Which boring bar set

[chucketn]

I'm putting together an order for LMS (got my tax refund, which included a $300 energy credit on a new heatpump) which will include a boring bar set. I'm wondering for hobbyuse, which would serve better, HSS or carbide? Materials would be theusual Aluminum, Brass, mild steel, and cast iron. What would be yourchoice and why?

Also, being an old retired fart, I'malways looking for better ways to grind tool bits. Does anyone knowof a source for the Baldor Grinder clone like HF used to sell (46727I think)? Can't seem to find one anywhere. I had a chance on thedisplay model at my local HF when they clearanced it, but theywouldn't let me use a 20% coupon so I passed. At the time the storemanager assured me it wasn't being discontinued... I haven't beenback since.




Chuck

 

[Brian Rupnow]

Chuck---I bought a set of the brazed carbide cheapies when I got started in this hobby 5 years ago, and they have served me very well. They work fine in aluminum, brass, or steel. It was only very recently, when starting the hit and miss engine that I am now building that I had to buy a boring bar with a squared hole for an HSS insert, and that had more to do with the fact that you can't make much of an offset bore with the cheap carbide ones, because the carbide cutting edge only extends about 3/16" or less past the shank.---Brian

 

[Tin Falcon]

I have one of these fantastic tool yes a little pricey .

Tin

 

[kvom]

I have a boring bar from Mesa tools that is similar to Tin's - uses inserts. Its diameter is 3/4", so the starting hole needs to be at least that size. I also have two separate carbide single piece (not brazed) bars of different sizes for small holes. I made holders for them.

A brazed carbide bar I bought cheap on eBay didn't give a very good finish, even after regrinding. You can have it for the price of postage. It's a 3/4" shank.

 

[gus]

I have one of these fantastic tool yes a little pricey .

Tin

Hi Tin,
I bought one with your expert advice and it cut very well and very good finishing.
These Warner Boring Bars with HSS inserts cost an arm and a leg but it is every cent paid for and will last forever. Now looking at bigger boring bars.
Bought some Chinese Boring Bars and they went to the scrap bin.
Foto show Warner Boring Bar with its tool holder.

 

[MachineTom]

I am an ebay guy, For small holes .250 and up I buy solid carbide Micro 100 bits, as long as you don't break them they last a long time, they can be shaped with a diamond wheel. They are just the best I've ever used in all materials from AL to Ti. The threading bars are also the best internal threading out there.

The trick with buying these is to buy the small lots, 3-5 bars, that gives you the best price most of the time. There is a guy who was selling "Used once only on plastic" Yeah Right!! after seeing his feedback, I purchases a lot of 5, they appeared unused.

Take the money for the awful brazed carbide stuff and buy a few solid carbide bits you will not be disapointed. First go the to Micro 100 website and learn the number codes so you know what your buying, regarding , hole size, depth of reach, shank size.

For boring over 1" deep you need a real boring bar, the ones that take square HSS bits are all over ebay, and carbide insert bars are as well, if going deep like a cylinder, you want the biggest bar that can fit the cylinder and the lathe. A 1/2" boring needs a 11/16-3/4 hole to be used.

 

[OrangeAlpine]

Everede is pricey but hard to beat if your looking for "conventional" bars. I say "conventional" because the bit is triangular. They are sharpened by grinding the end of the bit.
No need to grind top and side clearance.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=227&PMITEM=377-6010

Bill

 

[Philipintexas]

I bought a cheap set of assorted size bars that use HSS bits and made my own holder, I also have a boring head and use the carbide bits that came with it for shorter holes. Between the two I have all I need.

 

[Swifty]

The best thing about solid carbide boring bars, despite being dearer to buy, is that they absorb vibration better than other bars. Allowing a bit more overhang when boring deep holes.

Paul.

 

[goldstar31]

The best thing about solid carbide boring bars, despite being dearer to buy, is that they absorb vibration better than other bars. Allowing a bit more overhang when boring deep holes.

Paul.

Could you expand this please? I've been making my own tooling for- well, a long time.

Norman

 

[Tin Falcon]

The best thing about solid carbide boring bars, despite being dearer to buy, is that they absorb vibration better than other bars. Allowing a bit more overhang when boring deep holes.

Paul.

True. Steel bar should stick out 2 1/2 times the diameter of the bar solid carbide 7 x is still good.
Tin

 

[goldstar31]

That wasn't the statement. It said that 'they absorb vibration better than other bars' not how far 'they stick out' or what the diameter is.

I think that this is Young's Modulus of Elasticity but I'm prepared to learn.

