# making endmill holders for TTS system



## dovidu (Feb 23, 2019)

I used TTS ER20 holders for endmills previously.

It lacked rigidity when milling steel.

this is because TTS Er holders are designed quite inefficiently.

there's unnecessary stickout right below the spindle nose registering area



I decided, in order to maximize rigidity, I should get rid of all unnecessary part that lengthens the tool.

therefore, the most efficient design is endmill holder type, which holds specific endmill holder shank size.



also, the registering shouldn't register the spindle nose.

instead the tool should register the flat part of TTS collet inside the spindle.

i was able to reduce futher by doing so.



TTS ER20 + 8.5mm endmill = 95mm from spindle nose.

homemade endmill holder design = 45mm from spindle nose.



the result is roughly 2X the rigidity.

not only the tool is shorter, but the spindle is also lower. which lowers Z column flexing.



for industrial type machines, such as bridgeport, TTS might still have enough rigidity.

however, for most hobbiests and mid sized machine, rigidity cannot be sacrificed, especially when machining steel.

hack, even bridgeport needs more rigidity, when machining demanding materials.



this holder design achieves both benefits of:


simple, fast, and easy to use TTS system


maximum rigidity achievable by your milling machine (shortest tool stick out possible)


hope this might help others achieve better rigidity for their machining projects!

below is the pictures of the endmill holders and a 50 minute long video, that includes almost every process and details for making this endmill holder.


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## dovidu (Feb 23, 2019)

the tts holder is fine for machines with high rigidity, and for production setup, it's quite nice


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## Cadillac STS (Feb 23, 2019)

Nice idea and you could have a large amount of holders, one for each tool. 

What diameter is the through hole?  For example 0.500 endmill is it 0.501 for best fit?


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## mikey (Feb 23, 2019)

I use the TTS system with an RF-31 mill and have both the ER-20 and ER-32 chucks and have not noted a significant issue with rigidity. Given that an ER chuck extends further from the nose than your end mill holder, I can see why you might think so, though. 

The key issue with tool holders is concentricity, which has a significant impact on accuracy and tool life. An ER collet surrounds and clamps the entire circumference of the shank of an end mill. Unlike an end mill holder, it does this regardless of any variation in the OD of the end mill shank. This allows for maximum concentricity and improved rigidity and vibration damping. In contrast, the set screws of an end mill holder will displace the shank of the end mill to one side, creating an offset that results in a significant reduction in concentricity, accuracy and tool life. Moreover, since the set screw pushes the the shank to one side of the holder, there is a significant reduction in contact between the end mill shank and the inside of the holder, like this:




This configuration provides only two points of contact, one of which is a tiny set screw. So, not only is the area of contact very small with an end mill holder, it is far less secure than a collet. In addition, the smaller the end mill shank is the smaller the area of contact is and the worse this situation gets. So, with the offset inside the tool holder and the minimal area of contact chatter is far more likely, as is loosening of the tool in the end mill holder from that vibration. If you haven't experienced an end mill dropping out from an end mill holder and screwing itself into the work, you will.

I'm not trying to give you a hard time, honest. I just wanted to point out that end mill holders are NOT more rigid than an ER system, nor are they as accurate.

Your end mill holders reduce Z-travel for sure, though.


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## macardoso (Feb 23, 2019)

You made a mention that your design sits against the face of the TTS collet, not the face of the spindle. As I see it this will cause a non-repeatable Z height as the R-8 collet retracts into the spindle as it tightens. The tighter you make the drawbar the further your tool is pulled into the spindle.  This is exactly why Tormach designed the TTS to sit against the nose of the spindle. Furthermore, I think the wide contact area against the spindle nose would significantly increase rigidity compared to the small amount of stickout that you save by removing it.

With all that being said, there is no reason you couldn't make a tool holder of your design that had a larger diameter collar to reach the full spindle nose. You would still save a lot of stickout compared to the TTS set screw holders.


