All good we all build different things I just didn't think having a drill chuck or drill bit in a collet was a good idea but if there isn't a issue with up too 1/2ish then it does sound more convenient to use straight shaft with chuck and I could even buy a mt3 to jt2 adapter for like 15$ at kms and turn the mt3 side down beats spending 100$ just for the #40 and I'm thinking I'll end up boring most holes to size over a certain size anyways. Specially if there is any preciseness needed as drill bits fall short sometimes anyways I much rather use angular cutters then drill bits but then it's just more time spent working to afford to do anything.
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Tool Tooling up a milling machine
- Thread starter justin1
- Start date
Tool
One thing I will add, if you were not aware, the 4 flute end mills will not cut a slot that matches their marked diameter, but a two flute will. One of the main reasons for two flute milling cutters.
In the British Model Engineering press, the two flute end mill is often called a slot drill, for this reason.
It has to do with the flex of the end mill in relation to where the cutting is taking place, which is mainly as the cutting edge in action, sweeps across in front of the feed direction. Basically, as the cutting edge sweeps across the front, the edge at 90 degrees to it, has been fed in to the side of the cut by the flex. This makes the slot become wider than the cutter. A two flute end mill has the 'other' cutting edge, away from the wall of the slot, while it flexes.
I worked as an Aircraft Structures Tech in the Canadian Forces. We rarely used drill bits larger than 1/4 inch, and most often, the chuck was closed by bumping it shut with the air power, and bumping it open with a strike from the palm of the hand on the drill chuck. It does not take a bunch, to provide an adequate grip on a drill, with a decent drill chuck, nor is spinning it loose much of an issue on a decent quality keyless chuck or a collet !
In the British Model Engineering press, the two flute end mill is often called a slot drill, for this reason.
It has to do with the flex of the end mill in relation to where the cutting is taking place, which is mainly as the cutting edge in action, sweeps across in front of the feed direction. Basically, as the cutting edge sweeps across the front, the edge at 90 degrees to it, has been fed in to the side of the cut by the flex. This makes the slot become wider than the cutter. A two flute end mill has the 'other' cutting edge, away from the wall of the slot, while it flexes.
I worked as an Aircraft Structures Tech in the Canadian Forces. We rarely used drill bits larger than 1/4 inch, and most often, the chuck was closed by bumping it shut with the air power, and bumping it open with a strike from the palm of the hand on the drill chuck. It does not take a bunch, to provide an adequate grip on a drill, with a decent drill chuck, nor is spinning it loose much of an issue on a decent quality keyless chuck or a collet !
DPittman
Ultra Member
I did know that either.
(been out of commission for a few days, so I’m a bit behind with these comments)
FYI: @justin1- I’m new to milling, I got my bench top MD45 6 months ago, so I’ve been down your path. Tooling up is an unending adventure. It’s been said several times before, don’t over-buy at the start because: what you think you need may change; and no use finding a bargain if you recently paid full price for it. Two weeks ago, I got a set of premium annular cutters from a pawn shop (via Kijiji listing) for 1/2 price. They were new, still in the box and something I’d been wanting for quite awhile. A couple of months ago I went to see a dividing head I found listed on Kijiji. It turned out that the seller was downsizing and moving to a condo. I got all the stuff in pics below (+more) at far less than 1/2 price.
FYI: @justin1- I’m new to milling, I got my bench top MD45 6 months ago, so I’ve been down your path. Tooling up is an unending adventure. It’s been said several times before, don’t over-buy at the start because: what you think you need may change; and no use finding a bargain if you recently paid full price for it. Two weeks ago, I got a set of premium annular cutters from a pawn shop (via Kijiji listing) for 1/2 price. They were new, still in the box and something I’d been wanting for quite awhile. A couple of months ago I went to see a dividing head I found listed on Kijiji. It turned out that the seller was downsizing and moving to a condo. I got all the stuff in pics below (+more) at far less than 1/2 price.
