Hopper Work Statement

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I have pictures of modified fab drawings for the hopper and other sheet steel up at


Let me know if you have time to work on any of this to produce any of the drawings by midnight, this Wednesday. We need to generate DXF for CNC torch table. Best packing from 4x8 and 5x10 sheets should be sought.

If we have this by Wed., we can test these on CNC lasers and routers. Otherwise, we can spend until Dec. 10 to generate the DXFs.

If so, we need to secure a CNC torch service that can do it within a week turnaround.

What file formats are acceptable to CNC Torch operators?

If you have time, please let me know what you can do on this so that I can manage completion by allocating appropriate resources. I will ask for help from others, and if I find none, then I will complete the DXFs myself. Unfortunately, we do not have access to a version of Solidworks compatible with the original CAD files, which are found on the wiki at http://opensourceecology.org/wiki/CEB_Press#Mechanical

On this tight schedule, manual generation of DXFs from existing fab drawings is the quickest route, unless someone can generate updated complete 3D CAD. We do not have that capacity off hand.

For the hopper, one could take the original Solidworks and update the hopper. The interface of the hopper to the frame and supports is identical, though the grate attachment has a slight modification.



On Mon, Dec 3, 2012 at 11:46 AM, Chuck Harrison <cfharr@gmail.com> wrote: W.r.t. hole alignment accuracy (avoid match drilling) is there a tolerance requirement we can pass on to a cutting contractor on these hopper drawings?

[+- 1/8 for sheets and holes. It is +/- 1/32 for frame]

I know a local waterjet cutter who is moderately sympathetic to ose. Waterjet process would give a reliable 0.010in tolerance, better edge finish, and genuinely bolt-ready holes. He also makes some nice self-fixturing assembly/weldment designs in aluminum. I'll ask what he can do with the hopper parts.

[Find out file requirements and cost per hour.]

I think I'm seeing a priority on achieving one-day build, even if involves a bit of "cheating" (in the sense of having most of the steel precision pre-cut prior to the build).

[Cheating means documenting the real time of cutting. That time can be substituted directly with our own CNC torch table. The build should take less than 8 hours if we get it right. Since first time is always tough, I expect a 4 hour build once we streamline everything. ]

I'll have a bit of time on a Torchmate table this week. I may see what mounting a soapstone/sharpie on it achieves. Are there particular problems I should look out for based on your past bad experience?

[You need an assembly that allows up-down flexibility while not allowing any side-to-side motion, while allowing for downward-push force. You also need grease resistance and ability to negotiate irregularities in nonvirgin metal.]

(Dec. 7) I believe all hopper individual parts are uploaded now. I am not planning to do the nesting.