End mills.. need help.

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negatronix

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Hi,

I'm new to machining, and have a question regarding end mills.

I am looking at purchasing a Grizzly go755, which comes with a spindle adapter R-8 x MT#3.

My question is this. Do I purchase a set or R-8 collets or R-8 endmill holders to hold the endmill, and ball endmill tools. If not the collets, what are collets used for?

Sorry for the total newbie question, I am just getting started with all of this and have zero experience.

Thanks, -Kory
 
If it has a r8 spindle I would just buy r8 collets. Any adapter is going to take up some of your work height. Yes collets are for holding tools on a mill and they hold stock on a lathe
 
If you can afford it I would also buy both styles of end mill because I prefer to hog out material with the ball ends and the finish the surface with a flat once I get close to the finished measurement. I seem to have better luck clearing large quantities of chips with the ball nosed than I do with the flats. The flat and Ball nosed sets are available at HF for about 80 bucks each for a pretty complete set and if you have coupons you can have a pretty decent set of both for around a hundred and twenty bucks easily. That's what I did and those bits are good enough for a beginner to figure out what they are doing without ruining a high dollar bit making a newby mistake. Welcome to our little gang and I hope you find everything you are looking for and the knowledge you need to get going. If you ever need help or have an issue all you need to do is start a thread or ask a Mod. We are here to help and provide assistance when and where we can.

Bob
 
I have only ever used the R8 collets for my work. The only end mill holders I have are for end mills whose shanks are too large to fit any of the R8 collets.

I don't like the extra length of unsupported end mill sticking out of the spindle that you have when using end mill holders. It reduces rigidity,and it does,as mentioned,take up your vertical space.

Keep your collets free of oil,and also the shanks of the end mills you are putting into them. Tighten the draw bar well. I have never had an end mill suck out of an R8 collet. But,my journeyman did once. I think he must not have tightened the draw bar enough.
 
Thanks everyone! I will be purchasing a set of R-8 collets, a set of 2 and 4 flute end mills, and a sets of small and large ball cut end mills with 7/8" shanks. I believe the tools that I selected are all HSS-TiN.

Thanks,
-Kory
 
George,

What brand of R8 collets are you using? The reason I ask is that I have nothing but trouble when trying to use the collets on my mill. The end mills either try to pull out, on "regular" operations, and push in if I'm plunging. I use a Kurt automatic draw bar which snugs them in as good as can be. I keep oil away from the collets as well as end mills but still haven't been able to rely on the setup. The only place I can see maybe being a problem is that I've got some cheap Chicom collets.

For this reason I prefer to use end mill holders instead of collets. Combined with a Weldon shank end mill they are rock-solid. My mill has enough head room where the extra extension of the holders isn't much of an issue though.

JMHO

-Ron
 
Well I might as well add two more cents. I have a Bridgeport mill and use R8 collets and for the last 45 years or so. Can’t recall ever having a problem with using collets, and that goes for in lathes and collets used anywhere else in the shop. The draw bar is used with a standard wrench. I do not gorilla the torque went tightening the collet. The threads on the draw bar look great. I dislike using the end mill holder type because of the extra length as others have noted. But it’s a necessity above 7/8”. Because many other folks share my R8 collet experience as with no problems. I suspect that any issues using collet type holders is unique to that machine and not a general wide spread common reoccurrence...Good Luck.
 
I have sucked the work out the vice before but never the tool out the collet. I have one end mill holder for my big old end mill but thats all.
 
I am just using cheap Chinese collets. The only one I have found to be faulty is a 3/16" one which is way off center on the 3/16" hole. I have not found any trouble with these collets. I actually have used 3 separate sets. I had 2 vertical mills at work,and mine at home. All outfitted with the same collets.

I'm inclined to think your Kurt draw bar isn't tightening your collets tight enough. That's the only conclusion I can reach,based on my experience,and those of others here. Is your draw bar tightener adjustable to make it tighten more? Do you need higher air pressure? I have never used one myself,so can only pose these few questions.

I tighten mine with a standard draw bar hammer. The one with a brass head on 1 end and the hex wrench on the other end of the head. I hold the brake lever while tightening. The handle of the standard hammer is not really long,but I get good,secure collet tightening with it. I am a large guy,but am 73,so I doubt I'm tightening unusually tight.
 
Now that you mention it, I have seen some issues on the air draws at school. Both holding and releasing. It would slip so they turn up the psi, then turn it back down and cant get it to un screw.
 
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