Weight on the X-plate

Following on from the thread about the aluminium x-rib and plate, weight came up and got me thinking if anyone has removed the extruder feed from the arm and mounted it elsewhere?

Seems a bit odd hanging a relatively heavy lump on a sensitive part and using a delicate screw to jack it up and down.

Being a Bowden style extruder, surely the feed could be place anywhere?

Edited 1 time(s). Last edit at 03/27/2014 05:13PM by Davek0974.

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

If weight isn't the major factor then the advantage of the current position is that it minimises the amount of twist and movement in the tube. That has a secondary effect on the hot end as it twists. If the extruder didn't track with z height then I think the tube would need to be quite a bit longer to accommodate the change in height of the hot end and I suspect it is not good to make the tube too long.

Maybe a little longer tube but mount the extruder near the Z column or even on top of it, this would remove all or nearly all of the twist and just leave a linear bending action, that would stop the PTFE unscrewing from the brass ends too??

Just wondering

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

Exactly right Dave.
Something like the existing Acrylic X rib could be mounted on the other side of the vertical extrusion (with an offset to allow for the Zrunner to pass by)
It would be about 30mm displaced from the existing extruder position.
Much more important when wanting to run multiple extruders.

Your point Bob is important in that we need to look at the curvature change in the Bowden with Z changes.
As far as twisting is concerned, the current twisting with X position will be no worse with a new fixed extruder mount
Greg

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Ormerod #17

I wonder whether the extruder really needs such a large stepper motor? It's nice having 4 identical steppers, but perhaps the extruder could use a less powerful but lighter one, especially if the gearing was increased? This would reduce weight when multiple extruders are used.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
I wonder whether the extruder really needs such a large stepper motor? It's nice having 4 identical steppers, but perhaps the extruder could use a less powerful but lighter one, especially if the gearing was increased? This would reduce weight when multiple extruders are used.

Personally I would stick with the standard motors and go for off-axis mounting.

More gears would increase backlash etc and these are pretty tough little motors, fitting a smaller one could induce a weak spot.

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Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

We used to use NEMA14 motors for the extruder drive on Mendel and Huxley, and it was geared down more that the Ormerod extruder drive. Generally, they were fine, but could get quite warm, particularly printing ABS or with a 0.3mm nozzle, where the extrusion pressure is a bit higher. The extruder needs the torque of the motor, and dropping to a NEMA14 reduces torque greatly, so we switched to using NEMA17. Also, we get more motor for the same price, and it's easier to order, handle and pack the kits with the motors the same size.

Mounting the extruder(s) off the X axis would probably help z leadscrew longevity. They were put on the X axis to add some mass to it, to reduce the chance of wobble in the Y direction, and damp out vibration, but I think there is probably enough mass and stiffness there anyway. I think mounting them at the top of the Z extrusion (so they don't effect the Z axis height), with the Bowden tube exiting the extruder pointing along the X axis (the Bowden tube wouldn't need to be lengthened then) would seem to be about the best position. Much like the position of the extruder on the Mendel we now use! Eg: [reprappro.com]

Ian
RepRapPro tech support.

If not now,this will be more of an issue with the triple extruders, At this point I've got mine hanging from the inner slot and it is working just fine.
Adding two more, where the slots are will add quite a bit of torque to the x rib, But I guess that has been tested by the RRP guys already, and found to be working.

Any news on the triple extruders by the way?

Edited 1 time(s). Last edit at 03/28/2014 06:11PM by 5dala.

5dala, how did you manage to get your extruder hanging on the inner slot? Mine won't fit there, because the motor fouls on the z-runner when I try to rotate it into position.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Not quite sure how you mean, i just hooked it on there.. But yes there was a slight problem with the x carriage hitting the stepper for a while, But i ghetto fixed it with some tape
Btw, the x-carriage could use if not a biigger bearing,then at least a more robust way to mount the bearing. Hmm since I do have a printer, I could mod it.. nah tape will do for now
Attached some pics to show how mine looks

Several of us have replaced the 9mm x-carriage bearing by a 10mm bearing, as part of the solution to preventing the print head sagging.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].