Very good to know and I appreciate the confirmation. I really do appreciate everyone’s advice and I totally understand that R8 is more popular in North America where as MT is more common in Europe. From a bit of research and from all the comments here I don’t think it will make that much difference for my use case even for a power drawbar setup or native spindle taper tooling. @David_R8 I found a couple of options for boring heads and facemills in MT3 on Amazon.ca so I’m not too concerned with tooling options. I think I’ll have to make a couple of draw bars to work with the different standards but other than that and again for my specific use case, I have a feeling MT3 will be just fine.
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MT3 vs R8 spindle taper
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Sigh....sorry I have to write this....
OMG OMG no pin, pin broken, what am I to do????? Take it to a machinist to fix it.....W A I T!!! (Insert your won name here) I am a machinist, problem solved.
You guys so funny.
OMG OMG no pin, pin broken, what am I to do????? Take it to a machinist to fix it.....W A I T!!! (Insert your won name here) I am a machinist, problem solved.
You guys so funny.
I turned my Craftsman floor standing drill press into a mill press by having a friend use his lathe to bore the spindle for 5/16" shafting. To make sure the drill press would survive I bought a spare spindle from Sears before he started. The drill press has MT3 tooling which consists of a few holders 3/8", 1/2, 5/8" and 3/4". Along with that a couple of stub arbors and a boring head with MT3 shaft. I used it principally for milling aluminum castings for my Gingery Lathe. Don't think I ever used the boring head.
Once I bought my mill with R8 tooling I did buy an MT3-R8 holder. extends about 1.25" below the bottom of the spindle. And then the MT3 would fit into that. Not sure why I bought it or the MT2-R8 adapter. Haven't used either.
Key thing to remember, especially with a small mill is that you don't have a huge amount of height from spindle to table. Especially once you add a vise. Wasn't an issue with the floor standing drill press.
Using R8 with the flattened 3/4" (19mm) TTS collet means the R8 tooling doesn't protrude far. For that matter although you want to go CNC eventually, R8 collets holding say a 1/4" mill also means you get maximum distance from tool tip to table. Your MT3 tooling won't give you that. You automatically lose about 1.25" or more with the holder.
Here's the drill press. Although not measured there is not a large distance between the end of the fairly small diameter spindle and the back of the drill chuck. But add in the tool holder like in the next picture and that subtracts from milling height.
So here's the R8 to MT3 adapter holding a 3/8" MT3 milling cutter holder and a ball mill. It's at the 5" mark that the R8 taper begins. Even if the spindle on the mill only protrudes 3/4" from the quill of the milling machine you still have 2.5" + 0.75" = 3.25" sticking out. Compared to fitting that 3/8" ball mill directly into a collet. I can take a picture of that to show the difference after I get back from doggy walk.
Once I bought my mill with R8 tooling I did buy an MT3-R8 holder. extends about 1.25" below the bottom of the spindle. And then the MT3 would fit into that. Not sure why I bought it or the MT2-R8 adapter. Haven't used either.
Key thing to remember, especially with a small mill is that you don't have a huge amount of height from spindle to table. Especially once you add a vise. Wasn't an issue with the floor standing drill press.
Using R8 with the flattened 3/4" (19mm) TTS collet means the R8 tooling doesn't protrude far. For that matter although you want to go CNC eventually, R8 collets holding say a 1/4" mill also means you get maximum distance from tool tip to table. Your MT3 tooling won't give you that. You automatically lose about 1.25" or more with the holder.
Here's the drill press. Although not measured there is not a large distance between the end of the fairly small diameter spindle and the back of the drill chuck. But add in the tool holder like in the next picture and that subtracts from milling height.
So here's the R8 to MT3 adapter holding a 3/8" MT3 milling cutter holder and a ball mill. It's at the 5" mark that the R8 taper begins. Even if the spindle on the mill only protrudes 3/4" from the quill of the milling machine you still have 2.5" + 0.75" = 3.25" sticking out. Compared to fitting that 3/8" ball mill directly into a collet. I can take a picture of that to show the difference after I get back from doggy walk.
Wow I really appreciate the detailed explanation! I’m not sure I understand why the MT3 collets would extrude any further than the R8. Say for examples using something like this:
Collet Set, 3MT, Set of 4 2023
Morse Taper Collets 2023 Set of four #3 Morse taper round collets; 3/8"-16 internal drawbar thread; Made of high grade tool steel; Hardened and ground...
