[Micro Milling]

I have some questions about end mill holders.

Sometimes I need to lower my endmill in the holder so I tighten it down at a point that is not on that groove. I do this so that I can clear some tight areas that I need to cut in. It seems to work, I don't go ultra low with it. Do any of you do this or see any problems with doing this?

I was also wondering why there are endmill holders with 2 allen screws, is this so that I can lower my end mill in a lower slot, and have it grab in the groove? Should I get this type of end mill holder in the future?

My other question is on my current end mill holder it seems that the allen screw is getting a bit worn. When I tighten my end mill the allen key is difficult to pry loose from the screw. Do any of you have this problem?
Do any of you know the exact size of the allen key that fits a single screw 3/8" end mill holder?

How tight should I tighten down the end mill? Does it have to be tight or just enough to fit in that groove so it doesn't spin. I could see it holding with it not being that tight.

Can I get replacement allen screws for my end mill holder?

Thanks,

[vigilante212]

Well its best to try and tighten down on the flats so the endmill wont pull out or spin, you can also make flats or grooves in the endmill using a grinding wheel if you have a carbide wheel(at least i think its carbide)

As for the 2 screw holes one is enough, I believe the other is just for more adjustment options. You can buy replacement screws thier usually standard sizes. For tightness i usually go finger tight and then 1/2 or quarter of a turn, but this varies from person to person. Just dont over tighten or leave too loose, I worked with a guy who used a leverage bar to tighten every bolt nd I did not enjoy working after him

[christinandavid]

Hi,

You must tighten onto the flat for this type of holder to be effective. Homemade flats should be made on a surface grinder with a wheel of the correct width if possible - but rough flats made using a bench grinder are adequate if they are ground accurately enough.

Note that some tools are ground with a slightly tapering flat so that tool self-tightens if it starts to pull out. Another option you could consider for a bit more security on a homemade flat is to use two short grub screws and tighten the first onto the cutter and then tighten the second on top of the first.

Feel that these types of holders, when used correctly, are most suited for roughing cutters - due to the clearance between shank of tool and holder bore size, the cutter will never run quite true. A collet chuck is best for accuracy/tool life, and in some cases can be a better option if you need to move the tool out to gain the reach you require.

DP

[Andre' B]

The two set screws are for tools that need to screws when you are pushing things very hard, usually insert cutter bodies.
http://www.kennametal.com/e-catalog/...y%3A5097&logo=

[tizm]

answer #2 was very good! i agree with everything said! if your not taking too much of a cut or plunging into the part,you prob. dont need the flat but it is recomended!

[dertsap]

answer #2 was very good! i agree with everything said! if your not taking too much of a cut or plunging into the part,you prob. dont need the flat but it is recomended!

flats are a must have when using side lock holders , its simply dangerous otherwise , it would take nothing for the cutter to pull out on any kind of side cutting and will push use if facing

[tizm]

Yes,i said flats are recommended! A must?? no! If your using a z-carb in 3oo series ss than probably but i cut alum. and 1018 daily without grinding a flat on my tool

[Geof]

On a small low powered machine which cannot take a healthy cut and a high feed you can get away without flats but don't try it on a real machine.

[RICHARD ZASTROW]

Once upon a time, eons ago, there were Putnam tool holders for larger sized end mills and larger sized end mills. The end mills had two flats and the Putnam end mill holders had two screws in them.

Weldon shank tools fit in the Putnam holders because the screw in the Putnam matched up with the Weldon spec. shank. (Also fit the non-pullout collet "wedge")

Some Putnam shank end mills also had a groove near the end of the shank that fit Putnam "Quick Switch" tool holders.

Ah trivia, what fun. LOL
Dick Z

[claas900]

I was searching and came across this post. I have a question. My new to me mill has an R8 spindle and came with a bunch of end mills. I was going to just get a end mill holder set but am not having any luck finding one that holds Double sided end mills.
But now I see someone recommend just getting a Collect Chuck? Is that deep enough for a double sided end mill?

