First engine and its from a pm research casting kit

Discussion in 'Engines From Castings' started by Rb72, Jan 25, 2019.

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  1. Jan 25, 2019 #1

    Rb72

    Rb72

    Rb72

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    I am starting to build a pm research 2a steam engine from their casting kit. Have not worked with castings before and have run into a problem with how to hold the cylinder head casting to machine it. Its a roundish disk about the diameter of a quarter and a little over .175 inches thick. I need to turn it down to the diameter of the cylinder casting and then face one side to total a thickness of .125. I found a link where they sandwiched a part between the chuck and the tailstock using double sided tape, emery cloth on the chuck side and puck on the tailstock side.

    Is that the standard method or is there another way to handle this? Any suggestions would be appreciated.

    I am just a hobby machinist with not alot of experience at this point. Based on the threads I have followed on the forum this is small potatoes compared to the amazing builds being done by others.
     
  2. Jan 26, 2019 #2

    deverett

    deverett

    deverett

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    I would hold the casting in your chuck to face off one side first.
    Then you can do basically what you have found out, but I would put a sacrificial piece of metal between casting and faceplate - you don't want to gouge it trying to get the final thou cut! That means you will need two pieces of double sided tape. Before sticking the casting, put a central centre pop on the machined side then put your tailstock centre into the pop mark and this will centre the casting as you stick it to the tape. You can leave the tailstock centre in the pop mark for security.

    No doubt others will have their ideas, but this will get you going.

    Dave
    The Emerald Isle
     
  3. Jan 26, 2019 #3

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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    I've made several PMR steam engines. The company's castings are often lacking in adequate material to grab. So when you make these odd types of "clamping" setups, two comments:

    1. Light, Light, Light Cuts
    2. For Lathes: Low, Low, Low Speed.

    ...Ved.
     
  4. Jan 27, 2019 #4

    Rb72

    Rb72

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    Thanks for the advice and help. I will be giving that a try. I will be testing the method out on some scrap before the real deal. I think that’s the only part that is a challenge to hold so far anyway.

    Rick
     

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