Reamer bit guide

[Zhangliqun]

Looking for a better way to widen keeper bar holes to 9/64". Somehow even the best hard drill bits designed to cut steel get ripped and frayed on the edges and don't work anymore after just a few keeper bars so I figure a reamer bit must work better since widening holes is what a reamer does.

I'm a bit lost in the internet maze looking for the right bit, open to all viable links and suggestions.

[Possum]

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Go to Radio Shack, they are called chassis reamers I think. Alot of hardware stores have reamers too. Don't know why you're having problems, are you holding the keeper in a vise when you drill?

[belwar]

Looking for a better way to widen keeper bar holes to 9/64". Somehow even the best hard drill bits designed to cut steel get ripped and frayed on the edges and don't work anymore after just a few keeper bars so I figure a reamer bit must work better since widening holes is what a reamer does.

I'm a bit lost in the internet maze looking for the right bit, open to all viable links and suggestions.

Use a basic chucking reamer.... $12 from mcmaster.

Part number 2975A37

I can always make the holes bigger for you.

bel

[Possum]

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A reamer really isn't a good idea actually. It is a taper and won't widen it uniformly. I don't understand why you are having a problem, I've been using the same 9/64 drill bit for about six months, widening holes in keepers. What kind of keepers are you using????

[jonson]

Only Tapered reamers are tapered Possum but the common ones are parallel.
You could try just sharpening that drill bit a tad off centre and that will cut bigger.

[David Schwab]

Maybe using a drill lubricant would help. Are you using a drill press? You aren't forcing the drill are you?

I've had the same set of bits for years, and I've never had one get damaged drilling low carbon steel.

[Joe Gwinn]

Looking for a better way to widen keeper bar holes to 9/64". Somehow even the best hard drill bits designed to cut steel get ripped and frayed on the edges and don't work anymore after just a few keeper bars so I figure a reamer bit must work better since widening holes is what a reamer does.

What size are the holes before reaming? I assume that the material is 1018 steel or the like.

Drill bits don't work all that well for making slight increases in hole diameter - the drill tends to catch and tear, and the harder steels (like a cobalt drill bit) will be chipped in the process.

A Unibit step drill would work well, and 9/64" is a standard size. Some unibits are long, with about 0.5" at each step diameter, which should work for keeper bars.

Failing that, one can buy straight chucking reamers in almost any size. Here is a 9/64" straight chucking reamer. Use only in a drill press, and hold the workpiece in a vice or fixture.

9/64" straight chucking reamer

Reaming and step drilling require lubrication. I would use black sulfur oil painted liberally onto the reamer or bit with an acid brush. The traditional approach is to use an old catfood or tuna can with top removed to hold the oil.

You will also want a sharp countersink in a handle for deburring the holes.

[Possum]

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I use a drill vise to hold when I drill them out and have no problems, if you're holding it with your hand I could see where that would cause things to go wrong. Drill vises are cheap at Harbor or on Ebay...

[David King]

Chucking reamers need to run a bit slower than drill bits. They also can't remove much material. Ideally .005 or .010" at a pass or less. In a pinch you can take 1/64" out but I'd avoid any more than that. Clear the chips before the flutes get filled up or you will kill the reamer.

I still don't understand what you are trying to do or why. Drills drill out holes everyday and they do it about as well as anything out there except in brass where you need a slow spiral drill or a specially prepared cutting edge that won't pull the drill into the hole (0º rake angle).

[Zhangliqun]

Drill bits don't work all that well for making slight increases in hole diameter - the drill tends to catch and tear, and the harder steels (like a cobalt drill bit) will be chipped in the process.

That tearing and chipping is what I'm running into. And yes, I'm using a drill press and a clamp. Nothing moves but the bit.

I do not force it in there, my little drill press just doesn't have near enough torque to try anything like that, it would stop dead while the belts continue rub against the shaft. So I just lower the bit with light gentle jabs into the hole to avoid abusing either the bit or the keeper, or the press itself for that matter.

And still I get this tearing/chipping so I think you must be right, Joe.

I think the chucking reamer is the answer.

PS, in case it wasn't clear, I am widening existing holes, I am not drilling new holes. Original size of hole is 1/8". I like the keeper holes just a shade wider in case the bobbins, baseplate, and/or keeper are slightly off in spacing relative to each other.

Interesting that the 1/8" bit I have cuts the steel like butter when making my own keepers but because my press doesn't have much torque, it will stop dead with the 9/64" bit, so I have to make the 1/8" holes, then widen them.

[Possum]

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Ahhhh, sounds like you need a more powerful drill press I bet. That would explain alot...

[jonson]

Dealt with this a long way back, and the other way with a predrilled hole is to sharpen the bit to a much steeper angle as almost 30degrees. This helps the bit to run true to the origional centre and may cut better if your bits are good quality and stop the snatch and chipping you are getting.

[David Schwab]

I do not force it in there, my little drill press just doesn't have near enough torque to try anything like that, it would stop dead while the belts continue rub against the shaft.

Tighten your belt. They loosen so you can change speeds.

[Possum]

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It sounds to me like his drill is too underpowered and losing power or is too low speed? Change your gear belt to the highest speed, put a little oil on the piece you're widening. I have a Delta drill press and do what you're doing all the time with an old drill bit and not having any problems, its just a cheapie from Lowe's. Go to Harbor Freight they're not expensive:
- Harbor Freight Tools - Quality Tools at the Lowest Prices

[David King]

+1 "Tighten the Belt"