Metal Lathe -- Concave Radius Turning Attachment

 Small radius curves, like the Wheel thimbles and small pulleys are turned using a form tool; a chisel ground to the desired profile. But with metals and small lathes this becomes impractical from a tool pressure perspective at about 0.10" to 0.25", depending on the metal, and about 0.50" for plastics. You can turn larger radius curves in a few other ways:

• Freehand, with a special chisel, like on a wood lathe. The chisels are small and it is very slow on metals. It is also difficult to make repeatable parts.
• Remove most of the material with standard tooling, then smooth it up with a large rat tail file. Tricky.

Or you can use a radius attachment. However, most are made for convex curves (which are much easier to free hand and/or make with conventional tooling), and those that will turn convex won't do deep curves, such as a low friction ring or wheel thimble. So I made my own. 

It covers 11/16-inch to 2-inch and up to 1-inch past the pivot deep. Enough for my needs. 

Somehow it reminds me of one of the robots on the old MST 3000.

It looks dead simple, but it must be very rigid, very compact, and quite precise, so it took a good many steps:

• Careful band saw work
• Milling a slot
• Facing and turning a rod down 
• Concentric boring
  
• Threading several times
• A square hole
• Indexed milling of the hex at the top 
• Fitting the bearing surfaces so that it turns smoothly but with no flex
• Parkerizing of some parts for rust prevention
• Grinding the custom chisel
  

It replaces the tool post and is rotated in use by a 6-point socket with a T-handle from above (see below). The chisel is symmetrical to cut both ways. It uses tiny 1/4-inch blank pieces.

 

I made the 1/2-inch drive Tee handle from #4 rebar with some welding and careful grinding. Why waste good rod? It fits perfectly and is used with other setups on the same lathe.

So Far I'm Down (if I had not moved out of stocks) About $450,000 Since Inugeration Day. Wow. That Stings.

 Yeah, I hate politics, but some things need said.

 A trained monkey could handled the economy better. Just hands off. Oh, and I think it's pretty funny that Trump says the last tariff deal with Canada was terrible ... when he was the one that signed it (CUSMA 2018--Google it). Of course, we should know by now he has no use for actual facts, even those he should remember. Did he forget, or was the truth simply not the message he wanted to sell?

 Weird. It makes me feel weird, trying to say a few bucks here and there, when it is evaporating at that rate. But controlling your burn rate never hurts. I spent the morning in the shop welding up some parts for a recycled anchor chain fence. It was relaxing. I'm trying to think of good uses for retired anchor chain for an article, but I don't think this counts. Maybe.

Thankfully, we bought two new cars (both Japanese) a few years ago, so we will have no need to check prices for at least 15 years. We don't drive that much these days. No commute is nice.

 ----

Do I think the tariffs will help in the long run? I think there are reasons not.

• Industry will NOT change production systems for a policy that will very likely change.
• Trump Is unpredictable. He considers it one of his strengths in negotiations, and for his style, I get what he believes. But big business needs predictability. 
• I've never believed in isolation as a cure for anything. Step up and fix the problem. Become competitive at something. Play to your strength.

The value of empire (the US has been leading a non-imperial empire sine WWII--we inherited it from the British) is free trade and worldwide security. We're blowing that. So much for a making America great. We are weakening it. I'm ashamed.

 ---

 Note that these were all conservative arguments. Apparently they are no longer Republican values. And that is really weird.

I've gone kind of shop-crazy this winter

  

Just a few of the projects:

Lathe-related

·         Shim or re-fit all lathe control handles. They were sloppy.

·         Cross slide lock (homemade). Required for facing. Or you can keep one hand on the main crank.

·         New cross slide hand wheel (homemade). The original was too small and did not have a bearing.

·         Tailstock lapped to ways. Bad alignment.

·         Center finding gauge (homemade).

·         Compact depth gauge (homemade).

·         Bump center (homemade). It’s a thing made from ball bearings to help align work in chuck.

·         Milling 90 degree plate (homemade) that bolts direct to compound.  Also hold-down bars and studs.

·         Milling 90 degree plate that fits vertical slide (below) (homemade).  Additional hold-down bars and studs. Toe clamps from 2-inch schd 40 pipe (homemade).

·         Marking/bolting 90 degree plate (homemade).

·         Vertical slide.

·         Vice for vertical slide.

·         Fitted milling vice. Handle needed re-machined. Mounting holes.

·         Keyway mod in lathe tailstock. Stock keyway was omitted at factory due to casting error.

