Thanks Ixb1 !! I will try do it .
Minh-Tanh, since you never build the ringless combustion engine.
And other newbeginners too..
Follow my instruction how to lap the cylinder and piston:
Lets take a look at a typical lapping job - that of producing a fine finished bore and piston for an IC engine. In fact, piston and bore are both lapped in separate operations (NOT both together). All of these operations will be carried out in the lathe (and I need hardly mention the importance of keeping lapping compounds off the machine, particularly the chuck and slideways). For the bore an expanding lap is ideal, and this should be some 3-4 times the total length of the bore. The first grade of abrasive would be mixed with light machine oil (10W or lighter) and liberally coated on the inside of the workpiece. Similarly, the slurry would be added to the outside (and inside assuming it is of the ventilated type) of the lap. The lathe would be started at about 300rpm (for a nominal 1" bore) and the lap passed rapidly through the bore, keeping it moving back and forth without it coming out the bore. How to hold the lap? well, perhaps the best way is with a 'floating' tailstock holder, and failing this holding with the hand is a method as good as any. Be careful when holding the lap by hand as it's possible it may jam, hold it lightly and expect the unexpected. Remember also that unless the lap is maintained dead parallel with the bore (an almost impossible task) it will tend to bell-mouth the bore a little - hence the reason for making the work a little longer than finished size and trimming to length later. When the inside of the bore has achieved an all-over grey appearance, with the fine scratches appearing even and criss-crossing both ways, and with no evidence of any deeper scratches (as might be left by the reamer) it's time to move onto the next finer grade. The work will have to be removed from the chuck to clean it properly, and this should be done with clean paraffin oil followed by hot soapy water. The same procedure applies to the lap and all traces of the abrasive must be removed. The process continues until you reach the 'flour' grade of abrasive by which time the finish on the workpiece should be very fine indeed. A final polished finish, should this be deemed necessary, can be achieved using metal polish (diluted Autosol, or some liquid chrome cleaner). Surface muct be smoth and crosshatched dull grey before last lapping with piston into cylinder with chrome polishing paste. The lap should be a separate 'finishing' lap so there is no chance of contamination with the coarser grades of abrasive which might be embedded in the main lap. The piston is treated in a similar way except of course the lap is female. Work will continue with the coarse abrasive until (using the un-trimmed bore as a gauge) the piston will not *quite* enter the bore. At this stage finer grade abrasives are used and work continues until the piston will just enter the bore tightly. At this stage, it is usual to finish mating the two parts by using metal polish and briefly using the piston to lap the bore directly. Great care needs be taken but this method ensures that the fit is good for the entire length of the bore.
To create tapered cylinder: Piston create tapered piston when the piston is lapped into the cylinder at final stage.
To test fit is correct: Dry piston/cylinder ---> tight to enter into cylinder. Oiled piston/ cylinder ---> The piston is loose fit in BDC cylinder and tight in TDC.
In the drawings where cylinder material is made of steel also use high tensile steel as you can find in the old driveshaft from the car to example front drive wheel car where drive shaft is hard enough against abration. To machine the steel from drive shaft, the steel must be annealed first. Uneccesary to harden the steel again after the work is ended since the steel is hard enough due it's an alloy steel.
Cast iron can you use from old cam shaft from car engine, between cam is cast iron not hardened who are good as piston material.
It's my experience since i has builded some combustion engines such as model diesel engine and glowplug engine.