With a “quick release” sort of setup with TTS or even just custom straight shaft holders the stick out would be the same because the collets (either the R8 or MT3) need to be a little shorter than the spindle bore so that the holder registers against the spindle
Again I’m a total newbie here but just going with what I’ve seen others do such as this:
There are times, perhaps not very often, where you need that extra space.
The R8 holding the tool I stead of a TTS collet holder or even 3/8" tool holder is all longer and perhaps makes that one operation impossible.
So given the opportunity I'd rather have R8 all other things being equal.
I can take a photo of a TTS 3/8" holder with the ball mill for comparison.
The R8 holding the tool I stead of a TTS collet holder or even 3/8" tool holder is all longer and perhaps makes that one operation impossible.
So given the opportunity I'd rather have R8 all other things being equal.
I can take a photo of a TTS 3/8" holder with the ball mill for comparison.
And yes. With those MT3 holders you het the same advantage.
I think, but haven't checked, that MT3 spindles can have smaller diameter spindles and bearings. I believe bigger is better?
I think, but haven't checked, that MT3 spindles can have smaller diameter spindles and bearings. I believe bigger is better?
Yeah this probably true but given the price point I doubt the difference is anything but the end of the spindle shaft…I cant see an Asian budget manufacturer machining the same castings in two different ways for larger bearings or shaft…of-course I could be totally wrong. But I think I’m going to go for the MT3 one that’s in stock rather than wait for 3 months and have the machine get stuck in China due pandemic lockdowns(which is why the seller is telling me the R8 version is going to get to Canada in Feb23)
Here's a TTS holder for 3/8" end mill. The advantage of the TTS costs about 1.75" in milling height.
Now if I hold a 3/8" cutter in an ER32 collet then I lose another 0.5" or so.
And of course the R8 collet lets go with about 3/4 turn on the draw bar and gentle tap.
Not trying to convince you one way or the other. Just so you know. I'd try and get some measurements on spindle bottom to table distances on both R8 and MT3. Losing 0.5" to 1" of milling height doesn't sound like much until it happens on a regular basis.
John
Now if I hold a 3/8" cutter in an ER32 collet then I lose another 0.5" or so.
And of course the R8 collet lets go with about 3/4 turn on the draw bar and gentle tap.
Not trying to convince you one way or the other. Just so you know. I'd try and get some measurements on spindle bottom to table distances on both R8 and MT3. Losing 0.5" to 1" of milling height doesn't sound like much until it happens on a regular basis.
John
Thank you so much for taking the time to take pictures and provide additional information. Just to make sure I’m tracking: holder #3 from above is TTS in R8 while the er32 collet is in an MT3? I’m still not sure I understand the advantage of R8 over MT3 in terms od Z height. This is actually a very important aspect for me since it’s something I really suffer from on the CNC routers. Again appreciate your help and patience in explaining this to me
If you have a 19mm or 3/4" collet in your MT3 spindle the TTS will have to bear up against the base of the quill in order to properly register. So all the photos except for the first one were R8 on my mill.
Now look closely at the first photo which is the craftsman drill press that I modified to have a draw bar.
I don't have a 3/4" MT3 collet to try but it's unlikely TTS tooling would properly bear up against the bottom of the quill. I'll go measure some diameters and report back.
And there's no such thing as a dumb question.
Now look closely at the first photo which is the craftsman drill press that I modified to have a draw bar.
I don't have a 3/4" MT3 collet to try but it's unlikely TTS tooling would properly bear up against the bottom of the quill. I'll go measure some diameters and report back.
And there's no such thing as a dumb question.
Oh I see what you are saying now. I found this picture from a 2015 article of someone who got a mill with the MT3(https://longezproject.blogspot.com/2015/03/cnc-mill-conversion-part-23.html?m=1). So if I understand the concept of TTS, it has to register against the quill otherwise it’s not doing what’s it’s supposed to do, this is independent of the spindle taper as long as you find a way for the spindle to hold a 3/4” shaft, which the MT 3 can do just like the R8
So busybee sells a MT3 collet set good to 3/4".
www.busybeetools.com
The OD of the spindle on my drill press is 34mm while the outside of a TTS holder is 36mm. There's still just enough of flange that I can touch the spindle. The question would be how far would the 3/4" MT3 collet protrude and would it prevent mating the back of the TTS holder with the face of the spindle.
I believe MT3 is right on the edge of working for TTS.
COLLET SET MT3 11 PC
These collets are very useful when the distance between machine-table and spindle is limited.
www.busybeetools.com
I believe MT3 is right on the edge of working for TTS.
