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View Full Version : I know what a wet spot is. But whats the flat spot for?



lugnut
06-01-2007, 04:54 PM
I have a simple question. A friend was in my little shop the other day and picked up one my end mills and then asks: Whatís little flat section ground into the shank for? I couldnít answer his question other than maybe some types of collets or chucks require the flat spot. Iíve made several attempts to find the answer on the web and even dug out my 16th edition of Machineryís Handbook and I canít find a reference to it.
Thanks
Mel:confused:

Swarf&Sparks
06-01-2007, 04:57 PM
set screw?

speedy
06-01-2007, 05:01 PM
The flat spot is for workshop machinery using normally aspirated engines with one or more carburettors:)

Swarf&Sparks
06-01-2007, 05:04 PM
so blown mills are out of the question?

alanganes
06-01-2007, 05:05 PM
Machines that use "end mill adapters" hold the endmill in with a set screw.
Here is one type:
CLICK HERE (http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=210-1032&PMPXNO=948435)


-AL A.

speedy
06-01-2007, 05:14 PM
so blown mills are out of the question?

Not at all; just don`t expect to be able to utilise tooling with flat spots to the same extent:D

Swarf&Sparks
06-01-2007, 05:17 PM
so I should change the dashpot oil in my SUs?

speedy
06-01-2007, 05:30 PM
so I should change the dashpot oil in my SUs?

Only if its black:) . If you`re running them on a Harley then dump the oil.

JCHannum
06-01-2007, 05:33 PM
The actual name for that style of end mill is Weldon Shank.

The flats are for set screws and are what makes the solid endmill holder a more solid retaining system than collets, regardless of other's opinions.

Swarf&Sparks
06-01-2007, 05:37 PM
sorry about the thread hijack but, no, MG :D

A.K. Boomer
06-01-2007, 05:56 PM
I have a simple question. A friend was in my little shop the other day and picked up one my end mills and then asks: Whatís little flat section ground into the shank for? I couldnít answer his question other than maybe some types of collets or chucks require the flat spot. Iíve made several attempts to find the answer on the web and even dug out my 16th edition of Machineryís Handbook and I canít find a reference to it.
Thanks
Mel:confused:


Its for a very primative endmill toolholding system -- oops, did i just say that outloud?

Swarf&Sparks
06-01-2007, 05:58 PM
Yup, ya did, and it's probably not CNC qualified.
Oops, did I say that out loud?
:D

JCHannum
06-01-2007, 06:11 PM
Solid end mill holders with Weldon Shank end mills are entirely suitable for CNC use and are common in CNC applications due to their rigidity and accuracy.

Alistair Hosie
06-01-2007, 07:58 PM
Is Enco stuff smaller than usual ? Or is Enco just a trade name for anything made by Enco? I just thought enco lathes were quite small.Alistair

ckelloug
06-01-2007, 08:02 PM
Alistair,

If I understand it correctly, the little tiny lathes are from Emco; the cheap machine tools on the American side of the pond are from Enco.

--Cameron

JCHannum
06-01-2007, 08:06 PM
Enco is a tool distributor. They sell many brands of tools, but generally sell economy imported tools under their own name. They are not a manufacturer.

Emco is a manufacturer of quality machine tools. They are an Austrian manufacturer and have a line of high quality CNC & manual tools in the medium and smaller sizes.

http://www.emco.at/index.php?changelang=en

fcdnorton
06-01-2007, 08:10 PM
the flat is for a set screw for use in a R-8 end mill holder and for CNC tool holders for indexing.

oldtiffie
06-01-2007, 09:09 PM
so blown mills are out of the question?
They are here!

You spend too much time on those cray boats off WA getting tossed around.


My mill is hard enough to get on with at the best of times and spends too much time in the dark and is jittery enough as it is.

I am certain that if I told it it was going to get a "blow job" that boosting or having a "turbo" fitted would not enter its mind.

