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Resetting a broach with RKIII fixators
This project consisted of a horizontal broach for engine blocks being rebuilt. The broach was made in the early 60’s and was having considerable problems holding tolerances and high tool usage. The broach OEM was overseeing the rebuild and wanted to find out how flat and straight the ways were.
Upon arriving and setting up the Hamar L-723 tri scan laser we discovered that one end of the broach was leaning back almost .500” and the opposite end was leaning back approximately .250”, while the table’s in the middle of the broach were leaning forward .125”. The flatness of the rails varied about .090”.
When performing a visual inspection of the foundation we observed many broken feet that were supposed to hold the broach down and at each end the hold down bolts to keep the broach from translating were both sheered off. These sheered bolts were 1-1/2” diameter bolts. After seeing this we recommended that the broach needed to be rigidly held and supported. Due to the length and weight of the broach and the translational movement RK III fixators were used. The old (feet) and jack bolts were cut off and out and new gussets were made.
We cored new holes and used Unisorb V-100 standard epoxy grout, we also made new stops at each end of the broach, only we now used two at each end.
Where the tables flip the part in and out of the broach there was no support at those points, so we had to torch through and affix the RK III's at those points also.
This whole procedure incurred more time and expense to the rebuild job, but the broach is now very stable and running well within tolerance limits. The operator said after running for a couple months that the tool change frequency dropped dramatically and that the parts are running great. Previously he had to have tradesman continually shimming and trying to keep the part in spec.
After we had pulled the old jacking screws out and seeing how they were “washed out” it was clear that the broach was moving side-to-side and front to back constantly.
Resetting a broach with RKIII fixators
