# Q About Indexable Cut Off Tools



## mattthemuppet2 (May 18, 2015)

Hi all,

busy thinking about tooling for my new to me 6 x 18 size lathe instead of working on an exam. I'm quite happy grinding HSS tools and get good results, but one issue I keep butting up against is parting >1in diameter parts. The HSS parting tool I ground from a 1/4x3/8 blank works ok, but I can't grind it to part larger parts without losing its ability to resist flex. I've been looking at those Iscar style indexable blades - Shars has a 3/4in tall one for reasonable money that uses GTN style inserts. Providing that the QCTP I plan on building can get the tip low enough to be on center, is there any reason to use a P or T style HSS blade over this?

thanks!
matt


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## T Bredehoft (May 18, 2015)

There comes a point where the power hack saw or the band saw is more efficient than a cut-off tool. I too would like to be able to part off 2" dia aluminum, but even 1 1/2" dia is asking for trouble.


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## mattthemuppet2 (May 18, 2015)

true, I just don't have either of those, at least ones capable of cutting steel  The only power hacksaw I have is me  I did buy some nice 14/18tpi Morse hacksaw blades which should make it easier, but the last effort took me at least an hour - 10min to go 1in into a 3in steel blank, then 1h+ to hacksaw through the rest. It was a good work out though..


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## Doubleeboy (May 18, 2015)

I really like my gtn insert tools, but they are not from Shars they are name brand and cost.  For that money, if you don't have a  power saw yet I would put my money towards that, even a POS Harbor Freight saw can be tuned up and give you years of service cutting thousands of parts for you.  First things first, a simple power saw long before you go to insert parting tools.  I have 2 very rigid lathes, parting is a breeze with either HSS or carbide.  I cant remember the last time I tried to part anything over 1.5".  The drama is to great.   Big stuff I try to leave extra material on part so it can be cut with power saw then remounted on lathe and faced.

michael


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## T Bredehoft (May 18, 2015)

I bought some 13/16 4140 round stock, have been hand hacksawing off lenghts, not because I wanted to, but 1) 54 inches is too long to hang  out the back of any lathe, and  2) my lathe is only 1/2" thru. Builds character. Muscles, too. 100 strokes at a time, about 5 passes for this stuff.


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## Karl_T (May 18, 2015)

Don't want to offend you, but a 6x18 lathe is likely not rigid enough to run cutoff inserts on one inch shafts.

Save yourself some money and grief. Cut it with a hacksaw and face.


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## Firestopper (May 18, 2015)

Karl_T said:


> Don't want to offend you, but a 6x18 lathe is likely not rigid enough to run cutoff inserts on one inch shafts.
> 
> Parting requires a rigid machine... period!  Even after you set everything up properly, if the lathe has any flex (tool holder,cross slide etc.) it will end up in a broken parting tool.


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## mattthemuppet2 (May 18, 2015)

no offense taken Karl, that's why I'm asking  A horizontal bandsaw is near the top of my list of things to get, along with a proper mill, but those will have to wait until after our next move. Doesn't make sense to pay for something twice! I do have one of those small benchtop bandsaws but it doesn't have enough power for cutting steel of any useful thickness. I actually tried it on this project and it just dulled the blade.

I'll stick with the short parting tools that I have and get cracking with the hacksaw. I'll make sure to change arms every so often so I don't get any rumours started


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## Andre (May 18, 2015)

A quality bandsaw blade won't dull from one use unless what your cutting is very hard. Did you replace the wood blade with a metal cutting one? The tooth geometries are completely different and TPI is much greater on a metal one.


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## mattthemuppet2 (May 18, 2015)

it was a generic Sears blade that came in a pack of 6 for $25, so most likely carbon steel. Fine for cutting alu and brass, not so much for steel. TPI was probably a little fine (8 or 10tpi, cutting a 1in piece) and I'm sure it was running too fast as the tiny motor bogged badly otherwise. Just the wrong tool for the job!


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## juiceclone (May 18, 2015)

Cutoff/parting tool..HarborFreight "tile" blade I think it was. about $10 does NOT flex


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## kd4gij (May 18, 2015)

On a small lathe like that a HSS parting blade will be better than inserts. If you have a 4 1/2" angle grinder you can get cutoff wheels for them .  For harder metrial I will start with a parting tool and finish with the band saw. Before I got the bandsaw I used the angle grinder with a cutoff wheel. Hack saw is to much like that fou letter word { work}


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## mattthemuppet2 (May 18, 2015)

that tile saw is an interesting idea, I'll put that in my mental storage.

