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Mongtec BT end mill holders

151 article numbers on BT40 · BT50 · BT30. Weldon side-lock, Whistle Notch and coolant-channel end mill holders on the BT taper, Ø6 to Ø50 mm. Mongtec Precision is a Taiwanese brand, designed and engineered in Taichung, Taiwan.

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Side lock: the most positive grip there is

A Weldon holder clamps a set screw against a ground flat on the tool shank. Nothing else grips as positively — the tool physically cannot rotate in the bore, whatever the cut does. That is why roughing cutters, high-feed mills and anything taking a heavy radial bite are held this way.

What you give up is concentricity. The screw pushes the shank sideways against the opposite bore wall by design, so a Weldon holder always runs out more than a collet, a hydraulic chuck or a shrink fit. On a roughing pass that costs nothing. On a finishing pass it costs surface finish, and on a small tool at speed it costs tool life. The rule that works: rough in Weldon, finish in something concentric.

Whistle Notch, and why the angle matters

A Whistle Notch shank has an angled flat instead of a parallel one. As the screw tightens it does two things at once — it locks rotation like a Weldon, and the ramp pulls the tool back against the holder face. That gives axial location as well, so the tool cannot creep out under a pulling cut. Use it where your cutters are shanked for it; the SLB series covers Ø6–40 mm.

Coolant delivery

Two families here do it differently. The K-version SLA holders add coolant channels to the standard Weldon body. The SEMC series is a dedicated coolant-channel design, Ø16–40 mm. Both guide flood coolant down the outside of the tool to the cutting zone rather than relying on the machine's external nozzles — which is what gets chips out of a deep pocket instead of recutting them.

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.

End Mill Holder with Coolant Channels — 30 article numbers

Article no.	d	D	H	L
BT40QSEMC16Q55	16	32	17	55
BT40QSEMC22Q55	22	40	19	55
BT40QSEMC27Q55	27	48	21	55
BT40QSEMC32Q60	32	58	24	60
BT40QSEMC40Q60	40	70	27	60
BT40QSEMC16Q100	16	32	17	100
BT40QSEMC22Q100	22	40	19	100
BT40QSEMC27Q100	27	48	21	100
BT40QSEMC32Q100	32	58	24	100
BT40QSEMC40Q100	40	70	27	100
BT40QSEMC16Q160	16	32	17	160
BT40QSEMC22Q160	22	40	19	160
BT40QSEMC27Q160	27	48	21	160
BT40QSEMC32Q160	32	58	24	160
BT40QSEMC40Q160	40	70	27	160
BT50QSEMC16Q70	16	32	17	70
BT50QSEMC22Q70	22	40	19	70
BT50QSEMC27Q70	27	48	21	70
BT50QSEMC32Q70	32	58	24	70
BT50QSEMC40Q70	40	70	27	70
BT50QSEMC16Q100	16	32	17	100
BT50QSEMC22Q100	22	40	19	100
BT50QSEMC27Q100	27	48	21	100
BT50QSEMC32Q100	32	58	24	100
BT50QSEMC40Q100	40	70	27	100
BT50QSEMC16Q160	16	32	17	160
BT50QSEMC22Q160	22	40	19	160
BT50QSEMC27Q160	27	48	21	160
BT50QSEMC32Q160	32	58	24	160
BT50QSEMC40Q160	40	70	27	160

