Center drilling problems

[Susquatch]

No I was referring to the MT EM arbor as a holder

Sorry, I guess I don't understand your question then @DPittman. Maybe it got lost in the complexity of this thread. Prolly be a lot easier to follow if I was 50 years younger.

Best Morse Taper End Mill / drill bit holder I know of is a collet. Even works pretty well with carbide. That said, I'm not a big fan of the Morse taper to begin with.

 

[DPittman]

Adhesive? Red Loctite?

Yes I bet red loctite would work. I was just under the impression that @Degen
had some other method to hold the bit in place other than the weldon flat./set screw.

 

[YYCHM]

Yes I bet red loctite would work. I was just under the impression that @Degen
had some other method to hold the bit in place other than the weldon flat./set screw.

Didn't @Johnwa first mention this using a 2MT stub arbor?

When I had my 7X12, I made two MT2 drill bit holders, one in 3/8", the other in 1/2". The drill chuck consumed too much of the bed length. I held the drill bits in place with nothing more than a set screw

 

[PeterT]

@PeterT I have a few Carbide drills and they are definitely worth the money, but they don't grip well in normal drill chucks and can actual damage the chuck from what I understand. You need to use the higher grip strength of collets.

Yes I have a small selection of carbide drills & some of my spot drills are carbide too. But what I was mentioning regarding @Susquatch question about enlarging BIG holes is we are somewhat limited to HSS or cobalt for the typical Silver & Demming type drills - that's what I speculating would either be expensive if they are even available in carbide (for increased stiffness). So some other options might be annular cutters or spade drill which have a solid shank.

 

[Former Member]

So other than heat shrink fit and the weldon flat what else is there?

ER Style collets and several other new styles that increase the the holding power under these new high speed high power machine center to prevent pull out of bits.

 

[Susquatch]

IMO, once you have a hole that you want to then enlarge by larger diameter drilling, the section view becomes essentially a variant of one of the pictures I posted. The prior hole will present a 90-deg edge to the 118-deg or 135-deg or whatever drill angle so there is a good chance of catching just like the spot drill example. I suspect that's why some advocate just drilling with the big drill to begin with, but that's not always possible. So I don't know of a reliable solution other than drill selection & a bit of start hole technique. Stub drills have less stick out so will be more rigid for the same material. Carbide is stiffer than HSS but cost prohibitive, assuming they even make them. I've heard the 135-deg drills focus their forces more obliquely which could be helpful & often have different relief geometry than conventional drills. Whether that cures all problems or just helps I cant say. Maybe one could chamfer a matching drill angle on the crest of the prior hole, but now that's another tool/step. Not as convenient or time efficient. Pecking the initial drill contact can be helpful. I find that holding some friction on the TS barrel can be beneficial too. Its a crude form of anti-backlash & might reduce the propensity to draw the drill into the cut (snatching conditions). So on a lathe, this could be a TS feed screw wear issue whereas a mill will have a different feed mechanism & be different.

Personally I consider drilling conventional holes to be a roughing procedure. Accuracy typically comes with boring bar type tooling. So its maybe a matter of personal choice as to when to stop with the drills & start with boring, probably dictated by material type & machine capacity. Some people acknowledge the drill kick & basically don't care if they are going to be boring anyways. Not ideal, but kind of pick yor battles strategy. Deep drilling like gun drilling is whole different subject I have no experience with. For large diameter conventional holes up to say 2" depth, I actually prefer annular cutters. You are removing much less material vs a drill & even have a resultant core slug to use for another project. But this has depth limitations obviously unless you can flip the part in which case 2x cutter length. So as usual... depends...

I have used annular cutters for really big holes and like them.

I like your idea of some tension on the tailstock. I will have to try that.

I guess I will have to buy a selection of spotting drills to try. I like that they will be short and stiff. I am not concerned about the time required to change tools. I am on no hurry to do anything anymore. Life is a journey not a destination - at least not a destination I am in any hurry to reach. So I'm quite happy to use a spotting drill to "chamfer" the edge of my holes before drilling the next size up.

I agree that using a big drill right up front is not really practical.

 

[DPittman]

ER Style collets and several other new styles that increase the the holding power under these new high speed high power machine center to prevent pull out of bits.

There is some misunderstanding I think going on here. I understand that er collets and their holders offer an alternative to a chuck but my question was in regard to the MT edmill holder that @Johnwa
had suggested. You stated that you had used the weldon flat method with the EM holder but that it caused some loss of accuracy so I was wondering if you had a better method of using the EM holder.

 

[Former Member]

There is some misunderstanding I think going on here. I understand that er collets and their holders offer an alternative to a chuck but my question was in regard to the MT edmill holder that @Johnwa
had suggested. You stated that you had used the weldon flat method with the EM holder but that it caused some loss of accuracy so I was wondering if you had a better method of using the EM holder.

