Reamers

[woodchucker]

Your solution does not match what is being sold on ebay that the op showed.
They have a square end. There also was a pic of a counterbore (orig pic).
And there are some MT reamers on ebay as well.
But your solution does not match any that have been shown or mentioned.

 

[rwm]

they look like straight shanks... does it say MT somewhere?

I think I got fooled by the picture, which appears to show a tapered shank. It is probably not.

 

[ChazzC]

I looked a little harder.

Jig Bore Style Reamers | Alvord-Polk

I don't have any jig borer reamers, but Robert's photo does not show a reduced shank behind the flutes, although it could be the angle. I do have straight chucking reamers, none of which have cutting edges on the face or a larger center hole (only a small center hole used to support the reamer during grinding).

On the other hand, all of my counterbores have cutting edges on the end and large, deep center holes (1" CB):




@rwm, could you provide a side view of the cutter?


I also dug a little deeper: I did find some photo's of "Jig Borer Reamers" showing the ends (quotes because I couldn't find any from a manufacturer), and they do show cutting edges on the end, but not extending deep to the center, more like what you see on a HSS shell mill. There is also a larger center hole, but not as deep as what Robert's photo shows.

Looking for what these reamers are, I only found one explanation for the difference in construction: short stiff shaft and end-cutting to precisely locate & ream the hole because the "drilled hole may be off location a little:" this doesn't make sense to me, because if you are using a jig-borer, all of the operations should be equally precise, and you wouldn't want the final, operation to be the one that determines the location & size. The only "authority" that I found was Moltrecht (Machine Shop Practice, 2nd Ed, V1, pls 436 – 437), and he doesn't say anything about end cutting.

 

[ChazzC]

I have a specific question but I think there are a lot of knowledge gaps about reamers. Maybe other questions will get answered here.
Firstly, why does this reamer appear to NOT have a "lead in." It has a square edge like and end mill. How would this center? Is this really a reamer?

View attachment 491172


Secondly, I know spiral flute reamers are good for holes with cuts or keyways. Why are all reamers not spiral flute? Why straight flute?
Thirdly, why do "hand reamers" often have an MT shank? That would appear to mean they are meant for machining.

Robert, can you get us a side view of this cutter?


Thanks,


Charlie

 

[Flyinfool]

As shown above a piloted c'bore will have a setscrew between flutes to hold the pilot in. I have non center cutting end mills that look a lot like the cutter in the OP post. the hole in the end is a center hole for grinding the cutting edges. it looks to have the 60° included angle of a center. Mine started life as a 1.000 dia. after a couple of shapenings it is now a 0.950 Dia. Yes it needs another sharpening.

 

[extropic]

My earlier reply was influenced by the OP calling it a "Reamer". It may just be an end mill, not a reamer at all.
As is common on HM, important information is missing from the OP. If it's a "Reamer", it's a jig bore style reamer.

I'd like to see the diameter of the cutter, the diameter of the (assumed to be straight) shank specified and the profile picture.

 

[rwm]

The pic is from this eBay ad.

1-1/2" Spiral 6 Flute Chucking Reamer 3" Flute Length 1" Shank | eBay

Find many great new & used options and get the best deals for 1-1/2" Spiral 6 Flute Chucking Reamer 3" Flute Length 1" Shank at the best online prices at eBay! Free shipping for many products!

www.ebay.com

So far I'm believing it is an end mill...

 

[woodchucker]

I'm with Jim it looks like a counterbore. The only thing I don't see is the set screw to hold the guide in there.

 

[extropic]

It does seem to be a Jig Bore Style Reamer. Not a chucking reamer. That opinion is based largely on the proportions and, of course, I've seen no evidence of a bore for a pilot. Like I said before, I'd use it like a end mill (I don't have a jig bore).

OMG! A false title on an eBay listing. That never happens.

 

[ChazzC]

The pic is from this eBay ad.

1-1/2" Spiral 6 Flute Chucking Reamer 3" Flute Length 1" Shank | eBay

Find many great new & used options and get the best deals for 1-1/2" Spiral 6 Flute Chucking Reamer 3" Flute Length 1" Shank at the best online prices at eBay! Free shipping for many products!

www.ebay.com

So far I'm believing it is an end mill...

Thanks for link; however, I’m more confused, but maybe because of what looks like a shop modification: never seen an end mill with a flat ground along the full length of the shank. Have occasionally seen with just a plain round shank but usually with a Weldon shank. My SHARS 1-1/4” x 3/4” shank (which has an unusual face):





And an Accusize, which more resembles the eBay find:




Proportions seem to be more end mill -ish than the various photos I’ve seen of “jig borer” reamers (flutes seem too long and no reduced shank). But the shank is unusually long.

I vote modified end mill.