never seen anything like it

This topic has 8 replies, 7 voices, and was last updated 17 June 2011 at 00:04 by JohnF.

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12 June 2011 at 20:45 #70223
Speedy Builder5
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@speedybuilder5
Just picked up some new French metric (I guess the same as UK metric – just French made !) reamers from a car boot sale. I have never seen reamers like it, but was assured that they will cut accurate holes in steel, brass etc.

A third of the circumference have no cutting flutes, and the other two thirds have normal flutes. Anyone used / seen these before ?
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12 June 2011 at 20:45 #5543
Speedy Builder5
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@speedybuilder5
Reamer
15 June 2011 at 18:56 #70385
Speedy Builder5
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@speedybuilder5
344 other people never seen anything like it – surely some one knows.
15 June 2011 at 19:18 #70386
Anonymous
Since there are no pictures, technically you’re the only person who has seen it!

Regards,

Andrew
15 June 2011 at 19:58 #70388
Roderick Jenkins
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@roderickjenkins93242
Robert,

Taper reamers for making the holes for musical instrument pegs have only 3 flutes on half the circumference, the rest being plain. If you try to cut a hole in a soft material like wood using a conventional reamer the reamer tends to pivot around the cutting edges in turn and you end up with a facetted hole. I guess a similar thing can happen in soft metals, it certainly can happen in sheet material. I would expect your reamers to be very accurate, if a little slow cutting. Spiral flute reamers are now available for musical instrument which helps to eliminate the problem but they still have a least one flute missing (or at least that’s how it is on my lute peg reamer).

Rod
15 June 2011 at 20:43 #70389
dcosta
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@dcosta
Hello Robert!

When I started my intereste in engineering, in the beginning of the eighties, I saw reamers like that many times in professional shops. At that time I heard they being called something like “backed reamer”. In its name (that in portuguese is descriptive of the reamer, not just a name), the third of the circumference without cutting flutes is the “backed” part of the reamer. I think they were of common use here in Portugal.

I’ve used one or two and, yes, they work very well.

Only now I thought about how that reamer work. I think that the function of the “backed” part is to crush small bosses left by the normal flutes and also to (kind of) polish the surface.

I only recently re-started my interest in engineering and in the meatime I think I lost them. Tried to find them with no luck.

Best regards

Dias Costa
15 June 2011 at 22:26 #70395
Chris Trice
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@christrice43267
Bit of a cross between a reamer and a D-Bit maybe.
15 June 2011 at 22:38 #70398
Nobby
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@nobby
Hi

If the reamed hole is a bit small .On the 1/3 plain section you can add say .001 shim etc.& ream by hand.Having said that I havent seen them

Nobby
17 June 2011 at 00:04 #70448
JohnF
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@johnf59703
Hi Robert,

Yes I have used this type of reamer some 40 years ago in industry, they often came with carbide inserts in the plain portion to prevent wear–always with a carbide cutting tip as well. They are a little slow cutting and you really need to flood with coolant or oil and run relatively slow.

They cut a very straight hole and yes they operate similar to a D bit but cut faster and more efficiently. If memory is good they were designed by PERA [production engineers research organization] They never caught on with the major tool makers and I have seen few since–still have a couple somewhere I think!

Regards John
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