Really underground garage
Join Date: Aug 2010
Location: mnts of Va
General lathe ramblings,might help somebody?
Never turned a bowl.But have "turned" some pretty big/heavy column bases.Well over 36" and thats column diam.,mucho larger at base.Anyhowour wimpy lathe would'nt know what to do with it in its wildest dream.So took a que from machineshop world and made a vert. turning cntr.Which consisted of a steel/wood lazy suzan to fit base.Then had a welded up adj circular track(mounted vert) for router.It worked too easy.But that prolly wouldn't work on bowls?Might could have it angled?So,iffin you ever get a ho tub sized bowl.........
I always had acess to some nice old Amurican "Iron" WRT lathes so never needed one here.Then this gotta have job shows up.Litterally went to Sears(20 years ago)one eve. and snagged their pole lathe.Knocked job out,paid for lathe,ect.ect.Its taking up too much realistate now and have a frind with a nice old turning lathe so ours is out the door.
IF,and thats considering all of the above,a lathe proper was needed here.........and this would include some hefty bases or bowls,I'd start with a significant chunk of steel I-Beam.In the 8-10 x 24 and as long as necessary.....prolly 6' long?This would be mounted on some serious skids,8x8 wood sections.Then go find a transmission out of an old truck,mount disc brake setup on outboard end or tailshaft.Then find an appropriate chuck.
Concrete is a wonderful thing.We've added in the last cpl years,several retrofit conc "chunks",precasted to fit several machine bases.It has worked just ok in the damping part.These are just bolted to exst. sheetmetal.Always thought if they were suspended on springs,as low as possible that it might be worth the effort?We've done some pretty gauldang impressive custom cast work with conc.Multi faceted,complex shapes.........So following is just some practical advice/info.
Stress risers really are a factor in conc world.No likey sharp corners.At the very least on iside corners of forms(this results in an outside corner on your cast)add a 45* chamfer pc.It really softens these subsequent outside corners.very worth the effort.We've even gone so far as to use cove mould.Work on trying to see where the conc. is in compression vs tension......where is the potential crack originating from?Radius that spot to move stresses further away.Another way you can approach it is with models.........uh and not computer models.Simply shoot up a real quick scale model,fill it with sackrete and then smack the ch*t out of it with a sledge hammer.Takes only a few minutes to build and pour,might save a little conc. this way down the rd.
You can strengthen key areas of your cast by running threaded rod in as rebar and using big honkin steel plates as wshrs with attendant nuts on outside,usually near tension side.These can also be utilized to hold form together.Gotta go........glues dry,BW
Last edited by BWSmith; 09-15-2010 at 08:34 AM.