My Table traverse for Chinese mill.

[BaronJ]

Hi Guys,

Not too much to report today.



I've opened up the hole in the plastic plate and used the dummy mandrel to support it through the aluminium mounting plate. This is fastened to the mill bed end with the leadscrew spindle coming through. The tumbler operating lever is secured into an aluminium block secured into the plastic plate just behind the two black gears. The operating lever is 6 mm diameter with an M5 threaded end. This is screwed into the aluminium block.



The plastic block is intended to ride on the boss extending from the mill table end and is prevented from coming off by the large flat head screw to the left in the first picture and the bridge with the control lever running through it on the right. The bridge is 13 mm high and 6 mm thick held by two M4 countersunk screws from the rear. The aluminium block can just be seen underneath the two gears. Its secured by heating it and pressing it into a machined slot in the plastic plate. The plastic is too soft to provide a good threaded hole securing the control lever



The is a close up picture of the large flat headed screw that I made to prevent the plastic block from slipping off the mill table boss. The screwdriver slot was made by hacksawing a slot across it. The mark at one end is where I slipped a little when sawing it. The holding thread is M6 with a nut and washer behind the mounting plate.




These last two pictures are just general views of the assembly.

I intend to cut teeth into the bridge so that I can make a dog clutch to prevent the tumbler from being pushed out of mesh.

More to come:
Comments welcome !
Thanks for looking.

 

[BaronJ]

Hi Guys,

I got somewhat further today. I've got the dog clutch finished and tested.





A couple of pictures of the business end of the dog clutch. The whole thing is made from some bits of scrap brass tube and a damaged "N" type socket. The dogs are turned down bits of a 2 mm diameter steel pin that I came across. The brass tube is 1/4" bore. I milled off two flats so that they were a loose fit into the slot in the piece of aluminium bar that the control lever passes through and soldered the collar made from the "N" socket on the end so that it fitted level with the slots. Afterwards I turned things down to size.



Having already found a suitable spring. I then put the control lever and dog into the mill and cross drilled a 1.5 mm hole all the way through. Having removed the control lever I then milled a 3 mm long slot in each side of the dog tube. The slotted fingers are not mine, they were already cut in the bit of tube. I eventually turned them off.



This is when I milled out the three slots to take the dog pins. That last slot looks a little rough. For some reason a corner chipped off the 2.5 mm slot drill. However I used a file to finish off the slot.



This is a trial fit to make sure that the dog clutch fitted into each slot without jamming or riding.



Again a trial fitting of the spring and retaining pin. Just to make sure that everything moved smoothly and didn't jam anywhere. The retaining pin is a filed down bit of a used pop rivet shaft. Its a nice fit into the 1.5 mm hole and retains the spring exactly. It won't fall out if the spring pressure is removed.
The green pen marks are what I used to locate where I needed to put the control lever for each of the dog clutch positions.



This photograph shows all the bits used in construction of the dog clutch and its operating collar. The piece of wood that they are sat on is 40 mm square so that it gives some indication of size. The black operating collar is a short length of Acetyl plastic drilled through 1/4" with a hand turned finger grip near one end. The other end was turned down to match the turned brass dog support at the other end. The wires are 1 mm diameter spring steel. I heated the end to red heat and pressed then into the Acetyl rod. The other end was heated to red heat and bent through 90 degrees with 2.5 mm long legs on them. You can see the 1 mm holes drilled into the brass dog support collar where they fit into.



This is the assembled clutch. The wires hook into the holes and allow the dogs to be pulled back in order to clear the notches and allow the tumbler plate to be moved up or down.





This is a couple of views of the finished assembly complete with the end cap. I just used a little super glue to secure it. It really needs to have been about a millimetre longer or drilled in the end with a fastening screw.

Its just a matter of putting it all together now and making the speed controller.
For the time being I'm just using the variable voltage power supply to control the speed. But that will be another thread.

All in all this has been an interesting exercise in what can be done with bits and pieces salvaged from various bits of scrap. If I had to do this again I would have stuck with the original design but used larger gears to get the higher traverse speed.

Thanks for looking.