Thread: taper problem

Mike, It does work. You could try shimming it to see if the taper is corrected.You can chuck a length of 25mm round bar wasted in the center of about 100 to 150mm length for 50mm, the two sections at either end separated by the waste should be turned without tailstock support and measured for diameter. The shimming operations should try to get these two diameters the same. You don't want the tailstock involved as it probably won't be on center. You want to shim the lathe mounting pads or feet. Unlevelled lathes can give the same problem, bed twist that is.

Originally Posted by morrisman

My Sheraton model AR: I've noticed turns about a 001 to 002 taper when I am turning anything in it ...e.g., along a 50mm length . Apparently it's possible to correct this by shims under the corner of the bed ..the shims twist the bed enough to correct the taper .

Has anyone done this with success ?

Mike

OK thanks swarfy

I was reading Harold Halls web page and he mentioned using shims to fix the problem.

BTW Mr. forum moderator, a Sheraton 9" lathe is a South Bend 9" clone as is a Hercus . Both were made here under license I presume. Seems a somewhat pedantic thing to go moving a post when the difference in the three lathes is only minor

Yes, you may need to try a variety of thicknesses to get it right.

Originally Posted by morrisman

OK thanks swarfy

I was reading Harold Halls web page and he mentioned using shims to fix the problem.

BTW Mr. forum moderator, a Sheraton 9" lathe is a South Bend 9" clone as is a Hercus . Both were made here under license I presume. Seems a somewhat pedantic thing to go moving a post when the difference in the three lathes is only minor

morrisman, pedantic? Could I suggest that if you have a probem with what the mods do, that you take the issue up via a PM or by clicking the report a post icon?

At the end of the day, the admin and moderators reserve the right to delete, edit or move any thread or post, as clearly pointed out in the forum rules.

The issue you have raised, albeit rather impolitely, has been referred to the Admins and Mods and I'm sure they will give it some consideration.

Could I refer you to the heading of the Hercus Area? It clearly states

A place for Hercus Owners to discuss/register/buy/sell all things to do with Hercus Lathes

You don't have to machine a bar and "waist" it to set the lathe bed. If you find that the job is tapered, simply chuck a length of solid bar in the chuck and place a dial indicator at the end. Set the D/I so the stylus is located on center and then tighten the bolts in the lathe "feet". Check the D/I for movement. If there is no movement, add a shim to the appropriate "foot", tighten the bolt and check the D/I again. If the D/I has moved in the right direction and moved the amount required then your done. Turn a piece of stock and check it for taper. You may find that the source of your taper may be from the tool wearing away. It doesn't have to wear much to produce an error that is readily seen. This is why the test piece is "waisted" to prevent wear on the tool. Check it with a solid bar as described first. An error can also be found as a taper that is the result of leaning on the lathe while machining is taking place. Sounds crazy but this actually does happen. Leaning on the lathe will actually bend the bed if the lathe is not supported correctly.

Originally Posted by Kody

You don't have to machine a bar and "waist" it to set the lathe bed. If you find that the job is tapered, simply chuck a length of solid bar in the chuck and place a dial indicator at the end. Set the D/I so the stylus is located on center and then tighten the bolts in the lathe "feet". Check the D/I for movement. If there is no movement, add a shim to the appropriate "foot", tighten the bolt and check the D/I again. If the D/I has moved in the right direction and moved the amount required then your done. Turn a piece of stock and check it for taper. You may find that the source of your taper may be from the tool wearing away. It doesn't have to wear much to produce an error that is readily seen. This is why the test piece is "waisted" to prevent wear on the tool. Check it with a solid bar as described first. An error can also be found as a taper that is the result of leaning on the lathe while machining is taking place. Sounds crazy but this actually does happen. Leaning on the lathe will actually bend the bed if the lathe is not supported correctly.

Ok good advice. . I know the concrete floor isn't level , it slopes a few degrees in both directions , lengthwise and crosswise as I've checked it with a spirit level . I've also noticed the taper when boring as well as outside turning. Isn't cast iron wonderful stuff . It is malleable to some degree .

Mike

Originally Posted by morrisman

Ok good advice. . I know the concrete floor isn't level , it slopes a few degrees in both directions , lengthwise and crosswise as I've checked it with a spirit level . I've also noticed the taper when boring as well as outside turning. Isn't cast iron wonderful stuff . It is malleable to some degree .

Mike

From my experience, even well made and level concrete floors will twist a lathe if its just put on the floor without jacking or adjustment screws. One foot only needs to be out by a few thou for it to show up on your finished work...

Cheers,

Simon