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Recent content by matra

  1. matra

    Old criterion vs new precision import boring heads

    Over the years I was using quite a number of boring heads; many makes in many sizes. All will produce consistent bores once adjusted and locked, the big difference is the quality and accuracy of adjustment and the time and effort to get the right setting. I have had good experience with the...
  2. matra

    Measuring the alignment of a slide dovetail with the adjacent face.

  3. matra

    Surface grinder coolant needed?

    I cannot imagine doing surface grinding without a coolant - especially for precision work. Working with coolant is actually a much cleaner process, with no dust to settle on other machines (even though I have my grinding in a separate area some dust can always get through) and in the lungs, less...
  4. matra

    Remagnetizing a weak magnetic v-block

    Yes, I was using a similar approach using a large capacitive discharge spot welder. The wire (or rather a 1/8" copper bar in my case)should be secured in the gap, I used wood wedges.
  5. matra

    Markforged Metal Printer- Thoughts/Information?

    I knew that 3D printed metal parts are expensive to make in a system like this, but only reading this realized how many more hidden costs are there - and this even not considering the amortization cost of the machine, the cost of the real estate it takes, and the fact that you can probably make...
  6. matra

    Need a 127 tooth gear

    5/8" is actually not that thick. I was getting quite a good cuts even on 2" steel. And I did cut gears on a watrejet. Most machines have quality settings and on the higher quality the cut is slow but nice. And it does take a little tweaking with all the other waterjet parameters. The gear will...
  7. matra

    How to remove engraving

    I agree in principle. However sometimes one encounters a terrible scribble probably done by a troglodyte using a flint. And often there might be some other dents and marks. I must admit that on three or four occasions I did not hesitate to erase marks like this from machinist squares, parallels...
  8. matra

    Which material for change gears?

    Yes, Phenolic C (C for canvas filled) is the right material, though there is a wide range in quality. I cannot remember who was my original supplier as I do have a large stock bough decades ago, but the right material is not that brittle at all. This gear was made for the "Type 70 Servo Feed"...
  9. matra

    Which material for change gears?

    I am not sure what material you do have in mind. I've cut dozens, maybe hundreds, gears in canvas reinforces phenolic, many out of material cut out from a plate. The canvas in the stock is arranged in many layers creating a random pattern of fibres that is very strong. Here is one of two...
  10. matra

    Machining pockets with ultra-thin (.01mm) floors: methods, fixtures, part integrity

    Good application for electron beam welding if part done in stainless or similar. Prepare a 0.01mm pocket at the bottom of your part and make the foil disc same diameter as the pocket. I assume a similar results can be achieved with laser welding, but I have experience only with EBW and this...
  11. matra

    Which material for change gears?

    A very good material for gears is canvas reinforced phenolic. It is strong, quiet and easy to machine (though dusty if machined dry and needs dust collection). In fact some machine tools, lathes, for example, do have phenolic gears in the gearbox.
  12. matra

    What tools to mill black zirconia

    Zirconia, alumina, beryllia...all are hard ceramics that can only be machined by grinding with diamond tools. Cutting out of flat sheets can be done on a waterjet.
  13. matra

    Is this South Bend lathe still a good buy?

    I think that as a beginner you should not buy a lathe in unknown condition, especially since the one you showing seems in poor shape. As a beginner you you will have enough challenges besides dealing with lathe related problems. And there is no shortage of good machines at very reasonable prices.