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<blockquote data-quote="Trickymissfit" data-source="post: 844208" data-attributes="member: 25383"><p>drawing is interesting, but also done wrong for a manual machine. But still usable (just harder). I see the critical pin hole, but the way they went about it is backwards.</p><p> </p><p>Reaming a 3/16" hole plus three tenths minus none on a manual machine is just insane! And I might add not fun on a CNC machine! Perhaps a SIP or something like that! You got that much run out in the tool holders! And the bearing pack in the spindle is probably more than that by itself (most use ABEC Five bearing sets, and you double the error). Yes it can be done, but not one part after another! That's jig grinder work five days a week. Plus the way the drawing was done allows the locations to seriously stack up.</p><p> </p><p>* here's how I would have done it. Got a piece of gauge stock that was about 3/4" thick. Had the pin holes put in it and ground. Then I'd have the pin holes in the plates done on a separate operation. Use the plate to locate the part to pin hole locations with gauge pins. Then cut the rest of the part. </p><p> </p><p>* this reminds me of a valve body that was used on the M1 tank. It had seven holes that were about six inches deep. Four of the holes had four steps in them that went all the way down to 10mm. Easy? Well first you had to hold a single digit micro. The error was four tenths, plus a total of four tenths compound error and concentricity too!!!! This was off a TACOM drawing, and was totally insane. After fighting it for 18 months a salesman offered to do a reamer for these four holes on his dime! We thought he was insane, but had no money in the reamer except time. The reamer showed up about six weeks later, and it was like nothing we'd ever seen before. He instructed the operators on how to use it, and we never looked back. After a one week trial we found that his run out was solidly in the two tenths range and the micro was outstanding. We bought twelve of them at $4200 a piece. It took roughly six and a half hours to cut one valve body, and another four to check it out per TACOM's specs. I built an air gauge to check the part in about a half hour, so we actually got one part per eight hour shift. I ordered in a dozen or so of brand new Ericson tool holders that were a little undersize in the bore. Had the bores ground dead strait and with as little run out as possible, and this eliminated having to indicate the reamer to the spindle everytime we inserted it. (saved about a half hour).</p><p>gary</p></blockquote><p></p>
[QUOTE="Trickymissfit, post: 844208, member: 25383"] drawing is interesting, but also done wrong for a manual machine. But still usable (just harder). I see the critical pin hole, but the way they went about it is backwards. Reaming a 3/16" hole plus three tenths minus none on a manual machine is just insane! And I might add not fun on a CNC machine! Perhaps a SIP or something like that! You got that much run out in the tool holders! And the bearing pack in the spindle is probably more than that by itself (most use ABEC Five bearing sets, and you double the error). Yes it can be done, but not one part after another! That's jig grinder work five days a week. Plus the way the drawing was done allows the locations to seriously stack up. * here's how I would have done it. Got a piece of gauge stock that was about 3/4" thick. Had the pin holes put in it and ground. Then I'd have the pin holes in the plates done on a separate operation. Use the plate to locate the part to pin hole locations with gauge pins. Then cut the rest of the part. * this reminds me of a valve body that was used on the M1 tank. It had seven holes that were about six inches deep. Four of the holes had four steps in them that went all the way down to 10mm. Easy? Well first you had to hold a single digit micro. The error was four tenths, plus a total of four tenths compound error and concentricity too!!!! This was off a TACOM drawing, and was totally insane. After fighting it for 18 months a salesman offered to do a reamer for these four holes on his dime! We thought he was insane, but had no money in the reamer except time. The reamer showed up about six weeks later, and it was like nothing we'd ever seen before. He instructed the operators on how to use it, and we never looked back. After a one week trial we found that his run out was solidly in the two tenths range and the micro was outstanding. We bought twelve of them at $4200 a piece. It took roughly six and a half hours to cut one valve body, and another four to check it out per TACOM's specs. I built an air gauge to check the part in about a half hour, so we actually got one part per eight hour shift. I ordered in a dozen or so of brand new Ericson tool holders that were a little undersize in the bore. Had the bores ground dead strait and with as little run out as possible, and this eliminated having to indicate the reamer to the spindle everytime we inserted it. (saved about a half hour). gary [/QUOTE]
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