Regards

N

 

[Tin Falcon]

goldstar31: I think you and I were typing at the same time.
I was only commenting on swiftys statement not trying to answer your question.


actualy swifty made 2 statements

1 carbide absorbs vibration better than steel.
2 carbide allows the tool to stick out further than Steel.
my comment has to do with the rues of thumb for boring bars. explaining acceptable lenght not siupported buy the tool holder.
carbide is stiffer ,deflects less therefore you can have a longer boring bar of a given diameter.
Tin

 

[petertha]

Ive been eyeing this TMX 'mini' set which uses common CCMT inserts. Unfortunately I dont think they can be purchased individually like the larger ones they offer. Looks like the set is orientated to smaller bore diameter ranges I'd see myself doing moreso than big stuff though.

I bought some TMX 1/2" lathe toolholders a few years ago to try. They seem well made & cut great, at least with the particular inserts I selected. At th etime it seemed the inserts cost same or less than brazed carbide tools from local suppliers, sometimes cheaper if you can find an ebay deal on high grade USA stuff. I believe TMX originates from eastern block europe. Any feedback or comments?

 

[Swifty]

Hi Norman, I'm not saying that other boring bars are no good, just that from over 35 years experience in a toolroom, more so in the last 5 years that I worked, the advent of solid carbide boring bars solved a lot of vibration problems when turning tool steels. This was more evident in small, deep, holes. The structure of the carbide was more rigid than conventional bars. Very hard to flex a carbide bar compared to steel bars.

I made a lot of small boring bars out of solid carbide rod, used a diamond wheel to form the profile and relief required. The carbide was not held by hand, but in various fixtures when grinding. A carbide boring bar we purchased had a steel end soldered onto it to allow the use of disposable tips. This was the best of both worlds, rigid bar plus replaceable tips,
Better mention that this bar only had a 10mm dia shank, the hand made ones were about 8mm. I still use the bar with tips and some of the handmade ones.

Paul.

 

[Swifty]

Here is a link to carbide shank boring bars, partway down the page they show overhang advantage.

http://www.korloy.com/korloy_en/contents/file/207 Carbide shank boring bars.pdf

Paul.

 

[goldstar31]

I think that readers might have to forgive me but it a lot longer than a mere 35 years since I had my first experiences with carbides. I guess mid 1930's! Again, I was doing fault analysis on breakages of rockwool products way back in the early 1950's. Yep, carbides again.

But none of this is a very old man in a workshop with a somewhat equally ancient lathe. I don't have the facilities of a huge company with endless monies etc etc. I have no doubt that almost everyone here is pretty similar- not as old and perhaps not as financially viable but will raise a few similar comments when they will say, but I am only making a 'wigwam for a goose's bridle' or something similar. I've looked in my little restricted place and find that I have a boring head. I made it. I have a pair of in line boring bars to do things like Quorns and an assorted of heap of boring bars and internal thread cutting lathe tools -which- bluntly, would cost an arm and a leg-- and only be used once in when Boxing Day fell on an Ash Wednesday.

Now I was a pretty astute accountant- or so my marks and material success suggested- and I frankly wonder just how much it is going to cost the other punter if 'carbides or whatever are chosen'
Perhaps someone will add their own- perhaps as jaundiced remarks.

 

[Swifty]

Norman, I only made a comment about carbide boring bars after MachineTom mentioned that he used them. I also stated that they were dearer (so not for everyone). I have made no adverse remarks about conventional boring bars. I have lost count of the number of press tool diesets that I have bored with mild steel bars fitted with HSS tips made from broken cutters.

As far as Young's Modulus of Elasticity is concerned, I have no idea what that is, I am just speaking from practical experience.

Paul.

 

[cncjunior]

This is a reply to goldstar31
With the carbide boring bars, the bar material itself is carbide. Due to it's denser (heavier) nature, carbide doesn't vibrate as easily thus reducing chatter. Because of the reduced vibration characteristics the carbide bar can be extended further from the holder thus going deeper into the bored hole. You typically only see carbide bars using carbide inserts though. Sandvik, Kennametal, etc has them.

This is my first post so if it is garbled please bear with me.

 

[goldstar31]

But CNCJunior you have only instanced what is essentially a very small piece of carbide. The rest is steel and roughly the same as it would have been had it all been steel. What you are calling carbide- simply isn't.

Moving to the point of vibration- Paul's version of events, if a boring bar is designed only to protrude the needed depth of the bore the vibration- whatever it is, is minimised. You are NOT hanging a cutting tool at the end of some uneeded bit of metal be it carbide, tool steel or assegai.

Mine, and I have just had one out in use- simply extends to where it should be. It's actually not even hss but silver steel fashioned from a blank -on the lathe and then hardened, let down and then ground on the homemade tool and cutter grinder. It was walloping its way through 1.5 inch cast iron. from a blank sawn block and doing a 3/4" hole.

No magic, nothing up my sleeve, nothing fancy and cost virtually pennies.

Oh, and I'm NOT an engineer, I'm a weary old bean counter soul of 82! As you Yanks say 'Go figure'

Norman