I think I bought these inexpensive T-handle Allen wrenches more than 25 years ago. Over time the some of the plastic handles developed fine fractures near where the hex wrench and handle join. I decided to try repairing the fractured plastic handles with stainless steel ferrules and these will also improve the strength of the handles. You can see the fracture line in the photo showing the handle diameter being machined on the lathe.
Rather than first drill and then bore the stainless steel T-303 rod, I decided to first machine the plastic handles to a diameter 0.002" larger than the next nearest fractional drill. This allows direct drilling the ferrule hole diameter to fit for a press fit and avoid any tedious boring on the lathe. Sometimes the drills can slightly over-size the hole IDs so the 0.002" larger plastic handle diameter usually ends up with a 0.001" difference in diameters and an easy press fit. The ferrules were press fit using an arbor 1 ton press.
Last edited by Paul Jones; 02-20-2016 at 11:05 PM.
Machining stainless steel on my 12" geared-head lathe is a lot easier than doing it on my 7" mini lathe but I use both machines for stainless steel machining.
It really depends on the grade of stainless steel where some machine much better. Annealed stainless 304 (Machinability = 45%) is by far more difficult to machine but good if doing welding. I prefer using T303 annealed stainless (Machinability = 78%) for machining if no welding is required and it is stronger (but not as strong as T316).
When machining on the lathe, I find the T303 stainless machines to a perfect finish with Kennametal inserts of the KC9110, KC730 and KT315 grades of carbide (and all available in packages of 5 or 10 through Buy It Now on eBay) . I usually run the lathe at 500 or 800 RPM with carbide tools for under 2" diameter stainless steel but could go at higher RPMs. I use my #8 position at 0.0011" on the quick change gear box and then use the E through B settings that doubles the feed rates for each gear change. You know the best RPMs by listening and looking. I usually use Tap Magic Xtra-Thick heavy-duty cutting fluid as my cutting oil for stainless and use it very sparingly (it doesn't take much to improve the finish). I also use M42 Super High Speed Steel with 3/8" and 1/2" square cross sections. M42 super high speed steel is a premium cobalt high speed steel designed for high hardness and superior hot hardness that works particularly well with stainless steel. The M42 is great for the mini lathe and my Unimat SL lathe over carbide inserts when limited by the horsepower of the motor when the diameter of the part is large for the lathe swing. Likewise the new Drill Hog drill products work well for stainless steels because of their superior hot hardness.
Thanks for asking and I hope this helps.
Last edited by Paul Jones; 02-22-2016 at 09:51 AM.
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