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Mongtec BT power milling chucks

51 article numbers on BT30 · BT40 · BT50. HC and CT-type power milling chucks on the BT taper for sustained heavy stock removal, Ø16 to Ø42 mm. Mongtec Precision is a Taiwanese brand headquartered in Taichung, Taiwan.

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Mongtec BT power milling chucks — dimensioned drawing — Dimensioned drawing from the Mongtec catalogue. The dimension letters are the columns of the table below.

Built for side load, not for squeeze

An ER collet clamps by squeezing a short slit sleeve. A power milling chuck clamps a long, plain cylinder through a needle-roller mechanism that converts nut torque into a large, evenly distributed radial force over a much longer contact length.

The difference shows up under side load, which is what roughing actually applies. A collet resists the tool being pulled out; a milling chuck resists the tool being levered sideways. That is why the milling chuck is the standard choice for high-feed roughing, deep slotting, and any operation where the cutter is trying to walk out of the holder rather than simply spin in it.

HC and CT

HC is the compact series: Ø20–42 mm capacity in body lengths from 80 to 300 mm, with the clamping range printed as two figures (for example 3–25 / 32) because reduction sleeves extend the chuck below its nominal size.

CT is the long-reach series, Ø16–42 mm, catalogued in three body types and in lengths to 450 mm on BT50. This is the family for reaching into a deep cavity while still taking a real cut — the extra dimensions in the table (L1, L2, ℓ, ℓ1, ℓ2, d1, L0) describe the stepped nose that gets the body out of the way near the cutting end.

What it costs

A milling chuck is heavier and bulkier than a collet chuck at the same capacity, and it is slower to change tools in. It also has a nose diameter that will foul work a slim collet chuck would clear. Use it where the cut justifies it, and keep collet chucks for everything else.

Article numbers — dimensions in mm

Dimension symbols are the catalogue's own and refer to the dimension drawing printed for each product. A dash means the catalogue does not print a usable value for that cell; those are confirmed in writing at RFQ. Where a table's printed header disagrees with its drawing, a note above the table says so.

Power Milling Chuck — 17 article numbers

Article no.	d	D	L	Capacity
BT30QHC20Q80	20	50	80	3-16 / 20
BT30QHC25Q90	25	59	90	3-20 / 25
BT30QHC32Q110	32	72	110	3-25 / 32
BT40QHC20Q90	20	50	90	3-16 / 20
BT40QHC25Q100	25	59	100	3-20 / 25
BT40QHC32Q90	32	72	90	3-25 / 32
BT40QHC32Q105	32	72	105	3-25 / 32
BT40QHC32Q165	32	72	165	3-25 / 32
BT40QHC42Q130	42	99	130	3-32 / 42
BT50QHC20Q105	20	50	105	3-16 / 20
BT50QHC25Q105	25	59	105	3-20 / 25
BT50QHC32Q110	32	72	110	3-25 / 32
BT50QHC42Q110	42	99	110	3-32 / 42
BT50QHC32Q165	32	72	165	3-25 / 32
BT50QHC32Q200	32	72	200	3-25 / 32
BT50QHC32Q250	32	72	250	3-25 / 32
BT50QHC32Q300	32	72	300	3-25 / 32

