[EvolveES]

and i also remember there being more posts on here, i just took a quick glance and was going to read them all in depth later...i must have been dreaming too

[shred]

Here's some more information for your consideration, as per Tormach, "Set Screw holders are our most popular and affordable tool holders. They are commonly used for general milling applications. Set screw holders are intended to be used with end mills that have a Weldon flat on them." http://www.tormach.com/product_tts_holders.html It sounds like they understand the reason things are the way they are in the industry and try to get that info to their customers. take it or leave it.

It's funny because Greg Jackson, the president of Tormach, was the one that told me it would be fine to use the setscrew holders on mills without flats. He was right.

[yulolaf]

It's funny because Greg Jackson, the president of Tormach, was the one that told me it would be fine to use the setscrew holders on mills without flats. He was right.

Hmmm, I wonder why it's written right there on their site, maybe it was written by some engineers or machinists in his employ who actually know what they are talking about and the guy in the office might not be up on how things should be, wouldn't be the first time.

[LeeWay]

It just means that is how they are designed to be used. The only difference is that we are saying it doesn't matter. You can still use non flat type end mills with good results in this class of machine.

[yulolaf]

Hey, don't shoot the messenger. I posted documented reasons why Weldon flats exist, if you choose not to listen to them that's your business. If you have setscrew holder tooling I don't see any reasons put forth why you should get non weldon flat endmills for them instead of ones with weldon flats, the cost is the same and the benefits are documented. I never said you can't use smooth shank endmills if that's all you have but just putting the info out there for the next time you go endmill shopping to get what is recommended.

[LeeWay]

I wasn't actually doing that. Just relaying my experience. I have a 1/2" 4 flute coated stubby end mill that can hog off some steel. To be honest, I expected it to have a flat when I ordered it. It doesn't. I still have zero issues with just the set screw on the side of the smooth end mill. Now the tolerances in the holders and the end mills themselves must be very close to work the best. I will try to get them with flats in the future for anything 3/8" or larger, but especially for smaller end mills, it just doesn't matter. That increases your selection so you may be able to save some money this way. Not to mention being able to reduce stick out even closer than a flat would allow. Until you have one slip, you have more options.

[SCzEngrgGroup]

and i also remember there being more posts on here, i just took a quick glance and was going to read them all in depth later...i must have been dreaming too

There were. The admins were nice enough to delete all the trolling, purely argumentative, and insulting messages, which have no place here.

Regards,
Ray L.

[johnedward]

I like the setscrew endmill holders better than ER20 holders because:
1. Cheaper
2. More rigid
3. Gives you a better view of what you are cutting
4. Easier to put an endmill in a set screw holder than in a ER20 collet holder (never really sure I get the thing tight enough).
5. Personal opinion: not convinced that cheap ER20 collets really give you enough of a difference in run-out to improve the cut quality. If I used really small end mills, I might care, but I don't.

I tend to use endmills with weldon flats because it is more convenient. Since I never buy any without, I can't really comment on how important this is.

I agree and I only buy weldon flat shanks too because I know they work as they should in a setscrew holder, no surprises, no risks but will work in a collet holder equally as well.
john

[TurboStep]

MD, thanks for your kind comments. I hadn't noticed that my post had been deleted.
Ray, here is a copy of my original post. Please let me know what part of this particular post you find "trolling, purely argumentative, and insulting". I honestly don't see anything of that nature. There was certainly none intended:

Lets try to get this thread back on track..

...I am so used to hearing the carbide end mills scream unless you back way off on the speeds and feeds that i just assumed it was normal...

I'm surprised that nobody has commented this statement, but as you have also discovered using the set screw holders, carbide end mills don't "scream"! I run carbide end mills in ER20 holders to the limits of my 1100 (and sometimes beyond ) and they perform wonderfully.

...I guess the conclusion is that the set screw holders are much more rigid than the ER20 collet holders...

While I'm quite sure that set screw holders are more rigidly constructed, that's by no means the only factor to consider.

...and the chips even looked better, a little thicker and more shiny. I couldn't believe it...

Your chips looked thicker??? Are you sure the cuts were the same?
I own several set screw holders but all except one sit in the drawer. I use ER20 holders for roughing, finishing, drilling and thread milling. I you're "backing off" then you should review your speeds and feeds and perhaps also check the condition of your end mills - even if you decide to stay with set screw holders. Were you using Tormach ER 20 holders? I do own some ebay ER20 holders but I only use them for drilling. The Tormach holders are made of a different material with better vibration dampening properties.
Step

[EvolveES]

Ahh, yes, i remember skimming your post yesterday. And i will be the first to admit that i am new at this machining thing and just learning as i go, but i enjoy the hell out of every minute of it. I'm sure i will make several mistakes and false assumptions along the way. The truth is that yes, i had come to accept that the carbide end mills will scream, mine usually did when i used the conservative feed rates from G-Wizard. I can also remember picking up parts at another machinists house for years and he has a Bridgeport VMC and his machine would routinely be making some horrible screaming noises, he has done it for over 20 years so i assume he knows what he is doing, so i just accepted it.

