Recent content by jasonh

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  1. J

    Melting chromed-brass bathroom fittings

    To make my brass parts I collect and melt non-plated brass plumbing fittings. The exact original alloy is a bit of a mystery other than that it is originally cast and presumably can be re-cast. I often find the resulting part has a very tough outer layer that is hard on tools. If you can get...
  2. J

    CAD, CADCAM on Linux

    Here's a tool/library I wrote (multi-platform). deadsy/sdfx I use it to generate models for 3d printing. I haven't used it as input for a metal cutting CNC machine but if you can turn an stl into a suitable tool path you're golden. E.g Here's an ETW Wallaby cylinder head.
  3. J

    Greetings from Germany

    Sehr gut. Du bist der Meister des Kleinen!
  4. J

    Plans for casting

    The Dave Gingery Books have a few engines all of which require home casting and entry level machining. I can vouch for the stirling engine and the atkinson engine as being good runners.. The atkinson "differential" engine is apparently a PiTA to get working.
  5. J

    camshaft design Possibly not the answer you are looking for, but I wrote some code (Go) and one of the things it does is cam design. Flat flank and three arc cams can be designed from parameters. E.g. Here's a ETW Wallaby camshaft with 3-arc cams.
  6. J

    Where to buy acrylic sheet in the US? Online or retail stores in CA, OR, WA.
  7. J

    Trying to understand cam shaft gearing. Help needed.

    btw: z = "zahn" = "tooth" E.g. zahnarzt = tooth doctor = dentist. See, it all makes sense!
  8. J

    Arduino based CNC

    A common el-cheapo solution for using arduino as a cnc machine controller is: arduino (running grbl firmware) + grbl shield to give 3 axis stepper control. That combination works well for what you pay. Q- Is arduino limited as a machine...
  9. J

    Making a set of Wallaby castings

    I crowd-sourced the resolution of the engine block casting defects to the assembled sandcrabs of alloy avenue. They came up with some pretty good suggestions of things to fix and things to try. While in this day and age it is possible to buy software packages that simulate the pouring and...
  10. J

    Making a set of Wallaby castings

    Ok- let me see if I can pour an engine block.... I have a core. It's still a ***** to get out of the core box. It broke in a couple of places, but I fixed it with wood glue. I have a pattern with core prints attached. The patterns were a good pull from the sand. Careful attention to pattern...
  11. J

    Making a set of Wallaby castings

    I've been slouching towards getting the engine block cast. It needs a core and therefore a core box. The core makes a hole in the casting for: 1) Through holes for the cylinders. 2) A water jacket around the cylinder liners. 3) Crank cavities at the base of each cylinder. 4) A camshaft gallery...
  12. J

    My first I.C. engine, a variation on the theme of Webster

    I tried putting an endmill in a drill chuck once- and found at that it wasn't a good idea. I guess drill chucks aren't really built for radial loading. I hadn't heard that collets and endmills were bad- in fact I thought it was a good idea- at least I've never had a problem with it.
  13. J

    Making a set of Wallaby castings

    Ok - so I wasn't happy with surface finish of the brass, and machining it was a PITA. Time to take some (hopefully) corrective actions. * Try a proper gating system. Some of the posts I saw at alloy avenue suggest a well at the bottom of the sprue along with a narrow/deep runner. * No sprue...
  14. J

    Horizontal stirling motor

    That has the same basic layout as 1/2 of the Dave Gingery Stirling engine. I've built one of those.
  15. J

    Casting con rods

    Yes - I stand corrected. It looks like most commercial engines used forged steel for the conrods. But- some engines do use cast/forged/billet conrods made from Al. It looks like it's mostly in performance applications (race cars, dragsters, etc.) where the benefits of having a lower weight...