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Posted: 9/3/2016 5:05:43 PM EDT
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The "Why no 80% Monocores" thread got me thinking. If I was to decide I wanted to mill my own monocore, what would be the process?
Mostly I'm curious whether it would be better to start with a bar and bore it for the bore diameter and then do the fancy cutting, or if the boring should be done afterward. For a .22LR can, it could be short enough to use a mini-lathe, but are there boring bits that would work on such a tool that would be appropriate for that? What other issues am I not thinking of? |
| Drilling a long hole and keeping it straight really isn't a big deal. Make sure you clean up the face, and get a good spot drill. Start the hole with a good jobber or screw machine drill the same size as your long drill and go at least an inch or 2 deep to get a straight start. On a lathe, your tail stock needs to be straight and on the center line of your spindle. Proper feeds and speeds are important to make sure your tool lasts. A properly sharpened drill with equal cutting edge lengths, and a point in the center is what makes the drill go straight. Drill the hole first and then mill the monocore. Drilling through interruptions sucks and can cause the drill to wander. |
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Quoted:
Drill the hole first and then mill the monocore. Drilling through interruptions sucks and can cause the drill to wander. This is what I was looking for. I saw issues with keeping the long boring job straight. I wasn't sure if there were other problems, which your response really points out. |
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Assuming you have access to actual machining equipment . . .
Find material slightly larger than the OD you want, drill it with a center/short drill/longer drill in either a lathe or mill, then turn the OD with the part between centers. The requirement to drill a perfectly straight hole that is concentric with the outside surface is negated when you turn the OD between centers at the end as machining the OD at the end is obviously going to put it concentric with the hole you drilled. |
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Quoted:
Assuming you have access to actual machining equipment . . . Find material slightly larger than the OD you want, drill it with a center/short drill/longer drill in either a lathe or mill, then turn the OD with the part between centers. The requirement to drill a perfectly straight hole that is concentric with the outside surface is negated when you turn the OD between centers at the end as machining the OD at the end is obviously going to put it concentric with the hole you drilled. That makes a lot of sense for managing concentricity. Would it be better to turn the OD before or after milling the "details" of the core? |
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That sounds like a much more complex setup than a mini-lathe would be capable of.
I'm rather glad I asked all of this before doing much pricing. The best prices I can find on mini-lathes are in the $600 (for anything with decent reviews and decent capabilities), such as the Grizzly 7" x14" lathe. While it's fairly compact (and a much better price than the smaller Harbor Freight 7X10 or 7X12 lathes!), it's more complex than I am ready to dive into. It's going to be quite a while before I can set aside time to learn how to use one... Thanks all for the help! |
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Square bar stock.
Drill / machine mount end and drill through. Mill core as needed using square body to index. Turn body between centers so bore is concentric to OD. Fit OD tube. Engrave. Paint / powder coat / anodize / ceracote - Shoot untill dirty - Post brag pics... File next Form 1 - repeat.. 
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