There is quite a pile of drill bits in the broken cutters box because today I sorted, checked and inventoried two of the four drill indexes, the wire gauge and the fractional. A lot of the drills are “bad” due to the grip end suffering some damage from the chucks that held them. I imagine that the plow up bumps and ruts on the grip ends would lead to a bad hold, helping to further damage the chucks and giving a less than square drill path. Many others just have cutting end chips/erosion. I expect to get to the other two indexes in the next few days. Might be our best strategy would be to start off with new chuck jaws or new chucks at the same time as culling out all the drills with bad grip ends.
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thank you Bob!
Bob and I had a chance to talk about this. IMHO, the drill chuck is not always the best way to go. If possible I’d use the closest sized collet chuck. Certainly the more standard sizes are available down to at least 1/8". I have a lot less problems with slippage (hence no side damage).
cheers!
Boy today is the day we don’t agree on things. LOL
I would not advise using collets for drills, the collets will be destroyed.
IF this HAS TO DONE, then I recommend we get a set collets just for drills, have them marked in their own rack, and only drills that match the collets can be used and they are segregated. That those drills, and only those drills be marked and used with “Drill Collets”. Personally, I think this would still be a disaster because people won’t bother and interchange things resulting in damaged collets damaging cutters and the cutters not seating properly and having high runout. If you believe that folks won’t mix things up then go for it.
I would recommend we first get a chuck that uses a key/wrench so they can be tightened more than the keyless chuck. This solution allows all the intermediate sized drills - Imperial and Metric to be used, otherwise then two sets of collets are needed.
down to 1/32nd
https://www.mscdirect.com/product/details/08401853
yeah, that adds up to too much money for a simple task. my opinion comes from this use in a cnc machine where everything is colleted. A good drill chuck will always work.
Photomancer Board Member
July 9 |
Boy today is the day we don’t agree on things. LOL
I would not advise using collets for drills, the collets will be destroyed.
IF this HAS TO DONE, then I recommend we get a set collets just for drills, have them marked in their own rack, and only drills that match the collets can be used and they are segregated. That those drills, and only those drills be marked and used with “Drill Collets”. Personally, I think this would still be a disaster because people won’t bother and interchange things resulting in damaged collets damaging cutters and the cutters not seating properly and having high runout. If you believe that folks won’t mix things up then go for it.
I would recommend we first get a chuck that uses a key/wrench so they can be tightened more than the keyless chuck. This solution allows all the intermediate sized drills - Imperial and Metric to be used, otherwise then two sets of collets are needed.
down to 1/32nd
https://www.mscdirect.com/product/details/08401853
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nicksilva
July 9 |
thank you Bob! Bob and I had a chance to talk about this. IMHO, the drill chuck is not always the best way to go. If possible I’d use the closest sized collet chuck. Certainly the more standard sizes are available down to at least 1/8". I have a lot less problems with slippage (hence no side damage…
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So there I am spinning around in the spindle with a quarter inch HSS cylinder up my butt when the quill asks me “What is that up your butt?” I can confidendly say that it is quarter inch, which is my size, cylindrical, smooth and HSS; why, it could be a quarter inch drill shank or a quarter inch end mill shank. How should I know the difference? Then the quill inquires: “Well, have you been experiencing any lateral forces?” Well, now that you mentioned it; I have only been experiencing axial and torsional forces, so that must be drill shank in my butt. Without those dreadful lateral forces, I am having a much easier day of it. Oh no, the maker is reaching for an end mill; things are about to get rough! Quill: “Why don’t you text for an Uber ride to Ray Thompkin’s garage and get yourself rolled underneath the pantograph in there?” Quill, you go ahead and yell at that maker to back away with that evil looking end mill, while I text the ride out.
Question: Will a collet be damaged if loaded by the draw bar empty? (Think slightly undersized drills in certain cases) The only reason there are drill chucks is: because Adam ate the apple. Seriously, because they can accommodate a wide range of diameters; in all other attributes compromise is tendered in exchange for this one property, albeit, a really useful one. OK, robo calls is what we now have because Adam ate the apple.
