Determine the right size quick-change steel holder
- Our tips.
Quick-changesteel holders based on the "Multifix" system are very popular with DIY enthusiasts, as changing turning tools is quicker and easier with the help of the holder. The turning tool is clamped in the steel holder and aligned to the correct height (spindle centre). The set height is secured using a lock nut. This means that the next time the steel holder is inserted, the turning tool is immediately set to the centre again. However, the question often arises as to which size of quick-change steel holder is suitable for which lathe in order to ensure precise machining of the workpiece.
To find out which size of quick-change steel holder is suitable for your lathe, the following parameters are important:
1. width of the top slide
The quick-change steel holder fits the lathe perfectly if the width of the top slide corresponds to the width of the holder.
1.1 Quick-change steel holder too small
If, for example, the holder size is too small, the turning tool must be clamped further out in order to be able to machine the workpiece. This can then lead to undesirable vibrations in the turning tool.
1.2 Quick-change steel holder that is too wide
If the holder is too large / wide, the maximum turning diameter that can be machined on your lathe is reduced, as the turning tool is closer to the turning axis due to the holder protruding too far.
2. height of upper edge of top slide to centre of spindle
In addition to the optimum width of the holder, it must also be taken into account that the cutting edge of the turning tool must be set to the centre of the spindle with the aid of the holder (Fig. 1). Otherwise, precise machining of the workpiece is not possible. To ensure this, the dimension "s" (Fig. 2), which indicates the height between the top edge of the top slide and the centre of the spindle, serves as the basis. Dimension "s" must not be exceeded by the support height of the base body (dimension "h") plus the height of the turning tool up to the cutting edge (Fig. 3).
Rule (Fig. 4):
Dimension "h" + height of turning tool to cutting edge < dimension "s"
If the dimension "h" plus the height of the clamped turning tool exceeds the dimension "s", the cutting edge is above the centre of the spindle and precise machining of the workpiece cannot be guaranteed. The height can be adjusted using a smaller turning tool. However, it should be borne in mind that due to the existing support height of the base body, the turning tool cannot be adjusted as far down as required and thus brought to the centre of the spindle.
If you would like to use a smaller holder size in order to bring the cutting edge of the turning tool to the centre of the spindle, please bear in mind that you may then also have to use a smaller turning tool (Fig. 5) that fits into the holder.
3. dimensions of the stud bolt
The through-holes in the base bodies of the quick-change steel holders are standardised and can also influence the choice of the correct holder. In order to securely fasten the base body to the top slide, the stud bolt must fit precisely into the hole in the base body.
3.1 Stud bolt is firmly anchored
If the stud bolt of your lathe is firmly anchored in the top slide and the diameter is too small for the bore of the holder, you can use our adapter sleeves to centre the holder and optimally fasten the base body to the top slide. This means you do not have to switch to a larger quick-change steel holder and save on the maximum turning diameter of the workpiece to be machined. This also eliminates the need to manufacture a new stud bolt, as you can attach your quick-change steel holder in a short space of time with the help of our assembly sets.
3.2 Stud bolt is replaceable
If the stud bolt on your lathe is interchangeable, you can easily replace it with a suitable stud bolt. In our range you will find stud bolts for the respective sizes of quick-change steel holders according to the "Multifix" system and suitable for our respective paulimot lathes (e.g. for the C2, PM3800 etc.). The threads of the stud bolts are optimally matched to the lathes and you can upgrade your lathe to a quick-change steel holder in no time at all.
Consider the parameters when purchasing the quick-change steel holder
Please note that both the width of the top slide and the dimension "s" must be taken into account in order to define the optimum size of the quick-change steel holder. The dimension of the stud bolt is of secondary importance, as you can usually replace the stud bolt or adapt the diameter of the stud bolt to the hole in the base body.
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