Holes & Threads

Bores and  axes:

What do we consider a "bore"

To us, a bore or a hole is a hollow cylindrical feature in a part, it can either have a bottom or be completly through the material. De counterpart is generally an axis or a bar.

In general, bores are mainly used to accept an axis, bar or bolt. Therefore in most application an oversize is desired.

Our software recognizes bores and axes and applies a slight oversize (0,+) to it according to tolerance klass H7.

What do we consider an "axis"

To us, an axis is a cyliderical feature that extends the workpiece. It's general purpose is to be implemented in a bore/hole. Therfore, it's important that it's diameter is slightly smaller then that of the bore. If not, there is a good chance these parts can't be used in an assembly.

Axes are recognized by our software and are automatically compensated toe fullfill this requirement. Thus appling a negative tolerance (-,-) from the g6 tolerance class.


A H7 is a tolerance class for bores that has a positive tolerancefield. It makes a hole larger then the nominal value stated on the design. 

A g6 on the other hand is a negative tolerance class appllied to axes. 


values in µm

Boring vs. milling:

Although we use the term "boring" we only bore the most common diamters, all the rest are milled. Milling is concidered a slower operation, but it requires less tooling. 

The depth of the holes are similar we generaly obtain a depth of five times the diameter for either boring or milling.

The main difference between boring and milling is the fact that boring in a non through hole setup leaves a tapered bottom, where milling leaves a flat hole. The tapered angle is 140°.

What about tight fits?

95% our customers are looking for a "loose fit". If however you do need a thight fit, you can accomplisch this by adjusting the size in your 3D model. compensating the tolerance we try to achieve. This will end up with a whole without an oversize and an axes with oversize, does creating a thight fit.


All the common used types of threading can be applied by YouniQ: metric, metric fine, BSP, UNC, UNF, etc.


Since the use of intelligent step files or annotated JT files (AP242, JT or ISO 14739-1:2014|) is still not very common, it complicates the communication of where threaded holes need to be and what type (left vs right, coarse vs. fine). So if you're not using normed annotation in your 3D models you'll need to transfer this knowledge by means of a sketch or 2D plan (bummer). Thus increasing the chance for human errors. In a later stage we'll make it possible to annotate threads in the design.

Tapping vs. thread milling:

At YouniQ, most of the thread are tapped. We also have the possibilties to add them by thread milling. This can be usefull if you want to add left-handed threads. 


All holes that needs threading will be chamfered so the bolt will enter the thread smoothly. This chamfer however is not inteded for screw sinking, this needs to be in the 3D model.