I used a 4 1/2in angle grinder to cut the 3 1/2" octagon out of 1" steel plate (A36 I think, scrap freebie), boy that was a mess. Ended up needing to finish off the job with a hacksaw as I only had 1 cut off disk left. I wonder how a sawzall with a 8/10tpi bimetallic blade would fare? I even asked the machinist/ repairguy at work if I could use his bandsaw and he said no


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## pineyfolks (May 19, 2015)

http://www.harborfreight.com/6-amp-...-rotating-handle-reciprocating-saw-62370.html  Get some bi-metal blades and you'll be in good shape.


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## AR1911 (May 19, 2015)

+1 on the HF bandsaw. Best $200 you will ever spend. If you don't have room, consider one of the porta-band saws. 
And I sure would not run carbide parting tools on a 618.


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## kingmt01 (May 19, 2015)

juiceclone said:


> Cutoff/parting tool..HarborFreight "tile" blade I think it was. about $10 does NOT flex
> 
> 
> 
> ...


Looks like the bisque jointer blade I just used as a slitting saw 30 minutes ago. 

OP I'd say your band saw is too fast as is. You need to change the pulleys to slow it down. I seen some one on YouTube parting with a hand hacksaw under power. I think it was toolbalcane or how ever it is spelled. I've not tried that one myself.


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## Andre (May 19, 2015)

You can find horizontal bandsaws on CL, that's where mine came from when my dad and grandfather bought it many years ago. It sat mainly unused and in disrepair, when I got into this I fixed it up first thing and it's been a reliable and back-saving machine ever since. Best tool in the shop, hands down.


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## mattthemuppet2 (May 19, 2015)

roger that on the horizontal bandsaw, I'm 100% with you all there, just not until I've moved into a permanent place sometime next year. Our last move across the US came in at $1/lb, so a small HF bandsaw is going to be upwards of $100 to move, which doesn't make much sense, plus eastern WA is a bit of a machinery desert.

My benchtop bandsaw is one of those slightly cute little 9 or 10in 3 wheel hobby models. It does a somewhat ok job on alu, but the motor is smaller than a mug of coffee and pretty feeble so slowing it down means that pressure on the blade just stalls it.

I'll check out my sawzall on a piece of steel later in the week. I have some spare blades for it, so even if I dull one I'll still have others to use.


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## kingmt01 (May 19, 2015)

If you slow it down correctly by changing the pulleys it will have more power.


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## ogberi (May 19, 2015)

I use a Ryobi variable speed sawzall (corded) with Lennox bimetal blades, or some off-brand bimetal for nasty stuff.  Low speed, frequent application of cutting fluid, and of course eye protection.


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## mattthemuppet2 (May 19, 2015)

kingmt, no can do unfortunately - it doesn't have pulleys, only a rheostat that slows the motor, presumably reducing its torque at the same time. It's pretty weedy - I can pick it up off the floor with one hand if I have to!

thanks for the feedback ogberi, that's very helpful. I got a couple of Morse 8/10tpi bimetallic blades from that Morse free trial offer, so it's worth a shot.


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## mattthemuppet2 (May 19, 2015)

also, thanks to Mikey I'm going to think about a rear mounted parting blade as another option, even if only for small diameters. He suggested P1 or P1N blades (1/16 and 0.04" think) which should work well given that they match the thicknesses of a couple of tools I've ground myself. Is there any benefit to going to cobalt (M42) over HSS for either of those blades? The cost is around double, but it's not like I'll be using a lot of them, as long as I don't snap them.


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## kingmt01 (May 19, 2015)

A rheostat on a motor is a really bad idea. It not only cuts the torque but will burn up the motor. Someone posted a video the other day with the parting tool turned upside down & cutting above center letting the chips fall down away from the tool instead of building on top of it. The way it was explained made a lot of sence but I haven't tried it yet.


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## John Hasler (May 19, 2015)

kingmt01 said:


> A rheostat on a motor is a really bad idea. It not only cuts the torque but will burn up the motor. Someone posted a video the other day with the parting tool turned upside down & cutting above center letting the chips fall down away from the tool instead of building on top of it. The way it was explained made a lot of sence but I haven't tried it yet.


I think it's probably a universal (series) motor and the rheostat controls a thyristor that varies the voltage.


