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techtalk:ref:tools147 [2020/08/24 23:19] hippysmack [Rocker Arm Bushing Reamer (94804-57)] |
techtalk:ref:tools147 [2021/06/25 02:15] hippysmack [Reamers] |
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| * [[techtalk:ref:genmsr11|Cutting Oils, Soaking Oils and Lubes]] | * [[techtalk:ref:genmsr11|Cutting Oils, Soaking Oils and Lubes]] | ||
| * [[techtalk:ref:tools030#general_drilling_and_tapping|General Drilling and Tapping]] | * [[techtalk:ref:tools030#general_drilling_and_tapping|General Drilling and Tapping]] | ||
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| + | Reaming is the process of cutting a larger hole to a specific diameter. ((oldmetal of the XLFORUM http://xlforum.net/forums/showthread.php?t=51086)) \\ | ||
| + | The purpose is to not only make the hole the correct diameter but also to align it and square it with the part that goes into it. \\ | ||
| + | This usually means aligning it with a hole, or bearing, opposite and at the other end of a shaft. \\ | ||
| + | Reason is because the cast part can not be manufactured to hold the required alignment tolerances (and in the case of aluminum, the required abrasion resistance). \\ | ||
| + | So, the cast part is made to accept a bushing made of a harder material that can endure the force and abrasion potential that goes with it. \\ | ||
| + | The bushing is then inserted into the casting but, because of the nature of casting, it is not in exactly the right place both in horizontal position and axis angle. \\ | ||
| + | So, the bushing is made with a smaller diameter hole than is required to allow for the precise alignment by reaming. \\ | ||
| + | Line reaming is the process of using additional support features found in the engine to help provide shaft alignment. \\ | ||
| ====== Types of Reamers ====== | ====== Types of Reamers ====== | ||
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| * This usually means line reaming (aligning it with a hole, or bearing, opposite and at the other end of a shaft). | * This usually means line reaming (aligning it with a hole, or bearing, opposite and at the other end of a shaft). | ||
| * Line Reaming: ((oldmetal of the XLFORUM http://xlforum.net/forums/showthread.php?t=51086)) | * Line Reaming: ((oldmetal of the XLFORUM http://xlforum.net/forums/showthread.php?t=51086)) | ||
| - | * Line reaming is the process of using additional support features to help provide shaft alignment. In this case of reaming cam bushings, it is the cam cover and its associated bushing that is used to "line up" the reaming tool so that the bushing hole in the right crankcase is cut to the correct size diameter, is properly located horizontally, and is cut square to the intended shaft axis. | + | * Line reaming is the process of using additional support features to help provide shaft alignment. In this case of reaming cam bushings, it is the cam cover and its associated bushing that is used to "line up" the reaming tool so that the bushing hole in the right crankcase is cut to the correct size diameter, is properly located horizontally, and is cut square to the intended shaft axis. |
| + | * Flute spirals. ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717904&page=3)) \\ All 3 reamers here are "right hand cut" meaning they all cut while being spun in the same direction as a drill bit. \\ Reamers come in different cuts as in straight, forward spiral, reverse spiral etc. Looking at the last one, you may think is cuts in reverse rotation but it does not. | ||
| + | * Straight reamers are by far the least expensive to buy. It also makes holes that aren't true cylinders. \\ They can have a lobed wall shape. This lobing goes hand in hand with amount of material being reamed away. \\ In our case it's a small amount of removal so the lobing is also very small. \\ For us it's ok for pinion & #2. But a spiral is nicer albeit usually 2X the cost. \\ It's also fine for 1-3-4 if bushes have no oil groove in bore. \\ Grooves in bore need the gap bridging action that spirals provide. \\ This is where you need spirals. | ||
| + | * Forward Spiral reamers will give a truer (but not perfect) cylinder. \\ Forwards gives the lowest cutting forces = easiest to hand ream with. \\ But they can 'grab' into the work (like a drill sometimes does). | ||
| + | * Reverse Spiral reamers are the best of the 3 for surface finish. \\ High cutting forces due to the reverse rake at the cutting edge makes the roundest holes of all three when driven by hand. \\ High safety in use. It won't toss you any curve balls but they dull quick. \\ All reamers when dull are useless. | ||
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