Is there an stl file of the bed ?

Hi,
I wanted to get a drawing of the bed in order to get some measurements so I can make one out of aluminium. There is an stl of the bed-rib which I can use. The Ormerod repository only seems to have bed.dfx. I am using DesignSpark Mechanical to generate the measurements, which unfortunately will not import dxf files. I cannot seem to find a tool that will convert this dfx into an stl file which I can import. I can look at bed.dxf with EModelViewer but cannot use this to export it to another format. Could someone convert this for me or show me a free tool that will do the job. I just want to take measurements so I can make the part without having to tear down my Omerod to use its bed as a template.

Could someone also tell me what function the cardboard piece has. Is it thermal insulation or to absorb jolts etc. I ask because I am considering using some Silicone rubber I have, to cast a replacement mat for the cardboard. I thought it would be tougher but just as forgiving. Is this a good idea?

Alan

Quote
alanbattersby

....Could someone also tell me what function the cardboard piece has. Is it thermal insulation or to absorb jolts etc. I ask because I am considering using some Silicone rubber I have, to cast a replacement mat for the cardboard. I thought it would be tougher but just as forgiving. Is this a good idea?

Alan

the cardboard piece is for thermal insulation, so silicone rubber would be a bad idea, I tried using the very same between the bed and glass and it conducts the heat very well

Erik

Here you go Alan
I had to make it into a solid before I could export it as STL so I made it 3mm thick. The cardbooard as far as I am aware is for thermal insulation.

John

..but it sure looked pretty and sticked to the alu plate and glass like removable glue, and that was my cunning plan




Erik

ditto on the insulation and silicone alone being a bad idea - anyone know any blowing agents for two part silicone? Air/gas entrapment would aid the insulation (primary role), and soften it too - I'm pretty sure that the flexibility of the bed, up to an extent is a good thing, and having a compliant insulator would be the way to go particularly if replacing the mdf. The cardboard itself does add to the springiness of the bed (which heads off head crash issues), and on a rigid frame it may be helpful to have something even softer (and more elastic) than cardboard to give under the glass then spring back.

I've been mulling over the merits of various materials I have to hand for this (should I get round to making a rigid bed) : - 1mm neoprene foam, 3mm corolux, 2mm cork, 2mm polythene foam sheet (hard flooring underlay, on a roll from homebase), two part silicone (not much chance without foaming) or space filling PU foam - most of these have a lot of merits and all have a working temperature high enough for the bed, and if I do make a rigid bed I'll compare some with corrugated cardboard (which is probably a winner on most points and maybe overall depending on how you weight the benefits, particularly if price has a positive weighting )

Ray

[edit] indeed ormerod168 that silicone does look good - and holding the glass to the heat spreader would also be a good thing - maybe it would be most useful between the pcb and the aluminium heatspreader and between heatspreader and glass to aid heat transfer as a thin "solid " rubber sheet, and below the pcb as a soft blown foam to stop slippage between these plates?

Edited 2 time(s). Last edit at 01/24/2014 05:01PM by rayhicks.

John,
Thanks very much for the stl and thanks to everyone else for the comments on thermal barriers.

Alan

Quote
rayhicks

I've been mulling over the merits of various materials I have to hand for this (should I get round to making a rigid bed) : - 1mm neoprene foam, 3mm corolux, 2mm cork, 2mm polythene foam sheet (hard flooring underlay, on a roll from homebase), two part silicone (not much chance without foaming) or space filling PU foam - most of these have a lot of merits and all have a working temperature high enough for the bed, and if I do make a rigid bed I'll compare some with corrugated cardboard (which is probably a winner on most points and maybe overall depending on how you weight the benefits, particularly if price has a positive weighting )

Bunsen Burner Mat (Calcium Silicate) ? [www.ebay.co.uk]

yeah djb, that'd be good for insulation indeed

Ray

Re Bunsen Burner Mat (Calcium Silicate)
Lightweight, Flat, Rigid (especially 4.5mm versions - but I have come across thinner mats ) and it can cope with very high temperatures
Would have to be careful of dust when cutting it

Daryl

How about printing a coarse honeycomb structure out of pla then putting a layer of silicone on that to absorb vibrations, would that work?

Going back to the original question, Inkscape [www.inkscape.org] is a vector drawing tool (like Adobe Illustrator) that can import dxf files. It's free, and pretty good!

Ian
RepRapPro tech support

Ian,
Downloaded Inkskape on my PC , could load dxf but not save it in any format that DesignSpark Mechanical would import, and stl is not a save option in the windows version I am using.

Alan

Sorry, I suggested Inkscape as I thought you wanted to take measurements, and this would be quite easy to do in Inkscape.
Another option would be to import the dxf into OpenSCAD and use it's dxf linear extrude function to create an stl. OpenSCAD can be a bit fussy about dxf files (it needs everything as line segments, no curves), so you need to open the dxf in Inkscape, edit it, then save as a simplified dxf to use in OpenSCAD. There's a tutorial here: [repraprip.blogspot.co.uk]

Ian
RepRapPro tech support

This is how I got the dimensions for the bed and it might help for future reference:

In DesignSpark, open the Ormerod.step file found in the Ormerod-Master zip - this is a fully assembled model of the printer. You are told that the drawing is read only.

Deselect everything in the structure list, open the Y-Axis tree and select the BED component - just the bed plate is displayed.

You can select and copy the component - paste it into a new design and cast dimensions over it using the PULL tool with the ruler option.
Or you can SAVE AS an stl/dxf or other supported file format.

I'm guessing that the STEP file may not be updated immediately/regularly as components get modified but it's a good starting point for jobs like this.

Edited 1 time(s). Last edit at 01/27/2014 05:46AM by markm.

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Mark

Ormerod #350

Does anyone have the STL file kicking around for the aluminum bed upgrade?

Thanks!

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Green Machine - slowly becoming multicoulored!