Mine either - hence the reply.

Now thanks to you, me and the mill will have to take a BIG Valium and a stiff drink, cool our jangled nerves and have a good lie down for the rest of the day.

The problems you cause!!

Paul Alciatore
06-02-2007, 01:16 AM
Possible hijack here, but I have always wondered ...

So the holders that use a set screw to hold a milling cutter are considered more ridgid. But, you have a cutter in a hole and a set screw is tightened against it from one side. Now, doesn't that force the cutter off center in the hole? OK, so it is a close fit, but still there must be some clearance and the cutter's shank is going to be forced against the opposite side of the hole by the set screw. So some flutes are cutting more than others, aren't they? I always wondered if this is the reason for using collets.

Worse yet, the constant pressure against the side of the holder's hole will, over time, cause the metal to deform and the situation will become worse. Do these holders have a limited life? 1000 hours or so and then the trash bin?

lazlo
06-02-2007, 01:19 AM
The flats are for set screws and are what makes the solid endmill holder a more solid retaining system than collets, regardless of other's opinions.

LOL! I didn't think you could resist JC! :D

By the way, thanks for the chasers -- I can't believe you remembered that! :)

lazlo
06-02-2007, 01:25 AM
Now, doesn't that force the cutter off center in the hole?

Yes, it does. But the high quality (read: expensive) endmill holders have the hole ground eccentrically with the shaft, so that when the set screw takes up the slack, the cutter is back on center. The Chicom endmill holders don't do that.


Worse yet, the constant pressure against the side of the holder's hole will, over time, cause the metal to deform and the situation will become worse. Do these holders have a limited life? 1000 hours or so and then the trash bin?

Probably so. The ETM (high-quality) endmill holders I have are drop forged. The Bison endmill holders are as well.


OK, so it is a close fit, but still there must be some clearance and the cutter's shank is going to be forced against the opposite side of the hole by the set screw. So some flutes are cutting more than others, aren't they? I always wondered if this is the reason for using collets.

You might as well have asked if you need to calculate the diametral pitch for a clean knurl ;)
Grab a beer and read through this:

Endmill Holders (http://bbs.homeshopmachinist.net/showthread.php?t=23818)

Cheers,

Robert

JCHannum
06-02-2007, 08:26 AM
By the way, thanks for the chasers -- I can't believe you remembered that! :)
You are quite welcome. I can assure you it was a matter of luck and had nothing to do with mental prowess.

barts
06-02-2007, 11:46 AM
Possible hijack here, but I have always wondered ...

Worse yet, the constant pressure against the side of the holder's hole will, over time, cause the metal to deform and the situation will become worse. Do these holders have a limited life? 1000 hours or so and then the trash bin?

No. Steel doesn't work this way at room temperatures; if the load on a piece of steel is below the elastic limit, it will always spring back. Steel doesn't "creep" under load at room temp., unlike other soft metals such as lead. For fun, hang a weight on a piece of lead solder; over time the solder will get longer and thinner.

tattoomike68
06-02-2007, 01:37 PM
The actual name for that style of end mill is Weldon Shank.

The flats are for set screws and are what makes the solid endmill holder a more solid retaining system than collets, regardless of other's opinions.

Yep I think anyone who wants to do much milling should have a few of the common sizes they use.

Collets dont hold up very well to heavy milling and The endmill can pull out giving the machinist fits and scrap parts.

Carld
06-02-2007, 10:00 PM
The set screw type holders are by far the most rigid holders available and have been used for at least 100 years and are still being used even in CNC machines. Colletts are no match for the rigidity of the Welden type holders.

The hole in the holder is NOT machined off center but is a snug fit for the end mill and the end mill does not move around in the holder.

If you buy cheap holders they are not a close fit and can't be used for heavy duty use because the end mill will wallow out the bore.

