Author Topic: Insert Boring Bars - any hints or tips please?  (Read 5905 times)

Offline propforward

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Insert Boring Bars - any hints or tips please?
« on: August 31, 2018, 01:22:05 AM »
Can anyone give me some advice on what to look for in boring bars that use inserts?

I have not had much luck with my cheap set of brazed carbide boring bars. I haven't given up with that, but I want to be able to machine smaller bores than my set will allow, so I was looking around for small boring bars sets and found this:

https://www.travers.com/everede-set-1-steel-boring-bar-set-3-different-316oslash-34oslash-with-cdcd-07-cvm2-coated-inserts-right-hand/p/24-570-786/

It looks like a good, general purpose set, that will cover a good range of model engineering bores.

Comments, thoughts? I have zero experience of insert tools. I grind my own HSS tools for external machining - works plenty well enough, but I need something a bit better for boring.
Stuart

Forging ahead regardless.

Offline b.lindsey

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Re: Insert Boring Bars - any hints or tips please?
« Reply #1 on: August 31, 2018, 02:02:48 AM »
Well the description say 3 boring bars, the picture shows four but also only lists two diameters. Curious as to what is actually included :thinking:

Bill

Edit: what minimum and maximum bore sizes do you contemplate making over time?

Offline zeeprogrammer

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Re: Insert Boring Bars - any hints or tips please?
« Reply #2 on: August 31, 2018, 02:36:13 AM »
A bit pricey for me but I'm interested in seeing what you find out.

I'd bought an accusize off amazon and it's done what I want but I'm still learning.
Keep in mind...I have near 0 experience with such things.
I've had more 'luck' with cheapo carbide I got from LMS.

If you're thinking to try index versus carbide...maybe go for something cheaper or smaller and try it out?

I do like index for turning/facing but others may argue that other cutters are better.

I'm no help. I know.
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Offline propforward

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Re: Insert Boring Bars - any hints or tips please?
« Reply #3 on: August 31, 2018, 02:50:32 AM »
I'll take any opinions right now. I don't mind spending a bit on the "right" tool if it's good quality and will last, but the range of available tools is overwhelming and I don't know where to start.

I'm going to look into that accusize, just to see what it is.

Edit - that accusize looks like what I am after for larger bores.  :ThumbsUp:
« Last Edit: August 31, 2018, 02:55:29 AM by propforward »
Stuart

Forging ahead regardless.

Offline propforward

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Re: Insert Boring Bars - any hints or tips please?
« Reply #4 on: August 31, 2018, 02:53:19 AM »
Well the description say 3 boring bars, the picture shows four but also only lists two diameters. Curious as to what is actually included :thinking:

Bill

Edit: what minimum and maximum bore sizes do you contemplate making over time?

Travers descriptions are poor, they seem to use the same heading for multiple items. The set I showed has 4 different boring holders in it. At least when I read the product spec that's what it looks like to me.

I would like to bore 1/4" upwards - or do people generally just drill and ream that size, and start boring on larger diameters?
« Last Edit: August 31, 2018, 02:56:21 AM by propforward »
Stuart

Forging ahead regardless.

Offline Ian S C

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Re: Insert Boring Bars - any hints or tips please?
« Reply #5 on: August 31, 2018, 03:02:53 AM »
For the smaller sizes, stick with HSS, apiece of 1/4" HSS will grind up to make a boring bar from(in my case) 3/16" up, and seems to last for ever.  I do use carbide tools, but only for larger stuff, or as in the last big job, boring out 30 mm holes that had been gas cut to 35 mm.

Ian S C

Offline zeeprogrammer

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Re: Insert Boring Bars - any hints or tips please?
« Reply #6 on: August 31, 2018, 03:09:13 AM »
1/4" bore is pretty small. Drill then ream?
My problem with boring has been getting a large enough hole that the boring bar will fit into.
Generally on the order 7/16".
But I know some members make their own boring bars (and I don't) so their range is much different.

Please keep in mind...I really don't have the experience of others.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline crueby

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Re: Insert Boring Bars - any hints or tips please?
« Reply #7 on: August 31, 2018, 03:14:38 AM »
I like the small boring bars, mine goes to about 5/16". Great for doing sizes that I dont have reamers for, as well as square bottom holes. They also dont wander on long holes like drills can.

Offline propforward

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Re: Insert Boring Bars - any hints or tips please?
« Reply #8 on: August 31, 2018, 03:16:55 AM »
Maybe I'm trying to go too small? Maybe I should start with a 1/2" bore and figure that out first?

EDIT: crueby posted while I was typing, and sums up exactly my interest in boring holes to size.
Stuart

Forging ahead regardless.

Offline zeeprogrammer

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Re: Insert Boring Bars - any hints or tips please?
« Reply #9 on: August 31, 2018, 03:45:14 AM »
One of the things that I ran into...wasn't just the boring hole size but the depth. Keep that in mind too.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline Steamer5

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Re: Insert Boring Bars - any hints or tips please?
« Reply #10 on: August 31, 2018, 09:54:25 AM »
Hi Stuart,
 I’m no expert, I got mine from Greenwood tools in the U.K. ( not the cheapest )there bars start with one that will do 6 mm.
Range runs 6,8,10,12 mm. There site will tell you the max depth etc.
recently used my 12mm to bore a tube, 100mm, to a nice sliding fit on a 19mm rod, lots of passes with no adjustment to take out the spring.
The QCTH I made for the 20mm bar of had for 15 years is going to help lots for any bigger holes in the future! Thinking of getting some more bars to fill in the gap!