Attachments
New tooling- - - -R8 collets vs R8 collet chuck & ER collets
As I understand the difference:
First - ER collets have a more flexible size range. Example: a ½” ER collet can hold either a ½” or a 12mm EM but that’s not recommended to do that with an R8 collet. The size range of each R8 collet is much smaller than that of an ER collet but the R8 has better surface contact and correspondingly better grip. ----- Is this correct??
Second - It’s easier to change tools with an ER collet system since you simply change the collet to accept a different diameter tool, the collet chuck stays-put, and the drawbar is not involved.
Third - (not sure where I heard this, but the KISS principle gives it credibility to me) The ER system has flexibility whereas the R8 collet has better rigidity and accuracy.
Fourth - R8 collets are shorter than their ER cousins and use up less Z travel.
FYI: I have a set of both metric and imperial R8 collets and I have no ER collets on my want list.
I’m sure I can recall seeing comments on other Forum threads (months ago) where members have both a set of R8 collets as well as ER collets and they prefer the R8 collets.
In Post 102, @Susquatch reinforced @Downwindtracker2 's comment with - “I have a few R8 collets, but rarely use them anymore. I vastly prefer ER”
Then @Dabbler said “the R8 system is far poorer design that the ER system. In every way the ER system is better” Then @thestelster just reinforced their comments.
WOW. Double WOW!! These comments were completely unexpected. Do I need to rethink R8 collets vs an ER collet system???
I’ve had no issues with my R8 collets. I really like them! Maybe it’s just my inexperience, but I’ve had no pullouts or tool slippage (with EMs up to ¾” in mild steel). Maybe that’s because my 1,000-pound benchtop mill is small compared to the size and power of a BP.
Aside – in my Second item above, I referred to the drawbar not being ‘involved’ when changing an ER collet – in contrast, an R8 collet is ‘committed’ to a specific diameter. This reminded me of the difference between ‘involved’ and ‘committed’. With a bacon & eggs breakfast, the chicken is involved but the pig is committed.
As I understand the difference:
First - ER collets have a more flexible size range. Example: a ½” ER collet can hold either a ½” or a 12mm EM but that’s not recommended to do that with an R8 collet. The size range of each R8 collet is much smaller than that of an ER collet but the R8 has better surface contact and correspondingly better grip. ----- Is this correct??
Second - It’s easier to change tools with an ER collet system since you simply change the collet to accept a different diameter tool, the collet chuck stays-put, and the drawbar is not involved.
Third - (not sure where I heard this, but the KISS principle gives it credibility to me) The ER system has flexibility whereas the R8 collet has better rigidity and accuracy.
Fourth - R8 collets are shorter than their ER cousins and use up less Z travel.
FYI: I have a set of both metric and imperial R8 collets and I have no ER collets on my want list.
I’m sure I can recall seeing comments on other Forum threads (months ago) where members have both a set of R8 collets as well as ER collets and they prefer the R8 collets.
In Post 102, @Susquatch reinforced @Downwindtracker2 's comment with - “I have a few R8 collets, but rarely use them anymore. I vastly prefer ER”
Then @Dabbler said “the R8 system is far poorer design that the ER system. In every way the ER system is better” Then @thestelster just reinforced their comments.
WOW. Double WOW!! These comments were completely unexpected. Do I need to rethink R8 collets vs an ER collet system???
I’ve had no issues with my R8 collets. I really like them! Maybe it’s just my inexperience, but I’ve had no pullouts or tool slippage (with EMs up to ¾” in mild steel). Maybe that’s because my 1,000-pound benchtop mill is small compared to the size and power of a BP.
Aside – in my Second item above, I referred to the drawbar not being ‘involved’ when changing an ER collet – in contrast, an R8 collet is ‘committed’ to a specific diameter. This reminded me of the difference between ‘involved’ and ‘committed’. With a bacon & eggs breakfast, the chicken is involved but the pig is committed.
There you go then. Put a check mark in the "I learned a new thing today!" box, and try again tomorrow!
It's a pretty easy to draw, 'action/reaction' diagram, as long as you start from the idea that every cutting tool bends or flexes a little, proportionate to it's size and the cutting loads placed upon it. When you consider that they have managed to show the effects of tidal influence, in a cup of tea, it is less of a headache to wrap your mind around that an end mill bends as it takes on a cutting load!
