4 degrees taper reamer

Brian Rupnow · Sep 28, 2014

I am looking to buy a 4 or 5 degree included angle tapered machine reamer that starts out at about 2mm diameter at the small end.--Doesn't really matter if it is metric or imperial. I want it for machining the taper in model carburetor throats. Does anybody know where I can buy one in North America?---Brian

WOB · Sep 28, 2014

It's easy to make a D-bit reamer of the desired dimensions out of drill rod. Unless you are going to cut a lot of throats, you would not need to harden it.

The only readily available tapered reamers that can be bought over the counter that I know of are these: http://www.mscdirect.com/browse/tn/...-s-Reamers/Repairman-s-Reamers?navid=12106146. The first one http://www.mscdirect.com/product/details/02058774 seems to have an included angle of about 6 deg.

WOB

Scott_M · Sep 28, 2014

Hi Brian
My first thought was a taper pin reamer but that angle was to shallow about 1.2 deg inc. I then found this. https://littlemachineshop.com/Reference/Tapers.php
It would seem that 4-5 degrees is a bit more than most standard reamers. I could not find any special reamers "by the degree" like you can find for special sizes. And those all start around 5mm at the small end.
You might have to make it.

Scott

kvom · Sep 28, 2014

You can get a 1/8" taper endmill with a 2-degree taper per side at McMaster-Carr. It's about 3mm at the tip. They also have 3-degree per side as small as 3/32 which is 2.4mm.

D-bit with 2mm tip seems really delicate with only a single cutting edge, but could be worth trying.

ShopShoe · Sep 29, 2014

Brian,

I second the experience that D-bit tapered reamers can be easily made. I made a little one to make carb. jets for a car I was working on. "Try it, you'll like it."

--ShopShoe

deverett · Sep 29, 2014

Brian

Herewith a few pics of a cone reamer I made a while ago for a carburettor:

Using a round nose tool to get the initial shape, topslide set over to the required angle.

Milling ALMOSt half the diameter away. In this size, 5/16"" dia, I left 4 thou over the half thickness to allow for final honing and to maintain the cutting edge

After hardening and tempering

If I can do it, anyone can, especially one with your capabilities!

Dave
The Emerald Isle