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## dovidu (Feb 23, 2019)

Cadillac STS said:


> Nice idea and you could have a large amount of holders, one for each tool.
> 
> What diameter is the through hole?  For example 0.500 endmill is it 0.501 for best fit?



actually, as you can see in the vid, you gotta go lower.
so if 0.500 -> you have to machine 0.499~0.4995
then heat the holder and slip fit. then set screw on both sides to secure the tool.
at least that's what i've done


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## dovidu (Feb 23, 2019)

mikey said:


> I use the TTS system with an RF-31 mill and have both the ER-20 and ER-32 chucks and have not noted a significant issue with rigidity. Given that an ER chuck extends further from the nose than your end mill holder, I can see why you might think so, though.
> 
> The key issue with tool holders is concentricity, which has a significant impact on accuracy and tool life. An ER collet surrounds and clamps the entire circumference of the shank of an end mill. Unlike an end mill holder, it does this regardless of any variation in the OD of the end mill shank. This allows for maximum concentricity and improved rigidity and vibration damping. In contrast, the set screws of an end mill holder will displace the shank of the end mill to one side, creating an offset that results in a significant reduction in concentricity, accuracy and tool life. Moreover, since the set screw pushes the the shank to one side of the holder, there is a significant reduction in contact between the end mill shank and the inside of the holder, like this:
> 
> ...



i see your point, but what i have done is actually different.
the holder ID is smaller than the tool.
the set screw is there on both sides to further secure the tool.


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## dovidu (Feb 24, 2019)

macardoso said:


> You made a mention that your design sits against the face of the TTS collet, not the face of the spindle. As I see it this will cause a non-repeatable Z height as the R-8 collet retracts into the spindle as it tightens. The tighter you make the drawbar the further your tool is pulled into the spindle.  This is exactly why Tormach designed the TTS to sit against the nose of the spindle. Furthermore, I think the wide contact area against the spindle nose would significantly increase rigidity compared to the small amount of stickout that you save by removing it.
> 
> With all that being said, there is no reason you couldn't make a tool holder of your design that had a larger diameter collar to reach the full spindle nose. You would still save a lot of stickout compared to the TTS set screw holders.



true, this will not be useful for cnc operations or repeatability operations.
i have made the holders so i can machine hard steels easier and deeper
the TTS, i also thought the spindle nose registering would increase the rigidity,
but in reality it's way worse than, say using a R8 collet.


tool stick out is too long with TTs
consequently the spindle has to be positioned higher, which will induce more column bending.
everything's gotta be short and close to maximize rigidity. especially on hobby class machines


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## dovidu (Feb 24, 2019)

macardoso said:


> You made a mention that your design sits against the face of the TTS collet, not the face of the spindle. As I see it this will cause a non-repeatable Z height as the R-8 collet retracts into the spindle as it tightens. The tighter you make the drawbar the further your tool is pulled into the spindle.  This is exactly why Tormach designed the TTS to sit against the nose of the spindle. Furthermore, I think the wide contact area against the spindle nose would significantly increase rigidity compared to the small amount of stickout that you save by removing it.
> 
> With all that being said, there is no reason you couldn't make a tool holder of your design that had a larger diameter collar to reach the full spindle nose. You would still save a lot of stickout compared to the TTS set screw holders.


my personal experience with TTS er chuck vs my endmill holder design, TTS is 1/2 the rigidity.
i can barely make 1mm cut in hard steel with 8.5mm (0.33inch) endmill (S45C kinda hard stuff)
with my short design i was able to achieve the same DOC, except it is quieter and easier.
so i'd say maximum doc 2mm in steel, 5mm in aluminum
with tts the maximum stable doc with alu was 2~2.5mm


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## mikey (Feb 24, 2019)

dovidu said:


> i see your point, but what i have done is actually different.
> *the holder ID is smaller than the tool*.
> the set screw is there on both sides to further secure the tool.



I don't understand. If the holder ID is smaller than the tool then how do you get the tool into it?


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## dovidu (Feb 24, 2019)

mikey said:


> I don't understand. If the holder ID is smaller than the tool then how do you get the tool into it?



in the vid, i heated the tool 260~350 degrees celcius.
this expands the tool holder by <thou or so
as it cools, it shrinks


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## mikey (Feb 24, 2019)

Oh, okay, my error. I admit that I fast forwarded through most of the video as it was close to dinner time and I missed that you made a heat shrink tool holder. My apologies to you. That should definitely be solid enough. 

I am not sure why you're so limited in your depth of cut in aluminum with an ER collet, though. I've taken 3/8" deep cuts with a 3/8" roughing end mill held by an ER-32 collet on my Sherline mill with no problems and can easily do the same on my RF-31. Something is off.


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## dovidu (Feb 24, 2019)

3.8" deep cuts with sherline? that's whopping 10mm DOC
is that even possible? i have sherline as well...


