Reamers: straight or spiral flutes?

[Rotate]

For general applications, do I use straight or spiral fluted reamers? What's the difference?

Albert

[bighammer]

There isn't a lot of difference at least at slow or hand speeds, but a spiral reamer will cut smoth in a split bushing, a straight flute will dig in at the seam. Also a sprial reamer will cut true in a pully or gear or whatever with a key way in it. Some people like the finish of a spiral better used at higher speeds, big thiny is to buy the best ones you can afford.

[Thrud]

With interrupted cuts in holes - you must use a spiral reamer for those. Spirals are slightly more expensive but handier in general. I would only buy the specific reamers you need - it is pretty rare to actually need a full set. Buy the best you can afford in M-42 or T-15 HSS if you can get them. Use lots of cutting fluid and NEVER, EVER turn them backwards or you will damage the cutting edge! Clean after use and return to their protective tube.

Dave

[SGW]

I'm partial to the spiral reamers, myself. As Dave said, buy them as you need them. Odds are you'll never, ever, need a 29/64" reamer and other odd sizes for anything, so there is little point in buying a full fractional set. One at a time, buying top quality isn't all that expensive.

[lynnl]

For reaming a 'one-time' hole of a specific size, I've found that using a hardened dowell pin or piece of drill rod of proper size with one end ground at an angle of 45deg or more has worked fine. ... in the absence of a reamer that size. (Saw that in one of the HSM books.)

[Rotate]

Thank you all for the wealth of infomation.

Albert

[spkrman15]

Some guys at my work were working on the cell phone towers and broke a 13/16 reamer. They gave it to me. Their boss told me they paid 60 or 70 bucks for it. I drilled out some drill rod i had in the shop just tight enough not to fit over the broken shank. Then i heated the rod up. Slid it over the shank and let it cool. Next i brazed the drill rod to the reamer and put it back in my lathe. Machined down a new shank with a 1/2 diam for the drill and tried it out today. Voila Succes. Works good too. I almost broke my arm in the hand held drill. After that i used the Drill press. Ran truer then i hoped for.

Spkrman

[Thrud]

Albert
As LynnL stated, you can make a toolmakers reamer as he suggested or a D-Bit reamer for the odd ones. Of course, this also presumes you have some O1 (oil hardening) ground drill stock on hand. Guy Lautard's "Machinist Bedside Reader #1" see page 52 explains how to do this in detail.