Model Hit&Miss Engine cylinder bore

[Jerry B]

I Have A Metal Lathe 9x19,I Am Having Problems When I Bore A Cylander,I Have Did Every Thing I Know, The Bore Is Tappered Can You Help Me,Jerry B

[gbritnell]

Jerry, the first thing that I would ask is what brand of lathe do you have? The next question is what condition is it in? Generally if your machine is cutting a taper and is in good condition it's because the headstock is not lined up with the ways. Although there isn't an adjustment for this (that I know of) you can still check it to see. Take a piece of round stock and chuck it up and true it (in a four jaw), or as close as your 3 jaw will hold it. Now put a dial indicator in your tool holder and try and get the tip as close to the center of the shaft as possible. Now move your carriage back and forth and see if you get any taper reading. If you do then the headstock could be out one of two ways. It could be turned from the axis of the ways or it could be that it's not parallel with the ways. (not in the same line up and down). What diameter are you boring and how bad is the taper? Let me know when you find out something and we'll go from there.
gbritnell

[Ted Utess]

Good Morning Jerry---I also have a 9x20 lathe that I currently am making model engines with. I am self-taught. I also am having the trouble of making cylinders that are TAPERED. I SURE would be interested in any reply you receice. I now use a reamer and then hone to get the taper out. It is a tediuos , time consuming job. I will watch with interest. Ted

[Buddy Harley]

Assuming that the lathe is in good working order and you have removed the backlash as you make cuts. My guess would be that the problem is with the cutter. The boring bar should be a large as possable, the radius at the cutter tip should be as small as possable and as square to the bore axis as possable.
When heavy cuts are made the tool can deflect away from the cut as it proceeds down the bore. There can be several reasons for this, such as tool radius and rigidity of the boring bar, also feed rate can can have an effect. You may also be getting chip build up between the bore wall and the boring bar.

Yours is one of those problems that probably could be solved in a minute if I was standing there, but difficult to solve in words. At this point, based on the information given, I would look to the cutter itself.

Start looking for the problem at the cutter tip and work your way out to the handwheel if necessary. Of course, it may be that you aren't holding your mouth just right! LOL

[Buddy Harley]

Just a note: Problems with the headstock alignment, carrage or tailstock will be revealed in ID and OD cuts. If your OD cuts are good then the machine is probably good as well, for ID cuts. Throw a chunk of round stock (fairly stout)
in the chuck make a pass or two and check the dia. in several places. If the OD reamins consistent then the problem is probably not in the machine.

[Jerry B]

I Have A Grizzly Lathe , I Took It A Part Looking At Every Thing,Just About Give Up ,But Looking Closer I Find Some Bolds On The Headstock They Was Ajustable, Thank You For The Help,Jerry B

[gbritnell]

I'm assuming that the bottom of the headstock is machined flat and parallel with the axis of the spindle. (one can only hope) so the adjusting bolts would then be to line the axis of the spindle with the centerline of the lathe. Meaning that it would line up with the center of the tailstock. If in fact that's what those bolts are for then put a piece of stock in the spindle and run a dial indicator along the side of it until you get it aligned with the ways.
gbritnell

[Scott L A-1 Machining]

A lathe that size needs to be level!! You are probably out of plum and its twisting the bed. Level it up and try again.

[KeithW]

I've got an 11" Sheldon. I level it about once a year. It's amazing how much a big piece of cast iron will flex. Another handy little item is a piece of 1" swamp cooler shaft. Hollow so it's not too heavy. Centerless ground, nice and straight. Mount it between centers or in a chuck. Mound your dial indicator in the tool holder. By spinning the chuck by hand and moving the tool holder around you can find lots of usefull things. On mine the head stock and tail stock were not the same height. That makes for some interesting shapes .

keithw