# I need a turning tool made.



## Harvey (Jan 12, 2018)

I need a 5/32" dia (5/16" Wide) round-nosed cutting tool made so I can groove the three rollers in my Harbor Freight slip roller and allow me to form a large radius bend in a piece of 5/16"OD 4130 tube (.035" wall).  I think my HF rollers are mild steel.

The guys explained how to make this tool in another forum but since it would be my first time to grind my own tool, I lack the confidence to do it right.  I probably need only one but if the price is right, it might be a good idea to have two made so I can have a backup.  My quick-change tool holder can take up to 5/8 square tooling.

Thanks,

Harvey


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## Ulma Doctor (Jan 12, 2018)

Hi Harvey,
i'm happy to grind tooling for you.
i have HSS in 5/16, i'll grind up a couple tools that may help out 
send me a message, i'll need an address


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## dlane (Jan 12, 2018)

Shouldn’t be a problem, do it


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## JimDawson (Jan 12, 2018)

Harvey said:


> I lack the confidence to do it right.




Harvey, the best way to gain confidence is to just do it.  As long as the cutting edge is sticking out farther than everything else, then it will work.  May not be perfect, but you're not getting paid by the hour either, you can always grind again.


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## RandyM (Jan 12, 2018)

JimDawson said:


> Harvey, the best way to gain confidence is to just do it.  As long as the cutting edge is sticking out farther than everything else, then it will work.  May not be perfect, but you're not getting paid by the hour either, you can always grind again.



Yup, try and try again. If you are too afraid to make mistakes nothing will ever get done. I know this stuff can be scary, but you have to try. And a tool bit is probably the best thing to experiment on. You just keep grinding until you get it right. You don't scrap the bit until it is ground down to nothing.


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## kdecelles (Jan 12, 2018)

RandyM said:


> JimDawson said:
> 
> 
> > Harvey, the best way to gain confidence is to just do it. As long as the cutting edge is sticking out farther than everything else, then it will work. May not be perfect, but you're not getting paid by the hour either, you can always grind again.
> ...



Amen. I ground my second-ever bit last night . Turned like garbage. Wasn't the bit, was SFM (speed) issue. Way too fast. Read the books , follow the notes, "read the chips"


Sent from my iPhone using Tapatalk


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## Harvey (Jan 12, 2018)

Thanks Guys.  Please understand that I appreciate your encouragement to try grinding my own tool bit but I've decided to take UlmaDoctor up on his kind offer to make a tool bit for me.

My reasoning is multifold:  My sole grinder is a worn-out Harbor Freight pedestal grinder that I bought 20 or so years ago and have only used it (so far) to sharpen my lawnmower blades.  Yes, I could spring for a new (better) grinder, and a wheel suitable for grinding tool bits but that would be quite a price increase for the one 5/16d round-nosed bit that I need right now.  While I will understand that your logical rebuttal will be that as a lathe owner I will likely need a quality grinder for fabricating additional custom tool bits in the future; the truth is that I've owned my Grizzly 12x36 lathe for 7 years now and this is the first and only time I've needed to make a custom bit.  I MAY eventually resort to buying a better shop grinder in the future but as you can see, it's not financially justifiable right now.

That said, I'm not closing down this discussion of trying my hand at "rolling my own".  I'm always willing to learn about and embrace new skills.  Heck, that's why I joined this fine forum!

Harv


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## HBilly1022 (Jan 12, 2018)

I'm in the "just do it" camp.

The best way to learn is to have an experienced machinist at your side showing you what to do and then trying it yourself. But most of us don't have that opportunity. So the second best way is to try it and if something doesn't work out, there is a huge community of people on this forum that are eager to help you get through it.  There have been times when I needed a lot of help and always got it. There is a real sense of satisfaction when it all comes together and you finish the part. And it is made of metal, so you will get to admire your work a very long time.

Edit, posted while you were responding. I have a cheap grinder too and have found a way to balance the wheels that works great. Now the cheapo grinder feels and sounds smooth. If your interested there is a thread that shows it. https://www.hobby-machinist.com/threads/bench-grinder-run-out.65262/#post-545463


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## hermetic (Jan 12, 2018)

Don't think for a minute you will have a problem making the tool, you will need to square up your grinding wheel with a wheel dresser, or a piece of scrap, but form tools of this type need a powerful lathe and a very rigid set up if you are going to plunge it straight in, so take out the bulk of the slot using conventional lathe tools, then use the form tool to bring it to the correct size and shape. Good luck with it!


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## Downunder Bob (Jul 30, 2018)

By all means take up Ulma doctors generous offer. When you get the tool take some photos of it from all angles, for future reference, and then try to copy it on your grinder. Start with  a scrap of mild steel until you get the hang of it. Then get  a piece of HSS and grind your own tool alongside of the one UD made for you. You might surprise yourself, it's not hard, just requires a basic understanding of why it cuts, clearance and rake angles, and some patience and practice. Good luck and have some fun.


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## Harvey (Aug 7, 2018)

Thanks Downunder!

Harv


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## BaronJ (Aug 8, 2018)

Hi Harvey,

Have you seen the "diamond tool holder" ! 

https://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=2&Itemid

Well get a piece of round HSS the diameter you need and make a tool holder for it.  Grind the end flat at about 30 degrees, and you have your tool to machine the groove that you want.  5/32"  is a common HSS tool steel size.


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## Downunder Bob (Aug 8, 2018)

Harvey, see above, from BaronJ, that is the ultimate best answer for your problem. If making the toolholder from scratch is too difficult you can get one on mail order, for the actual tool bit, an old center drill with a blunt or broken end makes the perfect cutter, various sizes available. Can also use up old ends of broken, worn out milling cutters as turning tool.

This tool is the most simple to grind, one flat face on the end at around 12 deg. is all you need.

When you order the tool holder, you have the option to order with the tool grinding guide, makes life simple, get the perfect angle every time. The bonus is you also have a great general purpose tool holder for all normal turning, with very simple regrinding,


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## MarkM (Mar 26, 2019)

By now you should have an understanding of tool geometry with owning a lathe for seven years.  Just think where you would be if you had tried to grind some tools from the get go!  It s a skill needed and to be able to manufacture your own tool will save you money, time and allow you to complete jobs in house not depending on your wallet for all your tooling needs.  The hss is so cheap!!! even quality stuff is reasonable.  Grab a proper grinding wheel while your at it. Grab some HIGH SPEED STEEL ( sounds like you have relied too much on inserts) and a drill bit for the requird radius to compare your grind and have at her!  Seven years,  Really!


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## Illinoyance (May 13, 2019)

Even a badly worn grinder can give decent results with the right wheel.  Get a friable white aluminum oxide wheel.  Learn to grind your own tools.  You will profit by the knowledge.  The groove you want do not have to be precise radii.  You just need a template to grind to.  Radius gauges are really handy for that.  You can drill a hole in thin material and use taht as a template.  Don't worry about ruining a tool bit.  If you mess up on the first attempt, just grind the end back a bit and correct the radius.

The suggestion of making a tangential tool is a good one.  A drill blank would make an ideal form tool.


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## Downunder Bob (May 18, 2019)

If you have a tangential tool holder you can make lots of circular profile tools from worn out / broken taps and center drills etc.


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