Blunt hand rea.mers

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Blunt hand rea.mers

This topic has 20 replies, 14 voices, and was last updated 16 August 2017 at 22:05 by Andrew Tinsley.

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15 August 2017 at 16:00 #312173
Andrew Tinsley
Participant
@andrewtinsley63637
I am housebound at the moment with a nasty bout of sciatica. Having nothing better to do, I started thinking of sharpening some blunt hand reamers. If you have the right kit, this is a not a difficult job. BUT the reamer will finish up a thou or two undersize.

I started to consider my machine reamers, now these can easily be sharpened, and as the cutting edge is at the front of the reamer. You finish up with the original diameter.

So why not regrind the hand reamers in the same manner? OK these are plain shanks and you will need to make a MT adapter for machine use. Maybe not quite so easy to get everything in alignment. However if you have a self aligning reamer attachment, then any alignment errors do not matter.

Sounds a great way of saving your blunt reamer. There must be a snag somewhere otherwise the idea would have been hit upon before now! So where am I going wrong?

Andrew.

Edited By Andrew Tinsley on 15/08/2017 16:08:04
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15 August 2017 at 16:00 #25443
Andrew Tinsley
Participant
@andrewtinsley63637
15 August 2017 at 16:34 #312179
Neil Wyatt
Moderator
@neilwyatt
I have a chipped 1/2" hand reamer. the chip is on the taper and I have thought about cutting the end off and resharpening it as a machine reamer as an experiment.

The only reason I haven't is because I already have two 1/2" machine reamers!

The bugbear is that the flutes may not be evenly spaced, so I guess you need to index using the flute you are actually grinding.

Have a try and let us know how you get on.

Neil
15 August 2017 at 16:57 #312188
Clive Hartland
Participant
@clivehartland94829
I have heard/read that if you draw a carbide tool down the face of the flute it will sharpen the reamer, anybody ?

Clive
15 August 2017 at 17:02 #312190
ega
Participant
@ega
Clive Hartland:

Yes, the same tip was given to me by a toolmaker friend. I think the effect is rather like setting up a cabinetmaker's scraper.
15 August 2017 at 17:25 #312196
Nobby
Participant
@nobby
Hi Guys
Yes Clive its called bumping up a reamer . we used ot quite often you can also put a shim say about 2 thou along side the reamer
Nobby
15 August 2017 at 17:26 #312197
colin hawes
Participant
@colinhawes85982
It is true that any hard edged tool such as a high speed lathe tool bit can be scraped very firmly along each flute of a reamer to raise a minute burr that will have the effect of sharpening it. This may not work on a badly worn reamer as it can only be expected to increase the diameter a maximum of 0.002" at the cutting edge. I used this method occasionally during my toolmaking years to make a reamer cut oversize. Colin
15 August 2017 at 18:06 #312207
Mark Rand
Participant
@markrand96270
Back to the original question:- You can sharpen hand reamers in the same fashion as machine reamers, but you'll need to cut off the tapered part first, otherwise it'll still be cutting on that (blunt) tapered length.
15 August 2017 at 18:10 #312209
colin hawes
Participant
@colinhawes85982
Doesn't a hand reamer size the hole on it's parallel section? Colin
15 August 2017 at 19:29 #312233
MW
Participant
@mw27036
I would just run a small sharpening stone up the side of it or maybe a diamond lap or file, normally on 1/2" theres plenty of room to do this without scuffing up the geometry.

Michael W
15 August 2017 at 19:55 #312237
Sam Longley 1
Participant
@samlongley1
I had a problem with my change wheels on my warco not fitting on the bushes & even the ones fitted had to be removed with a puller. I took them to a toolmaker friend who ran a 14 mm reamer through one but it was still slightly tight. He ran a carbide burr up the face of each edge of the reamer & not only did it cut better but it took anothe couple of thou off & the gear wheel fitted as did all the rest after reaming.
15 August 2017 at 19:59 #312238
Clive Foster
Participant
@clivefoster55965
Wonder how far down the parallel portion does a blunt hand reamer get blunt?

