Home Made HSS Boring Bar

[rgray]

Other than general durability will hardened drill rod make for a more ridged boring bar than normalized rod? If the Young's modulus doesn't change with hardening wouldn't that mean the stiffness would remain the same? Sorry but everything I learn is from reading so I might have that all messed up.

Cheers
Shawn

I'm at a loss to find understandable answers to that. I was told that in the past and didn't bother with tool steel because of it.
I was making my boring bars from 1144 stressproof. When I did make one out of 0-1 drill rod that I hardened and tempered , It seemed to work much better and seemed stiffer. Maybe its all psychological. I put more work into it it's gotta be better "right"
I copied this from wikapedia. I also searched for young's modulus numbers for 1144 and 0-1 but couldn't find any.

• rigidity and strength: the strength of material is characterized by its yield strength and / or its tensile strength;
• rigidity and stiffness: the beam stiffness (for example) depends on its Young's modulus but also on the ratio of its section to its length. The rigidity characterises the materials, the stiffness regards products and constructions: a massive mechanical plastic part can be much stiffer than a steel spring;
• rigidity and hardness: the hardness of a material defines its relative resistance that its surface opposes to the penetration of a harder body.

Another thing I ment to add earlier....HSS is available in round also. My van norman boring bars use a round HSS insert in the cutter carier.

 

[chips&more]

There are many options to this subject. You could have the pride to make one yourself. You could buy a double end one on say eBay for around 14 bucks and it will have square holes. Or, you could get the best of the best and find a solid carbide shanked boring bar that accepts carbide inserts. And unless you are a bargain hunter, this carbide boring bar will give you sticker shock big time! But, if you do a lot of boring, it’s worth it, chatter…what chatter? Good Luck, Dave.

 

[Bishop]

My head wants to think that a hardened steel bar will be stiffer than a non hardened bar of the same material. I would be interested in knowing for sure though. I have hardened a few parts but it's more for durability and because I like heating things up red hot and dunking them in oil. : )

 

[Dranreb]

I made this bar from unknownium to take round HSS because I had some lying in a draw, the 45 deg end is good for when I want to face an internal shoulder as it can project beyond the end of the bar.







Bernard

 

[Al Slitter]

As I am looking for a better way of doing up a boring bar I ran into this process, discussed in The Home Shop Machinist.
http://bbs.homeshopmachinist.net/threads/43179-What-material-are-boring-bars-made-of

(Quote) In a tool room I worked in hundreds of years ago, we used to make chatter free tools from cold roiled mild steel.
The tool was drilled about 7/8 of its length & tapped @ the end, eg: 1" bar drilled 1/2" & tapped 5/8" fine thread,
molten lead was poured in leaving 1" of thread, they were left in the canteen freezer over night, a hi-tensile bolt was torqued up cut off flush & welded.
The difference in surface finish between std & the lead damped tools on the same machine was astonishing.
Cheaper than carbide in the bigger sizes.

 

[Bishop]

Filling a bar with lead sounds like a cool trick, will store that one away in the grey matter for the future. It's not a boring bar but to add to the thread. Here's an internal threading tool I made from O1 tool steel on the lathe. Makes getting the correct angle on the cutting tip quite simple, a small boring bar/ internal grooving tool could be made the same way I suppose.

 

[John Hasler]

I wonder how a lead-filled piece of schedule 160 pipe would work out as a boring bar. Or a piece of a scrapped rifle barrel fiilled with lead.

 

[lotechman]

Other than general durability will hardened drill rod make for a more ridged boring bar than normalized rod? If the Young's modulus doesn't change with hardening wouldn't that mean the stiffness would remain the same? Sorry but everything I learn is from reading so I might have that all messed up.

Cheers
Shawn

Yes almost no difference in Young's modulus. Stiffness and vibration damping is what is wanted. Strength really doesn't matter... well almost doesn't matter. The frame of a machine tool works on the same principle.... stiffness is primary.