How to use Vee bearings and T-rails

Our Vee bearings and T-rails offer the user a simple way of constructing smooth running linear systems with a high load capacity and, in the case of the stainless steel version, corrosion resistance too. For this example we are selecting the following parts:

4 pcs EV W3X ( Vee Bearings)

2 pcs MB3 (Metric bore Concentric bush)

2 pcs MB3X (Metric bore Eccentric bush)

2 pcs T-3 x 1000mm ( T-3 rails 1 metre long)

The first thing to do is to decide the width of the track and then choose what material the T-rail will be attached to. In this example (see drawing) we have selected a piece of steel or aluminum 50mm wide and 1 metre long. Let’s call this the “support”. The precision of the system is dictated by how accurately this support material is manufactured.

The Rail and Support

Drilling the T-rail is easy. The flats are not hardened, only the tip of the vee, so normal drilling techniques can be used. Our preference is to clamp the T-rail to the support material and to drill pilot holes through the T-rail into the support. This means the centres will match. Double check that the T-rail edges are still parallel. Then drill through holes in the T-rails and drill and tap the support.

Finally bolt the T-rail onto the support. We tend to use dome head machine screws. Make sure the screw heads do not interfere with the carriage or rail edges. Also make sure that the rail edges are parallel.

The Carriage and Bearings

In this example we are making a carriage 150mm x 150mm with 4 no. W3X bearings. So again, select the material, steel or aluminium, for the carriage. The hole centre positions for the bearings (dimension “A” on the drawing) can be calculated as:

A = Width of support + 2 x TE + 2 x A1

The value for dimension TE can be found here http://www.euro-bearings.com/veerails.htm (TE in this case is 6.35mm).

And the value for dimension A1 can be found here http://www.euro-bearings.com/veesizes.htm (A1 in this case is 19.05mm).

NOTE: Dimension TE is the offset of tip of Vee rail from the support material. A1 is the dimension from centre of bearing to bottom of Vee. In our example this is 50 + (2x 6.35) + ( 2 x 19.05) = hole centres 100.8mm.

The eccentric bush MB3X allows 1.07mm of lateral adjustment.

Drill the holes through the carriage plate at 100.8mm centres (in this case 8.2mm diameter clearance holes for the M8 bolts we will use to secure the bearings).

Insert the concentric bushes into 2 bearings and insert the eccentric bushes into 2 bearings. Firmly secure the concentric bushed bearings to one side of the carriage plate and tighten. Loosely assemble the eccentric bushed bearings to the carriage plate and slide the carriage onto the T-rails. Now adjust the eccentric bushed bearings by feel (or feeler gauge) to achieve the pre-load required. Slide the carriage back & forth to ensure there are no pinch points. It is recommended to use hex cap head bolts and nyloc nuts through each bearing bush.

IMPORTANT: Make sure the outer ring of the bearing is turning on the inner ring of the bearing and NOT on the bush. The bearing should be an interference fit onto the bush.

Euro-Vee Bearings

euro-vee

EURO-VEE BEARINGS

Our Euro-Vee Bearings are available in 4 sizes which can take radial loads from 100kg up to 800kg. A cost effective linear sliding system can be built using our corresponding T Rail and Euro-Vee Bushings for applications requiring either vertical or horizontal movement.

The bearings are sealed and lubricated for life and so will tolerate being used in dirty environments. The Vee Bushings are used to mount these bearings. We have both concentric and eccentric bushings on stock, in both imperial and metric sizes.

A typical system would use a pair of rails with a minimum of four bearings acting as wheels for a carriage. Half the number of bearings would be mounted on the concentric bushings and the other half mounted on the eccentric type. All the bearings are held in position on their bushings by a bolt fixed through the centre of the bushing. By rotating the eccentric bushings it is possible to tighten the bearings onto (or off) the track. The eccentric bushings have a hex head so that they can be rotated with a spanner before their fixing bolts are tightened back up. The system should be designed so that the main loads are taken by the bearings on the concentric bushings.

The T Rail can either be drilled and bolted down (to a square edge) or it can be welded into position. The body of the rail is soft so it can be easily drilled. The top edge of the rail (where the bearing runs) is induction hardened and polished.

It is also worthing knowing that our Euro-Vee Bearings can be run on round (hardened and ground) linear shaft.

Example applications include:

  • packaging machinery
  • laboratory automation
  • woodworking machinery
  • vending machines
  • sliding doors (eg machine tool doors)

Our Euro-Vee Bearings are also available in stainless steel.