Purchasing my first boring bars

SharkTamer · Jan 20, 2017

I'm a very green machinist so bare with me if I say something stupid

. I work at a welding fabrication shop doing CAD design and I am moving a lathe I purchased last year into a building on premises. I'll have access 24/7 to my lathe, and the mills and welding machines if I provide my own tooling and materials. Some work we get right now requires really simple machining (mostly boring ~6" i.d. pipe) that I could now do on the clock while also getting paid a price per part for using my machine and tooling. My lathe is a summit 14 with an aloris axa tool post. I have a good amount of aloris holders that came with the lathe and tool post.

I'm basically looking for suggestions on boring bars assuming most of what I'll be boring is crappy low grade 6-8" pipe. I don't mind investing a little money into good tools, but I'm still on a tight budget so I'll most likely be buying second hand on ebay. I'm not used to buying my own tooling and I've always found the amount of styles of inserts a little overwhelming, so any suggestions there would be helpful. What style inserts are most affordable and will be available for the foreseeable future. Thanks in advance.

[486] · Jan 20, 2017

just make one, they're a pretty easy beginner project

here's the first one I made, along with a holder for the tool post

make it as big as you can

jscpm · Jan 21, 2017

Well, I definitely won't be baring with you, because I only get naked with women.

As far as the boring bar is concerned, maybe make a few before buying one. That way you will have some idea what you are buying.

dian · Jan 21, 2017

S16N-SDQCR7 | eBay

edit: look for dcgt 07 inserts.

John Welden · Jan 21, 2017

If you're just boring big old shit ass pipe, I'd make make my own bar. Especially if you have to bore deep into the pipe.

If you want a carbide insert bar, buy a normalish size one and weld it to the side of a big bar of steel. You could do this whole project for very cheap and you wouldn't have to machine anything. Shop made shit tooling like this is done all the time.

John Welden · Jan 21, 2017

dian said:
S16N-SDQCR7 | eBay

edit: look for dcgt 07 inserts.

It would be stupid to go with a relatively weak insert style like that for what the op wants to do.

dgfoster · Jan 21, 2017

[486] said:
just make one, they're a pretty easy beginner project
View attachment 189141
here's the first one I made, along with a holder for the tool post

make it as big as you can

In fact, I would suggest skipping the QCTP for the mount of the the boring bar. As pointed out above, rigidity is a major factor. Just get a nice beefy hunk of square bar out of your stock rack , a good beefy piece of round stock, and make something along the lines of what 486 did. Maybe use a brazed-on carbide cutter rather than HSS, though HSS would work fine too just two or three times slower.

Denis

Mike C. · Jan 21, 2017

" Maybe use a brazed-on carbide cutter rather than HSS, though HSS would work fine too just two or three times slower."

How much slower it is depends on how bad that nasty pipe decides to gum up and stick to it, chipping the carbide. HSS is really great for boring bars, as you usually have to slow down to prevent chatter, anyway. If you are running at HSS speeds anyway, just use HSS.

dian · Jan 21, 2017

John Welden said:
It would be stupid to go with a relatively weak insert style like that for what the op wants to do.

i missed the 8", but you can get them bigger, you know. they work really well. if op spends $10 and likes the result, he can make a big one like that.

dgfoster · Jan 21, 2017

Mike C. said:
" Maybe use a brazed-on carbide cutter rather than HSS, though HSS would work fine too just two or three times slower."

How much slower it is depends on how bad that nasty pipe decides to gum up and stick to it, chipping the carbide. HSS is really great for boring bars, as you usually have to slow down to prevent chatter, anyway. If you are running at HSS speeds anyway, just use HSS.

The last boring bar I made a month ago for a fab shop was double-ended. 1.25" bar. One end took HSS 3/8" cutters and the other brazed-on carbide. Use whichever end better fit the task. That is the nice thing about shop-made tools; you can customize them to suit.

Denis

CarbideBob · Jan 21, 2017

John Welden said:
It would be stupid to go with a relatively weak insert style like that for what the op wants to do.

Yes this is a weak ass insert.
One can only go .250 deep at .020 per rev with it but not in the shown bar as you will run out of front heel.
Certainly not a bar peeler at .080-.150 per rev. but I do not think the OP needs that sort of feed.
Not a 50-100 HP spindle here.
Rough stock is going to need a decent edge prep on the insert. Negative and honed will take this abuse.
Not as nice on low HP as a positive for light cuts. T-land edge is the go to but not standard unless you go with cermet which the OP may have enough speed to run at this size.
Bob

John Welden · Jan 21, 2017

CarbideBob said:
Yes this is a weak ass insert.
One can only go .250 deep at .020 per rev with it but not in the shown bar as you will run out of front heel.
Certainly not a bar peeler at .080-.150 per rev. but I do not think the OP needs that sort of feed.
Bob

There's no good reason to go with that insert style.

