# lathe bit wont cut.



## cjsrch (May 29, 2010)

the otherday i got some new 1/4 inch tools for my sherline from harbor freight.
despite them being listed as carbide brazed tips these things WONT CUT! if i go light on a cut they just chirp and get really hot FAST. if i go a little heavier on a cut they just chirp then BIND and stop the lathe.
Switched back to my old tools ( even tho they are damaged)they too are carbide tips and was able to do light cuts and cuts three times deeper then what i tried with the HF tools. am i doing somthing wrong? maybe they are not on the centerline? i was cutting "free cutting steel" from mcmasters.



Should i try HSS or carbide inserts .Any one know if the carbide inserts from HF are decent ? or should i just go online and get the carbide brazed from sherline since they seem to work.


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## steamlogger (Jan 2, 2008)

Look for a set of insert cutting tools from Harbor Freight. I use them with my 8X14 lathe. 

http://www.harborfreight.com/5-piece-indexable-carbide-tool-set-39931.html


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## Semper Vaporo (Jan 2, 2008)

Are the new bits taller than the old ones? Sounds like the face is rubbing before the cutting edge engages the work-piece. If you shim the outside end of the tool so the cutting edge is lower it may work better. of course that also changes the 'angle of attack' a wee bit and the bits may not cut quite as well as if the angle were more proper.


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## ralphbrades (Jan 3, 2008)

It does sound perculier... Put a piece of scrap bar on the chuck and "draw a line" with the tool in the saddle across the end of the piece. Rotate the piece 180 degrees and do the same. In theory you should then just mark the same line. If you have cut two lines then the tool tip is not on the axis of the lathe and you will need to shim it to the centre. I have two sets of indexable tips tools from the same manufacturer (Glanz) and I keep a length of shim metal to stick under one set to bring it level with the axis. 

regards 

ralph


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## Kovacjr (Jan 2, 2008)

Take 6" scale and place it in between the stock and the tip of the tool bit. Using the tool bit to hold it vertical. Is it perfectly vertical? Is it leaning in to the stock? Sounds like it will be by how you are cutting. You want the tip just below the centerline of the stock.


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## cjsrch (May 29, 2010)

i will try again when i get home. but it was with 3 diff bits. tried a LHturn a rh turn and a threading tool. non would put a mark on the metal.


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## Gary Armitstead (Jan 2, 2008)

As a machinist by trade for almost fifty years, I would have to say that most likely the cutting edge of your toolbits are ABOVE center.


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## xo18thfa (Jan 2, 2008)

I second Gary's call. I believe the Sherline comes with a solid open side tool post that does not allow for height adjustment of the tool. You will have to shim the tool so the height of the tip is just "TT" below the center line. If the tip is above the center line, it won't cut.

If that is the type of tool post you have, I suggest getting a quick change tool post for your lathe. QCTP uses an adjustable tool holding block that locks to the post. You can change tools in a snap and get the exact setting every time. http://www.littlemachineshop.com/ has quick cahnge for the Sherline, check out part # 2477


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## toddalin (Jan 4, 2008)

You get what you pay for at Harbour Freight. Hopefully you'll only need to use the tool once, because that's about as long as it will last, if you are lucky. Case in point. When I buy a sanding belt from Lowe's/Home Depot/OSH (paying about twice the price) and run a piece of wood over it I hear "SHHHHHHHHHH..." When I run that same piece of wood over a Harbour Freight Belt I hear "SH!T, SH!T, SH!T, SH!T..." as it tears up the wood on the belt seam.


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## xo18thfa (Jan 2, 2008)

I don't want to start a mud throwing contest over Chinese imports, but I have never ever bought a good cutting tool of any kind from Harbor Freight. Every single tool was junk. McMaster-Carr and Travers Tool carry carbide tool with 1/4" shanks. Invest is quality tooling, they last a lifetime.


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## Gary Armitstead (Jan 2, 2008)

Ditto to what Bob just said







NEVER invest in cheap cutting tools. Buy good grade cutting tools from McMaster-Carr and you will have tools that will cut AND SAVE you money and frustration There is NO SUCH THING as a good, cheap cutting tool-whether end mills or lathe bits.


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## rkapuaala (Jan 3, 2008)

I think Gary is right. I bought a set of those cheap bits a few months back and they work fine with a few shims in them to raise them up. If they are too high, then he'll probably have to find a lower post or something.


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## Dwight Ennis (Jan 2, 2008)

There is NO SUCH THING as a good, cheap cutting tool-whether end mills or lathe bits.I'd expand on that and say there's no such thing as a GOOD cheap tool. There are a few "adequate" low priced tools, but generally speaking, when it comes to tools, you get exactly what you pay for. MHO of course.


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## SE18 (Feb 21, 2008)

Todd, cool sound effects you got going on there  

I usually hear ka-ching ($$$), when something breaks from HF, like my bottle jack over the weekend


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## jimtyp (Jan 2, 2008)

You may have the cutting tool edge installed upside down. Can you switch the rotation of the head the opposite direction? Or install the edge of the cutting tool the opposite?


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## RailCat (Apr 10, 2009)

Hello, 

Another thing to check is to make sure the tools have adequate clearance under the cutting edge. Our shop tried a batch of chinese tools we got real cheap. They only had about two degrees under the cutting edge. We had to regrind them in order to use them. Around 8-10 degrees should work well with mild steel. They were also very brittle compared to Kennametal or ACT. 

Scott


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## cjsrch (May 29, 2010)

well. the tip of the tool was sitting 1/8th inch higher then the old tools cutting edge even tho the bits 'shanks' are the same. i made a small 'rocker post' so i can change the bits height downward


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## xo18thfa (Jan 2, 2008)

Posted By cjsrch on 06 Feb 2011 10:58 AM 
well. the tip of the tool was sitting 1/8th inch higher then the old tools cutting edge even tho the bits 'shanks' are the same. i made a small 'rocker post' so i can change the bits height downward 

It was probably rubbing the front of the bit then. Your rocker post will fix that. I used a rocker post for many years with great success. You will develop "an eye" for ir real soon.


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## Gary Armitstead (Jan 2, 2008)

Glad you got it to work. Machining is NOT rocket science. When a cutter won't cut, it's usually a very thing to fix. Some of my lathe bit holders on my 12" Clausing lathe use the old fashioned rocker bar uder the holder. Real easy to set the bit on center. I also have a quick-change post and sometimes i have to shim the bits up or down to get proper center adjustment.


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## rkapuaala (Jan 3, 2008)

Dumb question,,, I know, but what does a rocker post look like?


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## Gary Armitstead (Jan 2, 2008)

Notice the crescent shaped piece in the center of the lathe tool post. That's the rocker.










The holder above holds this type of tool bit holder. The rocker piece goes under the holder and then you can adjust to cut on center. This one happens to be a LEFT HAND turning holder.


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## cjsrch (May 29, 2010)

or in the case of mine it is a 1/8th inch thick cut off of a 1.25 inch rod. ( looks like the thing sitting inside the "bowl" in the first post except i mount mine the other way and then have the tool rest ontop of it and then use the two locking screws to adjust the angle


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