The harder you push a 4FLEM, the wider the slot it will produce! And, the more jagged the step along the one edge will be.
Drawbar tightening???
@Susquatch – said above, “If anything, I over-tightened it. That led to a lot of research on how much to tighten an R8 drawbar. Ya, I prolly over tightened it - so that wasn't it. But I made a smaller wrench to address that problem anyway.”
This got me thinking about how I was tightening the drawbar. So I used a torque wrench to confirm that I’ve been tightening the drawbar to between 21 and 25 ft/lb. I have not been able to find a recommended torque for a R8 drawbar (7/16-20) which is a 7/16” diameter bolt with course thread. But for a 7/16” grade 5 bolt the maximum recommended torque is 37 ftlb if lubricated and 52 ftlb if plain dry. A mill drawbar is definitely not plain dry, but it’s not intentionally lubricated either. These numbers are for a bolt that is torqued once. I therefore (arbitrarily) picked a conservative maximum number to be 80% of the 37ftlb (which is 30ftlb). So, from now on I’m going to add a bit more elbow grease and torque my drawbar to a target of 25 to 29ftlb. I’ll also check occasionally (with the torque wrench) to see how I’m doing.
@Susquatch – said above, “If anything, I over-tightened it. That led to a lot of research on how much to tighten an R8 drawbar. Ya, I prolly over tightened it - so that wasn't it. But I made a smaller wrench to address that problem anyway.”
This got me thinking about how I was tightening the drawbar. So I used a torque wrench to confirm that I’ve been tightening the drawbar to between 21 and 25 ft/lb. I have not been able to find a recommended torque for a R8 drawbar (7/16-20) which is a 7/16” diameter bolt with course thread. But for a 7/16” grade 5 bolt the maximum recommended torque is 37 ftlb if lubricated and 52 ftlb if plain dry. A mill drawbar is definitely not plain dry, but it’s not intentionally lubricated either. These numbers are for a bolt that is torqued once. I therefore (arbitrarily) picked a conservative maximum number to be 80% of the 37ftlb (which is 30ftlb). So, from now on I’m going to add a bit more elbow grease and torque my drawbar to a target of 25 to 29ftlb. I’ll also check occasionally (with the torque wrench) to see how I’m doing.
Agree with Dabblers last post, love my Hardinge R8's. I've ER collets for a 40 taper mill and R8's on a vertical mill so have used both but don't much interests in putting an ER chuck on the R8 mill.
I agree ER is a better collet design, but saying ER is better then R8, if your spindle is R8, not so much so. Reduced daylight, reduced rigidity and less accuracy (you end up with twp surfaces contributing to error). And its still the same fairly light spindle.
imo it becomes gnat hair splitting at some point or least in the realm of person preference.
Likely. DOC, material, rigidity, feed etc will play a part. I would guess its not usually an issue on a light bench top machine and for me it only has been on more aggressive cuts, either higher speed or removal rate
No, this is not correct. The ER has more contact. The majority of gripping forces on an R8 collet is at the front, while the ER is spread over the whole collet length. The one great advantage of the R8 or 5C collet is that it can hold very short parts, but on the ER it should grip the part at least 70% of the collet length. (When I have to hold very short parts in my ER collet, I'll put a small piece of the same diameter I plan on machining, at the very rear of the collet, so that the collet jaws are gripping parrallel.)
If your milling machine spindle takes R8 collets, stick with that. But the OP's mill has a NMTB#40, so going ER route is extremely versatile.
I will have to learn to be a little less brief about what I say. Perhaps too much info is better than too little.
Regarding R8 draw bar torque.
My mill has a very deliberate oiling port at the top of the drawbar. The Bridgeport manual says to add a few drops of spindle oil periodically. Therefore, I put a few drops of spindle oil in there every so often. I believe it does three things. It lubricates the nut system at the top, it lubricates the drawbar thread, and it lubricates the collet cone.
This was all stated MOSTLY to point out that the lubricated torque specs DO APPLY.