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dian · Jan 21, 2017

well, this insert style has solved most of my boring problems. i have plenty of very different boring bars i have been using and im switching to these, currently trying to find a carbide one. i dont buy them for $10 though and have to admit i have no need to take off 0.25" at 0.10".

also, its very easy to say go and grind your own, but not so easy to do it and come up with something that works well, especially if you have not been in the trade for many years.

CarbideBob · Jan 21, 2017

John Welden said:
There's no good reason to go with that insert style.

I do admit I do hate making them.....a royal pain to grind and hold the a and b dims,....why can't the world just use squares and triangles?
Bob

John Welden · Jan 21, 2017

CarbideBob said:
I do admit I do hate making them.....a royal pain to grind and hold the a and b dims,....why can't the world just use squares and triangles?
Bob

I just can't imagine this fab dude dinking the tip off that insert in his shitty old pipe....

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henrya · Jan 22, 2017

I'd buy these 4 items:

3/4" boring bar
A12SCLPR3

Right and left handed versions of these turning tools:
SCLPR�83V

These inserts fit all three holders above:
CPMT3252MF KC73�

If you don't have an Aloris boring bar holder for a 3/4" bar, you'll need one of those too.

Unless you need to bore more than 5-6 inches deep with minimum taper this set up will cover almost all your turning and boring.

crossthread · Jan 22, 2017

I just wanted to add something from someone who has made a boatload of boring bars. Do yourself a favor and buy round HSS blank bits. It is then very easy to drill a cross hole in your bar stock, drill a hole and tap it into the the end of the stock to hold the blank and you are done. It takes time to come up with a square hole or a flat with a keeper. Drill the hole on a 45 degree angle for blind hole boring on the other end of the bar stock. And yes make it as big as you can for the size hole you are boring. There is nothing more fun then trying to hit a spec with a springy boring bar.

Job Shopper TN · Jan 22, 2017

Dudes aren't kidding when they say make it as big as you can. We have a bar laying around somewhere, has a 2" threaded shank, bar is 4" diameter and holds a 1"-shank turning tool! Big ol' thing.

That might be the thing to do, in fact. It depends on what you have to hold it. I think having a small AXA-size tool post will limit you... If you have enough of this job to make it worth it... make a solid block with a 2" or 1.5" hole through that bolts straight to your compound. Then you can do some pretty serious boring. We have such a device made to fit 2" threaded shanks like the bar I mentioned above, or similar-styled VDI holders from our CNC lathe.

henrya · Jan 22, 2017

OP is running a 14" lathe. Probably better with high positive inserts than anything else when you consider using an AXA tool post. If you make a big honking bar you'll want to make a block that holds it directly on the cross slide. Running the big honking bar cantilevered off the AXA isn't going to be super rigid. And I wonder if you have the power for hogging cuts anyway. If the bores are very deep the shop made monster will be better. I still say buy the items I listed above. You can start with the bar and inserts and add the turning tools later as budget permits. I think you'll find you use those three tools most all the time. Its more money, but long run you'll get lots more use from them.

SharkTamer · Jan 23, 2017

Thanks for all the feedback guys. I've decided to buy a 12pc interstate brand carbide tipped boring bar set off ebay for 40 bucks just for kicks. I've also decided to follow a few suggestions on here and make my own boring bar. I have a 1" aloris boring bar holder, so I'll make a 1" boring bar to use with it. If it isn't rigid enough I'll make my own holder to attach to the compound as suggested. I also realized I said I had an AXA tool post but it actually is a BXA tool post. I did a quick search online and I think I understand the BXA is basically just a taller/larger tool post than the axa.

To henrya, I already have a right hand turning tool that came with the lathe. It uses mitsubishi inserts. It's a MCLNR-124B NE4 (Not really sure of the manufacturer). Someone has milled the shank down to fit in an aloris holder and I think the manufacturers name may have been on the top of the shank that is now gone.

Also does anyone know of a guide to making boring bars? Or suggestions on alloy to use? Thanks.

Purchasing my first boring bars

Plastic

Hot Rolled

Titanium

Titanium

Diamond

Diamond

Diamond

Diamond

Titanium

Diamond

Diamond

Diamond

Titanium

Diamond

Diamond

Titanium

Titanium

Cast Iron

Titanium

Plastic

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