1.125" and .875" Reamers with 1/2" Shank

Does anyone know where to buy a 1.125" and a .875" reamer with a 1/2" shank similar to VEX’s (to be used on a drill or drill press)? We want to ream out waterjetted bearing holes (1/4" Aluminum). We could also use the 1.126" reamers offered by VEX, but we aren’t sure if that would be too loose for the bearings.

Any help would be great! Thanks!

We just used a 1-3/16" flap wheel from McMaster. Put it in the hole and spin it with a drill until you get the fit you want.


We (WCP) made some a few years back as a select run for teams, if you need a couple I can check if I have any left. Just email me @ rc at wcproducts dot net.

I have never been able to find large reamers with a shank small enough to run into drills so we just made some.



you can turn down the shank on a lathe with a carbide tool. Insert life will be very bad but we’ve successfully done this before.

Sometimes it will do very well as not every manufacturer hardens the shank end.

Similar to what Chak posted above, I just recently purchased this reamer here:
http://www.wttool.com/index/page/product/product_id/34286/category_id/14691/product_name/RDX+Straight+Flute+High+Speed+Chucking+Reamers. I’ll post an update once it comes in.

We’ve had good luck using a step drill for final finishing in bearing pockets. We have never used them for gearboxes, but for chain and belts it’s been great.

There are a lot of flavors out there, but we’ve liked Irwin bits the best out of what we’ve tried: http://www.irwin.com/tools/browse/drill-bits/unibit-step-drills

Annular cutters are what we always fall back on for this. If the holes are already cut near their final size you’ll want a guide to keep the cutter centered (2x4 with the appropriate through hole seems to work well, but I like a chunk of uhmw or something slippery). Otherwise just have a pierce done to mark position and the use that as a pilot for the cutter.

Once you get the arbor, the cutters are affordable considering how long they last.

We’ve always had issues making bearing holes for the 1-1/8’’ od flanged bearings. Another mentor of ours got us http://www.hougen.com/cutters/magdrill/Hougen-Annular-Cutters.html#m2 hss
In 1-1/8. It is awesome! The hole is perfect, and borderline press fit. The bearing “pops” right in. A hit of locktight will keep the bearing in place , but we usually encapsulate it anyway so it can’t fall out.
We don’t have to ream at all.

I still have a 1-1/8" spade bit, the kind you use for wood, that I modified to cut bearing holes in 0.125 aluminum or thinner sometime around 2011. Yes it works. You cannot do it with anything other than a drill press however.

What modifications did you make?

I have been looking for a 1.125 reamer but these are very hard to find in metric countries.
Is using an adjustable reamer a good idea?

This is how I modified it.

https://i.imgur.com/9dCqJwhm.jpg Side by side comparison
https://i.imgur.com/tmSWHTlm.jpg Original width before a light grind
https://i.imgur.com/9ZCo0Atm.jpg Finished width after grinding to get the correct hole size



Just cut a .250 pilot hole in the material and counterbore.

Personality we just drill a .250 pilot hole and use a step drill bit with has the 1.125 hole as the last step.


+5 for the step drill bit solution. It makes for a great slip fit, so I recommend adding retention using screw/rivets at the flange (e.g: versaframe gussets) or loctite.

Just a little update 1072 has been using it and it has been very helpful. Anand turned it down on the lathe and we use it in hand drills to bore out bearing holes on plates and 2x1. The only thing is you have to be careful to keep it straight or it will catch and hurt your wrist… Its also pretty heavy and can tip the drill so keep that in mind. Other than that it has been great, would recommend!

A 1/2" reduced shank 1 1/8" drill bit will also work. Trick is low rpm and a very solid clamping solution. One big win over step bits is you can get nice square profile holes in thicker walled material and deal with narrow box section when you only want a bearing hole in one side.

We use step bits in thin walled material.

We use a heavy duty cross slide vice on a 16" drill press. Low rpm and slow feed rates makes for very nice holes.

This typically is a cheaper solution than many other cutters as you can get a high quality bit for under $40 USD.

+1 for this solution, we have since moved on to greener pastures for the drive-train. For other applications we have used this quite successfully in the past.