I am finally getting around to a few jobs on My DSG 1307.


It had two main issues I needed to fix before firing it up.


First was a constant oil leak. This proved to be a simple fix. the DSG has a nice feature where the gear box drain plugs are at the end of a piece of plastic tube. this allows you to put the tube into a bucket to drain without oil going everywhere. this plastic tube had set like a rock and was no longer gripping on the barbed ends. New tube will fix this.


Second and more pressing was a very tight cross feed hand wheel action. On investigation this turned out to be caused by a swollen nut...... The DSG has a back lash elimination system of two opposing nuts. These nuts are made of die cast "pot" metal and one of the nuts had swollen to the point that it was so tight on the cross slide lead screw that I could not wind it off the un worn end of the lead screw. I got it off by using a hack saw to cut down to the major diameter at 3 points 90 degrees from each other. I then used a screwdriver in the saw slot to brake the remainder of the thread. This enable me to remove the nut without damaging the lead screw.


The next job is to make a new nut, so I started to work out what the tread is. I had assumed that because it is an English lathe with all imperial fittings that it would have an imperial screws, although both nuts are clearly stamped with a capital M. A quick check with the calipers indicated that in was metric with a 5mm pitch. The funny thing is that the minor and major diameters of the screw look to be imperial!!! In discussion with BT he asked was it a 29deg or 30deg acme thread form. I had assumed all acme thread were the same. So I mounted the cross slide screw in my new Mitutoyo Optical Comparator and low and behold it is nether...it is 34deg.....While I was at it I checked the pitch witch is dead nuts on 5mm.


Has anyone come across a 34deg Acme thread?


Next step is to grind up a cutting tool.


Cheers


Piers
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