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Drill Chucks
Drill chucks FAQ
Specifications of drill chucks and keyless drill chucks
Q1 What are the differences between drill chucks, keyless chucks, and multi-keyless chucks?
Q2 What are the differences between tapered-type and threaded-type?
Q3 How high is the runout accuracy of drill chucks?
Q4 What is the structure and mechanism of drill chucks like?
Q5 What are the differences between models with “EL” and without?
Q6 Can drill chucks be distinguished by the letters in their model number?
Q7 What is “JT6” marked on the mounting side of a drill chuck?
Q8 What are the differences between JTS2 and JT2 taper?
Q9 What is the suitable model of drill chuck when having it chuck a 3/8 inch diameter shank 　tool?
Q10 Can drill chucks be used with impact drivers?
Q11 What is the marking “B4634” on a drill chuck?
Q12 What are the differences between JIS-standardized chucks and other ones?



Q1 What are the differences between drill chucks, keyless chucks, and multi-keyless chucks?
A1 We manufacture and sell drill chucks roughly classifying them into 4 categories in terms of function.
Drill chucks
1) Drill chucks		 Keyless drill chucks
2) Keyless drill chucks
Multi chucks
3) Multi chucks
 		 Multi-keyless drill chucks
4) Multi-keyless drill chucks
1) Drill chucks
    Most popular drill chucks. Tighten the tool with a chuck key.
2) Keyless drill chucks
    Drill chucks tightened by hand; no need for chuck keys. The tool can     be changed quickly.
3) Multi chucks
    Drill chucks in which a tool is tightened with a chuck key. Lightweight     drill chucks developed for use on electric drills and air drills.
4) Multi-keyless drill chucks
    Drill chucks for electric drills and rechargeable drills. No need for     chuck keys, tightened by hand.
Q2 What are the differences between tapered-type and threaded-type?
A2 Tapered/threaded-type means the way to mount the drill chuck on the mating spindle. Generally, tapered-type chucks are mounted on machine tools while threaded-type chucks are on electric drills and air drills. However, even so, sometimes tapered-type chucks are used to air drills.

  • Tapered drill chucks
    Tapered-type chucks are the ones of which mounting part is conic shape and mounted by being driven in to the spindle. A tapered-type chuck is fixed to the spindle on both taper sides adhered to each other with surface pressure. There are some types of taper such as Jacobs taper, Morse taper, etc. Jacobs taper is popular in Japan and U.S. while Morse taper is popular in Europe.


  • Threaded drill chucks
    For threaded-type chucks, the size of mounting thread to the mating spindle is 3/8-24UNF or 1/2-20UNF.
Q3 How high is the runout accuracy of drill chucks?
A3
  • JIS(Japanese Industrial Standard)-certified Drill chucks
    Runout accuracy of JIS-certified drill chucks for machine tools and portable electric drills is specified as follows:

    Drill chuck

    Model

    Circumferential runout

    For machine tools

    Tapered

    normal

    MG

    0.08mm or smaller

    E

    0.20mm or smaller

    For portable electric drills

    Tapered

    Normal

    E

    0.20mm or smaller

    Lightweight

    EL

    Threaded

    ELB

    ※

    ”MG” class stands for “machine grade” and indicates runout accuracy grade for machine tools specified by JIS

    ※

    The point at which the runout accuracy is measured is specified by JIS. For 13MG, the runout accuracy should be 0.08mm at 110mm distant from the head of the chuck.

    ※

    ”E” class stands for “Electric”; electric drills and means runout accuracy grade for portable electric drills.

    ※

    Before the standard is revised, a grade called “MS”, of which accuracy is 0.04mm, had existed, but it has been abolished already. The name of our relating company, MS Industry is derived from it.



  • Drill chucks of overseas standard
    Although original industrial standards used to exist in individual country in overseas,, currently, these standards have been unified into ISO standards.
Q4 What is the structure and mechanism of drill chucks like?
A4 image of drillchucksA drill chuck structurally consists of 4 basicparts;
a body, 3 jaws, a nut and a cover. This structure is basically the same among drill chucks, multi chucks, and multi keyless drill chucks though there are some differences in the form of the parts. When the cover is rotated, the nut rotates as well and pushes up the 3 jaws. Then, the jaws move forward along with the 3 slots on the body and hold the tool. The picture in the right shows a ball-bearinged drill chuck that has a slide ball bearing built-in. On the contrary,ordinary,
JIS-certified drill chucks do not have any ball bearing withi.

Q5 What are the differences between models with “EL” and without?
A5 Drill chucks of which model number is accompanied with “EL” are lightweight ones. Originally, they were developed as lightweight chucks for electric tools, and “EL” stands for Electric and Light. As these chucks are lightened by adopting smaller body by one size, be sure to use a chuck key (chuck handle) smaller by one-size as well.

