Accusize Industrial Tools R8 Shank Er40 Collet Chuck, 7/16'' -20 Drawbar End, Max T.I.R. 0.0002'' O.D to I.D. 0223-0240

The first thing I did was to check the runout. My PM-30MV mill spindle runout is barely measurable at 0.00008. The body OD of this R8 ER32 chuck shows 0.0001 when mounted, but the inside surface of the ER32 surface (where the collet will mount) shows 0.0003. So it just barely misses its advertised 0.0002 spec, even when allowing for my spindle 0.00008 addition. But it is PLENTY good enough for my hobby machinist needs.The machining is beautiful; fits perfectly into my mill, and the nut is smooth. Two small things to mention:- It is laser etched with "CanCNC", not "Accusize" as shown in the listing photo. Others have mentioned this. I'd expect that ordering from Accusize should truly be an Accusize brand. I'd hope that the manufacturer will comment on this.- The flats across the chuck's body are spaced at 41.90mm. Perhaps that's normal for a true Bridgeport mill. Mine is a Precision Mathhews mill and the flats on its spindle are 40.85mm. The PM supplied spindle C-wrench measure at 40.92mm, so it's a fairly snug fit. And so the wrench will NOT fit this Accusize chuck body. No big deal (I'll use my mill to knock a mm off of the body flats), but thought I'd mention it.

Fit, finish, feel and function are all good.Wish it came with a proper size backup wrench since my spindle does not lock.Now I need a wrench.

I have an ER40 chuck for the lathe, so figured Id get some ER40 stuff for the mill. It works. Honestly havent checked the precision on it.

The media could not be loaded.  I received the collet chuck today and decided to check it's accuracy right away in case I had to send it back as others have done. I was pleasantly surprised. There was a small burr along the keyway of the R8 adapter that I removed first. After I thoroughly cleaned everything these were my readings.The TIR of my Bridgeport R8 spindle is 0.00063"The TIR of the collet chuck installed was 0.00095"The difference was 0.0003 which is acceptable. I did not compare the directions of the runout. Wouldn't matter for me anyway. R8 is keyed and only goes in one way.I have a fairly cheap set of import ER40 collets so I installed a 1/4", and installed a cutter. By sheer luck if there is any runout in the collet, it's in the proper direction so as to cancel any additional collet error.The test indicator in the video measures in 0.002mm increments. The runout is ~12 increments giving a total of 0.024mm or 0.00095".Not bad at all. I'll keep it.

I have ER32 collets for my lathe and wanted to use them for the mill to hold cutters. Borrowed a friends Collet Chuck was not impressed, it was one of the really cheap ones here on Amazon. The Accusize had good reviews both on Amazon and a number of other websites. First, when I chucked it up, I measured the run-out and compared it to the spindle run-out.... added less than 0.0003" to my already 0.0004"... um, after cleaning the spindle morse taper and re-installing I couldn't get anymore than the 0.0004" run-out of the spindle (using a Starrett 0.00001" Dial Indicator)... So I think paying a bit extra was worth it. I had spent a bit more on the collet set a couple years ago, so that they don't keep compounding the run-out in the final cutter assembly. This whole rig isn't a high precision setup, but is a reasonable alternative to very pricy super-precision ground units. For my light mill is a very good option. I'd look for Accusize items again.

The first R8/ER40 unit I received had ER socket 0.002" TIR running in my mill spindle. Pin in collet runout about the same. This mill spindle is good - 0.0001" in the R8 socket taper, and pins in R8 collets routinely show 0.0005" or less. I sent that unit back for an exchange. The replacement shows ER socket TIR 0.0002" to 0.0003" depending on pull up. Pin runout is 0.0002" to 0.0008", and is collet dependent.Cosmetic and detail workmanship are great on both units - very chrisp features and the grinds are beautiful. The metal is hard and resistant to marks from fit up into the spindle and wrenches.Looking through the reviews I get the feeling most of these are good, but for whatever reason some were not made correctly. I rate this item entirely by the quality of the good one.

Excellent product, makes tool change much easier,With accuracy.

It appears that the body of this was machined all at once, instead of at multiple machines and stations, resulting in an item that is concentric inside and out. No measurable runout detected, well within the tolerance of my lathe. Much better than the 2 others that I threw in the scrap pile because they could not hold a part true.