Please make sure all linear movement components are lubricated prior to use. Using non-lubricated components will have a reduced overall life. The recommended grease for both the Ball nuts and SBR20UUOP bearing blocks is Lithium Soap grease. It's difficult to narrow down the exact grease to use, even SKF recommend 3 different greases, these are LGEP 2, LESA 2 or LGMT 2. I have been using LGMT 2 without issue but don't currently have any long term data so use at your own discression. These greases should be available from lubricant retailers and are around $10 for 450g. It is not recommended you mix different types of greases.
The BF12 Bearing block
The BF12 Bearing block is a "floating"
bearing block. The roller bearing inside is not held in place and is
free to move up and down the sleeve in the bearing housing. There
are two rubber grommets either side that are designed to keep
foreign material out of the bearing. Another part of the BF group is
a circlip, this clip will hold the roller bearing on the end of the
Ballscrew. The BF12 bearing housing only supports the weight of the
bearing and the Ballscrew and is designed to keep the Ballscrew
shaft aligned. It's not put under any shear force or other loads
form the axis moving so it is only held in place by 2 bolts.
Assembling the BF12
The BK12 Bearing block
The BK12 Bearing block is a fixed bearing
block and it's construction is designed to bear all of the loads
associate with the movement of the Axis it supports. Because of these
loads it has 2 Roller bearings for strength and once assembled they
cannot move inside their housing and remain rigidly in place at all
Assembling the BK12
Insert the Rubber Grommets into either side
of the BK12 Housing. The 2 Shaft pacers and Shaft retaining nut are used
on the Ballscrew shaft at a latter stage.
The RM1605 Ballscrew Unit
The RM1605 Ballscrew unit will consist of a
16mm machined rod with thread and mounting surfaces and is fitted with a
Bull Nut and Mounting Flange. The most important thing to know about
your Ballscrew is you should never wind the Ball Nut past the threaded
part of the ballscrew, the ball nut is filled with ball bearings which
will spill out and are difficult an time consuming to re-insert. The
orientation of the nut is not specific and it could be facing the other
way, this will make no difference to operation. The M6 Oiling point will
accept an M6 grease nipple.
The RM1605 Ballnut Housing
The Ballnut Housing is very straight
forward and is designed to connect your Ballscrew with the axis it is
going to move
Attaching the Ballnut Housing to the Ballscrew Unit
Align the RM1605 Mounting sleeve on the
Ballnut Housing with the Ballnut Body on the Ballscrew Unit and slide
on, take care not dent or scrape the Ballscrew thread. Rotate the
Ballnut Housing until it aligns with the mounting points on the Ballnut
Flange. Insert the 6 M5x12mm Alenkey head bolts and tighten.
Attaching the BF12 Bearing block to the Ballscrew Unit
Insert the floating end of the Ballscrew
shaft into the BF12 Bearing block. The shaft should pass through the
roller bearing in the BF12 until the Circlip groove is visible on the
With a pair Circlip pliers or needle nose
pliers open the circlip and slip it over the shaft until it drops into
the retaining groove.
To test, hold the BF12 in one hand and
rotate the Ballscrew shaft, the Ballnut and Housing should move back or
forth. You may feel some unwanted resistance, this is most likely from
the Rubber Grommet between the roller bearing and the RM1605 thread. To
resolve this you can try; oiling the grommet, working the Ballscrew
until the action frees up, work the grommet on a larger shaft to try an
increase the ID of the grommet, trim the grommet, or (if all else
fails), remove the grommet completely.
On the fixed end of the Ballscrew shaft
insert a Shaft Spacer, then the BK12 Bearing unit, and then the second
Shaft Spacer. The first Shaft spacer should rest up against the end of
the RM1605 thread on the Ballscrew. The first roller bearing will sit up
against the spacer and the final Shaft Spacer up against the last roller
bearing. The thread for the Shaft Retaining nut should be visible.
Slide the Shaft Retaining Nut along the fixed end of the Ballscrew until it meets the Retaining Nut thread, tighten the nut on the thread until it is firmly finger tight. The Retaining Nut will need to hold both Shaft Spacer and both roller bearings firmly in position. Tighten both the grub screws, these will hold the nut in position.
Attaching the Motor Coupler to the Ballscrew Unit
As there are many types of Motor couplers
available and it will be difficult to customize these instructions to
the particular type you have received, so instead, I will give some
fairly broad instructions and try and cover all bases. First up there
are 2 general methods in which a coupler will attach to the shaft. These
are Jaw (or clamp) and Grub screw, and, your coupler may have one or the
other or a combination of both.
With the Grub screw type there will be one
or two threaded holes passing from the exterior of the coupler to the
interior where a grub screw will protrude. With this type, the grub
screw is tightened directly against the shaft to hold it into position.
To test the Ballscrew Assembly, rotate the
Motor Coupler and the Ballnut and Ballnut Housing should move forward or
back. Again, if the there is some unwanted resistance to the coupler
being turned it is most likely the rubber grommets in the BK12 Bearing
unit, please carry out the remedial steps listed with the BF12
Assembling the other Ballscrew Units
Please repeat the instructions above for
all other Ballscrew Assemblies.
This site was last updated 02/15/15