R8 collets

[Former Member]

I'm still thinking about pulling the trigger to buy my first mill (likely soon) - so I'm learning about tooling. I realize that starting off with the right collets (for your intended purpose) is quite important. I recently watched what Joe Pieczynski had to say about collets (Joe puts out a lot of good videos). The last 5 minutes of the video give a great visual explanation of the difference between R8 and R8-ER collets -- have a look @eric_brackenbury:

joe pieczynski collets youtube - Search Videos

www.bing.com

"Joe Pieczynski: Collets- Types, Pros, Cons, and general info"

I have a couple of collet questions & would appreciate feedback (I think this is a good place to ask rather than starting a new thread):
- Which grips better - an R8 collet that is properly sized or an R8-ER collet? (I understand that the size range of an R8 is much less than the ER but if sized correctly - which is better?)
- If using a carbide end mill - what is the best collet? or is a different holder needed? (when being used on a benchtop with a max power of 2 Hp)
- Is collet accuracy that important for a hobby guy not intending to make precision parts? (0.0002 vs 0.0006). I've seen accuracy shown as 0.0006 TIR - what is TIR?
- Amazon has a BETOOLL 13 psc R8 set, 1/8 to 7/8 at $128.38 - is this a good deal

13pcs Precision R8 Collets Set 1/8 - 7/8" Mill Chuck Holder for Bridgeport .0006 : Amazon.ca: Industrial & Scientific

13pcs Precision R8 Collets Set 1/8 - 7/8" Mill Chuck Holder for Bridgeport .0006 : Amazon.ca: Industrial & Scientific

www.amazon.ca

the above shows material as 65Mn - what's that?

Thanks
Craig

Since I turned my mill into CNC I switch from R8 collets and R8 fix Weldon holders to R8-ER32 holders, 4 from Accusize (1 a smaller size and straight shank) and 1 from another supplier.

The main reason is Carbide tooling and the grip strength with the ER collets.

Disadvantages with each as follows:

Collets, grip limited by draw bar strength, limited size spread and grip range.

Weldon, need flats (Carbide has less chance of flats), also adds bending to bit, so true running is thrown of a bit.

ER need a mounting holder to achieve best hold, you have to build one. I have 3 different slots mount on my work bench for this 2 are for ER32 on is for a smaller size (still for the mill but allows a deep reach small bit application also from Accusize so it still needs to mounted in a ER32 or R8 Collet).

Remember for me its about production and ease of set up moving from one size to another (my CNC does not have an Auto Tool Changer).

 

[PeterT]

@Susquatch I suspect you are right. The implied rule or guideline is probably to size the nominal R8 bore for the nominal shank. Use a 1/2" collet for a 1/2" EM etc. We are assuming (or hoping) the shank will be ground just slightly undersize & it will grip as it should. Most of the HSS & carbides I have are about 1 thou under. In the IMP world, that makes for just a few collets because there actually aren't that many nominal shank sizes. The issue usually arises when discussing metric EM's or buying an incremental R8 set to span in-between distances & that's probably more what I was wondering about. Metric EM's (not always but typically) match nominal shank diameter to cutter diameter, so I assume that means metric R8's & a more complete incremental set is required. So that's what I mean, someone bought a 1/16" increment IMP R8 set, but I have my doubts that would be the right path to fit metric EM's as a rule just because it within the range on paper.

 

[Former Member]

One other thing I have seen soft R8 (emergency) collets that allow you machine the size you need. I have never used them so beyond that can not comment.

 

[CWret]

Our street party/bbq last night had about 60 attendees (not bad for just 24 residences) but it was a late night for a guy that is normally an early riser, so I'm a bit slow responding - but here goes.

I had a friend, Moose, who was considered an expert in his field. When questioned in court, he would say "I'm an expert because I made more mistakes than the other guy". I'm trying to avoid mistakes or poor purchases and appreciate all your comments.

@RobinHood @Canadium - thanks for the clarifications on TIR

@Susquatch your post #75 had lots of good input. I should have been more specific about the mill I'm considering (2Hp is too vague). I'm looking at getting a large (over 850 pound) bench top RF-45 clone.
You mentioned that an R8 with a drawbar can be tightened better/easier than an ER with a wrench - that answers a question that I forgot to ask.
Getting a small set of R8 1/16- 3/4 & 6mm& 12mm - great - if I'm only getting a few then higher quality makes good sense. I can add a complete set of ER32 later.

@RobinHood @Susquatch - OK I'll give more importance to TIR when selecting smaller sizes

@Susquatch @PeterT @Degen - R8 end mill holder (weldon) - thanks for pointing out that option but I think they are overkill for me (at least for now)

@eric_brackenbury
- thanks for getting this discussion started about collets
- I'm glad you added the link to your goldsmithing - nice work. I can certainly see where accuracy for you is very important
- lastly: When I was a young teenager, John DeGruchy (along with Francine and Annette) were frequent visitors to my parent's house. I'm guessing with your trials riding and age you likely knew him (for others, John is a Canadian Motorcycle Hall of Fame inductee). In the early 1970's I graduated from my Hodaka to a Bultaco Pursang (250 seniors class) that I bought from John at Sonic.


Thanks again everyone for this interesting and helpful information.
Craig