BUT, I don't like dirty oil contaminating the collet cone so I ALWAYS clean up the cone with a lint free rag before installing a collet.
I don't know exactly where I got this info, but my records say that Bridgeport recommends an R8 drawbar torque of 25 to 30 ft-lbs, and Tormach recommends an R8 torque of 30 ft-lbs.
I am quite capable of easily applying 200 ft-lbs, so I need to be careful of how much I apply. Thirty is more than enough.
Your independently derived 25 to 29 is just fine IMHO.
Regarding ER vs R8.
Again in the spirit of providing too much vs too little info..... This business of which is better, R8 or ER is not really simply one vs the other. Like sooooo many other things, "IT DEPENDS".
It is true that I prefer ER over R8. But not because they are inherently superior in the way I think you think I meant. Which I didn't mean....... LOL!
R8 collets have been used for years and they work just fine PROVIDED that there is a good fit between the collet ID and the end-mill shaft OD. Because they only have 3 leaves, a good fit is imperative. Without a good fit, the contact area goes WAAAY down and that can result in the tool slipping. But a good quality R8 collet with a good close fit is actually IDEAL and should not be frowned on. I apologize if what I said before implied otherwise. It was certainly not my intent.
However...... If that fit is not a good fit and there is any looseness in there, then I much prefer an ER Collet. ER means Extended Range. (although some say the R means the RegoFix adaptation of prior E Collets). Regardless, the 3 expansion slots in an R8 collet only run front to back. So the three fingers can only be easily bent at the end of the holder. On the other hand, ER collets have 3 slits from one end and 3 from the other. As a result, the 6 fingers can be evenly bent to conform to the shaft shape and can also be bent to conform to a shaft size variation of around a 16th. Thus a close fit is not required - but is still desirable.
Another option not mentioned is end mill holders. These don't use a collet. Instead a grub screw tightens onto a ground flat on the endmill shaft and a precise fit is an absolute requirement - no ifs ands or buts.
Also, the stack up on an R8 collet is less which provides more Z room.
The inherent concentricity of an R8 Collet is better because there is only one taper instead of 2.
ER is better for drilling because of the broad range of drill sizes and the longer bearing length of the fingers.
I also like ER because I don't have to fiddle with the drawbar all the time. The concentricity of my ER collets is only a few tenths.
I don't really like to use a drill chuck in my mill because it takes too much Z cranking.
Best use of a cordless drill ever. My mill crank takes a bronze handle with a 1/2 square hole. Take a large and long allen key for a 1/2" drive socket, chuck the hex in the drill and you've got a power knee. A game changer on mill time enjoyment
I pressed send right after @thestelster's post.
See my comments about perfect fit required for R8. Taken in that context, I agree with Stel's comments and those of other experienced machinists posted earlier.
There is no right and wrong here. It all depends.
What do I have and what do I prefer?
I have 6 R8 End Mill Holders. These are not collets. They are holders that require a tight grub screw to retain the end mill. I have them in 1/4, 3/8, 1/2, 5/8, 3/4, 6mm, and 12mm. I might get a few more metric ones someday.
I have a small set of mixed R8 Collets - some Hardinge and some? I rarely use them. It's not that they don't work, it's that it's just plain easier to use ER and much easier to use with drill bits.
I have a full set of ER32, and a half set of ER20 collets. The ER32 collets are my goto for almost all mill work. I would have preferred ER40, but since a box of ER32s and MT3 mandrel came with my old mill/drill, it was a no brainer to buy an er32 mandrel and use them instead of buying new er40s. I also have a small set of ER11 that is mostly used with rechargeable tools and with my little home made tool post grinder. I don't use the ER11 on the mill at all.
I have a REALLY NICE GS drill chuck that rarely gets used too. Basically only when I have to do a LOT of drilling. It takes up too much Z space and my mill table is already too close to the ground for my liking. No other reason for not using it.
One last comment. I must have been a really good guy in my previous life because the run-out on virtually everything I own is spectacular - usually a few tenths or less. I count my blessings for this.
See my comments about perfect fit required for R8. Taken in that context, I agree with Stel's comments and those of other experienced machinists posted earlier.