By analogy with a machine reamer the part that does the final sizing will be round the transition from taper to parallel. Once the hole is bought to size surely the rest of the parallel part is pretty much along for the ride doing little, if any, cutting so should remain sharp much longer.

So you sharpen the taper reducing making it longer and reducing the diameter at the front. Transition point to the parallel part moves backwards hopefully intercepting a still pretty sharp portion of flute.

Unfortunately none of the T&C manuals I have really address the problem of sharpening remorse without altering size.

Clive.
15 August 2017 at 20:39 #312245
Andrew Tinsley
Participant
@andrewtinsley63637
Hello,

I had forgotten the taper portion of a hand reamer. I suppose that could be cut off and sharpen the end of parallel section as per machine reamer.

To be honest I am not much of a fan of hand reaming. Sometimes it works, but often the finish is poor and cuts oversize. I have read the books and have learnt how to get the best out of hand reaming. But I am still not overly impressed.

I find a machine reamer and a floating reamer holder, to be just about bullet proof. I have yet to have anything but an excellent finish and a correct hole size. I can't claim that from my hand reamers.

OK so where am I going wrong again?

Regards,

Andrew.
15 August 2017 at 23:55 #312269
D Hanna
Participant
@dhanna35823
Hi Andrew. The hand reamer is sharpened the same way as the machine reamer, that is on the cutting lead. The machine reamer at a 45.deg chamfer and the hand reamer on the tapered 1 or so degree lead. Tool and cutter grinder needed for that one. A D bit grinder with suitable gear can do smaller up to about 3/8 inch.

Edited By D Hanna on 15/08/2017 23:59:47
16 August 2017 at 03:50 #312276
John Reese
Participant
@johnreese12848
I believe most, if not all, reamers are sharpened while supported between centers. If the end of a reamer is cut off The center will be lost. I suppose a reamer could be sharpened while held in a collet but suspect the accuracy will be less than if sharened between centers.
16 August 2017 at 03:52 #312277
Ian S C
Participant
@iansc
If the flutes are not indexed accurately, don't worry, this can ofted eliminate chatter by putting the cutting edges "out of step", that alone will not effect diameter.

Ian S C
16 August 2017 at 07:14 #312278
John Haine
Participant
@johnhaine32865
One of the excellent Machinist's Bedside Readers has info about a reamer stoning jig. Basically the reamer is mounted between centres, indexed by a blade engaging with a flute, and sharpened by a hone supported between the edge and an inclined plane that is set up parallel to the tapered bit. I'll try to dig it out.
16 August 2017 at 09:04 #312293
ega
Participant
@ega
Andrew Tinsley:

What floating reamer holder are you using, please?

I assume you are boring before reaming.

I would also be interested to know what allowance you leave for the reamer.

Trust the sciatica is better.
16 August 2017 at 11:37 #312306
Andrew Tinsley
Participant
@andrewtinsley63637
Hi ega,

I use the one that Hemingway sell as a kit. It's self aligning properties are surprisingly good and makes up for any lack of skill on the operators part. I usually bore to about 10 thou undersize before reaming. That is both for hand reaming and machine reaming. Sciatica rampant, can hardly walk! Getting old really is good fun!

John I completely forgot about the fact that the reamer is sharpened between centres! So that rather complicates the issue and probably makes it a non starter! Quite why I forgot this, beats me as I currently sharpen reamers on a friend's Quorn (until I finish mine!). So big black mark I am afraid. Did I say something about getting old?

Andrew.,
16 August 2017 at 12:38 #312310
ega
Participant
@ega
Andrew:

Thanks for the recommendation about the Hemingway kit.

I didn't like to ask if you had finished your Quorn (!) and hope you will soon be able to get back to it.
16 August 2017 at 22:05 #312417
Andrew Tinsley
Participant
@andrewtinsley63637
A senior moment about chopping off the tapered portion of a hand reamer. All one need s to do is stick it in the Quorn and grind off a couple of mms of the flutes back to the parallel portion and then grind the machine reamer profile on the end of the complete flutes. That way you retain the centre.

Andrew.
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