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Reamer Dreamer

C

cannuck

Active Member
This thread is a derivative of my indexable boring head thread from a week or so back.

I had been trying to bore a hole with indexed bar, but had to use my old vertical dovetail mill - that is simply not rigid enough to effectively maintain sufficient accuracy. I deferred the project to pilot drill and chucking tapered reamers to try to get round and accurate holes in 0.090 5052 sheet that I will connect up into slots by milling between holes.

I had been in the process of moving my reamers from outer (unheated) shop into a new set of drawers beside machine tools, and did a full inventory of the adjustables, expandables, hand, chucking and tapered stuff - only to find that the C2 tapered I needed was missing. Most of my reamers were bought decades ago by walking into tool shops and buying out of inventory. I spent a full day going from place to place in YXE and nobody had such a tool but by far more worrying had any clue that a chucking reamer is NOT a hand reamer and that tapered reamers exist in a series of progressive sizes!!! I ended up going to KBC to buy (from stock) on line.

I know I am shouting at the world the get the fxxk off of my lawn, but are others seeing this degradation of service in their areas?
 
cannuck said:
but by far more worrying had any clue that a chucking reamer is NOT a hand reamer
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Please let me add to your worries.

A chucking reamer is not a hand reamer by definition, but surely they can be used by hand if need be, no?
 
and vice-versa. Although chucking reamer doesn't have the handy taper to get it started by hand in the hole. Regardless a tapping stand or similar should be used.
 
cannuck said:
I had been trying to bore a hole with indexed bar, but had to use my old vertical dovetail mill - that is simply not rigid enough to effectively maintain sufficient accuracy. I deferred the project to pilot drill and chucking tapered reamers to try to get round and accurate holes in 0.090 5052 sheet that I will connect up into slots by milling between holes.
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I'm not quite following this logic. A boring head with its rotating single point cutter is usually the go-to method to make accurate holes in most circumstances. It should even override a non-circular existing hole in most cases, unless the existing hole is highly irregular, or hard material or some combination that might be flexing the BH tool shank. But your 0.090" thick + soft material combination should present no problem if the setup is rigid & sharp cutter etc. You could literally bore out a square hole to an accurate round hole with correct DOC & number of passes using a BH.

By comparison a drill is a roughing device. You can have unwanted centering deviation issues based on point geometry, slightly irregular cutting surfaces. And it particularly does not like a combination of big diameter to thin material ratio. That's a recipe for a not-so-good hole. Then along comes the reamer which is basically a 'hole following' instrument. It might correct some of the bad drill geometry but ideally you want a good pilot hole of the right dimension for reaming so it is left to remove a relatively constant annular thickness. Tapered reamers are better for thin material situations but they are still no guarantee because the flutes can do this funky self-feeding cutting action that results in a somewhat faceted hole. Weird but true.

Actually, without seeing your project, annular cutters might be another option vs drilling. They are short & rigid. But rather spendy to have a wide range of sizes.
 
0.090” 5052 screams “use a step drill” to me: they make them in an amazing array of sizes, like 1/8” - 1/2”, 1/4 - 7/8” and 1/4” - 2-9/16”. Search Amazon for “step drills for metal” and you’ll find a plethora of them.

I git this one 4 years ago (only usex it once, but it was perfect for a ~1-1/4” hole in sheet metal):

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That's a good suggestion. OP said 0.090" which is ~2.3mm. The steps on than particular drill are 5mm so should work. Not a reamed hole but for sure a more controlled way of progressivve drilling in thin stock.

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ChazzC said:
What I like about step drills (other than making truly round holes in thin materials) is that the bevel deburrs the hole.
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I'm never really developed any affection for step drills. I only used them occasionally and then only on sheet metal. Perhaps I should use them more often.

I do wish I had a nice set of greenlee punches.
 
Susquatch said:
I'm never really developed any affection for step drills. I only used them occasionally and then only on sheet metal. Perhaps I should use them more often.

I do wish I had a nice set of greenlee punches.
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Greenlee makes good tools and when I was in the trade hole punches took a beating. The pull stud on the 1/2" conduit punch always took a beating and either stripped or broke as it was the pilot for the rest of the hand K/O punches. About 4 years ago I saw this set on ebay China for $120 USD shipping included. The inside of the case was soft white styrofoam so I made the inside from a walnut board from a tree I had cut down years ago. Also the hydraulic cylinder did not have a coupling and it was just awkward to work with so I picked up quick connect from Princess Auto. I just looked on ebay, are we at war with China, the prices and shipping costs are just stupid. Not Greenlee, but for what I am doing now they are good enough.

TonyK.

Grimsby Ontario Canada.

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Current project involves a series of 22mm holes in 0.045” steel, need to be accurate enough to match between multiple layers of steel sandwiched together. Sequence will be layout and scribe, center punch, 1/4” holes using Roper Whitney #12 hole punch, step drill to tight fit to Greenlee hole punch arbor, punch to 20mm-ish, then final touch up with step drill with the steel sheets bolted together. The nice thing about stepdrills is they tend to remain concentric to the pilot hole, much more accurate than twist drills. If I had mega-$$$ and space I’d be doing the whole process on a nice big ironworker.
 
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