|Typical Lathe Rebuild Procedure
Here is a 26" LeBlond gap bed lathe as it appeared prior to the rebuilding process. The lathe will be tested under power to verify the proper operation of all functions. Notes will be made of any problems which need to be corrected.
This is a rear view of the same machine.
The lathe will be totally disassembled into it's major components
which will then be cleaned and inspected for any additional work which may be required.
At this point the customer will be informed of unforeseen problems and the costs associated with correcting them.
The various parts then go to our painting department
if the customer has chosen the painting option. There they are sandblasted to bare metal
to insure the strongest bond between the base metal and the finishing materials.
Headstocks, gearboxes and aprons are hand stripped to prevent sandblast dust from getting
into the bearings. The parts are then sprayed with pure polyester resin to provide the
hardest sub-base for the paint.
These pictures do not show the polyester system we are now using, but rather the castings are filled with Cuz, an autobody filler containing talc which is not as hard as the pure polyester resin. Once the polyester resin is sprayed on the castings it is sanded down and hollow areas are then filled with polyester glazing compound. The parts are then primed with a two-part epoxy paint and sanded with progressively finer grits of sandpaper.
After finish sanding with 400 grit sandpaper the parts are then
moved into the paint booth and finish painted to a high gloss with a two-part epoxy paint.
To the right the lathe bed ways are being ground on our 36" x 36" x 12' way grinder.
After way grinding or hand scraping the bodywork is touched up and
finished painted. Parts are then returned to the disassembly area where the lathe is
To the right you see the set-up for hand scraping a lathe saddle to the lathe bed. Prior to this operation we mill material off the bottom of the saddle and bond Micarda or Turcite to the saddle bottom to bring it slightly above where it was when it came from the factory. Hand scraping will bring it down to its original height and provide for proper alignment of the feed shafts and lead screw where they pass through the apron.
|On the left you see the actual hand scraping process. This involves coating the lathe bed with a thin layer of Prussian blue. The saddle is then slid back and forth along the lathe bed and blue is transferred to the bottom of the saddle. The blue indicates high spots where the saddle is contacting the bed. These spots are scraped away and the procedure is repeated many times until an even pattern of blue shows on the saddle bottom. This verifies proper bearing contact.
Once the saddle is scraped to mate
with the bed its top is ground perpendicular to the axis of the lathe bed on our way
grinder. The process then continues by hand scraping the bottom of the cross slide to mate
with the top of the saddle. The compound rest is done in a similar manner. Assembly of the
machine is carried on simultaneously with the way grinding , scraping, machining of parts,
The finished product is pictured to the left
and another one above. The machine is again tested under power for proper operation. A
test cut is taken on a piece of stock in a 3-jaw chuck. The lathe must hold .0001 per inch
on a 4" long cut. Additionally, it must give a good surface finish which is largely
controlled by the condition of the spindle bearings. If the finish is poor it may be
necessary to replace the spindle bearings which is an additional expenditure.