[How do I?] Setup CNC to ream a 12mm hole

[countryguy]

Hi Folks. Looking to reduce my cost and simplify a design. Currently I run a 12mm shoulder bolt thru a 12mm linear bearing embedded in aluminum. In short, the shoulder-bolt simply rides and slides inside the 1" long linear bearing.

Someone we all know and trust here suggested I could try to eliminate the linear bearing assy. To do this, I should try to setup a 12-mm precision reamed hole. Then use the .002 under shoulder bolt directly into the reamed hole.

I have wanted to learn how to do a precision hole for a time now so this is a perfect 1st ream project. I'll dig and read a bit, but as for a CNC process and order of ops what size holes do I drill first? Do I need the 11 or 11.5mm reamer and set the process up to 12mm

thanks everyone.
J

 

[JimDawson]

Spot drill, Drill, Ream

I would use a 13mm spot dill, that way you can drill & chamfer in one op. Then a 11.5 mm drill. Then ream with a boring cycle, G85 if you have that available. The G85 plunges and retracts at feed speed rather than rapid retract like a G81

 

[countryguy]

Thanks Jim. 13 in a spot drill. Gotchya. (yea!... more tooling will get the stuff on order.
thanks! J

Centroid can do G85 Boring & G89 Boring with Dwell

 

[countryguy]

Ps--- I'm in Boston again this week, but my Ditron 1um Gen II Mag. Read heads for the soon-to-be Mill X and Mill Y positioning are sitting on the porch. Upgrade soon!
(who needs firewood for 2017 anyway.. that can wait!).

 

[JimDawson]

The ones for my lathe DRO were supposed to be here on Wednesday, but it looks like someone screwed up and put them back on the plane to China rather than to LA from the Japan hub. Back in Japan as of the last tracking update, so maybe I'll get them on Thursday.