Lathe tools? Boring bars

[Member 66061]

I need some advice on lathe tools. I would like to get some boring bars left/right for this holder -
http://www.ebay.co.uk/itm/Mini-Quic...241026?hash=item1c5d2be102:g:Y0YAAOSwHJhXNXGn
Preferably indexable tipped, but i know nothing about indexable carbide tips. Ive been using cheap rubbish brazed tip tools and im starting to run out of them.
I plan to get some tools with tips like these - http://www.ebay.co.uk/itm/5-x-Carbi...isted-M0142-/291771352407?hash=item43eeed8557 but would like to get boring bars first, but dont know where would be a good place to buy them.
Hopefully you could help give me a bit of education on this, thanks

 

[optima21]

that boring bar tool holder is 3/8 bore (according to the ebay listing) so you can bore it out to 10mm boring bars are more readily available (and cheaper) like these

http://www.rdgtools.co.uk/acatalog/10MM_Shank_Boring_Bars.html

these are a couple of small boring bars I have,made from round bar, the smaller one (10mm diameter) has a 1/8" carbide tip which has be ground from the shank of an old carbide burr. the larger one (12mm diameter) has a 3/16 hss bit ground from an old centre drill

 

[Member 66061]

Excellent advice, thank you, just what i needed. I ordered the boring bar you suggested and will drill the holder if i need to.
It was well worth asking here first before buying, thanks

 

[addjunkie]

Normally one of your tool holders will have a v machined on the lower tool face to accept round boring bars, failing the there is the other holder for round bar.

I use a set of these type of things....different size bars all using the same tip

 

[Kram]

Shape makes a big difference - larger radius has a wider, smoother cut, but requires more cutting power. Round gives best finish.. small round inserts if its a small lathe.. easy to make a round holder. Strange they are not more common on ebay.

A sharp endmill will cut you but most inserts are very blunt. hss often gives a better finish because they are usually sharp.. Useful to get a diamond grinding wheel - sharpen each edge about 20 times, maybe a lot more with a QCTP and some copper shim.

www.ebay.co.uk/sch/Metalworking-Milling-Welding/11804/i.html?_from=R40&_nkw=%28sdjcr%2C+sclcr%2C+SNR%2C+SER%2C+SDUCR%29

You can grind or mill them to fit your qctp if you cant get 3/8.
www.ebay.co.uk/itm/222083861295
www.ebay.co.uk/itm/381614347529

For tips, this shop is good www.jurassictools.com I have bought a few. VBMT/DCMT/CCMT/CNMG are often cheap on ebay.

If your turning non ferrous, high positive top rake inserts will give a mirror finish.

 

[optima21]

A sharp endmill will cut you but most inserts are very blunt. hss often gives a better finish because they are usually sharp.. Useful to get a diamond grinding wheel -

funny you should mention that but I've bought some of these 3/8" shank slot drills to be used as boring bars with my boring head

http://www.ebay.co.uk/itm/141638326085

 

[hareng]

Keep your eye on this ends tomorrow no substitute for quality tooling. http://www.ebay.co.uk/itm/BRAND-NEW...000791?hash=item3ac7baa3d7:g:Kp0AAOSwAPlXhTik

Boring head at time was 12mm no boring bars any good at time so reamed it out 1/2". Now find cant get 1/2" any good and have to rely on cheap Chinese Glanze the only thing usable in a set bought 15 yrs ago, live and learn buy once.

 

[Kram]

A small one is also useful. I need an exact 7.97mm hole but my hss tool is only good 9mm+ so Ill grind another.

 

[Member 66061]

Ok, i got the boring bar and drilled the holder to 10mm, now i need to get it to work. I tried it out today and it squeals and chatters like f###.
Its set on centre and i have it square to the job. So what do i do now?

 

[Pete.]

I sometimes use hss slot drills as boring tools in my lathe. It can be tricky to get the cutting edge spot on with helix angles but generally they work very well.

