Unimat SL saddle removal.

Recently, whilst part way through a milling job, the saddle on my Unimat SL started to seize up. Obviously I couldn't carry on so the job (held in my dividing head) was removed from the machine so that the problem could be investigated.

The machine was stripped down to just the bed and saddle, and then removed from its wooden stand;

From underneath the bed looks like this;

Four screws and nuts hold the two 12mm dia. bed bars in place. The nuts are a bit tricky to undo due to them being rather close to the cast webs;

Usually I'd use a socket to remove them, but the socket I tried was too large and fouled the sides of the casting. So I ordered an 8mm box spanner;

Box spanners are narrower than sockets, and therefore not as strong. This one is made by Britool, and as you'd expect the quality is excellent. Its shown next to one of the screws that hold the bed bars in place. To remove the assembly the handle end of the leadscrew needs to be free of the casting, so the handle needs to be removed and the leadscrew wound into the saddle (not easy when its seizing up!);

Once the bed bars are unbolted the whole bed/leadscrew/saddle assembly can be lifted out;

The bed bars can now be slid out of the saddle, and the leadscrew removed for inspection.

I couldn't find any damage to the leadscrew, thankfully. I ran an M8x1 left hand tap through the saddle thread, removing some swarf and gunk, which has cleared the thread out allowing the leadscrew to turn easily in the saddle. Afterwards I blew the casting out with an airline. It seems the problem came from a build up of fine swarf and general gunk inside the saddle thread.

Re-assembly is simply a case of reversing the sequence.

Paul.