Another "cheap reamer" topic thread

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zippyslug31

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I'm pretty confused (skeptical) of the description found in the many Fleabay auctions such as this one where they state "Shank Diameter: 3/4/5/6/7/8/9/10mm( 1/8-3/8 inch )". Simply put - how can a reamer be both SAE and metric? This is just optimistic marketing, right?

I know you get what you pay for, but how can this even be useful for a person who is trying to ream a specific SAE-sized hole?
 
Oh, so for instance their "3mm shank" is used for the 1/8" reamer? I guess I now see the logic where they can theoretically create either on one machine simply by taking a little more (or less) from the given stock.
Thanks for clearing that up.
 
zippyslug31 said:
Oh, so for instance their "3mm shank" is used for the 1/8" reamer? I guess I now see the logic where they can theoretically create either on one machine simply by taking a little more (or less) from the given stock.
Thanks for clearing that up.
Click to expand...

you want the shank to me smaller in dimeter, than the cutting diameter, 1/8" is 3.175mm. Thus 3mm is the the largest standard metric size. thats smaller than 1/8".

Unless you have automated QA equipment, nice round numbers like 3, 4, 5 etc allow humans to work faster.
 
Dan_S said:
you want the shank to me smaller in dimeter, than the cutting diameter
Click to expand...
Clearly. Cutting diameter or smaller... not sure how this would work any other way! :D


EDIT: Well, I suppose one could have the holding portion of the tool to be whatever (i.e. larger) than the cutting diameter. Actually, I suspect these reamers in question are exactly this. But, yeah, the main body/shaft of the tool can't be any larger than the hole it's trying to ream out.
 
zippyslug31 said:
Oh, so for instance their "3mm shank" is used for the 1/8" reamer? I guess I now see the logic where they can theoretically create either on one machine simply by taking a little more (or less) from the given stock.
Thanks for clearing that up.
Click to expand...
Be careful with buying reamers. Suppliers can be fast and loose with their descriptions. Beware of suppliers that show at the bottom of their listing dimensions may vary by plus or minus 1cm! I have purchased quite a few reamers that were either wrong or not on size. Your best defense is the description and you owning a good micrometer. Do not believe the listing even, measure them with your micrometer! I bought what I thought was an over and under set (-0.001" and +0.001" over nominal size) of reamers and all were oversize. They were returned. I bought a reamer that was supposed to be 0.2490", I got a weird part from India that was marked 1/4" - 0.001", and it wasn't even that. I also got a refund for that part. Just couldn't keep that one in the house for fear it would be used one day, and threw it out.

On the other hand, I have bought US made reamers on eBay, and they were on size, almost to 0.0001". I also have purchased reamers from members on HM, which have proven to be good. But from now on, I measure every part I buy, if it is being used for an application that cares about size. When you show a picture of your mike showing the part is way off, you have every right to get a refund. Actually eBay is very good about that, especially if it is shown in the title and description. If the title and description don't match, send an eBay message to the vendor. That way you get it on record what the response is. It helps you get your money back if the item is not as described.

Don't buy from suppliers with weird vague descriptions, you will most likely be wasting your time and maybe your money.
 
Yeah, no ****! In that very link I had in my first post I found the following - "Please allow 1-3mm error due to manual measurement."
I thought 1-3mm variance is bad, but an entire cm?!?! Talk about junk.
 
zippyslug31 said:
Clearly. Cutting diameter or smaller... not sure how this would work any other way! :D


EDIT: Well, I suppose one could have the holding portion of the tool to be whatever (i.e. larger) than the cutting diameter. Actually, I suspect these reamers in question are exactly this. But, yeah, the main body/shaft of the tool can't be any larger than the hole it's trying to ream out.
Click to expand...

Even that is not an absolute.

I've seen reamers where the shank is the exact same size as the cutting dimeter, and ones where the shank is larger. what you get/need all depends on the use case.
 
Dan_S said:
I've seen reamers where the shank is the exact same size as the cutting dimeter, and ones where the shank is larger. what you get/need all depends on the use case.
Click to expand...
Interesting. How do those work; those are intended for holes who's depth is no greater than the length of the fluted portion of the reamer? Seems a bit limiting.
 
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