What are you machining?

[fizzy]

oooh aaah ouch eeee as the blue hot chips fall down your collar

Or worse

 

[Lewis_RX8]

Or worse

I paid for all 7.5HP of the triumph got to attempt to use them

 

[fizzy]

I paid for all 7.5HP of the triumph got to attempt to use them

Indeed so.
And lets not forget how big a leap carbide tooling is. That tiny delicate little tooltip can remove large amounts of tough metal and absorb vast amounts of power.

 

[Lewis_RX8]

Wait until you try the ceramic tips Fizzy.

What is special about these?

 

[Munkul]

What is special about these?

Nothing good about them unless you're trying to cut hardened stuff I believe...

 

[Lewis_RX8]

Nothing good about them unless you're trying to cut hardened stuff I believe...

I have seen is them on cutting edge engineering where he uses them for cutting the hard chrome off rams like you say but that's as far as my knowledge goes.

 

[Munkul]

I got a new 12mm boring bar last week, takes CCMTs. I was looking out for a S/H carbide bar on ebay but thought I'd take a punt.
Sold as a "reduced vibration" boring bar on ebay, paid £20. Of course it's a cheap import, but it looks nice, and it's made of some pretty hard material unlike the other 12mm bars I have which are cheap mild steel.
It performs better, too, better than the unbranded 12-16 bar which is now redundant...
Below is the picture from left to right - S12-16 boring bar, S12 "reduced vibration" and the C08 carbide bar. All at max stickout before they started squealing in mild steel.

 

[arther dailey]

Making a die holder at the moment for a training piece

The lecturer liked my two nuts together trick for how to sharpen drill bits that works on big or small ones just as good
View attachment 315573

Still getting better at the sharpening as I go but Intresting doing it on 24mm drills not the 10mm or so I'm used to doing

View attachment 315572

View attachment 315574

can you explain the two nuts trick ,no pun intended

 

[Kram]

Ceramics spray red hot chips

The hot chips problem, I have found two solutions!

External turning in reverse with a left handed holder or RH bar. The chips go away from you. 7mm off diameter was no problem, that is a big cut for this lathe!

These single edge chip breaker inserts, I like them as they break chips 100x better than normal. Instead of high velocity small C's, or high velocity curls, or stringers, you get thick, slow C's, or tight curlers (a bit lile a parting swarf wheel). Did not get burned, did not need the cardboard guards!

Problem is availability. I only know one shop with a few left, on clearance. I would have posted this before, but first I wanted to buy plenty for myself

I think KNUX style inserts are similar? Have not used them but only turning inserts I know, that are normally single edge.

 

[Lewis_RX8]

can you explain the two nuts trick ,no pun intended

Sure , quite simply just put two nuts or bolts and any hex together to get your rough angle for grinding a drill bit in

So when I am grinding and think the grind on the bit is quite hold up to two nuts and can hold up to a light to see if the grind if flat and the same on both sides at the 120° angle that you want for standard drilling

Just keeps you right as you sharpen probably not done in million pound CNC machine shops lol but works for the home shop learning to sharpen drills and if you don't enough you won't need the nuts anymore

 

[Hood]

Ceramics spray red hot chips
....

So does carbide if you are doing hard steel.

 

[arther dailey]

Sure , quite simply just put two nuts or bolts and any hex together to get your rough angle for grinding a drill bit in

So when I am grinding and think the grind on the bit is quite hold up to two nuts and can hold up to a light to see if the grind if flat and the same on both sides at the 120° angle that you want for standard drilling

Just keeps you right as you sharpen probably not done in million pound CNC machine shops lol but works for the home shop learning to sharpen drills and if you don't enough you won't need the nuts anymore
View attachment 320646

thats perfect , thanks

 

[m_c]

Ceramics spray red hot chips

The hot chips problem, I have found two solutions!

View attachment 320620

External turning in reverse with a left handed holder or RH bar. The chips go away from you. 7mm off diameter was no problem, that is a big cut for this lathe!

These single edge chip breaker inserts, I like them as they break chips 100x better than normal. Instead of high velocity small C's, or high velocity curls, or stringers, you get thick, slow C's, or tight curlers (a bit lile a parting swarf wheel). Did not get burned, did not need the cardboard guards!

Problem is availability. I only know one shop with a few left, on clearance. I would have posted this before, but first I wanted to buy plenty for myself

I think KNUX style inserts are similar? Have not used them but only turning inserts I know, that are normally single edge.

That's just a pretty extreme chip breaker, which is likely aimed for tougher materials where chip breaking is a problem.
For a chip breaker to work effectively, you need to run the cutters hard.