There is no right and wrong here. It all depends.
What do I have and what do I prefer?
I have 6 R8 End Mill Holders. These are not collets. They are holders that require a tight grub screw to retain the end mill. I have them in 1/4, 3/8, 1/2, 5/8, 3/4, 6mm, and 12mm. I might get a few more metric ones someday.
I have a small set of mixed R8 Collets - some Hardinge and some? I rarely use them. It's not that they don't work, it's that it's just plain easier to use ER and much easier to use with drill bits.
I have a full set of ER32, and a half set of ER20 collets. The ER32 collets are my goto for almost all mill work. I would have preferred ER40, but since a box of ER32s and MT3 mandrel came with my old mill/drill, it was a no brainer to buy an er32 mandrel and use them instead of buying new er40s. I also have a small set of ER11 that is mostly used with rechargeable tools and with my little home made tool post grinder. I don't use the ER11 on the mill at all.
I have a REALLY NICE GS drill chuck that rarely gets used too. Basically only when I have to do a LOT of drilling. It takes up too much Z space and my mill table is already too close to the ground for my liking. No other reason for not using it.
One last comment. I must have been a really good guy in my previous life because the run-out on virtually everything I own is spectacular - usually a few tenths or less. I count my blessings for this.
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Best use of a cordless drill ever. My mill crank takes a bronze handle with a 1/2 square hole. Take a large and long allen key for a 1/2" drive socket, chuck the hex in the drill and you've got a power knee. A game changer on mill time enjoyment
There you go. Another example of me not saying enough.....
Yes, my HD Dewalt cordless drill sits on the work bench behind my mill with a castle nut adapter in it for just that reason. (mine has a castle drive system instead of a square drive). But why wear out my knee screw needlessly......
I agree it was a game changer. Every so often I think about a Z Axis Power Knee too.
Edit - No - I don't put that cordless drill away every night. It sits on the bench with the castle nut mounted in it 24/7. The only time it goes anyplace else is when I need it for another job. Yes, it's messy. I DON'T CARE! I LIKE IT THAT WAY!
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Yeah, lots to be said in favor of the boot-simple Weldon Shank tool holders. They just work.
I like the idea of ER holders from the perspective that I got very used to having access to a large tray of collets for the matched sets of Milling Tool holders we had at work, so if I wanted three different, say, 1/2 inch shanked cutters, (rougher, finish mill, ball end, for eg.) I could set up three of that size, without needing to have multiples of every size, as you would with Weldon style. That is still how I see tooling up a mill, using multiple of one ER size chuck, with multiple sets of collets in hand, so as to allow maximum flexibility in use.
I'll also add that the mill I used most, had a push button to operate the air cylinder powered drawbar (no rattle wrench, it compressed a stack of spring washers, and used a draw stud), so setting up a bunch of cutters was pretty normal, rather than just swapping the cutter in one holder.
My go-to for Large cutters, (on a 40 taper spindle) was a Nikken Lyndex hydraulic milling chuck, that held on to the cutters like they were welded in, once you torqued down the outer nut. I stalled out a 7 1/2 HP milling spindle with a large HSS end mill in it, and it did not pull out! Needed a coat hanger to recover my undies, pert-near, but the mill did OK!
There are a PILE of different entire systems of tool holders out there, stick to simple at first, buy the fancy stuff later, if it looks to offer an advantage over what you have, but only then. Unless it's a bargain! LOL!
I like the idea of ER holders from the perspective that I got very used to having access to a large tray of collets for the matched sets of Milling Tool holders we had at work, so if I wanted three different, say, 1/2 inch shanked cutters, (rougher, finish mill, ball end, for eg.) I could set up three of that size, without needing to have multiples of every size, as you would with Weldon style. That is still how I see tooling up a mill, using multiple of one ER size chuck, with multiple sets of collets in hand, so as to allow maximum flexibility in use.
I'll also add that the mill I used most, had a push button to operate the air cylinder powered drawbar (no rattle wrench, it compressed a stack of spring washers, and used a draw stud), so setting up a bunch of cutters was pretty normal, rather than just swapping the cutter in one holder.
