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View Full Version : Boring Bar Advice



KenL
04-23-2009, 06:18 PM
Question for the group from a new member. I recently came back to metal lathe work after a long hiatus and purchased a Craftex 10x18 lathe (China iron I know, but it seems to work well!) I also purchased a bunch of tooling to get started including a double ended boring bar for 3/16" tools; it worked okay on my first project (a brass and wood faced plane hammer).

I am curious about the brazed carbide boring bar sets that I see in the catalogues and if they offer any advantage other than the increased durability of their carbide tips?

Ken in Ottawa

camdigger
04-23-2009, 07:02 PM
In general, HSS is capable of keener edges giving more efficient metal removal, but has less durability.

Cutting speeds for carbides are higher and due to their generally less keen edges so are cutting forces and power consumed per unit metal moved.

The carbide is strong in compression and abrasion resistant, but does not handle shock well (either thermal or impact shock). intermittent coolant (like when applied with a hand brush) or interupted cuts can severely shorten carbide tool life.

Carbides are capable of cutting harder materials than HSS.

Carbides tend to be bulkier which can be an issue in boring. Most carbide lathe tools are backed by steel so that the steel provides some toughness and microscopic give to help the brittle carbide handle the shock. Steel is waayyyy less $ than carbide too.

Carbides are, in comparison to HSS more expensive, and require special (green ) grinding wheels. New HSS inserts can be ground from inexpensive tool bit blanks for pennies each using a plain aluminum oxide wheel.

For my money, carbides aren't worth the extra hassle and $$ for any lathe smaller than 12-36. I use HSS bits in my 1440 for threading rather than carbide - less $ invested and in stock in the tool box instead of 7 - 10 day delivery, or a trip to teh tool store... The smaller lathes lack rigidity and the power necessary to take advantage of the carbides.

HSS tooling is easily and inexpensively customized using dremel tools, angle grinders, or bench grinders making lathe work more efficient through the use of form tools and appropriate tool shapes.

My $.02 cdn
Cam

brian Rupnow
04-23-2009, 07:23 PM
I have a 10 x 18 Craftex, and a set of the cheap generic carbide tipped boring bars . They work fine. Of course, this view may be a bit lop sided, as I have never used anything else.