Reamer Speed is measured by the rate at which the outside diameter of the tool moves in relation to the work piece. This speed is known as Surface Feet Per Minute (SFM) and is shown in the table below. The formula used to convert SFM to Revolutions Per Minute (RPM) is:


The speeds shown in this table are a generalization and it is recommended that the user start at the lower end of the range and build up to the maximum after trial indicates this is possible.

Fractional Size	Number Size	Letter Size
1/64 1/32 3/64 5/64 3/32 7/64 9/64 5/32 11/64 13/64 7/32 15/64 1/4 17/64 9/32 19/64 5/16 21/64 11/32 23/64 3/8 25/64 13/32 27/64 7/16 29/64 15/32 31/64 1/2 33/64 17/32 35/64 9/16 37/64 19/32 39/64 5/8 41/64 21/32 43/64 11/16 45/64 23/32 47/64 3/4 49/64 25/32 51/64 13/16 53/64 27/32 55/64 7/8 57/64 29/32 59/64 15/16 61/64 31/32 63/64 1″ 1-1/8 1-1/4 1-3/8 1-1/2 1-5/8 1-3/4 1-7/8 2″ 2-1/8 2-1/4 2-3/8 2-1/2 2-5/8 2-3/4 2-7/8 3″	#80 #79 #78 #77 #76 #75 #74 #73 #72 #71 #70 #69 #68 #67 #66 #65 #64 #63 #62 #61 #60 #59 #58 #57 #56 #55 #54 #53 #52 #51 #50 #49 #48 #47 #46 #45 #44 #43 #42 #41 #40 #39 #38 #37 #36 #35 #34 #33 #32 #31 #30 #29 #28 #27 #26 #25 #24 #23 #22 #21 #20 #19 #18 #17 #16 #15 #14 #13 #12 #11 #10 #9 #8 #7 #6 #5 #4 #3 #2 #1	UN B C D E F G H je J K L M N O P Q R S T Tu V L X Y Z

Material	Hardness BHN	Speed SFM	Speed RPM
Steel
Magnetic Soft	<120	65-82
Structural	<200	55-80
Plain Carbon	<250	40-50
Alloyed	<250	32-40
Alloyed (Hardened & Tempered)	250-350	16-22
Alloyed (Hardened & Tempered)	>350	10-20
Stainless Steel
Free Machining	<250	40-60
Austenitic	<250	16-22
Ferritic Austenitic	<300	16-32
Cast Iron
Lamellar Graphite	<150	40-60
Lamellar Graphite	150-300	32-50
Nodular Graphite (Malleable)	<200	22-40
Nodular Graphite (Malleable)	200-300	22-32
Titanium
Unalloyed	<200	32-50
Alloyed	<270	22-32
Alloyed	270-350	10-20
Nickel
Unalloyed	<150	16-32
Copper
Unalloyed	<100	50-65
Brass – Bronze	<200	65-82
Brass	<200	50-65
Bronze High Strength	<470	22-40
Aluminum – Magnesium
Unalloyed	<100	72-105
Silicon Alloyed < 5%	<150	105-130
Silicon Alloyed > 5 < 10%	<120	50-65
Silicon Alloyed > 10%	<120	40-60
Plastique
Thermoplastic	–	40-60
Thermosetting	–	50-65

Recommended Feeds For Reaming

Reamer Diameter	Feed (Inch/Revolution)
Up To 1/16 1/16 – 1/8 1/8 – 1/4 1/4 – 1/2 1/2 – 1" 1" +	.001 – .003 .002 – .006 .004 – .010 .006 – .015 .010 – .030 .020 – .050