My go-to for Large cutters, (on a 40 taper spindle) was a Nikken Lyndex hydraulic milling chuck, that held on to the cutters like they were welded in, once you torqued down the outer nut. I stalled out a 7 1/2 HP milling spindle with a large HSS end mill in it, and it did not pull out! Needed a coat hanger to recover my undies, pert-near, but the mill did OK!
There are a PILE of different entire systems of tool holders out there, stick to simple at first, buy the fancy stuff later, if it looks to offer an advantage over what you have, but only then. Unless it's a bargain! LOL!
Little doubt of us being accused of that!
I've an old drive for a wheel chair that seems about right for a rapid Z feed. Quite robust, a 24V so easily control and a solid gearbox. Another one I haven't gotten around to, less motivation though since I start using the drill.
That suplus guy near the bottom of the 427 had some. The name will come to me.
Really? When that happens to me, I just step out of them and walk away. "Wasn't me!" and "Who the Fk stunk up my shop!"
Good to hear that I’m not to far out in left field and that both @Dabbler and @Mcgyver use their R8’s even though they have ER’s. Thanks @thestelster for adding that R8 collets are a good match with an R8 spindle.
So not hurting any gnats is a good thing and also “It’s your soap”. I may not be the MVP, but playing in left field has me in the game and in the right ballpark (with my R8’s).
@Susquatch said “ER over R8…. superior in the way I think you think I meant. Which I didn't mean...” Yea, Susquatch I needed those clarifications. Now I have a much better understanding of why the ER’s work for you. Thanks guys for the new information & explanation of ERs vs R8s - this puts me back into my ‘comfort zone’. Also, now I have no burning desire to acquire a set of ER’s, but if I do, then ER40 will be the flavour of the month. After the comments I’ve read through today, I think some EM holders will find their way to my shop before ER40s. And as @trevj said, holders give reliable tool holding that is scary rock-solid. Also I learned today of a new use for a coat hanger.
Note1: BTW Susquatch - 1/4, 3/8, 1/2, 5/8, 3/4, 6mm, and 12mm = 7 pieces
Note2: ER= Extended Range - just one of the many things I learned today, way over my quota, and that's before the coat hanger.
Note3: “It’s your soap” – when you’re in the shower, how you use the soap is up to you. This is another way to say ‘sh-- or get off the pot’ or ‘pick a lane’. In my case today - it's choosing R8s or EMs
So not hurting any gnats is a good thing and also “It’s your soap”. I may not be the MVP, but playing in left field has me in the game and in the right ballpark (with my R8’s).
@Susquatch said “ER over R8…. superior in the way I think you think I meant. Which I didn't mean...” Yea, Susquatch I needed those clarifications. Now I have a much better understanding of why the ER’s work for you. Thanks guys for the new information & explanation of ERs vs R8s - this puts me back into my ‘comfort zone’. Also, now I have no burning desire to acquire a set of ER’s, but if I do, then ER40 will be the flavour of the month. After the comments I’ve read through today, I think some EM holders will find their way to my shop before ER40s. And as @trevj said, holders give reliable tool holding that is scary rock-solid. Also I learned today of a new use for a coat hanger.
Note1: BTW Susquatch - 1/4, 3/8, 1/2, 5/8, 3/4, 6mm, and 12mm = 7 pieces
Note2: ER= Extended Range - just one of the many things I learned today, way over my quota, and that's before the coat hanger.
Note3: “It’s your soap” – when you’re in the shower, how you use the soap is up to you. This is another way to say ‘sh-- or get off the pot’ or ‘pick a lane’. In my case today - it's choosing R8s or EMs
Re drawbar torque - thanks @Susquatch for confirming I’m on the right track. I didn’t plan to intentionally lube the drawbar threads (not mentioned in my manual) – I figured that I slopped enough around to look after that, but from now on I'll make sure the drawbar threads are not dry. Yes, I was keeping the spindle taper clean & dry, as well as the mating taper on the R8 collets. Lube or dirt there is a bad thing.