 

[hareng]

Ok, i got the boring bar and drilled the holder to 10mm, now i need to get it to work. I tried it out today and it squeals and chatters like f###.
Its set on centre and i have it square to the job. So what do i do now?

Speed way to slow or fast?
Cutter blunt?
Not on centre line rubbing? Too easy to be way out using various tool methods to do so, take a facing cut.
Tool flexing highly likely and what said earlier buy once and don't regret?
Too beefy a cut?
Video would come in handy.

 

[dobbslc]

Make sure it's got enough relief under the cutting edge. If it's on centre the tool itself can easily rub the hole your trying to bore, take a bit off on the grinder.
It also easy to have to much "stick out" to use a welding term and get a lot of vibration.

 

[Member 66061]

Speed way to slow or fast?
Cutter blunt?
Not on centre line rubbing? Too easy to be way out using various tool methods to do so, take a facing cut.
Tool flexing highly likely and what said earlier buy once and don't regret?
Too beefy a cut?
Video would come in handy.

TURN YOUR SPEAKERS DOWN! This truly is an awful sound
http://vid552.photobucket.com/albums/jj324/custarddribbled/VID_20160803_111121035_zpspwq78vpo.mp4
http://vid552.photobucket.com/albums/jj324/custarddribbled/VID_20160803_110741881_zpsvlsjkgru.mp4

 

[dobbslc]

I would say that part isn't far off from coming out of the chuck!
Can you turn the outer diameter and then use a steady on it?
Defiantly vibration and I would say from both the tool and part.

 

[ukracer]

TURN YOUR SPEAKERS DOWN! This truly is an awful sound
http://vid552.photobucket.com/albums/jj324/custarddribbled/VID_20160803_111121035_zpspwq78vpo.mp4
http://vid552.photobucket.com/albums/jj324/custarddribbled/VID_20160803_110741881_zpsvlsjkgru.mp4

You got a close up of the tool bit itself from a few angles.

 

[Bill Edwards]

^^^ That's nasty...

 

[hareng]

Theres movement/vibration.
Try again this time put some pressure with finger on tool purely isolate other varying things that could cause that issue. It may absorb or reduce the vibration, if so that's the problem as said earlier.
If no joy look at headstock bearings and gib strips, tubes in enough but would be better working closer.
Tubes can be iffy until trued up theyre rarely round.

 

[Member 66061]

I would say that part isn't far off from coming out of the chuck!
Can you turn the outer diameter and then use a steady on it?
Defiantly vibration and I would say from both the tool and part.

Its in the jaws tight, its not going anywhere. I faced the end before putting it in the jaws, its as true as i can get. It had already had a few cutting passes, so was true inside in the vid. I also had it slightly above centre height, which did improve things a bit.
Ive got everything tightened up as much as i can, gib strips, etc.

^^^ That's nasty...

I know thats nasy, try being next to it.
The howling, chattering and poor finish are obvious symptoms of vibration.
I got this little lathe for nothing and its done some good work, saving me money. Ive never ran it with a boring bar though.
My next four 12 hour shifts start tomorrow, so it will have to wait for now.

 

[Seadog]

There are two issues that I can see. Firstly, you're turning a piece of tube that has a large overhang, it's bound to vibrate - think wine glass and rubbing your finger around the rim. Secondly, there's a large overhang on the boring bar which is also going to vibrate. It's just not rigid enough. I'd use a much larger bar given the bore of the tube and support the outer of the part with a steady.
Also, the fact that you've what looks like a fairly thin piece of tubing, tightened in a three jaw chuck to point it's not going to move, would mean that if you were trying to finish bore this for use, and I'm assuming this is just a test piece, you would find that the jaws will have distorted the tube affecting roundness.

 

[Bill Edwards]

Its in the jaws tight, its not going anywhere.

Erm...
I've had things leave the chuck that were in tight under similar circumstances (lot of stickout without support). Tight or not it can happen.