Saturday, 20 April 2019

Unimat 3 fine feed milling attachment

On its own the milling post has only a simple lever to move the spindle up and down, there being no way of taking a cut or moving the tool by a set and accurate amount. This is where the fine feed attachment comes into play, allowing one to move the spindle up and down with a degree of accuracy. This is what the attachment looks like;


The main body on mine is raw aluminium, they also come in white and black.
Basically the body has a shaft running through it with a worm on one end and a graduated dial on the other, that can be turned using a 5mm Allen key. This worm turns a worm wheel which can be fitted to the spindle pinion assembly;


Fitting the worm gear is simply a matter of undoing a grub screw on the end of the lever assembly, removing the lever itself, and sliding the 'gear over the pinion shaft. Two slots on the end of the 'gear engage with the lever locking it in place.

The attachment itself has a pin running sideways through it which not only holds the shaft in place but also locates in a hole on the side of the milling head. A caphead bolt running through an oversized hole holds the attachment in place, and allows it to be swiveled up or down;


The attachment is shown here with the worm and gear engaged;


(Not the best photo I'm afraid!)
A 5mm Allen key can now be used to move the spindle up or down;


The shaft is graduated, each graduation being 0.1mm. A full turn of the shaft moves the spindle 1mm.

Rotating the attachment disengages the worm leaving the spindle free to be moved by the lever on its own, ready for either drilling or setting the tool close to the job;


A useful accessory.


Which needs a bit of a clean!

Paul.

2 comments:

  1. The fine feed attachment is still on my U3 shopping list, as I agree trying to set the height to take small cuts when milling is a nightmare without it.

    ReplyDelete
    Replies
    1. It can be done without the attachment. On the SL I use a dial test indicator to measure cuts, by setting it up with the plunger on the pulley (for example, any part that moves with the spindle if ok), moving the spindle the required amount, then removing the DTI before taking the cut. Perhaps I'll do another post explaining it.

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