Friday, January 14, 2011

Monty Remon's Taig Lathe Mods, Part 5

“We all suffer from trying to clamp the compound slide securely, so much force your fingers turn red and the little annular dovetail arrangement can't hack it and then the air turns blue! I fitted additional stops it the 'T' slots as I had seen on your (Nick) site and was contemplating trying the additional clamping slot in the body I'd seen there too. Well, I laid all the compound slide components out gave them a severe looking at and even with a cup of tea the solution (groan) never came, only a general direction. I had a piece of 1/2"x2"x3" alloy for the body, ok, for a 2" diam., annular dovetail! Next. A look at the end section revealed a few problems, the Taig body measured 0.435" thick, if 0.125" is taken off for the dovetail clamping there is only .060" metal remaining, to copy the 'U' channel arrangement only 30 thou left, not very stiff! However drilling down the middle then milling out a slot to house the split nut will retain rigidity. Great. I decided on drilling the 1/4" hole 1st., I attacked it from both ends, and met it the middle with no binding. The split nut housing presented no problems, just mill and drill.
Because as much metal as possible was req'd to chuck the work piece securely, turning down the the base to make a 2" diam., cylinder that is 0.130" deep, then under cutting at 45 degs was the next job, it was as entertaining as always mounting the work in the 4JC.”


The dovetail milling was next. I slipped a piece of steel rod through the appropriate 1/4" hole in the work piece and clamped down on this giving myself 1/2" clearance for the cutter. This was to be my first attempt at machining a dovetail in anger but my dovetail cutter was too small so I had to do it in stages, the profile is not correct but at least at least it turned out be an accurate cock-up that proves I am on the right track. (If I take the nose of one of my gib plates then I have good contact.)


“Next job, for the two brass clamps I used 1/8"x3/4" but would recommend that 1/8"x 1" is used so that the locating c/s screws can be positioned clear of the turning. Production turned out to be easy. The brass plates were bolted on to the face of a piece of 1/2"x2"x3" and set up in the 4JC. I turned the plates to get 1 3/4" diam., recess then switched to a 45 deg., cut, removed one piece and tried the fit - close but not enough. Bolted back in place, a deeper cut was taken then the same piece removed and tried for fit again, close enough! The clamps were removed and the holes c/sunk on the back side, deep enough to ensure that they are recessed. The clamping assy., must have less depth than the circular seating to make sure that the base is clamped to the xslide surface. Tickle with a file if req'd.
The only short coming with the system at the moment is easy location and locking on the top slide, readers may come up with a neat solution before I do. At the moment I can only locate and lock at either end of the xslide. The system req'd I drill and tap either end of the top slide between the 'T' slots and use a bolt and washer to apply the clamping force on the loose clamp. To set up the clamps are located in the 'T' slots and the screw/ washer assy., set a 1/4 turn out, the end clamp locked against this. The compound slide is seated against this end clamp and the other clamp seated against the slide and locked, the end clamp is then slackened off a touch the compound slide set to the req'd angle and locked using the end screw.”


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