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Discussion Starter · #1 ·
I have a project coming up soon and I need to step up my game concerning my boring equipment.

I have a qctp and the tool holder I have now will accept either a 1/2'' or 5/8'' boring bar. It's the same tool holder for both sizes,it has an insert that you slip in when using a 1/2'' bar.

One of these: https://littlemachineshop.com/products/product_view.php?ProductID=2283&category=1005208204


Am I better off just using the 5/8'' and calling it a day? And not worry about using a 1/2'' bar?

Obviously, the 5/8'' bar is going to be sturdier,but I'm worried about running in to an issue of clearance (not this particular project,just in general) and was wondering if the 1/2'' bar would be the way to go concerning that.

Also, all of the alphabet soup concerning the indexable inserts has me pretty much confounded.

This is the toll I'm looking at right now. Thoughts? Thanks!

http://www.ebay.com/itm/1-2-x-7-RH-...2?pt=BI_Tool_Work_Holding&hash=item4cf72b0e5c
 

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Honestly, you'll use the smaller one more often. And you won't have deflection issues unless you get greedy. Just make sure you get more than 1 box of inserts cause you might have a rough learning curve. Nothing shits in your cereal like having to work with an insert you'd gladly throw in the trash if you had another good one.
 

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Discussion Starter · #3 ·
Thanks Jerry!

So what's up with all the different inserts? I understand some have different radiuses and coatings. But these cmmt deals, are they good ones to setup with? Is there a more common or affordable type? Maybe these inserts can be used for other than just boring,too. I hadn't thought of that yet.
 

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If you haven't invested in a machinists handbook you should definitely do it. Its like a pocket encyclopedia for anything you want to know.
Definitely stay with indexible insert tools. And manufacturers make a BIG difference. I personally recommend sandvik. But there are a few other equally reputable brands kennemetal and a few others.
"Cmmt" is basically the style/shape of the insert. The numbers dictate size and radius.
A lot of the inserts we use run on a variety of different tools.

Since I'm here....here's a shot of the stash I have at work. This is everything we could ever use or want with the amount of tooling we have in my cell.
 

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Discussion Starter · #6 ·
So I found this deal on Ebay. It's roughly $2 per insert which is pretty stinking cheap.

It's a lot of 50 Kennametal ccmt 3251 inserts for $90 shipped. At four cutting faces per insert that should last me a life time.
http://www.ebay.com/itm/KENNAMETAL-...094?pt=LH_DefaultDomain_0&hash=item3a8d5ba6c6


I'm unsure is they are the correct insert for what I want to do though. I found this info concerning them : (no mention of aluminum,though it seems to be a good thing for stainless)


"KC935 - turning & boring profiling cutoff C2, C6 & K20 - K30, M20 - M35, P20 - P40

composition: A multilayered coating with optimized layer thickness over a cobalt-enriched substrate. Al203 over TiC over TiCN

application: Grade KC935 is fast becoming the favorite grade for soft and gummy workpiece materials. Successfully apply on most steels, martensitic, and ferritic, austenitic stainless steels, and heavier cutting in nickel base alloys. The TiCN/TiC coating layers are effective at low to medium speeds, and the outer alumina coating maintains hot hardness at medium to high speeds. The well balanced substrate maintains toughness and edge strength. The specially engineered coating surface provides a smooth, stable cutting edge that resists build-up and microchipping. If you like grade KC850, try grade KC935, and bring real flexibility to your metalcutting operations."


Thoughts?
 

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Ccmt's are good styles when talking smaller boring bars, they give you just about the most clearance you can get from a boring bar. The 3251 ccmt is a .0156 radius tip, this would be good for light cuts, I usually use this radius when running finish passes or trying to get a really good finish. I probably wouldn't try to take more than .05 a side with that radius and that's even a bit much.
If your going to be making bigger cuts than that I would move up to a .0312 radius insert.
 

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And pretty much any carbide insert is going to be ok for aluminum, steel, stainless steel.
What determines your tool life is going to be your surface footage, feed and depths of cut.

Hope this helps ya out
 

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Is my bike ok?
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Discussion Starter · #9 ·
That helps tremendously, thank you very much. My old leather drive belt on my machine slips pretty bad so I rarely ever take a cut deeper than .015-.020''. I good finish is more important to me than being able to cut quick. Also,having to only keep one style of insert on hand would make life easy. So it sounds like 3251 would pretty much do everything I need. Thank you for your input. That's exactly what I needed to know!
 
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