Drill guide fixture, for directing drills orthogonally into tubes in tubesheets

摘要

The fixture, in a first embodiment of the invention, comprises a flat base having a plurality of mounting holes formed therein, and a platform supported above the base, by a plurality of legs integral with both the base and platform. The base and platform are in parallel planes, and the platform has a guide bushing slidably engaged with an aperture formed in the platform. A lock screw, threaded into a tapped hole formed in the platform adjustably secures the bush in place. Plugs engageable with tubes in the tubesheet are passed into the mounting holes in the base to fix the base securely to the tubesheet, and the bushing receives therein a drill for drilling out a tube, in the tubesheet, which is directly aligned with the bushing. The bushing has an arcuate cut-out formed therein to accommodate the withdrawal of the bushing from the platform, without having to release the plugs, and its replacement by another bushing to facilitate reaming of the tubesheet. The cut-out permits the bushing to be extracted right past the lock screw.