Q6 Can drill chucks be distinguished by the letters in their model number?
A6 Typical meanings of the letters in the model number of drill chucks are as follows:

  • Letters related to runout accuracy
    As for letters related to runout accuracy of drill chucks, 2 accuracy grades are specified by Japanese Industrial Standards JIS4634 as follows:

MG

MG, which stands for Machine Grade, are letters given to drill chucks for machine tools. The runout accuracy is 0.08mm or smaller.

E

E originally means “Electric” = electric tools, and the chucks were defined as ones for portable electric chucks with these letters. However, some of them currently exist as ones for machine tools. The runout accuracy is 0.2mm or smaller.



  • Letters related to shape/function
    The letters related to the shape and function of drill chucks are classified as follows:

L

These chucks are light type and have the same chucking capacity as indicated in the model number, but the body is smaller by one size. They are drill chucks for only portable drills and these model numbers do not exist as ones for machine tools.

LL

Much lighter type. Although these chucks have the same capacity as indicated in the model number, their body is designed smaller by two sizes. This type of chuck in our lineup is 16LL only. (16LL: can chuck 16mm tool, but the size of the body is 10mm)

F

image of drillchucksThis letter is given to drill chucks of which outer cover is flute patterned. These chucks are for use in overseas.

D

These chucks were once special-sized to be provided to specific customers and have been standardized currently. Their model number includes D4 or D5 for the reason that their drawing number starts from DKS.

J

J8 model applies to this type. The maximum chucking capacity is 8mm and the mounting part is Jacobs No.1 taper. This type is frequently used as drill chucks for use in the U.S.

M

M8 model applies to this type. The maximum chucking capacity is 8mm and the mounting part is Morse No.1 taper. This type is frequently used as drill chucks for use in Europe.

Q7 What is “JT6” marked on the mounting side of a drill chuck?
A7 JT means standards called Jacobs Taper and the number affixed to it indicates the size. When the chuck is Jacobs Taper No.6, even if the description differs such as 6JT, JT6, or JT.No.6, they are the same. 13mm drill chucks that are used for machine tools usually have Jacobs taper No.6 in Japan, and this Jacobs taper No.6 (6JT, JT6, JT.No.6) is sometimes called Niban-han (means No.2 and half).

Q8 What are the differences between JTS2 and JT2 taper?
A8 JT2S is a short type of Jacobs taper No.2. The taper angle is the same as JT2, but the taper length is a little shorter than JT2. As the difference is just the taper length only, it is possible to mount a JT2S drill chuck on a JT2 arbor. Generally, JT2S taper is usually used in Japan while JT2 is popular in U.S.

Q9 What is the suitable model of drill chuck when having it chuck a 3/8 inch diameter shank tool?
A9 Drill chucks can hold the tool more stably when the diameter of the tool shank is as close to the maximum chucking capacity as possible. Therefore, to hold 3/8 inch diameter shank tool, we recommend a drill chuck of which maximum chucking capacity is 3/8 inch and runout accuracy is good, namely, 10MG.

Q10 Can drill chucks be used with impact drivers?
A10 Drill chucks and multi keyless chucks with a hexagonal bit are sold by manufacturers of electric tools and working tools. If you purchase these products, it is possible for you to use drill chucks and keyless drill chucks with impact drivers. However, be careful in using impact drivers as they forces large torque on the tool, which may make the tool trapped in the chuck and impossible to remove.

Q11 What is the marking “B4634” on a drill chuck?
A11 The marking B4634 is a JIS standard number of drill chucks. As for JIS standards, they used to be divided into 2 groups; drill chucks for machine tools as standard No.B6001 and for portable electric drill chucks as standard No.B4634. However, when JIS standards were reviewed in 1998, drill chucks for machine tools and portable electric drills were unified to drill chucks of which standard number is B4634. Drill chucks manufactured before this review in 1998 were marked with standard No.6001. In addition to it, some of them may be marked with the certification No.5675 at that time as well. Currently, our drill chucks are regularly audited by JQA, Japan Quality Assurance, JIS authorized organization to acquire a certification No.JQ308005.

Q12 What are the differences between JIS-standardized chucks and other ones?
A12 Sizes of drill chucks are specified by JIS standards as 5, 6.5, 10, 13, and 16 while light-weight types are 6.5EL, 10EL, and 13EL. Every company manufactures their drill chucks according to the dimensions and runout accuracy specified by JIS standards. Our company manufactures drill chucks of other sizes than specified by JIS setting our own standards for inter-office inspection that is equivalent to the standards of runout accuracy specified by JIS. Many countries used to be authorized by JIS, but currently, the only manufacturer authorized to label new JIS indication is YUKIWA. We manufacture and sell drill chucks for safe use as we have them inspected regularly from outside.