is designed to transfer heat from the stepper drivers and power mosfets to the underside of the board. Therefore your mounting method should encourage good airflow underneath the board.

If you mount the board vertically, make sure that cool air can enter at the bottom of the board, flow upwards behind the board, and escape at the top. Convection cooling will usually be sufficient, but if you are using high stepper motor currents then you may wish to add a fan below the board to encourage the upward flow of air. Make the spacing between the back of the board and the panel or enclosure large enough to allow a good flow of air.

If you mount the board horizontally then a cooling fan is recommended, especially if there are other heat-generating components in the vicinity such as power supplies, SSRs or stepper motors. Position the fan to blow air underneath the board (optionally along the top as well), especially along the row of stepper driver chips and between the power input and bed heater terminal blocks.

Important! The higher the motor currents you set, the more important it is to cool the board. Always use a cooling fan if you run a Duet 2 Wifi or Duet 2 Ethernet above 2.0A motor current.

My other printers currently have the board mounted vertically and open but I would prefer to have a box round the board for protection.  Previously, I have had the board mounted in a box vertically with a fan behind it - so lots of cooling - but the orientation looked untidy and it was difficult to connect the wiring.  I would prefer to have the board mounted (in a box) horizontally on top of the printer, though it could go on the side and vertically but again the connections would be awkward.  Mounting the board horizontally with air blown across underneath the board seems overall best, I think.

Update on cable chain and umbilical.

Oops - double post.

Cable Chain.

Printing cable chain links on my GinaRep Titan 3D printer.