Running a D.I. along a rod wont do .
You need to consider the rod may be chucked crooked or lose .
Use a D.T.I. and tighten a VERY round rod such as a old obsolete cheap printer may have . My surplus rod cost $USD 1 and was +/- 3 tenths !
Clock the rod close to head , then center the DTI face so rotating the rod makes equal excursions .... I.E. +.007" and -.007" Now carriage Right about 4 to 6 inches and rotate rod a turn and notice if its excursion is equal . if it is +.009 and -.009" the head is true on a plane with bed
The part of the rod you're using is only the place where DTI indicates zero center , which you find by splitting the difference ( -.009 and
+.009" ) . This part establishes a plain thru the head , as long as there's no play in the head bearings nor play in chuck , it is accurate . +.009 and -.007 means head is pointing high .Now repeat along the side of the bar to read if its cutting a taper .
Test the carriage slides on V ways . Junk Chineese 7 by 10 in USA , is notorious for having NO significant contact Carriage to V ways ! Use a microscope to see the lines you scratch in the slides with sandpaper to do a quick job of bedding in the slides . Unless you are rich and can simply pay a shop to true it !
Scrapping "straight down" means you must "see" how much material you must remove , before you start .
Next true the cross slide "ways" on the carriage . If these flats are not perfect , true them ( but clock the angle to the flats first to double check if the angles are same all over . Use a dowel pin and micrometer . If flats are nt true enuf to trust the flats against the dowel pin , you must guess how to scrape straight down !
You must draw a freehand diagram showing an exagerated condition of misallignment , to "see" what you must do . And rotate these angles in your mind . Text is poor method of conveying this to you .
My Harbor Fright junk chineese lathe 7 by 10" has far and near block slides with 3 screws each . To adjust , i shimmed .017" and blocks kissed the bed under ways . Next is adjust the outside 2 screws in each block slide to take up the slack . works well . The far Right screw adds a home made handle to lock carriage . I'll try to put R-8 collets in the thru hole , but i still lack the bearing info to calc how much lathe spindle is to be increased ! I dont want it too thin wall . 80206 bearings , but WWW has no info on these .
Wonder what I.D. is ?
I forgot , this is read in UK , well , we have no taxes on Chineese imports so they are very low cost and most agravatingly miss fit . But it is a challenge to try to make it do productive work .
$US 19 for a car polisher . I have 4 , ill buy 10 more ! I can see a way to create a hand held var speed 5/8" drill motor with the motor sideways rather than the common straight on type .
I like to invent , weld steel and design electronics stuff .
SU carburretter .... 30 years ago i got ideas from it . There is a simple way to carb a car that beat fuel injection . No need for a constant velocity piston like the SU . I use a simple plate that drops into the carb body and acts like a throttle blade , but it simply tilts . When closed , it exposes the high speed idle air to only one place . This hole in side , dumps some fuel in to keep engine alive , but this hole goes to another hole that if you put your finger over it , it will allow vacum to reach the other hole and then to the main venturi and fuel will be sucked out . Remove finger , engine dies .
This is what all attempts MISSED , they had too much air bypass away from that 'idle" mixture hole , and they had only a crude , adjustable screw to adjust idle . Mine is controlled by temp , RPM etc , thus the idle is always pecfect . Next big mistake they ALL made was to have a venturi that sucks fuel . Mine has 2 , one is the one described above , it has a 2nd venturi that does only AIR !! Now the controller can do ANYTHING to the mixture, its not limited .
Accellerating , the 2nd hole is closed to allow no excess air in . the first hole is richened easily by the fuel control that uses the same hole to deliver as the IDLE mixture ! Why not ? its always the closest to the main venturi effect ! It always has the fastest air flow , unlike the common throttle blade which loses air around both edges , then tries to deliver fast air past a small venturi above the throttle Blade . This was the big mistake , a venturi above the blade ! It requires another variable bypass past the venturi ! You cant do that !
Mine nix's that , by always putting ALL the air closest to the fuel hole , so faster air will pull more fuel out . Thus there is NO accelerator pump , no power valves , only a fuel controller that can position the throttles anywhere it needs to . When decellarating , it open the air only blade so engine has no "vacumn" , makes gas economy better and driving is easier . Your foot can no longer force this carb to open too much , as in the "modern" elect fuel injection !! ha ha ... Fuel controller knows its in nuetral , so fuel is not enrichened as much as if it's in a gear .
The RPM's rocket up in milisecounds something that not needed when gearbox is engaged ....
Inventing , improving is to feel alive , a human being ..... .