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## dovidu (Feb 24, 2019)

mikey said:


> Oh, okay, my error. I admit that I fast forwarded through most of the video as it was close to dinner time and I missed that you made a heat shrink tool holder. My apologies to you. That should definitely be solid enough.
> 
> I am not sure why you're so limited in your depth of cut in aluminum with an ER collet, though. I've taken 3/8" deep cuts with a 3/8" roughing end mill held by an ER-32 collet on my Sherline mill with no problems and can easily do the same on my RF-31. Something is off.



what's could be wrong?
maybe the vise?
the vise i am using is 15kg toolmakers vise.
one thing i suspect tho: the vise is held down by 2 toe clamps.

maybe i should clamp it down with 4 instead?
or change the vise to milling vise altogether?

since the vise is so big, it is indeed a bit high profile design,
i've had no problem with clamping power whatsoever.

if the spindle is good, and all the axis is good, maybe clamp down force is not enough?


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## dovidu (Feb 24, 2019)

mikey said:


> Oh, okay, my error. I admit that I fast forwarded through most of the video as it was close to dinner time and I missed that you made a heat shrink tool holder. My apologies to you. That should definitely be solid enough.
> 
> I am not sure why you're so limited in your depth of cut in aluminum with an ER collet, though. I've taken 3/8" deep cuts with a 3/8" roughing end mill held by an ER-32 collet on my Sherline mill with no problems and can easily do the same on my RF-31. Something is off.



oh, and also, the endmill is a little bit worn,
but 10mm depth of cut in AL, with sherline mill is unheard of.


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## mikey (Feb 24, 2019)

A Sherline mill doesn't know what it can't do so just don't tell it. I'm serious. If you own one then you know that with the proper technique, speed, feed and depth of cut the mill will do most anything a larger mill can do, maybe a little slower. I use mostly Niagara Cutter end mills, high helix for aluminum and when I need to make an ambitious cut, A-9 for cutting oil. I swear that I've cut pockets in 6061 with a 3/8" deep pass with a coarse pitch roughing end mill on my Sherline mill and just a simple Wilton machine vise to hold the work. Nobody told me I couldn't do this so I just went ahead and did it, and I've done this more than once. Same thing on the lathe. I take depths of cut that are two to three times what most Sherline guys use because the machine can take it if you use a good tool. Your machines are far more capable than you think.


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## dovidu (Feb 24, 2019)

mikey said:


> A Sherline mill doesn't know what it can't do so just don't tell it. I'm serious. If you own one then you know that with the proper technique, speed, feed and depth of cut the mill will do most anything a larger mill can do, maybe a little slower. I use mostly Niagara Cutter end mills, high helix for aluminum and when I need to make an ambitious cut, A-9 for cutting oil. I swear that I've cut pockets in 6061 with a 3/8" deep pass with a coarse pitch roughing end mill on my Sherline mill and just a simple Wilton machine vise to hold the work. Nobody told me I couldn't do this so I just went ahead and did it, and I've done this more than once. Same thing on the lathe. I take depths of cut that are two to three times what most Sherline guys use because the machine can take it if you use a good tool. Your machines are far more capable than you think.



cool, i definitely have to pay more attention to the techniques.
i find myself impressed. you must have quite a skill!


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## dovidu (Feb 24, 2019)

mikey said:


> A Sherline mill doesn't know what it can't do so just don't tell it. I'm serious. If you own one then you know that with the proper technique, speed, feed and depth of cut the mill will do most anything a larger mill can do, maybe a little slower. I use mostly Niagara Cutter end mills, high helix for aluminum and when I need to make an ambitious cut, A-9 for cutting oil. I swear that I've cut pockets in 6061 with a 3/8" deep pass with a coarse pitch roughing end mill on my Sherline mill and just a simple Wilton machine vise to hold the work. Nobody told me I couldn't do this so I just went ahead and did it, and I've done this more than once. Same thing on the lathe. I take depths of cut that are two to three times what most Sherline guys use because the machine can take it if you use a good tool. Your machines are far more capable than you think.



oh, and i think i misunderstood something.
when i meant 2mm DOC, i mean 2mm DOC vertically (below the work piece) and taking a whole width of endmill worth of material removal.
10mm DOC removing a small portion on the side of the endmill is ofcourse easy, i could do 30mm DOC with that.
what i meant is a full plunge cut, as seen in my video.

10mm plunge cut with sherline is impossible, that's impossible even on BF30.
even if that could be done, it would be a very messy cut


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## mikey (Feb 24, 2019)

No, not impossible. I have done a 3/8" depth of cut in Z multiple times with a rougher.


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## dovidu (Feb 24, 2019)

mikey said:


> No, not impossible. I have done a 3/8" depth of cut in Z multiple times with a rougher.


hm.. with rougher maybe possible, i only have standard cobalt endmills. i need to try that someday 
thanks for your feedback 

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