I am sure you can tune ER holders to run smoothly (as i have been trying to do), but i would be interested to see the max limit of a set screw holder, then transfer the same end mill to a ER holder and run the same exact cut and see how it does (you can go the reverse as well with another new cutter so the test is not biased to the first cut. If i have time in the next week or so i am going to try this.

and strangely to my (untrained) eye the chips looked much better, i did not measure any, but they were much more shiny and appeared to be bigger (maybe they were getting re-cut the other way or something?). this is all speculation though. Thanks for the feedback. and so far ALL of my tool holders have been purchased brand new through tormach.

[LeeWay]

The point is that I doubt you will even be able to do such a test on machines of this size and HP. You may see TTS pull out well before any set screw slippage. Easy to see if you have a PDB. Lots of guys complain about that. I can see some slippage if I leave my lever draw bar alone for a period of time. It loosens up over time.
When I run my big end mills and TTS, I use an impact wrench to tighten the draw bar. That is the only sure way that I will not get any pullout.

[Hirudin]

One thing not mentioned yet is that the flat also provides some space for the metal to deform. I'm not sure if that's an issue with end mill holders, as I've never used one, but it is something I've noticed with my boring heads. If the boring bar doesn't have a flat, the dimple left by the set screw will deform the shank a little bit, possibly enough that it becomes very difficult to pull the bar out of the boring head. Have any of you noticed issues with an end mill deforming after a set screw has been clamped down on it? Carbide too?

I'm not a physicist, but I can't imagine you're getting any more holding force by tightening the set screw against a flat as compared to a round shank. Basically, putting a certain amount of torque on the set screw produces a certain amount of axial force*. That force could be measured in PSI. It doesn't matter if the area of contact between the screw and shank is large or small, the amount of force will be equal.

Regarding pullout, it seems like pulling the tool down against the screw would certainly reduce catastrophic pullout but I wonder whether you could put enough preload on the tool to eliminate it completely. I imagine the amount of pullout possible wouldn't really matter in a roughing application though.

*as has already been discussed, ad nauseum, on this forum: the relationship will not be identical from screw to screw (or holder to holder) because the friction between the threads is not always going to be equal (tight threads, buggered-up threads, lubrication used, temperature, or any number of other factors)

[CNC-Dude]

If the boring bar doesn't have a flat, the dimple left by the set screw will deform the shank a little bit, possibly enough that it becomes very difficult to pull the bar out of the boring head. Have any of you noticed issues with an end mill deforming after a set screw has been clamped down on it? Carbide too?

Hirudin, I have observed this behavior on boring bars, but not on mills. I think the reason is that boring bars are made of unhardened steel with a piece of carbide soldered at the end, whereas mills are hardened all the way through. I will accept to be corrected to any of these two claims as I am basing on impressions not hardcore mechanical engineering data.

[SCzEngrgGroup]

Have any of you noticed issues with an end mill deforming after a set screw has been clamped down on it? Carbide too?

Endmills are FAR harder than the set-screws, even HSS ones. I've never see a mark on an endmill shank.

Regards,
Ray L.

[shred]

Anyway.. As this is now way way more argumentative than my deleted post commenting that the only time in years of doing it that way that I've seen non-Weldon flat tools change length in a setscrew toolholder in a Tormach is when they are crashed into something, I expect it won't be around long, so those of you risking life and limb by running non-Weldon flat tools should make a note to check the length if you crash them into something.

[johnedward]

One thing not mentioned yet is that the flat also provides some space for the metal to deform. I'm not sure if that's an issue with end mill holders, as I've never used one, but it is something I've noticed with my boring heads. If the boring bar doesn't have a flat, the dimple left by the set screw will deform the shank a little bit, possibly enough that it becomes very difficult to pull the bar out of the boring head. Have any of you noticed issues with an end mill deforming after a set screw has been clamped down on it? Carbide too?

I forgot to comment on this. Carbide no worry. HSS, yes. Many manufacturers temper the shanks and as I can speak from experience some go too far. I've seen more than a couple shanks get dimples from the setscrews and it can make it a bear to remove unless they have the Weldon flat, that's why that's all I get now if I can help it.