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Carbide inserts how many spares and price versus quality

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TQA222

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I am looking at buying a 8 mm shank parting off tool that uses a GTN 2 insert. This is from a UK supplier.

I am a hobby user and will probably part off no more than 20 items a year. Working mostly with brass ali and delrin with the odd item in cast iron, leaded steel or 303 stainless.

So I am thinking that a couple of spares will be enough. I can buy from the UK supplier of my parting toll and they charge $ 4.30 for one.

Being a tight Scots git I checked the online price. I could get 10 for $ 6.99 on Ebay or 1 for $17 US supplier. Curiously the label on the cheapies gave the same US manufacturer as the $17 one.

I checked Banggod but they don't seem to do them.

So my questions

Will 2 spares be enough. Bear in mind I live on a sailboat wandering around the Eastern Caribbean and my delivery logistics can be convoluted

Is there a benefit on having a tin coating.

and the sixty four dollar question is the $17 insert 25 times better than the 70 cent one. Or do they all come from the same factory and get different packing and prices like small outboard engines.
 

Dabbler

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cast and 303 will be the hardest on the blade... My current way it to buy 1 or 2 'quality' carbides, and then buy a box of offshore (10) and use them mostly and only break out the 'good' ones when I have problems... So far the 'good' ones are rarely used...
 

Bob Korves

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and the sixty four dollar question is the $17 insert 25 times better than the 70 cent one. Or do they all come from the same factory and get different packing and prices like small outboard engines.
Some are counterfeits. That is becoming more prevalent. Still, cheap inserts may not make it in high production shops, but they work well enough in my hobby shop and in many others.
 

pacifica

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You can find good prices on ebay , usually someone selling small lots- but you need to know what you want and do some searching. Example:
I bought a sumitomo cbn diamond shape insert for $17( for 60 hrc hardened steel), grainger sells it for over $80. Counterfeits are getting more clever, an example is the famous mitutoyo 6" digital caliper which is sold everywhere and many times as a look a like counterfeit.
 

mikey

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Why not use a HSS P-type blade? It cuts with far lower cutting forces than carbide and should work well on a mini-lathe. Cheap, easily sharpened, no replacing unless you break it. My blades last for decades.
 

benmychree

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Why not use a HSS P-type blade? It cuts with far lower cutting forces than carbide and should work well on a mini-lathe. Cheap, easily sharpened, no replacing unless you break it. My blades last for decades.
My sentiments exactly; and so easily sharpened as well. If you must buy inserts, get quantity, especially relating to your aquatic situation.
 

TQA222

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I saw this video of a simple modification to a parting off tool which encouraged me to buy the same tool and will be making the same mod.
Winky's parting off tool mod

The other reason is that I want to avoid grinding ordinary steel where ever possible. It gets into the fiberglass deck and rusts producing orange streaks.
 

jdedmon91

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I am looking at buying a 8 mm shank parting off tool that uses a GTN 2 insert. This is from a UK supplier.

I am a hobby user and will probably part off no more than 20 items a year. Working mostly with brass ali and delrin with the odd item in cast iron, leaded steel or 303 stainless.

So I am thinking that a couple of spares will be enough. I can buy from the UK supplier of my parting toll and they charge $ 4.30 for one.

Being a tight Scots git I checked the online price. I could get 10 for $ 6.99 on Ebay or 1 for $17 US supplier. Curiously the label on the cheapies gave the same US manufacturer as the $17 one.

I checked Banggod but they don't seem to do them.

So my questions

Will 2 spares be enough. Bear in mind I live on a sailboat wandering around the Eastern Caribbean and my delivery logistics can be convoluted

Is there a benefit on having a tin coating.

and the sixty four dollar question is the $17 insert 25 times better than the 70 cent one. Or do they all come from the same factory and get different packing and prices like small outboard engines.
I’d try to purchase at least 5 inserts for spares. I use insert cut off tool always. If you run them slow and carefully feed the they last just fine. It doesn’t hurt to run them slower. I part steel at 75 rpm. The next lowest speed is 200.


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macardoso

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I am 100% an indexable tool guy. I have used both the GTN-2 inserts and HSS blades and I will say that parting is the only time I opt for the HSS blade. I have far fewer problems than with the GTN type parting tool. I have found that if anything on the insert fails on a parting cut, your blade will snap or bend moments later. I went through 2 indexable blades this way and haven't had any issues since moving to HSS.

The one thing that is super nice about the parting blades is the insert has a cup shape to it that tends to make the chip narrower than the slot and ejects freely. Some HSS blades also have this cup shape, but to a lesser degree.
 

jdedmon91

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I am 100% an indexable tool guy. I have used both the GTN-2 inserts and HSS blades and I will say that parting is the only time I opt for the HSS blade. I have far fewer problems than with the GTN type parting tool. I have found that if anything on the insert fails on a parting cut, your blade will snap or bend moments later. I went through 2 indexable blades this way and haven't had any issues since moving to HSS.

The one thing that is super nice about the parting blades is the insert has a cup shape to it that tends to make the chip narrower than the slot and ejects freely. Some HSS blades also have this cup shape, but to a lesser degree.
One thing I notice about the GTN inserts I have not have any problems but I use the GTN-3 inserts. I even have Bangood blade and inserts. However I don’t run the fast probably the speeds that I run is closer to HSS.


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BGHansen

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I've had good luck with import GTN 2, 3 and 4's. I usually drop into back gear and slow things down, see nice curly-Q's on the bits.

That being said, have had very good success with a tapered-sided HSS blade too and use it on open spindle.

Sounds like from your use you will be well served to pick up 10 imports.

Bruce
 
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