Power Milling Chuck — 34 article numbers

Article no.	Type	d	D	D1	L	L1	L2	ℓ	ℓ1	ℓ2	d1	L0	G
BT30QCT16SAQ90	1	16	45	—	90	—	—	65	—	15	—	—	M10
BT30QCT20SAQ90	2	20	52	—	90	—	—	80	—	15	—	40	M12
BT30QCT25SAQ90	2	25	61	—	90	—	—	80	—	15	—	31	M12
BT30QCT32SAQ90	2	32	68	—	90	—	—	68	—	20	—	30	M18
BT40QCT16SAQ90	1	16	45	—	90	—	—	65	—	15	—	—	M10
BT40QCT20SAQ90	1	20	52	—	90	—	—	80	—	15	—	—	M12
BT40QCT25SAQ90	1	25	61	—	90	—	—	80	—	15	—	—	M12
BT40QCT25SAQ105	1	25	61	—	105	—	—	80	—	15	—	—	M12
BT40QCT32SAQ90	2	32	73	—	90	—	—	76	32	17	26	31	M18
BT40QCT32SAQ105	2	32	73	—	105	—	—	85	23	17	26	44	M18
BT40QCT32SAQ135	2	32	73	—	135	—	—	120	—	17	—	74	M18
BT50QCT16SAQ90	3	16	45	58	90	7	45	65	—	20	—	—	M10
BT50QCT20SAQ90	3	20	52	65	90	7	45	80	—	15	—	—	M12
BT50QCT20SAQ105	3	20	52	70	105	9	58	80	—	15	—	—	M12
BT50QCT20SAQ135	3	20	52	73	135	39	58	80	—	15	—	—	M12
BT50QCT20SAQ165	3	20	52	73	165	69	58	80	—	15	—	—	M12
BT50QCT25SAQ105	3	25	61	82	105	11	56	80	—	15	—	—	M12
BT50QCT25SAQ135	3	25	61	83	135	41	56	80	—	15	—	—	M12
BT50QCT25SAQ165	3	25	61	86	165	71	56	80	—	15	—	—	M12
BT50QCT32SAQ105	1	32	73	—	105	—	—	120	—	20	—	—	M18
BT50QCT32SAQ135	3	32	73	88	135	41	56	120	—	20	—	—	M18
BT50QCT32SAQ165	3	32	73	86	165	71	56	120	—	20	—	—	M18
BT50QCT32SAQ200	3	32	73	88	200	106	56	120	—	20	—	—	M18
BT50QCT32SAQ250	3	32	73	88	250	156	56	120	—	20	—	—	M18
BT50QCT32SAQ300	3	32	73	88	300	206	56	120	—	20	—	—	M18
BT50QCT32SAQ350	3	32	73	88	350	256	56	120	—	20	—	—	M18
BT50QCT32SAQ400	3	32	73	88	400	306	56	120	—	20	—	—	M18
BT50QCT32SAQ450	3	32	73	88	450	356	56	120	—	20	—	—	M18
BT50QCT42SAQ105	1	42	88	—	105	—	—	120	—	20	—	—	M18
BT50QCT42SAQ135	1	42	88	—	135	—	—	120	—	20	—	—	M18
BT50QCT42SAQ165	1	42	88	—	165	—	—	120	—	20	—	—	M18
BT50QCT42SAQ200	1	42	88	—	200	—	—	120	—	20	—	—	M18
BT50QCT42SAQ250	1	42	88	—	250	—	—	120	—	20	—	—	M18
BT50QCT42SAQ300	1	42	88	—	300	—	—	120	—	20	—	—	M18

Which article number fits your machine?

The drawing above is the published catalogue drawing, and the dimension letters are the columns of the table below. What Mongtec confirms for you is the interface on your machine, the reach for the operation, and the final article number. Send the machine and the operation; the check is free.

Send my machine and get the article number →

Source: Mongtec BT·BBT Tooling System catalogue, Ver 2026.

Check pull-stud thread and spindle standard before ordering. BT holders are supplied without pull studs, and the thread (M12, M16, M24) and stud form vary by machine builder and by region. Send Mongtec the machine make, model and the pull-stud drawing with the RFQ.

Frequently asked

Can a power milling chuck hold a plain shank without a flat?

Yes — that is the point of it. It grips the cylindrical shank over a long length rather than locking against a flat, so it is both positive and concentric.

What does a capacity printed as "3-25 / 32" mean?

The chuck is nominally a 32 mm chuck; with reduction sleeves it clamps down to 3 mm. Order the sleeves for the shank diameters you actually run and quote them with the holder.

Milling chuck or hydraulic chuck?

A milling chuck for roughing — it takes more side load. A hydraulic chuck for reaming, boring and finishing — it damps vibration and runs truer. They are complements, not alternatives.