View Full Version : adjustable hand reamers

09-05-2011, 01:11 PM
Are adjustable hand reamers designed to turn real jerky?
and make a nice clean hole crappy?

Just want to make sure I'm on the same page as everyone

Don't get me wrong, I appreciate the usefulness of a 208 sided
hole as much as the next guy.

granted, when you need 'em, nothing else will do the job.. just
wondering if I'm doing something wrong.


J Tiers
09-05-2011, 01:31 PM
you must be doing something wrong.

Tighten the adjuster nuts, possibly the cutters are rattling.

09-05-2011, 01:37 PM
no, they're tight.. and plenty of lube. I get long thin needle-like shavings.
They cut like nobody's business.. but the reamer itself is usually hard to
keep perfect on axis.. little bit of wobbling, I'm afraid.. and the finish isn't

09-05-2011, 01:42 PM
They work better in brass and cast iron than steel. You are doing it by hand not a drill press or hand drill I hope. They also work best with light cuts and they are a little hard to keep centered as they are turned and pushed down. If you have one of those tapping tables with the feed crank that holds the tap straight it may help you to get a straight hole with the adjustable hand reamer.

09-05-2011, 01:53 PM
Is the tool a genuine Chadwick & Trefethen reamer or some offshore brand? The grind on the cutting blades is critical, and the cheap tools I've seen never get it right. Even if it's a USA-made product, it may have poorly-reground blades.

David Powell
09-05-2011, 02:02 PM
My experience is that if you actually want a round hole you can only take the slightest cut. Put the reamer in the hole you have, adjust the nuts until it will turn but not shake nor cut, remove it, slacken the lower adjusting nut , back the upper nut a quarter turn, tighten the lower until tight, return the reamer to the hole, very lightly push down and gently turn the reamer with a tap wrench while feeding into the hole, it SHOULD then cut about 1/2 thou. Repeat until you get to size( or get fed up and put it on your mill and bore it with a boring head!) If high tide and moon phases are favourable you might get a round hole. By adjusting excessive pressure downwards on the tap handle to correspond with excessive feed you can get holes with as many or as few sides as you wish!! Holes " machined" using expanding reamers are of little use for piston valve cylinders in model steam locos. Regards David Powell.

09-05-2011, 02:09 PM
To the best of my knowledge adjustable reamers are meant for removing extremely small amounts at a time in order to creep up on a dimension. If you are leaving the usual amount for reaming (~.015") you may be trying to take out too much material. This would explain the biting and grabbing that you must be experiencing when you try to turn it in the hole to produce those long shavings.

The way I typically use an adjustable reamer is as follows: after I've determined that the standard reamer I used has left a hole slightly undersized because it is a bit worn (let's say a .625 hole is .6248) I will adjust the reamer such that it just barely slides over the large end of the reamer. Then I will just adjust the pressure till it just barely grabs at the upper end and using a tap handle turn it as I push it through the hole. I then test the fit and if it need more material removed I will just tighten the bottom nut a hair to add a little more expansion and repeat the process. In other words you do not want to use an expansion reamer the way you would a regular reamer but just to make micro-adjustments to the diameter. If you wanted to increase the diameter by .001 you would do it with several passes (or, at least, I would).

This is just my own method of use. If anyone has more experience with expansion reamers I would certainly listen to them myself but my method has always worked pretty well to achieve the size I wanted.

09-05-2011, 03:17 PM
Sound like you are taking too big a cut :eek:
once you have a bumpy hole you probably wont get rid with that tool :mad: you may clean up with a spiral reamer.
For a good finish with adjustable hand reamers in steel, take .001" max cut use plenty of thick oil.

If you are still having problems check -
-all blades are sharp.
-for damage to 1 or more blade.
-all blades have a lead in taper.
-for swarf under one blade. (strip, wash in degreser, light oil & reasemble - then do the same to the reamer :D )
-all blades are tight, one blade maybe slightly shorter than others.

Mount work on mill or drill, put adjustable reamer in chuck so everything is square & OPERATE BY HAND you should get a good finish

J Tiers
09-05-2011, 08:17 PM
Well, I wouldn't take out 20 thou in one pass, but I seem to do fine with 3 to 6 thou at least...... dunno about this "half a thou" biz......

Some are better than others, that's for sure. Never used an import copy.

Mine cut on the 45 chamfer, near as I can tell, and they seems to do quite well.

09-05-2011, 10:47 PM
There's another thread about adjustable reamers so I copied some of my post there for here. This is the method I use for adjustable reamers most the time.

Since the reamer is adjustable I have seen no reason to "set" it to a size. I drill the hole under size as close to .010" as I can get and adjust the reamer so it will slip into the hole. Then I release the rear nut 1/4 to 1/2 turn, tighten the front nut and ream the hole. I repeat that process until the hole is the desired size.

Usually the cut is about .001" in steel and maybe .003" in brass or cast iron.