A major feature of the Welden type holders is, the end mill will not move if correctly installed.

lazlo
06-02-2007, 11:08 PM
The hole in the holder is NOT machined off center but is a snug fit for the end mill and the end mill does not move around in the holder.

The hole is ground eccentrically on my ETM endmill holders, and it is on JTier's Bison endmill holders.

If the hole wasn't bored eccentrically by the amount of offset the setscrew causes, then it would add to the total runout of the holder, like Paul said.

Orrin
06-03-2007, 09:47 AM
So the holders that use a set screw to hold a milling cutter are considered more ridgid. But, you have a cutter in a hole and a set screw is tightened against it from one side. Now, doesn't that force the cutter off center in the hole? OK, so it is a close fit, but still there must be some clearance and the cutter's shank is going to be forced against the opposite side of the hole by the set screw. So some flutes are cutting more than others, aren't they? I always wondered if this is the reason for using collets.

I mde my own 5V end-mill holders for my Van-Norman milling machine. Drilling the hole for the set-screw was the last thing I did. I mounted the nearly-finished EMH into the mill and used a test indicator to check for eccentricity.

In most cases there was about a tenth, or so. So, I located the set-screw to compensate. Consequently, the end-mills run true.

Orrin

cybor462
06-03-2007, 10:03 AM
Boy do I remember this discussion:confused:
One thing I wanted to do but did not was not check the TIR of my MHC end mill holders. Got a set of them and they seem fine. I do not use collets anymore except for flycutting and those type of tools.
I wanted to check the runout before but forgot. So off to the shop now to check them. Who knows maybe I can put some horror stories of import holders to rest.......or maybe not! :rolleyes:

lazlo
06-03-2007, 10:39 AM
I mounted the nearly-finished EMH into the mill and used a test indicator to check for eccentricity.

In most cases there was about a tenth, or so. So, I located the set-screw to compensate. Consequently, the end-mills run true.

Very clever Orrin!

lazlo
06-03-2007, 10:44 AM
I wanted to check the runout before but forgot. So off to the shop now to check them. Who knows maybe I can put some horror stories of import holders to rest.......or maybe not!

Cybor, while you're measuring your endmill holder, could you check if the TIR "high-spot" is on the same side as the set screw?

The Enco endmill holder I have isn't bored eccentrically (to compensate for the set screw offset), but that's not to say that the "1st-Tier" Chicom manufacturers like Phase II and MHC didn't do it.

cybor462
06-03-2007, 12:55 PM
lazlo....I did not check that. I am working in the shop today so I will check it for you. I did however check the TIR of a few of the holders and they all are less than .0003 If I were to guess I would say .00025
My last word clone (it is made in the US, a Baker) is graduated in .0005 and my runout barely moved off the 1st line so when you double for TIR I guess it to be .00025

I know this is not lab quality measuring but it does tell me that these holders are all but dead nuts and will never be a problem in my shop.

For this day the chicom stuff gets a thumbs up!:D Unofficially speaking of course.

Now the disclaimer.....although I am almost half Chinese now because of the overwhelming amount of Chinese products I own and the poorly translated books I am forced to muttle through.. I need it to be known, I have not..will not...even think about making a profit off Chinese products..ooopppsss!!!!! I really do, but for this disclaimer I do not.:cool: :confused:

mochinist
06-03-2007, 01:51 PM
The set screw type holders are by far the most rigid holders available and have been used for at least 100 years and are still being used even in CNC machines. Colletts are no match for the rigidity of the Welden type holders.

The hole in the holder is NOT machined off center but is a snug fit for the end mill and the end mill does not move around in the holder.

If you buy cheap holders they are not a close fit and can't be used for heavy duty use because the end mill will wallow out the bore.

A major feature of the Welden type holders is, the end mill will not move if correctly installed.Well I know this is a home site, but if we are talking the best as far as holding power, and rigidity, then you have to go heat shrink tool holders. They also blow away the other style toolholders when it comes to concentricity and balance. Major coin to get tooled up though