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Several small 9x20 mods

Saddle / carriage lock - The original clamp remains unmodified.  I took a piece of 5/8 rod and reproduced the SHCS.  This screw was always full of chips and half the time under the compound making it hard to access.  I left the new screw attached to a 1/2" long piece of the 5/8 rod.  Threaded the original metric threads to match the clamp.  If you don't have a metric die than 1/4 x 20 will do but you will need to make a new clamp.  When the new bolt was complete I installed it on the saddle.  Hand tightened it and marked the locked position.  Removed the bolt, drill and tap a hole on the mark for a small handle / bar.   

saddle lock parts


This pic shows the un-locked position.   In this position the handle will sometimes catch the center gib adjustment screw.  This keeps me from moving the carriage towards me.  Not usually a problem while the machine is in operation.  Only during setup.  I may add some kind of stop to keep the handle away from the screw.  To lock simply swing the handle towards the operator.  No tools and a second to do instead of finding that allen key that is always right where I left it.  Where ever that was.  :)


Gib screws and saddle lock


Gib Screw replacement -   This pic also shows some new gib adjustment screws.  This mod is so simple but makes a huge difference in how the machine can perform.  You will need 8-32 x 3/4 for the compound and 8-32 x 1.25 for the cross slide.  You will also need an 8-32 tap.  I suggest a good USA brand.   They are not expensive and you will have to grind down the shank to tap the deep holes in the cross slide.  I did no drilling.  Simply remove the garbage set screws and the pins.  Tap the existing hole.  The cast iron is soft its an easy job.  When done flush the holes well to remove all the dust.  I do have jam nuts installed on the screws. they are hand tight and haven't moved.  I also checked the condition of the gibs while I had everything apart.  My cross slide was not bad.  The compound was horrible.  It was bent twisted and no where near flat.  If I had a piece of brass I would have replaced.  Instead I spent considerable time making it flat and lapping both gibs.  This also makes a big difference.  The flat gibs and larger screws make adjustments easier.  


Spider -   At least I think its called a spider.  Gunsmithing is where they are used??  2.25" od x 2" long scrap aluminum casting.  1" center hole.  Then bore one end to duplicate the nut that is mounted on the spindle.  The pic shows 2 set screws.  The one closest to the pulley came from the original nut.  This nut is used to control preload on the spindle bearings.  The set screw keeps the nut from spinning loose.  There is a small brass plug under this set screw.  You MUST use this plug or risk damaging the threads on the spindle.  The other set screw is one of 4 spaced evenly around the spider.  1/4 - 20 set screws act like the jaws of a 4 jaw chuck to center and secure stock.  The 2 tapped holes on the end are for the hand crank.


Spindle hand crank - The stock motor and speed selection is simply too fast for some operations.  Threading for one.  It is pretty basic construction.  The bushing and 1/2" shaft are welded to the 1/4" bar for security.  There are bushings in each end of the water pipe 1/2" id x 5/8" od.  I machined a special countersunk washer for the 1/4" x 38" SHCS to sit in.  So far the spider has not come loose. 

Here it is all painted and installed.  Notice the belt tension has been released?  There is NO counterweight on this crank.  Should I turn on the lathe with the crank mounted the lathe and I will be dancing.  I don't like to dance with my tools.  I unplug the lathe before I mount it just in case I have one of those moments of stupidity.  :)  With no tension on the belt the spindle shouldn't move any way but???



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