Question about cutting a radius and the insert used.

[EyeEmTrash]

I did not see this question posted anywhere so I hope it's not a copy cat question. This is probably an amateur question but it's been so long since I have had to make a cut like this on the OD. Right now my machines are down so I can't even test it out. This pertains to CNC lathe machines. Anyways, I have to make a cable guide roller. The area where the cable will sit in has a .128 radius. It's a half circle. I do not have any left or right hand grooving inserts. My questions are: Do I need them, or can I do it with a straight or neutral insert? If I can do it with a neutral, what is the maximum width the insert can be without messing up the radius too bad? I think the smallest one I have is about .06. In my head, I don't think I'm able to do it but I'm curious if I am thinking about it the wrong way. Thanks in advance.

Edit: so I stumbled across some grooving inserts. They are completely rounded. Here is a link to them https://www.kennametal.com/us/en/products/p.NR.1113217.html

Would I be able to use this instead? I never used this type of insert before but I have them on hand.

 

[rjwalker1973]

What control and do you have a print to get a better idea?

 

[Houdini]

In short no, a square tool wont clean up the bottom of the radius. but depending on what radii your .06 groove tool has it may get close enough depending on tolerance.

 

[EyeEmTrash]

In short no, a square tool wont clean up the bottom of the radius. but depending on what radii your .06 groove tool has it may get close enough depending on tolerance.

So I just stumbled across these in my insert drawers. https://www.kennametal.com/us/en/products/p.NR.1113217.html

I never used this type of insert before. Would this work?

 

[EyeEmTrash]

What control and do you have a print to get a better idea?

I use a Mazak. I don't have the print handy on this computer but if it's absolutely necessary, I can upload a picture. It's just a simple part. It's like the pulley system on a clothesline. It's basically a wheel that has a groove on the outside where the cable sits in.

 

[Houdini]

So I just stumbled across these in my insert drawers. https://www.kennametal.com/us/en/products/p.NG.2599522.html

I never used this type of insert before. Would this work?

Not a lathe guy, but I'm think'n no.
edit: It will leave a .0023" flat, if that's in tolerance than go for it.

 

[EyeEmTrash]

Not a lathe guy, but I'm think'n no.

I uploaded the wrong link. I fixed it before but you may have hit it before I did. Heres the correct link. https://www.kennametal.com/us/en/products/p.NR.1113217.html

 

[Mtndew]

I uploaded the wrong link. I fixed it before but you may have hit it before I did. Heres the correct link. https://www.kennametal.com/us/en/products/p.NR.1113217.html

I see no reason why those won't work. It has a .150" max cut depth and straight sides.
Send it!

 

[EmGo]

Heres the correct link. https://www.kennametal.com/us/en/products/p.NR.1113217.html

Yes. Just tell it to do a .016" radius. (.126 -.094)/2

 

[Houdini]

I uploaded the wrong link. I fixed it before but you may have hit it before I did. Heres the correct link. https://www.kennametal.com/us/en/products/p.NR.1113217.html

Looks good to me.

 

[rjwalker1973]

yes that will do it.

 

[CarbideBob]

You need a full rad grooving tool to do what I think you are after.
It can and will work better if smaller than your part radius if a groove.
BUT cable roller. You are basically cutting a thread normally here. You need a tool with rad that matches.
That is going to be a special.

 

[Dan from Oakland]

I'm confuserated!! If you are going to profile the groove, any full radius straight sided insert with a nose radius less than half the diameter of the bottom of the groove will be able to cut the part. probably goes without saying, but..... Any square insert will leave a flat at the bottom of the groove equal to the nose width of the tool.

 

[Houdini]

I'm confuserated!! If you are going to profile the groove, any full radius straight sided insert with a nose radius less than half the diameter of the bottom of the groove will be able to cut the part. probably goes without saying, but..... Any square insert will leave a flat at the bottom of the groove equal to the nose width of the tool.

Yump, That's why I did the CAD on his first insert, left a .0023" Deep x WO Insert flat, I guess if it was in tolerance you cld get away w/ it.
But he found a rnd one!

 

[sinha]

For a half-circular groove, only a full radius tool can be used. For a semicircle, calculations are ready.

 

[CarbideBob]

Is it straight groove or a thread. Cable pulley?????

 

[implmex]

Hi All:
Carbide Bob is assuming in post #12 that a cable roller has a threadform instead of a simple groove.
If that is so, then he is of course correct if you want to cut it conventionally.

However, as posted in a recent thread (by Mtndew I believe) Mastercam now has a special threading utility that allows a thread to be cut with an insert profile that need not fill the gullet.

I was curious, having not looked at it before, and it works like a Hot Damn.
It runs G32 passes...as many as you need to nibble out a big thread on a small lathe or as many as you need to machine a bigger profile with a smaller insert, and unlike the normal threading utility, it will accept all kinds of insert profiles whether Mastercam knows them as threading inserts or not.

So any full radius dogbone insert will work, and so will a custom ground or wirecut insert...you just need to define it in Mastercam (or whatever software you're using... assuming it can do this too).

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[EyeEmTrash]

Is it straight groove or a thread. Cable pulley?????

Yes it is a cable pulley, that's the word I'm looking for. I'm so out of my league on this site. I have no idea what you guys are saying sometimes with all of your fancy words ;D. They called it a cable guide roller but it's just a simple pulley.

 

[EyeEmTrash]

I'm confuserated!! If you are going to profile the groove, any full radius straight sided insert with a nose radius less than half the diameter of the bottom of the groove will be able to cut the part. probably goes without saying, but..... Any square insert will leave a flat at the bottom of the groove equal to the nose width of the tool.

thats basically what I figured, the radius insert part I wasn't too sure about so that helps too!

 

[EyeEmTrash]

Yump, That's why I did the CAD on his first insert, left a .0023" Deep x WO Insert flat, I guess if it was in tolerance you cld get away w/ it.
But he found a rnd one!

I probably could get away with that but I prefer to do it the right way