[judleroy]

Maybe i'm just crazy but i've had more tools come out of r8 holders then i've had come out of set screw holders. My machine uses cat 40 tooling and I have about 20 setscrew toolholders from 1/4" to 1". 99 percent of the time I use tools without flats. In 7 years on this machine I have never had a tool come out of a holder. I cut steel, brass, bronze, and aluminum of various types and hardnesses. If the tool has a flat I use it but mostly my carbide tools are without a flat. I take roughing cuts as a standard of 1/2 the tool diameter. For a 1/2" endmill in mild steel that would be 1/4" deep passes full width of tool at 25-30 ipm with the carbide tools I use. For 3/4" tools I run at 3/8" deep per pass.
None of my 1/2 or 3/4 carbide tools have flats and at one time I ran them 8-10 hours a day. I'm not saying tools can't come out of these holders...but in all that time i've never had one fall out. As a rule always be careful around spinning tools and wear safety goggles. Also Check that the setscrews are tight everytime you reload them in your machine. Thats of course my personal experiance and not a recommendation. Be safe.
Judleroy

[vigilante212]

Collet chucks are fine for smaller endmills say under 1/2" if there isnt a huge need for accuracy below .010 you can get it more accurate, but it usually takes alot more time and thier isnt any real guarantee it'll remain true thoughout the work.

Judleroy you may not see the endmill pulling out it may be spinning, signs of this can be chatter or bad finish marks. Its more evident in harder materials like Stainless or even in soft materials like aluminum if your taking max depth. Another thing is if you ever run a roughing mill without a flat it will most likly spin and break or stall the machine. Also I believe the standard for tooling rough cuts is usually 2/3 the tool diameter you need to check with the tooling your using though.

Now like you said though if your easy on tooling it may never spin or pull on you even with just a friction tightening from the locknut.

[judleroy]

I don't use roughing endmills. I use high performance carbide tools that are recommended for roughing and finishing. I know the signs of a tool rotating in the holder.
I get smooth finishes with no chatter marks. As far as I can tell I have never pulled a part off my machine that was out by more then .002 and that is due to variances in tool dia not runout. I will say that the machine and toolholders are the key not the programmer. I don't know of any industrial mill that will not hold those tolerances. If your out buy .01 you either need to replace your toolholder or your collet. If that does'nt work call a tech to fix your machine. As for tools I always consult the factory to get there recommendation for any tools I purchase. As for grinding flats most tool venders will tell you not to grind flats on there tools yourself. If you need a flat purchase it with the flat already there. If you want to grind flats consult them first or just use hss tools.
As I said before these are just my personal experiances and ultimatly you do what works for you.
Judleroy

[claas900]

Collet chucks are fine for smaller endmills say under 1/2" if there isnt a huge need for accuracy below .010 you can get it more accurate, but it usually takes alot more time and thier isnt any real guarantee it'll remain true thoughout the work.

Judleroy you may not see the endmill pulling out it may be spinning, signs of this can be chatter or bad finish marks. Its more evident in harder materials like Stainless or even in soft materials like aluminum if your taking max depth. Another thing is if you ever run a roughing mill without a flat it will most likly spin and break or stall the machine. Also I believe the standard for tooling rough cuts is usually 2/3 the tool diameter you need to check with the tooling your using though.

Now like you said though if your easy on tooling it may never spin or pull on you even with just a friction tightening from the locknut.

T/y.Where do I get a tool holder thats deep enoughf to hold a double sided end mill? I'm new but I would have thought a Collet chucks would be more accurate then .010? is a tool holder more accurate then .010?

[judleroy]

All good tool holders and collets should be way more accurate then .01...unless there broken. As for where to buy that depends on what taper you need. In general setscrew type holders are better for double ended mills because there thru bored so the tools don't bottom out. Collet chucks only allow a limited amount of room for longshank and double ended tools before they bottom out.
Judleroy

[claas900]

Thanks, I have an R8. I was just going to get a Mill holder from use-enco when I noticed it says for single end mills only. So that lead me a search for a double end mill holders and I have found nothing saying for double end mills. So I'm kinda at a stand still now as what to do.
My mill came with a bunch of double end mills but no holder.

[judleroy]

You can use double ended mills with standard r8 collets and dont really need a dedicated mill holder.
Judleroy

[claas900]

Thanks