Description

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DLY BK/BF ball screw support units form a base-mounted fixed-and-floating support pair for standard ball screw assemblies. BK is installed on the fixed or drive side, while BF supports the opposite shaft end. The series covers BK10/BF10 through BK40/BF40. Selection must be based on the actual machined shaft-end diameters and mounting dimensions-not on the model number alone.

DLY BK10 fixed-side and BF10 floating-side ball screw support set

BK fixed-side support and BF floating-side support with related retaining components.

BK Fixed Side vs. BF Floating Side

Item	BK Fixed-Side Support	BF Floating-Side Support
Installation position	Motor, coupling or drive side	Opposite end of the screw shaft
Main function	Axial location and fixed-end support	Support for the non-drive shaft end
Selection focus	Fixed-end shaft diameter, shoulder, thread and support dimensions	Floating-end journal diameter and support dimensions
Mounting form	Square housing with base mounting holes	Matching square housing with base mounting holes
Typical ordering method	Ordered separately or as the BK side of a matched set	Ordered separately or as the matching BF side

DLY BK fixed-side ball screw support unit front view

BK fixed-side support unit.

DLY BF floating-side ball screw support unit bearing view

BF floating-side support unit.

Matched BK/BF Models and Shaft-End Diameters

The BK and BF model numbers indicate a matched support group, but the fixed-side and floating-side shaft-end diameters are not always identical. BK10/BF10 and BK12/BF12 are the most important examples to check before machining.

Matched Pair	BK Fixed-End d1 (mm)	BF Floating-End d1 (mm)	Housing Width B (mm)	Housing Height H (mm)	Center Height h (mm)	Mounting Pitch P (mm)
BK10 / BF10	10	8	60	39	22	46
BK12 / BF12	12	10	60	43	25	46
BK15 / BF15	15	15	70	48	28	54
BK17 / BF17	17	17	86	64	39	68
BK20 / BF20	20	20	88	60	34	70
BK25 / BF25	25	25	106	80	48	85
BK30 / BF30	30	30	128	89	51	102
BK35 / BF35	35	35	140	96	52	114
BK40 / BF40	40	40	160	110	60	130

BK Fixed-Side Support Dimensions

All dimensions are in millimetres. The values for b and h have a tolerance of ±0.02 mm. Mounting holes are specified as 4-X drill-through holes with ØY counter bores and counter-bore depth Z.

BK fixed-side ball screw support dimension drawing and parameter symbols

BK Model	d1	L	L1	L2	L3	C1	C2	B	H	b ±0.02	h ±0.02	B1	H1	E	P	d2	X	Y	Z
BK10	10	25	5	29	5	13	6	60	39	30	22	34	32.5	15	46	5.5	6.6	10.8	5
BK12	12	25	5	29	5	13	6	60	43	30	25	34	32.5	18	46	5.5	6.6	10.8	1.5
BK15	15	27	6	32	6	15	6	70	48	35	28	40	38	18	54	5.5	6.6	11	6.5
BK17	17	35	9	44	7	19	8	86	64	43	39	50	55	28	68	6.6	9	14	8.5
BK20	20	35	8	43	8	19	8	88	60	44	34	52	50	22	70	6.6	9	14	8.5
BK25	25	42	12	54	9	22	10	106	80	53	48	64	70	33	85	9	11	17.5	11
BK30	30	45	14	61	9	23	11	128	89	64	51	76	78	33	102	11	14	20	13
BK35	35	50	14	67	12	26	12	140	96	70	52	88	79	35	114	11	14	20	13
BK40	40	61	18	76	15	33	14	160	110	80	60	100	90	37	130	14	18	26	17.5

BF Floating-Side Support Dimensions

BF dimensions must be checked against the floating-end journal of the ball screw. Do not infer the journal diameter directly from the BF model number, especially for BF10 and BF12.

BF floating-side ball screw support dimension drawing and parameter symbols

BF Model	d1	L	B	H	b ±0.02	h ±0.02	B1	H1	E	P	d2	X	Y	Z
BF10	8	20	60	39	30	22	34	32.5	15	46	5.5	6.6	10.8	5
BF12	10	20	60	43	30	25	34	32.5	18	46	5.5	6.6	10.8	1.5
BF15	15	20	70	48	35	28	40	38	18	54	5.5	6.6	11	6.5
BF17	17	23	86	64	43	39	50	55	28	68	6.6	9	14	8.5
BF20	20	26	88	60	44	34	52	50	22	70	6.6	9	14	8.5
BF25	25	30	106	80	53	48	64	70	33	85	9	11	17.5	11
BF30	30	32	128	89	64	51	76	78	33	102	11	14	20	13
BF35	35	32	140	96	70	52	88	79	35	114	11	14	20	13
BF40	40	37	160	110	80	60	100	90	37	130	14	18	26	17.5

Dimension symbols follow the supplied BK and BF drawings. Confirm the final support drawing together with the machined ball screw end drawing before production.

How to Select a BK/BF Support Set

For a New Ball Screw Assembly

Confirm the ball screw diameter, lead, total length and nut type.
Select the BK/BF housing size according to the machine base and shaft-end design.
Design the fixed and floating shaft ends from the correct BK and BF d1 values.
Check B, H, h, P, b and the mounting-hole specifications against the machine drawing.
Confirm whether the ball screw, end machining, supports, coupling and related accessories are required together.

For Replacement

Send the existing BK/BF model or clear photos of both supports.
Measure the shaft center height, housing width, mounting pitch and hole sizes.
Provide the fixed-end and floating-end shaft dimensions.
Confirm the coupling and motor-side layout before ordering.
Use the final approved drawing rather than relying on model markings alone.

For a more compact support structure, see the EK/EF ball screw support units. For flange mounting, see the FK/FF ball screw support units.

Ordering Information

For faster confirmation, send the BK/BF model, quantity, ball screw diameter and lead, total screw length, fixed-end and floating-end machining drawing, mounting layout, and whether a complete ball screw assembly is required. DLY can check the support units together with the ball screw, ball nut, end machining and coupling.