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## 4GSR (May 19, 2015)

juiceclone said:


> Cutoff/parting tool..HarborFreight "tile" blade I think it was. about $10 does NOT flex
> 
> 
> 
> ...


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## mikey (May 19, 2015)

mattthemuppet said:


> also, thanks to Mikey I'm going to think about a rear mounted parting blade as another option, even if only for small diameters. He suggested P1 or P1N blades (1/16 and 0.04" think) which should work well given that they match the thicknesses of a couple of tools I've ground myself. Is there any benefit to going to cobalt (M42) over HSS for either of those blades? The cost is around double, but it's not like I'll be using a lot of them, as long as I don't snap them.



Nope, HSS works for most common materials.


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## mattthemuppet2 (May 20, 2015)

thanks Mike! went and procrastinated for a bit by looking at the lathe to see how i could install a rear mounted cut off blade. should be doable with my plan to replace the compound, but annoyingly the 2 bits of stock i have are either too thin or too thick, so I'll have to do some more head scratching..


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## rick9345 (May 22, 2015)

juiceclone said:


> Cutoff/parting tool..HarborFreight "tile" blade I think it was. about $10 does NOT flex
> 
> 
> 
> ...


I like that idea


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## benmychree (May 22, 2015)

Karl_T said:


> Don't want to offend you, but a 6x18 lathe is likely not rigid enough to run cutoff inserts on one inch shafts.
> 
> Save yourself some money and grief. Cut it with a hacksaw and face.


I quite agree with you; insert parting is for industrial machines; I'd stick with HSS parting tools for small lathes; I especially like the T type, as they bind much less in the cut.  I have both HSS and insert tools, and tend to use the HSS for smaller work.  In my opinion, one should NEVER count on a parted cut as a finish I always plan to face the part off after parting, except when working on a turret lathe, where the cut is much more rigid and accurate and well finished cuts are much more possible than on engine lathes.


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## tkitta (May 22, 2015)

Parting with HSS bigger pieces is hard with my 13x24. You have to worry about binding the tool, heat, cooling etc.

Much easier to do it with a band saw. 

Of course very hard material will kill the band saw blade fast and not a carbide tipped tool but that is going into speciality territority. 

If using HSS cut-off tool make sure not to be too aggressive - I managed to get the spindle to stop when some debris got stuck in the channel on a 1/8 inch custom made HSS "grove tool". I was a bit shocked nothing broke and that somewhat tiny 1/8th by 3/8th piece of HSS wasn't affected at all.


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## GarageGuy (May 23, 2015)

Andre said:


> You can find horizontal bandsaws on CL, that's where mine came from when my dad and grandfather bought it many years ago. It sat mainly unused and in disrepair, when I got into this I fixed it up first thing and it's been a reliable and back-saving machine ever since. Best tool in the shop, hands down.



+1 on this.  I got my horizontal band saw on CL for $45, and I have a friend that found his at a garage sale for $15.  They are around.  Be sure to use a good quality American made blade.  Starrett bi-metal blades are available on eBay for ~$25.

GG


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## Andre (May 24, 2015)

kingmt01 said:


> If you slow it down correctly by changing the pulleys it will have more power.



I've always found the belts slip before the motor stalls out, what belts do you use?


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## Lindo (May 24, 2015)

Why is it,your side of the pond, US  wise you always have to buy tools to perform functions ?
Make your own hacksaw machine.When you see it cutting ,you will get far more
enjoyment,than putting money into companies like Harbour Fraud,sorry I meant Freight.
I made this machine from an old drill press,I used the motor,spindle,base,switches etc etc.
even end of cut switch from the belt guard interlock.
Uses standard hacksaw blades,cuts true and up to 80 mm dia steel.

https://plus.google.com/photos/112848589944601328801/albums/5840601232727851585
Necessity is the mother of invention.
Contact me if you want further info
Regards

John
Spain


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## John Hasler (May 24, 2015)

Lindo said:


> Why is it,your side of the pond, US  wise you always have to buy tools to perform functions ?
> Regards
> 
> John
> Spain


We don't.  Bill Gruby built a tool and cutter grinder.  I converted an old Avey drill press to a mill.  Plenty of other examples here.  Take a look at the shop made tooling forum.


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## jonkka (Jun 3, 2015)

http://www.harborfreight.com/carbide-tip-plate-joiner-replacement-blade-38840.html
 

*4 in. 6T Plate Joiner Circular Saw Blade *


Warrior - item#38840


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