The bed should never have been created with MDF

My funny way.....
I do not have a laser cutter...
I do not have all the necessary tools and often not even necessary screws.

I changed the 3 M3 with M4
I added 2 y-bearing-clamp Printed

Fortunately I'm printing

Dario

..so if I should order a new kit today, what will the bed be made of??

Erik

Erik: MDF. Though when customers contact me who have problems with it warping, I recommend using just 3 points for mounting; the two points against the Y axis extrusion, which are reasonably well supported and will only move a little bit, and the front central hole, between the heated bed contacts. If the MDF is still warped enough to push the front corners up, cut the corners off, so the MDF looks like a T. Though I have to say, I haven't had to do this - all our beds work okay! Must be the low humidity and stable temperature of our print room...

Ian
RepRapPro tech support

Ian, whilst I agree that using just 3 mounting points is best, I disagree about the 2 back points being well supported. They are too far away from the rear plywood rib, and in my build were sagging noticeably.



Worse, the amount of sag varied. If you intend to go on using MDF for the bed support in the kit, you could at least move the plywood rib to be behind the rear y-rod instead of front of it, so that the rear corners of the MDF are closer to the ends of the rib. Although I doubt that will be sufficient to completely eliminate the problem.

Edited 2 time(s). Last edit at 03/18/2014 06:45AM by dc42.

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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].

I think I said 'reasonably well supported'... at least, it doesn't droop as much as the front corners!

The current development version has the y-cross-rib on the other side of the back Y smooth rod, and has support going out to the corners of the bed insulator. The bearing clamps now hold the belt too, and the Y axis motor mounts are on slots, to provide belt tensioning. All of this will be able to be fitted to the current machine, though the back Y axis smooth rod has had to move, so the lasercut parts (y-axis-end-plates, y-cross-rib, y-rib and bed insulator) are all changing. The bed insulator will probably end up being made out of something more substantial than 3mm MDF, but we're still playing with all of this. We're also flipping the motor to the other end of the axis, as the homing behaviour is annoying! I think this should address all of the Y axis problems. The heated bed will be mounted on 3 points, and we'll be using the picture frame Swiss clips rather than foldback clips.

That's all I can say at the moment about forthcoming changes. I know it's annoying telling people about what's coming without telling them when, but sorry, I don't have a date yet for any of these changes! I expect we'll do kits of the lasercut parts for those wanting to change.

Ian
RepRapPro tech support

Ian, those all sound to me like good improvements. I look forward to the new parts becoming available.

Will you also be making the acrylic side pieces longer, to increase the spacing between the two smooth rods? This would make it easier to align the rods so that there is no twist between them, and reduce the effect of any residual twist.

Regarding the Swiss clips, will you be including lasercut MDF parts for them similar to the ones I show here [forums.reprap.org] ? They make it much easier to remove the clips, especially when the bed is hot.

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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].

I don't think the rod spacing has changed, and I don't think we've had much of a problem with it. The bed compensation can take care of any twist in the rods, so long as the bed edges are co-linear, which they should be with a 3 point mounting.

We're still playing around with fitment of the clips, nothing final yet.

Ian
RepRapPro tech support

Don't forget there is now the option of laser cut 3mm aluminium beds

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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.