Thread: What did you learn today?

3rd try lucky - Managed to cut 8tpi internal thread - chuffed

Grinding a small internal tool at a perfect 60 degrees by hand can be a right pain and I kept chasing the perfect angle until I only had a tiny stub left

A relatively tiny piece of swarf can jam an 8 tpi thread and make you wonder what you did wrong - was quite surprised

Some tool steels are extremely hard and difficult to grind, others are relatively soft and easy in comparison

Originally Posted by steamingbill

3rd try lucky - Managed to cut 8tpi internal thread - chuffed

Grinding a small internal tool at a perfect 60 degrees by hand can be a right pain and I kept chasing the perfect angle until I only had a tiny stub left

A relatively tiny piece of swarf can jam an 8 tpi thread and make you wonder what you did wrong - was quite surprised

Some tool steels are extremely hard and difficult to grind, others are relatively soft and easy in comparison

Probably Chinese tool steel, had the same problem, took longer to sharpen it, than blunt it.
Kryn

Today I was drilling some 8mm diameter holes about 5mm away from the corners of a 6mm thick piece of Acrylic.
Drilling the first hole just broke the whole corner off so the piece was useless and then I remembered that bit should be pointier for acrylic but didn't really want to waste the drill bit for just four holes.
So then I drilled the holes first in a larger piece of Acrylic then cut it to size - worked a treat.

I think I got lucky - learned that Aldi's cast iron gym weights might be made of reasonably good material. I needed to learn about how cast iron might behave on the lathe and how to hold the plates before attempting the rethread on the Myford plates

Decided to have a practice on some remaindered (4 for $5) Aldi cast iron gym weights.

Didn't encounter any sand or porosity, and came up with a snazzy smooth satiny sort of finish straight off a knife tool - quite different from the mild steel that I'm used to - the swarf looks like pencil sharpenings - very black.

Following various warnings on internet pages I covered the ways with paper towels and alfoil to prevent sand from skin of casting from damaging the ways, didnt see any sand in the cuttings. But the tool did need resharpening after a while.

The smooth finish on the rim was a huge surprise - after one deep pass with a freshly sharpened knife tool 0.1 - 0.125" depending upon whereabouts in the wobble I was cutting.

I read in a Harold Hall book that I could probably do 90% of my work with a knife tool so decided to try.

Looks like you've got some backing plates for big chucks.
Kryn

In the last few weeks I've been working with greasy sawmills, cast iron wood working machinery (restoration), and milling and handling lemon scented gum (lots of tannin), so my hands have been getting blacker and blacker.
I kept remembering what my mum used to say about her dad, who even though he was a blacksmith had soft clean hands and he did this by washing his hands every day with half a lemon. I tried it while not WOW it still did a pretty good job.
The spots where the splinters and cuts are stung a bit but it probably did some disinfecting as well.
You squeeze and rub the oils and juice into the skin and keep rubbing with the inner and outer parts of the lemon for about 5 minutes - longer than you think.
Definitely leave your hands softer afterwards and smelling nice too.

At our Community Shed Bob, a couple of the blokes brew bio diesel from fish and chip oil. One of the byproducts is glycerin, and after further processing with more KOH (I think, but not sure because I haven't actually done it myself) they get a very good hand cleaner. It is as black as Worcestershire sauce, and actually works best I think if you wet your hands with water to thin the glycerin cleaner a bit. Another member says that it works better still with the addition of some fine sand, which makes sense, as it would be similar to sand soap. It readily shifts most muck off your hands, leaving them soft and not cracked like some harsh degreaser type cleaners. I could confirm the details if it is of interest to anybody on the forum.
Rob.

Originally Posted by steamingbill

I think I got lucky - learned that Aldi's cast iron gym weights might be made of reasonably good material. I needed to learn about how cast iron might behave on the lathe and how to hold the plates before attempting the rethread on the Myford plates

Decided to have a practice on some remaindered (4 for $5) Aldi cast iron gym weights.

Didn't encounter any sand or porosity, and came up with a snazzy smooth satiny sort of finish straight off a knife tool - quite different from the mild steel that I'm used to - the swarf looks like pencil sharpenings - very black.

Following various warnings on internet pages I covered the ways with paper towels and alfoil to prevent sand from skin of casting from damaging the ways, didnt see any sand in the cuttings. But the tool did need resharpening after a while.

The smooth finish on the rim was a huge surprise - after one deep pass with a freshly sharpened knife tool 0.1 - 0.125" depending upon whereabouts in the wobble I was cutting.

I read in a Harold Hall book that I could probably do 90% of my work with a knife tool so decided to try.

Thanks SB I have 4 of the same here yet to do when ML7 lathe is back in working order ( I have two electrician's wiring up a reverse switch Thanks NcArcher and Woodnut )

Originally Posted by wheelinround

Thanks SB I have 4 of the same here yet to do when ML7 lathe is back in working order ( I have two electrician's wiring up a reverse switch Thanks NcArcher and Woodnut )

I've seen a few warnings about fine dust from cast iron on various web pages. One person hooked up a vacuum cleaner like a dust extractor and others have complained about having black material when they blow nose on a hankerchief after turning cast iron.

Bill

Originally Posted by steamingbill

having black material when they blow nose on a hankerchief after turning cast iron.

Any amount of time with an angle grinder will produce the desired effect.. actually any time on a dirt bike will do the same.

Originally Posted by variant22

Any amount of time with an angle grinder will produce the desired effect..

Don't remind me - over 200 grinding disks got turned to dust on that boat....

PDW

To stay out of BobL's fridge

Originally Posted by Stustoys

To stay out of BobL's fridge

Come to think of it I have a number of other dark and mysterious brews in the back fridge.
They are Trappist Ales from Belgium, probably not quite as mouth stripping as concentrated tannic acid wit a pH adjusted to 2.3 using Phosphoric acid.

Originally Posted by Stustoys

To stay out of BobL's fridge

Aw c'mon Stu, you'd never fit in a fridge, unless of course it was a refridgerated container