End Mill Holder (Weldon) — 99 article numbers

Article no.	d	D	L	M	Screw Quantity
BT30QSLA06Q50	6	25	50	M6	1
BT30QSLA08Q50	8	28	50	M8	1
BT30QSLA10Q50	10	35	50	M10	1
BT30QSLA12Q50	12	42	50	M12	1
BT30QSLA14Q50	14	44	50	M12	1
BT30QSLA16Q63	16	48	63	M14	1
BT30QSLA18Q63	18	50	63	M14	1
BT30QSLA20Q63	20	52	63	M16	1
BT30QSLA25Q90	25	65	90	M18*2	2
BT40QSLA06Q50	6	25	50	M6	1
BT40QSLA08Q50	8	28	50	M8	1
BT40QSLA10Q63	10	35	63	M10	1
BT40QSLA12Q63	12	42	63	M12	1
BT40QSLA14Q63	14	44	63	M12	1
BT40QSLA16Q63	16	48	63	M14	1
BT40QSLA18Q63	18	50	63	M14	1
BT40QSLA20Q63	20	52	63	M16	1
BT40QSLA25Q90	25	65	90	M18*2	2
BT40QSLA32Q100	32	72	100	M20*2	2
BT40QSLA40Q120	40	80	120	M20*2	2
BT40QSLA06Q100	6	25	100	M6	1
BT40QSLA08Q100	8	28	100	M8	1
BT40QSLA10Q100	10	35	100	M10	1
BT40QSLA12Q100	12	42	100	M12	1
BT40QSLA14Q100	14	44	100	M12	1
BT40QSLA16Q100	16	48	100	M14	1
BT40QSLA18Q100	18	50	100	M14	1
BT40QSLA20Q100	20	52	100	M16	1
BT40QSLA06Q160	6	25	160	M6	1
BT40QSLA08Q160	8	28	160	M8	1
BT40QSLA10Q160	10	35	160	M10	1
BT40QSLA12Q160	12	42	160	M12	1
BT40QSLA14Q160	14	44	160	M12	1
BT40QSLA16Q160	16	48	160	M14	1
BT40QSLA18Q160	18	50	160	M14	1
BT40QSLA20Q160	20	52	160	M16	1
BT40QSLA25Q160	25	65	160	M18*2	2
BT40QSLA32Q160	32	72	160	M20*2	2
BT40QSLA40Q160	40	80	160	M20*2	2
BT50QSLA06Q63	6	25	63	M6	1
BT50QSLA08Q63	8	28	63	M8	1
BT50QSLA10Q63	10	35	63	M10	1
BT50QSLA12Q80	12	42	80	M12	1
BT50QSLA14Q80	14	44	80	M12	1
BT50QSLA16Q80	16	48	80	M14	1
BT50QSLA18Q80	18	50	80	M14	1
BT50QSLA20Q80	20	52	80	M16	1
BT50QSLA25Q100	25	65	100	M18*2	2
BT50QSLA32Q105	32	72	105	M20*2	2
BT50QSLA40Q110	40	80	110	M20*2	2
BT50QSLA50Q125	50	98	125	M24*2	2
BT50QSLA06Q160	6	25	160	M6	1
BT50QSLA08Q160	8	28	160	M8	1
BT50QSLA10Q160	10	35	160	M10	1
BT50QSLA12Q160	12	42	160	M12	1
BT50QSLA14Q160	14	44	160	M12	1
BT50QSLA16Q160	16	48	160	M14	1
BT50QSLA18Q160	18	50	160	M14	1
BT50QSLA20Q160	20	52	160	M16	1
BT50QSLA25Q160	25	65	160	M18*2	2
BT50QSLA32Q160	32	72	160	M20*2	2
BT40QSLA06Q50K	6	25	50	M6	1
BT40QSLA08Q50K	8	28	50	M8	1
BT40QSLA10Q63K	10	35	63	M10	1
BT40QSLA12Q63K	12	42	63	M12	1
BT40QSLA14Q63K	14	44	63	M12	1
BT40QSLA16Q63K	16	48	63	M14	1
BT40QSLA18Q63K	18	50	63	M14	1
BT40QSLA20Q63K	20	52	63	M16	1
BT40QSLA25Q90K	25	65	90	M18*2	2
BT40QSLA32Q100K	32	72	100	M20*2	2
BT40QSLA40Q120K	40	80	120	M20*2	2
BT40QSLA06Q100K	6	25	100	M6	1
BT40QSLA08Q100K	8	28	100	M8	1
BT40QSLA10Q100K	10	35	100	M10	1
BT40QSLA12Q100K	12	42	100	M12	1
BT40QSLA14Q100K	14	44	100	M12	1
BT40QSLA16Q100K	16	48	100	M14	1
BT40QSLA18Q100K	18	50	100	M14	1
BT40QSLA20Q100K	20	52	100	M16	1
BT50QSLA06Q63K	6	25	63	M6	1
BT50QSLA08Q63K	8	28	63	M8	1
BT50QSLA10Q63K	10	35	63	M10	1
BT50QSLA12Q80K	12	42	80	M12	1
BT50QSLA14Q80K	14	44	80	M12	1
BT50QSLA16Q80K	16	48	80	M14	1
BT50QSLA18Q80K	18	50	80	M14	1
BT50QSLA20Q80K	20	52	80	M16	1
BT50QSLA25Q100K	25	65	100	M18*2	2
BT50QSLA32Q105K	32	72	105	M20*2	2
BT50QSLA40Q110K	40	80	110	M20*2	2
BT50QSLA06Q100K	6	25	100	M6	1
BT50QSLA08Q100K	8	28	100	M8	1
BT50QSLA10Q100K	10	35	100	M10	1
BT50QSLA12Q100K	12	42	100	M12	1
BT50QSLA14Q100K	14	44	100	M12	1
BT50QSLA16Q100K	16	48	100	M14	1
BT50QSLA18Q100K	18	50	100	M14	1
BT50QSLA20Q100K	20	52	100	M16	1

End Mill Holder (Whistle Notch) — 22 article numbers

Article no.	d	D	L	M	Screw Quantity
BT40QSLB06Q50	6	25	50	M6	1
BT40QSLB08Q50	8	28	50	M8	1
BT40QSLB10Q63	10	35	63	M10	1
BT40QSLB12Q63	12	42	63	M12	1
BT40QSLB14Q63	14	44	63	M12	1
BT40QSLB16Q63	16	48	63	M14	1
BT40QSLB18Q63	18	50	63	M14	1
BT40QSLB20Q63	20	52	63	M16	1
BT40QSLB25Q90	25	65	90	M18*2	2
BT40QSLB32Q100	32	72	100	M20*2	2
BT40QSLB40Q120	40	80	120	M20*2	2
BT50QSLB06Q63	6	25	63	M6	1
BT50QSLB08Q63	8	28	63	M8	1
BT50QSLB10Q63	10	35	63	M10	1
BT50QSLB12Q80	12	42	80	M12	1
BT50QSLB14Q80	14	44	80	M12	1
BT50QSLB16Q80	16	48	80	M14	1
BT50QSLB18Q80	18	50	80	M14	1
BT50QSLB20Q80	20	52	80	M16	1
BT50QSLB25Q100	25	65	100	M18*2	2
BT50QSLB32Q105	32	72	105	M20*2	2
BT50QSLB40Q110	40	80	110	M20*2	2

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

Weldon or Whistle Notch — does it matter which I buy?

It has to match the shank you already own. A Weldon holder on a Whistle Notch shank tightens onto a ramp and can let the tool creep; the reverse leaves the screw sitting on nothing useful. Check the flats on your cutters first.

Do I need the K version if my machine has through-spindle coolant?

Not if your cutters have internal coolant holes — there the coolant goes through the tool. The K and SEMC channels exist for solid cutters without internal coolant, where the flow has to be guided down the outside.

Why are there two screws on the larger sizes?

Above Ø25 mm the catalogue specifies two screws (M18*2, M20*2, M24*2). One screw at that torque would deflect the shank badly; two spread the clamping load and keep the tool straighter.