The Offcial Machinist Thread: Revised 01/04/2014

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velocity3x
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Mon Nov 14, 2011 5:43 pm

Gun Freak wrote:What's the significance/gain of using a live center over a dead center?
A dead center is used in combination with a faceplate (instead of a jaw chuck) and lathe dogs. A dead center rotates with the face plate and work piece. A live center is used in the tailstock and allows the workpiece to freely rotate.
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Gun Freak
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Mon Nov 14, 2011 5:51 pm

Thanks guys :)
Think one of these would work as a live center?
http://www.mcmaster.com/#ball-bearing-screws/=exosny
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Mon Nov 14, 2011 5:55 pm

Probably not very well if at all due to the fact there is no point to hold the work piece centered.
velocity3x wrote:A dead center is used in combination with a faceplate (instead of a jaw chuck) and lathe dogs
I'd like to see how your setting that up.
Look if you must.
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velocity3x
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Mon Nov 14, 2011 6:17 pm

jrrdw wrote:I'd like to see how your setting that up.
These are pics I found in the net. The last pic shows the dead center in the spindle bore of the lathe and a live center on the tailstock. The lathe dog is homemade. This setup is used for turning between centers. Turning between centers is how you make a crankshaft from a chunk of billet.
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Gun Freak
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Mon Nov 14, 2011 6:52 pm

Probably not very well if at all due to the fact there is no point to hold the work piece centered.
Ah yeah you're right. Is it ok for us to be discussing lathes here or should I just stick with the Offtopic?
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jrrdw
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Mon Nov 14, 2011 7:22 pm

Gun Freak wrote:
Probably not very well if at all due to the fact there is no point to hold the work piece centered.
Ah yeah you're right. Is it ok for us to be discussing lathes here or should I just stick with the Offtopic?
This is the "Machinist" thread so it's ok.


@velocity3x
It's hard to see the dead center but I get how it works. I was searching Youtube (keywords: using lathe dogs) for that set up in action but didn't really come up with anything worth posting...
Look if you must.
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Mon Nov 14, 2011 7:24 pm

Ok, in that case, DIY lathe V3 in design stage.
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turner
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Tue Nov 15, 2011 7:34 pm

abou the part earlyer, i wanted to make a sielencer for a qb78 air rifle. the barrel is 14.95mm od. do you think that making bushings to then slip a larger pipe onto the barrel be easy? i think im going to get a tube for the outside tommorrow.
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Wed Nov 16, 2011 12:22 am

turner wrote:do you think that making bushings to then slip a larger pipe onto the barrel be easy? i think im going to get a tube for the outside tommorrow.
It's a faily simple job, especially if you remove the front sight. Beware of ordering a complete silencer if you're in the US though.
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Technician1002
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Wed Nov 16, 2011 3:51 am

New video is online for centering with a 4 jaw chuck. Enjoy.
[youtube][/youtube]
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sharpshooter11000
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Sun Dec 25, 2011 2:25 pm

Don't know if this is the right section but does anyone have any good projects for a beginner machinist? I just got a small lathe for Christmas and I'm wondering what to make. Thanks in advance :)
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Sun Dec 25, 2011 3:16 pm

sharpshooter11000 wrote:Don't know if this is the right section but does anyone have any good projects for a beginner machinist? I just got a small lathe for Christmas and I'm wondering what to make. Thanks in advance :)
1st project: Simple machinist jack. You need 2 bolts. 1 2X4 hex bolt and 1 9/16ths X 2 hex bolt. Chuck the 2X4 bolt and drill it for tapping the 9/16th threads. Screw them together and you just built a simple machinist jack.
Look if you must.
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sharpshooter11000
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Sun Dec 25, 2011 4:45 pm

Thanks jrrdw :) I'll make one of those tomorrow, once I figure out how to cut threads. Any simple spud gun sorta things?
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Sun Dec 25, 2011 5:42 pm

Use a tap to cut the threads unless you have a really small boring bar lol.

Spudgun related: Pistons, smooth and true up cylinders, spark plugs for combustion's, customized washers and shims. The list can go on and on, it depends on what your building.
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JDP12
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Thu Dec 29, 2011 12:40 pm

Ok moving this to this topic from the one I started..

Need some .25" round stock steel, preferably hardened steel, turned down to a point and a hole drilled in the back. Please give me an estimate on pricing per one unit, and I'll let you know how many I'll need.
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