Small Epoxy Granite Filled "Watchmakers Lathe" Design Question

ACHiPo said:
Nice! How deep is the granite epoxy? How many layers did you cast it in? How much did it tweak the cast iron bed?
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I don't think it moved the bed much. The cross section is only about 1.5" x 1.5" so really not much. I was just hoping to get as much damping as possible.
 
I surface ground the the dovetail today and I've been trying to think of some way to measure across pins without the flat section of the dovetail. I was thinking about putting it on the surface plate upside down and making some kind of measuring fixture, but I'd rather not have to make something.

Anyone have any ideas?
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I take it you are needing to have a dimension so you can make the saddle ? If that is the case it won't be that critical because of the gib . I would measure the widest part (on the top) , decide your gib thickness . Now that is your saddle dimension , then fit the saddle on and measure for the gib . Piece of cake your the man .
 
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westsailpat said:
I take it you are needing to have a dimension so you can make the saddle ? If that is the case it won't be that critical because of the gib .
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Yea I'm not too worried about the width, but I would like to check the profile by mic-ing in several spots along the length to make sure the profile is in spec. If it's out the saddle will be loose on one end and tight on the other. I had some issues indicating the whole thing in on the sine magnet and would love the piece of mind knowing if the two sides are straight.
 
OK , I follow . This might be the right time to hone your scraping skills . Any chance you can get some CMM time ?
 
westsailpat said:
OK , I follow . This might be the right time to hone your scraping skills . Any chance you can get some CMM time ?
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My school doesn't have a single CMM on campus (super underfunded engineering program -- I'm transferring after the summer). Although a CMM would be perfect, sadly that option is out.

I would love to scrape all the ways on the machine. I really don't like the idea of ground on ground cast iron, I am adding oil grooves to mitigate any wear issues. We don't have any scraping equipment and even if a cobbled together a scraper, wouldn't I need some 45 degree reference to blue up the dovetail flanks relative to the top after scraping the top, or am I overthinking this?
 
Bummer about the CMM , but it would only tell you that you have a problem , you will know that once you have the saddle fit . OK quick and dirty . On a caliper , fit two diameters I would groove two pieces of round stock and hold them in place with a set screw on the caliper jaws . Set "0" and measure away . Those measurements will only differ at most .0005 , will that be good enough ? Maybe hi spot blue and stone down .? For your last question , that sounds right and no I don't think you are over thinking it . I think you have a good handle on it .
 
I'm sure all of these questions are getting old, but I don't know who else to turn to.

If I were to verify that the way dovetail is dimensionally how it should be, could I use the as-ground surface as a scraping reference for the saddle, or is it essential that the dovetail way be scraped first?
 
Do a search on this site , type in way scraping . Lots of info there , plus somewhere in there is a professional scraper , I forget his handle but it shouldn't be hard to find he has a paid commercial account .
 
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