What's new
What's new

Reamers with large chamfer


Sep 24, 2009
Does anyone know a good source for reamers with a larger than standard end chamfer?

Or possibly any other tools to produce the below image. I am from holes for some lee plugs and want to create the 45 deg at bottom of hole. I am tempted to try a 90 deg carbide spot drill. Just not sure about hole quality.

I would use a 90 degree drillmill, not a spot drill. 1/8 or 3/16"

With a 1/8 or 3/16 I assume you mean to interpolate it?

if that's a no-go, what size drill do you plan on putting thru?

I have ground larger chamfers on a reamer before. The fewer flutes, the better. A 4 flute would be ok if you did go the reamer route. I would grind off 3 of the cutting edges if you had a 6 flute reamer.

However, you have a +.0025 tolerance there, so most any machine should be able to hold that well enough when interpolating. And it's a lee plug, it'll deform anyway so if you're out of round .0005 there shouldn't be an issue.
Thanks. In this case its a .187 drill. These plugs are the stainless plugs and not sure they deform as well as the aluminum ones do.

The .0025" tolerance is the max deepening on the proof pressure you need to obtain.

I will look in to the options you mentioned. Thank you
I have not installed them myself, but have run parts with lee plugs. In my case, the tolerance on the print was way tighter than the spec from the manufacturer of the plugs. I am pretty sure the engineer put +.0002 on the size of the hole. The customer (not the engineer) revised that part of the print, giving me .0015" instead of .0002. The parts were 303 stainless, I assume the plug is also stainless. Just looking at the cross section view of a plug, they ought to deform just fine. Thin wall, steep ID chamfer. Plus I gather a lot of the sealing is done at the chamfer, if assembled right.
i used to work at a place that made, what they called, half drills. basically a drill rod with the chamfer on the end, then one half of the end is ground away, so it looked kinda like a spade drill. used for Lee plugs, they cut right on size. We would also send reamers out to have bigger chamfers ground on them
MAFord will take one of their off the shelf reamers and modify it with that chamfer for little to no extra cost/lead time. Just shoot them an email.
Ab tools will make that for you I am sure. I thought the prices and *most* lead times were reasonable. The will do SC, brazed carbide, HSS, coatings, etc.
How many do you have to run? I have successfully done lee plug holes with the before mentioned drill mills. In higher quantities I have also done a custom step drill to produce the feature. In the case of a custom tool my situation was such that the hole that received the plug was quite deep below the plug (30X dia or so) - the pilot on the step drill also created the pilot for the 30X dia drill.

Quantities always dictate making a custom though. A few parts, use whatever you can find on the shelf.
I would advise to machine two exact diameters with one tool, and a chamfer with another tool. There is a chance that a solid reamer with such a huge chamfer will kill the tolerances of both diameters as soon as this chamfer starts to cut the metal.
That is only a about a .015 chamfer per side. Are you sure a standard chucking reamer won't work? Drill close to size and depth and ream with a .251 reamer. Dwell at the bottom. Might push a burr so you might have to redrill small hole.

BTW in general a spot drill has no clearance on the body so probably won't work.
Interpolating with a drill mill has gotten us a lot of failures in the past. The more round the hole, the better the chance of fully sealing.

OSG makes a Reamer we have had great success with. Keep in mind the 45 degree lead does not go clear to the point, so your thru-hole must be large enough to allow you to cut your 45 deg. shoulder.
So far, all of our customer specs have allowed for an off the shelf reamer to do the job.
Last time I done some Lee plug holes i just used a 2, 90 deg drills slightly undersized and finished with a micro boring bar. 90 deg Spot, drilled the larger hole, drilled the smaller hole and finished with a micro.
my .251 dia HS reamer is ca. .205-.210 dia on the small end of the 45. seems that could work. ream slower feed towards the bottom to allow for cutting the angle.