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hand or machine reamers
- Thread starter savarin
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Hand reamers are meant to be turned by hand, machine reamers by machine. Hand reamers have a long lead in to the full size. Machine reamers have beveled cutting teeth on the end that do most of the heavy cutting, and a short lead in to full diameter flutes. Machine reamers usually have straight shanks or MT shanks, hand reamers usually have a square drive at the end of the shank.
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There is no law that says you cannot use a hand reamer in the tailstock under power. The cutting geometry on the hand reamer is such that it’s better at self-guiding and will have a square drive end, that’s about it. On the machine reamers you will typically see the flutes not equally segmented. This helps to reduce or eliminate harmonic chatter. I think the important thing is to find any kind of reamer and then more importantly have it make the size hole you need. Then all would be good…Dave
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Great question.
I know Bob is correct. Or at least that is what the books say. But, why....
I'm commenting so that I get alerted when there is a response.
Daryl
MN
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I have hand, machine, adjustable, single flute and then some oddball reamers. My most important and really my only concern when looking through my reamer inventory, is to find the size I need. Then I ream the hole with it. All the types work for me. Some not so great or have limitations, like the adjustable ones.
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It is VERY unwise to use an adjustable hand reamer in a keyed hole. You don't have to ask me how I know, I did it. Snap, crackle & pop !
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Running reamers by hand does not give a lot of power, but it does give a great deal of feel and finesse. For hand reaming, you want a light amount of stock remaining to be removed. The hand reamer taper will not even enter a small hole, and if it did, you would not be able to turn it as the cut progresses. The long taper makes the size grow gradually as the reamer advances. It is good for making the hole to size and round, but somewhat more difficult to make the hole go in the exact direction you want it to. That said, I have not tried using a tap follower with a hand reamer that has a center on the shank end, which might help a lot, come to think of it. For machine reaming, removing more material is not so difficult, and the hole can stay better lined up if you use a rigid spindle like a mill or a lathe to turn it. The work also goes more quickly under power, when time is money. chips&more's comments are worth reading again. With limited inventory tooling, often for a one off home shop job, we often want to do what we can with what we have. Where there is a will, there is usually a way.
The main rules with reamers of all kinds are to use plenty of cutting fluid, advance the reamer carefully but keep the chips coming (don't let it rub unnecessarily), and don't force it or bad things will happen. Never turn the reamer backwards in the hole.