Ah. So on that little mill the quill is just a tad larger diameter and seats the TTS completely . And clearly the 3/4" collet doesn't interfere with the inner part of the TTS tool.
I've been told that heavy cuts with 3/4" mills in steel in R8 holders is pushing their limitation. The tool may still turn in the R8 collet. It's the danger you face with either the MT3 collet turning or the TTS turning in the 3/4" (19mm) collet.
The solution is really simple. Don't take heavy cuts. As you are intending to go CNC anyway, or at at least adding power feed to say X axis, the dull and uninteresting part of hand cranking small cuts over and over again vanishes. A few lines of G-Code, start it up, go and grab a coffee and sit and watch or do something else while it's removing 1" of steel out of a 2"x 3" pocket.
Based on the information I found on both the tormach and LMS sites, TTS require modified Collets for both spindle tapers: R8 flat like you said and a slightly shorter collet in the case of MT3 so the collets are not interfering with what the TTS needs to do. I also think the groove in the TTS flange is specifically so that slightly longer or inaccurate length of the native collets(R8 or MT3) doesn’t prevent the holder from registering.So busybee sells a MT3 collet set good to 3/4".
The OD of the spindle on my drill press is 34mm while the outside of a TTS holder is 36mm. There's still just enough of flange that I can touch the spindle. The question would be how far would the 3/4" MT3 collet protrude and would it prevent mating the back of the TTS holder with the face of the spindle.COLLET SET MT3 11 PC
These collets are very useful when the distance between machine-table and spindle is limited.
I believe MT3 is right on the edge of working for TTS.
So I’d either need to buy this: https://tormach.com/tts-collet-mt3-30251.html
Or
Buy and machine down this: https://www.busybeetools.com/products/collet-mt3-3-4in.html
And since my lathe spindle is MT3 all I need to do is stick it in the spindle without a chuck and face it off by however much is needed to make the tts holder flush.
In any case a ready made solution is available and costs the same as the R8 version…unless I’m missing anything
Oh and in the photo above where you see the #3 on the cutter holder. That's tool table entry #3. So when I do a tool change the length of that tool is factored into the Z zero position so when I change from tool #4 to tool #3 the system knows where the edge of the cutter is.
Very nice. That would be the plan for the mill. I’ll use my Haimer in a probe TTS holder to set Z, then have all my tool heights programmed in linuxcnc. With my routers I do the same but because I’m using er20, I have to set each tool height against a tool setter before each op which is still very annoying even with 400ipm rapids
BusyBee is out of stock but yes. Stick the collet in the lathe holding a piece of 3/4" Stock just barely protruding. Face them both. Likely the collet is hardened so you will need carbide.
Now all you are left with is the ease of releasing the collet enough so the TTS drops out. That's simple triganometry. To let the collet expand in the horizontal direction Y it needs to move down in the Y direction following the hypotenuse of the collet angle. The R8 has a much sharper angle so will have to move less than the MT3.
I have on order one of these higher end tool setters.Very nice. That would be the plan for the mill. I’ll use my Haimer in a probe TTS holder to set Z, then have all my tool heights programmed in linuxcnc. With my routers I do the same but because I’m using er20, I have to set each tool height against a tool setter before each op which is still very annoying even with 400ipm rapids
Apparently it's left the country (China) so won't be hung up in the lock downs. Now the goal will be to touch the surface of the spindle to it to determine 0. Then each tool to it to calculate tool length and enter into the table.
Then use my probe to find the 0 position of the work held in the vice or clamped to the table.
This is also held in a TTS holder so I can also use the touch plate to determine the length of it. Eventually I'll have this all functioning so it's simple enough to remember and use without spending time figuring out what I forgot from a month ago.
I plan on using the same input for the tool height setter as for the probe. Should be interesting determining the length of the probe since it will likely move up while the touch plate on the tool setter moves down. Haven't quite figured out how I'll deal with that but then this is now a bit off topic for your original question.
Do you have a dial or digital tool setter? The process would be to set the probe against the reference ground surfaces of the setter and then move the quill to and down on to the “plunger” of the setter until it reads zero. The tool setter is obviously zeroed relative to the reference ground surfaces(using a gage or 123 block) The difference between the machine absolute position when the probe triggered vs when the quill reached zero on the setter is the exact height of your probe trigger point relative to the quill(which is your WCS reference for tool heights and probe height in Z)