I have never made a study of the guts of drill chucks, but can something that can hold a 1/64th inch diameter really hold fast some thing 1/2"? Is it possible that we need 2 or 3 ranges of size holding, with each better at holding that range than a more universal chuck can? I ask because we have had a lot of shank damage from bits spinning in the chuck. The current R8 chuck’s middle name is: “grip loss upon contact”
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Using a undersized anything collet can result in internal damage to the collet. R8 collets typically have three very small “slots” in them that allow for compressing the collet down.
When pressing in say a 3/8ths shank into a 3/8th collet, it should slide in snugly, not tight, snug. When the draw bar pulls the collet in and compresses the collet, the design still has a small gap in the slits but the full compressive force on the shank is achieved. In researching using drills in R8 collets: Universally the answer was NO, this included using Imperialor/Metrics cutters in the opposite type collet. The only reference I could find to a tolerance range was ±.002" and that was a person’s guess. If you were to measure the shanks of cutters I would suspect there is less than a .001" TIR between them.
If when the collet is compressed the slits are touching, then the full compression of the collet isn’t achieved. Torsional forces can allow the drill to slip - galling the inside of the collet.
Cutter shanks come in specific diameters that match industry standard sizes. The actual cutter diameter can be larger or smaller than the shank/collet diameter and is how sizes between collet sizes can be achieved.
Apparently, there are some different collets (not R8) that are commonly used with selected collets. The examples were typically for small machines like out Sherlines but for small bits, 1/32nd or less.
Any drill that IS used in a collet should never have been used in drill chuck (the shank can be damaged) and the shank should match the collet size exactly (use a micrometer to check).
Can drills be used in collets: Yes, but plan of having damaged inaccurate collets that will have more run-out when using cutters because of internal damage not visible.
I think it much wiser to buy a drill chuck that uses a key or wrench to tighten rather than just a keyless chuck.
They make collet adapters that are also used as an extension . would those collets be less expensive?
The extension could also be useful .I dont recall ever seeing small bits galled by a drill chuck they break instead. Most drill bits are probably damaged on the drill press from usimg too much pressure because they are in a hurry. Trust me because I have a pantograph .Perhaps a little research is needed.
The thing with collets is they are sized at specific intervals, so any drill in between will be mismatched, they really aren’t designed for drills. There are collet sets that can be used on drills that are made for R8, bit note, it uses a wrench to tighten like the drill bit above. But it will clamp and reduce TIR compared to a drill chuck. Drill chucks can pick-up all the between it min. and max. and does care if imperial or metric.
If you want collets: You limited to specific sizes of drills. Get a set of dedicated collets just for drills
If want any drill size between Xmin ~ Xmax: Then use a drill chuck, preferably one that is not keyless so it can be tightened.
Im not all that intetested in collets.Im just interesred in the galling problem. I looked at my drill bits at home and found several. They tended to all be close to the 1/4 inch range . i think most of mine were damaged using a hand drill. I dont know my own strength sometimes. Im still researching .this question.could the auto and metal shop be using tjem in hand drills and those chucks are causing the drill shank galling.
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FWIW, Bill Epps is just put a class out there, Tuesday 7/24 for sharpening the drill bits. I realize none of y’all need this, but other folks reading this thread might want to sign up – in 3 days, when it hits the calendar.
The use of an ER collet system could be a good answer to our drill bit holding woes, especially considering its low price. From what I could see online about the ER system, they are rated to hold diameters ranging from the nominal size to a mm smaller, 0.039 inches. Since the 12 piece set are spaced in nominal size at 1/16" diameters, that is 62.5 mils apart; 39 out of each 62.5 mils of each range gap will be covered. Without making a tap chart study, I can’t say for sure that all the important sizes will be covered, but raw probability say about 2/3rd of them should be. If we went with the 25 piece set with increments of 1/32" there would be over lapping coverage, alternatively the 20 piece metric set would more efficiently cover the ranges but efficiency at selecting the the right metric piece to hold a given imperial shank size would be lowered for most members.
I didn’t see a figure published for the holding range of an R8 collet, but I will observe that for the case of the 5C collets for use on the lathe, there is some range available. They are made to hold work pieces and I can say through experience that the dimensional tolerances of various mill rods of plastic and metals is not held so tight to nominal size as is the case for cutting tools. Some times I had to rely a bit on compression or stuffing a tad over sized rod into the the collet. But it always seemed to work out OK.
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