·         Mods to drill press milling vice.

o   Handles and gibs.

o   Wider jaws with 6 screws and pressure plate (homemade).

·         Three machinist’s jacks (homemade), mostly for use with the drill press and lathe.

·         Built shallow drawer under work bench for mics etc.

·         Built drawer under lathe (right side, for lathe accessories), with lift-out tray. More trays lower.

·         Built drawer under lathe (left side), for milling accessories) with lift-out tray. More trays lower.

·         Several other drawers to organize drills and boat fittings.

·         Organizer behind chip guard.

·         Ways cover (attached with aluminum strip embedded with rare earth magnets).

·         Shallow, removable chip tray under chuck-half.

·         Face plates (2). Fitted from older lathe.

·         Hand turning rest (wood or metal) for metal lathe (homemade).

·         Hand turning chisels for metal lathe (2) (homemade) .

·         Chuck spider (homemade) (accessory to chuck short stuff).

·         Parting tool holder using hacksaw blades (homemade). Very good for brass, not steel. Got 1.5 mm parting tool from Buyaholic.

·         Manual die holders (1.5- and 2-inch) (homemade). Not lathe mounted, but can start 1-, 1.5-, and 2-inch on lathe using chuck to keep it straight. Removable handles.

·         Die pusher with aligning fit (homemade).

·         Tap follower. From great uncle.

·         Die grinder tool rest mount (homemade). Includes short hose extension and air control valve.

·         Drip coolant at tool post. Mounts with magnet. Probably over kill. (Also a bad idea—can’t see what you are doing, mess in mechanism, corrosion. Better with a spray bottle or squeeze bottle.)

·         Indexing for lathe head (homemade) (24 increments). Great for making hex and square heads.

·         Precision filing guide (homemade). Can be used for end stop or depth control.

·         Larger dog for turning between centers (homemade). (I still have my old 1975 small home-made dog!)

·         Assorted custom handles for hex sockets and square drives (homemade) (chuck and tool rest).

·         Radius turning attachment. 0.625” to 1.5” (homemade). For wide pulleys, such as trailer rollers, genoa leads, and low friction rings. A precision job, requiring milling, turning, threading, and indexed grinding. But not much bigger than my thumb.

Other projects (all homemade using lathe, welder, band saw, drill press, etc.)

·         Bending lever, large stock. Up to ½-inch rebar.

·         Bending rod jig for vice, small stock. Bar stock and up to about 3/8-inch round … maybe.

·         Band saw table and stand. Fence from speed square. Sled from scrap.

·         Improved hold-down tee-nuts for drill press.

·         Tuned up cross slide vice for drill press. Now I can mill on the press, up to ½-inch steel plate with ½-inch end mill.

·         Centers (top and bottom) for drill press table. Good for accurate concentric drilling.

·         Wooden clamp to hold work from spinning.

·         Steel fence for drill press.

·         Drill press clamp (Keats Plate) for round stock center drilling.

·         Drum sander table.

·         Tool handles. Lots, mostly for files.

·         9-inch disk sander stand. 90 degree fence.

·         Cradle for angle grinder (just for spin-down). I’m going to upgrade this to 12-inch when I run out of 12-inch paper.

·         Scribe/awl from triangular file. Full length tang. Very hard.

·         Light bracket for drill press. Old eyes appreciate this.

·         Switched outlets to control air compressor and shop air filter.

·         HEPA-rated show air filter from 5 MERV 13 20x20 filters and a 20x20 box fan. Allows welding indoors. Every shop should have one. Also great for remodeling mess.

·         Soft jaws with magnets (both vices) . Aluminum and wood.

·         Parallels with magnets. Parallel edge clamps for non-magnetic parallels.

·         V-blocks. Many sizes. Wood, steel, and aluminum.

·         Table saw sled and mini-rip fence. More accurate and less dust.

·         Zero clearance insert for table saw. Less dust.

·         Two hole deburing tools; one from a counter sink and the other from a ½-drill with the clearance angle reduced (plus handles).

·         Edge deburing tool from a rusted triangular file plus a handle. My favorite.

·         Up-side-down holders for 5-minute and G-Flex epoxy.

·         Cradle for angle grinder (for spin-down).

·         90 degree and variable angle brace/clamp for welding

·         Mini-chipping hammer from rebar. My new favorite.

 

And I'm sure there were more. And I'm reaping the benefits, as I now have just the tool or jig I need to do things more quickly and with better precision. More practice helps too. 

The cost? Barely anything, since most were homemade. With welding, milling, and a lathe, you can make most things.