When you run the actual figures needed, you can end up requiring some quite scary feeds.
Looking at your photo, that looks like you started with about a 25mm bar.
Taking the numbers for the first general purpose DCMT 11 insert on APT, gives this chart -

Now lets take the lower end of the cutting speed, of 200m/min.
25mm bar has a circumference of 78.5mm, or 0.0785m.
Now to hit 200m/min surface speed, you need 200/0.0785, which gives us a touch over 2500RPM.

Then for the required feed rate, take that 2500 and multiply it by 0.12mm, which gives a nice round 300mm/min.

So to put that in to context, in order to reach the bottom end of the recommended machining area for the APT insert I picked, assuming a 25mm diameter bar, and a 25mm length of cut, you need to run the lathe at 2500RPM, and feed the length of cut in a maximum of 5 seconds.
It's not something that is practical on your typical manual lathe for a variety of reasons.


However, carbide can be made to work well, but you'll most likely be out with the recommended speeds/feeds.
Things like using polished inserts designed for aluminium can produce excellent finishes on steel, but you're far more likely to chip the insert, as the cutting edge won't be as durable.


And having just found the insert you're using, it's got the aggressive chip breaker as it's designed for being used at less than ideal speeds, which is what small parts require.
Out of curiosity, is there a feeds/speeds label on the insert box?
(I'll also add, that the shop will likely be re-stocking those inserts, as the stock message is the same for all of their products, it's just how they've set their website up to prevent backorders)

 

[Munkul]

Remember those speed and feed tables are usually generated specifically for CNC production speeds. As Hood says, you don't need speed necessarily to break chips, just an adequate DOC and good feed rate for the insert...

 

[Kram]

Thanks for the explaination m_c,
28mm bar, these are what Im using.

DCET 11T302 L-E UM25 Carbide Inserts for Precision Turning and Small Parts Machining

Carbide Inserts for Precision Turning and Small Parts Machining type DCET 11T302L-E UM25 by Uni-tip Carbide

www.shop-apt.co.uk

DCET 070202 L-E UM25 Carbide Inserts for Precision Turning and Small Parts Machining

Carbide Inserts for Precision Turning and Small Parts Machining type DCET 070202L-E UM25 by Uni-tip Carbide

www.shop-apt.co.uk

Box for the small ones, lost the 11's box, but the new order should arrive tomorrow.

I know depth and feed play a massive part of chip breaking, but I think its the shape of the chip breaker that makes these curl differently - the insert nose isnt trying to twist the chip with the second edge.

 

[Munkul]

Great for harder steels and rough cutting of flame cut or plasma cut steels and they take large amounts of material in one go, basically they are aimed more towards production work where speed is important.

For home use they are more limited unless you machine a lot of rough cut stuff and stand more abuse then tungsten. It comes down to your use and cost, can you justify spending the extra by increasing your speed or improved longevity.

What?! That's crazy talk. None of the above is correct, apart from "For home use they are more limited". You wouldn't choose them for cutting plasma-cut steel unless in a very specialised application.
I'm not an expert so I'll just leave this here

What are the Benefits of Machining with Ceramic Turning or Milling Inserts?

What are the Benefits of Machining with Ceramic Turning or Milling Inserts?

www.cutwel.co.uk

 

[Bullet2012]

Its not crazy at all and you certainly don't know what you are talking about to how about trying some, they work on all manner of things, often better than carbide, on other things they are worse so just another nice addition to have for when they are needed for the type of lathe work I sometimes do.

Cannot wait to see the pictures, bet they are awesome !

 

[My Old Landy]

I made a short video of the first cuts on the Raglan 5 inch. It runs well with the reconfigured motor. I will try the screw cutting gearbox next

 

[Kram]

Ive been making this tool holder and found time to test it. Cant think of anything to turn right now so just a pair of stepped radius grooves to see if it works.

Good finish tho my lathe lacks the rigidity for the full contact radius with this much stickout, I had to finish turn chuck by hand to remove chatter marks. Hoping a shorter peice, cast alu, brass and plastics should manage the full cut ok under power. It makes nice big curls of swarf.

I did expect the rigidity problem as I have it with my HSS concave radius tools.

 

[Brad93]

Ive been making this tool holder and found time to test it. Cant think of anything to turn right now so just a pair of stepped radius grooves to see if it works.

View attachment 331913
Good finish tho my lathe lacks the rigidity for the full contact radius with this much stickout, I had to finish turn chuck by hand to remove chatter marks. Hoping a shorter peice, cast alu, brass and plastics should manage the full cut ok under power. It makes nice big curls of swarf.

I did expect the rigidity problem as I have it with my HSS concave radius tools.

For that size insert you need at least a 20mm square shank tool.