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Thread: Project: Precision Vise

  1. #1
    Senior Member caster's Avatar
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    Project: Precision Vise

    I wanted to build a precision vise to use with my 3-in-1 lathe/mill/drill. I found a design on the web and I started to build as designed. I started this project last fall but winter shut me down before I could complete it.



    I cast with greensand but I used foam to build the pattern. I have a hot wire cutter, roughing shapes is very easy. My intention was to cast billets which I would machine, but this was very wasteful and time consuming. I got the base formed and I was getting ready to cast the next part when it dawned on me, why do I need to bolt the parts together when I can cast it as a single part. Additionally I can make a core that would make machining simpler. So I built a new vise pattern out of wood and an mdf pattern for the core.



    I have never made a core before, there is a first time for everything. I purchased some Sodium Silicate and now I was searching for a way to generate carbon dioxide to harden the core. I don't have any compressed CO2 so I thought I might used baking soda and vinegar but then I remembered my kids making geysers out of diet coke and mentos. I cut an empty coke bottle in half, placed it and the core in a small cooler added ~2" of diet coke dropped two mentos and closed the lid. I didn't know what to expect, I removed the bottle neck so I was fairly sure that I wont have a geyser but will it harden the core.



    Worked like a charm! I wanted to be certain that the CO2 would work so I left the cooler sealed for an hour. I have seen vids where the core hardens fairly quickly with CO2 gas but I was uncertain how much CO2 would be released from the diet coke. The results were great, I got a hardened core.



    I had an opportunity to cast this morning, I estimated the weight needed at 5 1/2 lbs of Aluminum. This is the first casting with my newly resurfaced furnace and the new oil burner. When I casted the original part in the fall it took about 20 minutes from start to pour, this new burner got the job done in 10 minutes. It takes me longer to set up the furnace than it takes to melt and cast.



    I had a bit of shrinkage next to the riser, I knew that part of the pattern was bulky and probably would shrink so I places a 3/4" riser. It was not enough, I needed either a taller or wider riser. The pattern was made over-sized with the intention to mill it down to size so this may not have any consequence. I still have the slider to cast and then machine the castings, more to follow.

    EDIT: cut the gate and riser, the shrinkage was 1/8". The surface is OK a little mottled but it will be machined, but I am undecided whether I should recast to eliminate the shrinkage.





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    Last edited by caster; 08-08-2015 at 04:42 PM. Reason: Added pics

  2. #2
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    DC + mentos = cured core. You sir are the hero of the day.
    I'll be interested to see what others have to say about your shrink. Im thinking having the thick cross section nearest the sprue with a big blind riser. Keeping an open riser that far from the sprue hot long enough to be effective for that size of a section without it being huge and/or being insulated seems challenging. Good call on the extra machining material. Hopefully it will be enough.

    Pete

  3. #3
    Senior Member caster's Avatar
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    Thank you.

    I was thinking of making the size of the jaw 1" but 7/8" is not bad I can gain some additional height by making the side rails a bit smaller. The beauty of casting is that a redo is fairly cheap. I was listening to a conversation between two guys, one used imperial measurements the other metric. The imperial guy was describing a part he made which was 1 inch in size, as a courtesy he translated to metric and said it was 2 1/2 centimeters. The metric guy being accustomed to using integral units asked why it could not be 2 or 3 centimeters, why was it 2 1/2? I wanted the vise to be 1 inch but at 7/8 it will also work.

    I thought brass jaws would work, softer non marring. But I can also make a pair from steel.

    Its not visible on the pattern but I placed a 1/8" rectangle on the bottom which secured the core to the bottom. Didn't think of the screws for the core. I guess using sharpened nails or pins will make it like thumb tacks/push pins and secure it in place.

    Caster

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    Well I recasted the part. I moved the sprue near the block added a 1 1/2" riser kept the 3/4" riser on top of the block and added a 3/4 riser at the far end. I am happy to say I can't detect any visible shrinkage.




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    Excellent thread... Casting a Kurt knock off for my baby vertical mill has always been a vision of mine. I'll be watching your progress very closely.

    I have hopes to use iron for mine. Just need to sort out a design, pattern making, casting iron, oh and find enough time to attempt the fore mentioned..lol

  6. #6
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    I was productive this morning and cast the slider. Now to machine the parts.





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    I got a few minutes in the shop and was able to mill the first reference surface. The casting seems good no noticeable poracity although a some greensand must have fallen and one corner did not fill completely. It will be reduced once I mill the adjacent sides although its an imperfection it will not hinder the working of the vise. The fly cutter leaves visible marks on the Aluminum but it cant be felt. It has a smooth surface which will polish well.



    Caster
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  8. #8
    Nice work, wish i could machine the vice i'm casting. Maybe in the lathe i'm casting?!
    I found that trying to find what I need and then make it work with what I have, is more trouble than designing what I want and doing it.
    me

    "Quick decisions are unsafe decisions."
    Sophocles

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    Got some more time and machined the first side perpendicular to the bottom.



    Then I machined the other side perpendicular to the bottom and parallel to the first side.



    And then I broke the mill.... It broke once before and I fixed it. This time its simple a lock screw that pinches the quill broke. I need to make one, simple but time consuming.




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    Last edited by caster; 08-10-2015 at 09:13 PM.

  10. #10
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    I fixed the quill lock and squared the base.




    Caster
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    Last edited by caster; 08-11-2015 at 04:39 PM.

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