Re sharpened machine reamers

I have been given a dozen or so 2MT machine reamers. Most seem to have been resharpened. Approximately one inch of the end of the reamers have been reground, reducing the radius by 5 to 10 thou.

The unground flutes are reasonably sharp, the reground length is very sharp. How would one use these reamers? Presumably one would use only the first inch of the reground part of the reamer?

I am unfamiliar with the professional use of such regrinds, so any info would be most welcome.

As an aside, how would you measure the diameters of the reamers, some of which don't have any size marking? A caliper across the maximum diameter? Seems a bit hit and miss when tried.

Thanks all,

Andrew.

I don't know how a resharpened reamer would work. I suppose you could use a test piece and then measure the reamed holes and then mark the sizes on the reamers for future reference. Be careful measuring reamers, I would rather use a carbide tipped micrometer than risk the softer jaws of calipers, unless they were cheap ones. Even so, the reamed hole is likely to be slightly different to the measured size. I did a lot of reaming during my job as a fitter with aircraft components and there are ways of getting a reamer to produce different size holes. Lots of cutting oil will cut a smaller hole than a light lube from an oily rag. Most people will get a bellmouthed hole with a hand reamer.

If they really are machine reamers then they're probbly scrap. A machine reamer cuts, and is sharpened, only on the bevelled angle at the end. The flutes are not sharpened. Given that they have been, either the reamers were being converted to specials, or the operator knew not what he was doing.

A V-shaped anvil micrometer would do for measurement, although the V angle required varies according to the number of flutes. Some reamers, like endmills, have non-uniform flute spacing in which case using a micromter gets complicated. Probably easier to ream a hole and measure that.

Andrew

Thanks both,

Over the years I have seen a small number of reamers that have been treated like this, so I have always assumed that whoever did the "sharpening" , knew what they were doing. This is the first time that I have actually owned some. The reamers are definitely machine reamers with the angled nose and 2MT taper. I assume they must have been ground for a specific diameter. Pity the ends can't be cut off and the original diameter reinstated. Only a few have no size markings, so returning them to standard would be good, but a fair bit of work, for something that would probably not get used much if at all.

Andrew.

Hi Andrew. Have you tried these to ream a through hole as if the reground part was cut with a grinding wheel at a rake angle to the axis it could cut on the small step and use the front diamiter as a pilot.

David

Hi Andrew. I have a couple of reamers 1/2" & 3/4" with reduced start of about 3/4" . I just use them as normal but make sure I go all the way through the bore with the full size area. They do seem to cut pretty easily and on size probably due to the undersize start reducing material removal. I imagine that they were reduced to get rid of a very blunt start after a lot of hard work in an industrial setting.

regards.

From my recollection of my assortment of machine reamers I have always assumed that the first 1" or thereabouts was tapered slightly to 'line up' the reamer (especially if held in a floating head). In fact I have a collection that came out of a toolroom and some have been re-ground on this tapered portion and some have been 're-sized' (signified by a grinding gouge in the shank and a size arc etched on the shoulder)

However, in respect to comments above by Old Mart and Andrew, these are all what I know as 'through reamers', whereas blind hole reamers are parallel at the nose, have a larger chamfer, and usually (but not always) have carbide brazed into the front 1" or so of the ends. To get over the problem of alignment with a blind hole reamer was the reason for the introduction of the superb adjustable and floating blade David Brown 'S' type reamers.

P.S Thanks for the acknowledgement of my prowess with reaming 'Old Mart'

............"a light lube from an oily rag"

Edited By Oily Rag on 13/12/2020 11:42:16

I didn't say you were any good with reamers, just that you could "light lube".

Sorry - cannot do at the minute as the 'lube houses' (pubs!) are all closed due to T3 restrictions. Come Friday however there is a vintage tractor run in which we will be visiting a number of 'lube houses' as the restrictions come off for the Christmas period. Raising money for charity from the 'lubers' I hasten to add, but probably indulging later that evening.

The reamers that I am querying are definitely machine reamers, no ifs or buts! The thought of reaming beyond the reduced diameter would fill me with dread. There is a definite right angle step from one diameter to the other. Being machine reamers (as Andrew said) they are intended to cut on the sharp angle at the beginning of the reamer, not on the flutes.

I can only assume that they are intended to ream only the short distance of the reground length. All very odd as the ones like this, that I have seen over the years have all been reground for the first 3/4" to 1" only. I would have expected the reground length to vary according to the depth of the reaming to be done.

Andrew.

They are obviously going to cut undersize to whatever is marked on them as they are.

You could always cut off the reground ends and add a new lead in taper on them, that way they may give you some more service life so long as the flutes are not badly worn to start with.

Phil

Phil P beat me to it, I would chop the reduced bit off and resharpen the end and give them a try in a bit of scrap bar, nothing to loose, they will ream a hole, you have just got to measure that hole and mark the reamer accordingly.

I did think of chopping off the reduced portions and then grinding a new cutting edge as per normal machine reamers. Most of the reamers that have a reduced in diameter on the end, are in fact clearly marked as to size, only 2 or 3 are without a stamped dimension.

I assume that reamers are made from HSS so I have nothing that I could use to chop off the ends. Any suggestions? or can one use an angle grinder with some sort of wheel ........ diamond , silicon carbide???????

Andrew.

An angle grinder would do the job, though hardly with precision results. So would carbide, but grinding is probably the way to go.

Are these things worth the bother though? The point of a reamer is to make accurately dimensioned holes. Sounds like a lot of work to get these bad boys back to anything like normal and once done can you measure the resharpened tools accurately enough to trust them? I can't imagine a reamer job where it's OK to use an off-spec tool.

Dave

Hi Andrew you will have to use a cutter grinder or a surface grinder with a dividing head to get the cutting edges all the same angle and length or it will cut on one tooth and will not cut correct size. I would just try it as is and do a through hole ream to see how it cutts now what have you got to lose unless you need it to ream a blind hole.

David

It strikes me, that if you chop off the ends, you will also lose the centre drilled part, which will make re-sharpening concentrically more difficult.
If you don't need to ream blind holes, what problem would extended ends cause you?

Bill

There are machine reamers that have a tapered front end, although not very common these days.

The best way to find the size of your reamer is like what others have said, is to ream a test piece . Sometimes you will get a slightly different size or result depending the coolant used. like a oil or a water based coolant.

Thanks folk

I suppose my queries are prompted more by curiosity than need to use the reamers. I do have the kit to regrind the reamers correctly, but hardly worth while. I sure would not be trying to remove an inch of reamer with a tool and cutter grinder, hence the query re angle grinder!

Thanks everyone,

Andrew.

These should be put in the bin marked 'May be useful one day' Because we all have one and only put things in there and never take them out