Its actually very simple to understand, this method requires the tightest fit possible, but with variances in holders and bits there must be slight clearance, because of this the bit never is perfectly centered. Second is the Weldon Flat as you tighten the screw against the bit further forces the bit off center. The third item is if you tighten it properly you deflect (bend the shank) in the holder adding an angle to the bit.

Here is a video to give you an Idea.

In my case the I have good holders, but the difference in hole geometry is visible to a good eye if you know what you are looking for between ER and Weldon style holders.

 

[Susquatch]

There is some misunderstanding I think going on here. I understand that er collets and their holders offer an alternative to a chuck but my question was in regard to the MT edmill holder that @Johnwa
had suggested. You stated that you had used the weldon flat method with the EM holder but that it caused some loss of accuracy so I was wondering if you had a better method of using the EM holder.

Ya, I misunderstood your original question.

Frankly, I don't think the loss of accuracy using an end-mill holder is worth worrying about.

Endmill holders work just fine for a crap load of users. I used them for ages on my old MT3 mill/drill and they worked just fine. You can always use a boring bar or a Reamer if you need more accuracy and you would likely have to do that with any holding system (chuck, collet, welden, etc) anyway.

In my opinion, the biggest problem with an end-mill holder is the limited number of sizes. You prolly can't get one for every possible drill size and even if you could you would go broke and run out of tool storage space. So.....

Back to a chuck or a collet......

 

[CWret]

As in the Arab Proverb, I'm -- "he who knows not, and knows that he knows not"
I learned a lot about my improper use of center drills here and I too am about to order some spotting drills. Thanks @PeterT , well sort of thanks because "I don't know how smart I can afford to get"

Craig

 

[Susquatch]

As in the Arab Proverb, I'm -- "he who knows not, and knows that he knows not"
I learned a lot about my improper use of center drills here and I too am about to order some spotting drills. Thanks @PeterT , well sort of thanks because "I don't know how smart I can afford to get"

Craig

I'd like to hear the rest of that proverb.

I've only heard it differently and never heard it called an Arab proverb.

"the more you know, the more you know you don't know"

"you don't know what you don't know"

"a PhD is someone who knows more and more, about less and less, until they know absolutely everything about nothing".

"many an impossible thing has been done by someone who didn't know it could not be done"

There are other varients too but those are the main ones that I know. I don't know the other ones that I don't know...... LOL!

And please let me know what you ordered and where cuz I'm striking out. I am not about to spend $50 for a spotting drill when the centering drills I have worked just fine so far...... I never knew that centering drills didn't work so I used them and they worked.

I'm no purist.

 

[thestelster]

the biggest problem with an end-mill holder is the limited number of sizes. You prolly can't get one for every possible drill size

Except for ER collets: ER11 (.5mm) to ER40 (26mm), and will hold anything in between. But, for practicality, just get a good keyless chuck. #1- Albrecht, #2-Rohm Spiro, #3-Rohm Supra, and be done with it, we're drilling holes!

 

[Susquatch]

Except for ER collets: ER11 (.5mm) to ER40 (26mm), and will hold anything in between. But, for practicality, just get a good keyless chuck. #1- Albrecht, #2-Rohm Spiro, #3-Rohm Supra, and be done with it, we're drilling holes!

My sentiments exactly.

But what did you mean by "except for"? I didn't imply that ER wouldn't work. I think they are just fine!

I have them and love them.

 

[CWret]

My Father Used this version:
“He who knows not, and knows not that knows not, is a fool! Avoid him. He who knows not, and knows that he knows not, is simple, teach him. He who knows and knows not that he knows, is asleep, wake him. He who knows and knows that he knows, is a wise man, follow him.”

 

[Susquatch]

My Father Used this version:
“He who knows not, and knows not that knows not, is a fool! Avoid him. He who knows not, and knows that he knows not, is simple, teach him. He who knows and knows not that he knows, is asleep, wake him. He who knows and knows that he knows, is a wise man, follow him.”

But what do you do with all those stubborn know-it-alls who believe in their heart of hearts that they know but don't?.

I ask this mostly because that guy in my mirror is a lot like that sometimes......

 

[CWret]

Sounds like requirements to go to Ottawa and become PM

 

[Susquatch]

Sounds like requirements to go to Ottawa and become PM

Ouch - that hurt......

 

[CWret]

Sorry. Out of line and uncalled for.

 

[gerritv]

Sounds like requirements to go to Ottawa and become PM

Yes, that would be the newest aspriant, Pierre P

 

[thestelster]

My sentiments exactly.

But what did you mean by "except for"? I didn't imply that ER wouldn't work. I think they are just fine!

I have them and love them.

Oh, sorry, you said End Mill Holder. I'm still half asleep. Same goes with 5C or R8 collets, you need one for every size.