Cheers Kerrin
Get excited and make something!

Offline kvom

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Re: Insert Boring Bars - any hints or tips please?
« Reply #11 on: August 31, 2018, 12:35:58 PM »
The travers set is 4 bars with 3 different size inserts.  For small bars I use solid micro carbide bars.  Can fit a 1/4" hole but obviously limited in depth.  My goto bar for long bores uses inserts and is 3/4" diameter.

Offline Ian S C

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Re: Insert Boring Bars - any hints or tips please?
« Reply #12 on: August 31, 2018, 01:52:49 PM »
This reminds me that there is a boring bar with a carbide insert with the Box - Ford A at the Menzshed, must get it out and see what size, got about a dozen spare tips for it.
Ian S C

Offline Baner

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Re: Insert Boring Bars - any hints or tips please?
« Reply #13 on: August 31, 2018, 02:17:53 PM »
Using insert tooling in hobby situations is one of those 'can of worms' topics. The usual argument runs something like: Insert tooling is developed for high speed, high rigidity, high accuracy CNC and doesn't suit the slower, less rigid, less accurate typical hobby lathes. However, plenty of home workshop's use them successfully . You can google HSS vs Inserts and find out all about it... :o

The main flaw for the home shop user, I feel, is the cost.

For Boring Bars, a simple clamp type HSS boring bar is incredibly versatile - one bar can be used for boring, internal threading, internal grooving etc. by simply grinding the tool bit to different shapes. In the case of indexable tooling a different bar plus a different insert is needed for each of the above operations.

I think it also comes down to how you work. When I use my indexable tooling the lathe is normally screaming at top speed, showering hot blue chips everywhere. I prefer the slower, gentler HSS cuts.
But there is a time and a place for both, and plenty of pros and cons to each.

My own boring bar collection is weighted to the side of indexable tooling (for no good reason), though making a better selection of HSS clamp types is high on the 'round tuit' list.

Anyway I'd suggest buying just the one indexable bar and a couple of different inserts and try them out before dropping a ton of money on a set.

But which one to get?

There are all kinds codes that refer to different holders and inserts, but for hobby use one of the more common (and the ones I use) are designated SCLCR for the holder and CCMT 6020x (Metric) or  21.5x (US)for inserts. The codes all refer to tool geometry.

SCLCR boring bar holders for CCMT 6020x (21.5x) are available from 6mm-20mm. You can also get regular turning tool holders from 8mm-16mm. This means you only need to buy one insert style for a wide range of holders. I don't think any other common inserts fit such a range.

There are various options for CCMT. For instance, the last number in the code (x) designates corner radius at the cutting tip: 60202 (21.50) is 0.2mm, 60204 (21.52) is 0.4mm etc.  This is important for hobby lathes as the larger radius makes for more cutting pressure, so more deflection and chance of chatter etc. You can also get  CCGT 6020x which is an insert for aluminum, CCMW 60204 which is an insert made of HSS, and CCMT CBN inserts which are ceramic, made for turning hardened steel.
CCMT's are readily available and there are plenty of cheap options.

This is just basic info for one style of holder and insert. Some other common hobby holders/inserts are: SDJCR/DCMT and STFCR/TCMT though they haven't the same range of bar sizes.

And there are hundreds of others. :)

HSS boring bars are easy by comparison. They are readily made at home, or purchased fairly cheaply. There's a book by GH Thomas called Workshop Techniques that has an excellent chapter on boring in the lathe, with how tos for making small hole boring tools and HSS boring bars. (The rest of the book is good too.)
Also this video covers making HSS bars:
<a href="https://www.youtube.com/watch?v=O9d_I0A4kzg" target="_blank">http://www.youtube.com/watch?v=O9d_I0A4kzg</a>


That's maybe more information than you wanted, Stuart.  ;D
All the fun of choosing tooling...

Dave.


Offline propforward

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Re: Insert Boring Bars - any hints or tips please?
« Reply #14 on: August 31, 2018, 02:35:17 PM »


That's maybe more information than you wanted, Stuart.  ;D
All the fun of choosing tooling...

Dave.

On the contrary, this is precisely the information I was looking for. I use HSS tooling for the same reason as you - I like to work slowly in my machining. So I was looking to find a boring bar set that maybe used HSS inserts - someone posted such a tool recently, but they couldn't remember details about the tool, or brand, and it seems to me that HSS inserts are pretty much unwanted in the manufacturing world, so likely approaching unobtanium.

Thank you for your thorough and detailed post. Based on that, I'm going to try the home made HSS route first, and look up that book. If I do try an insert tool, I'll likely do as you suggest and try a single bar with the more common inserts for a larger size bore. In the meantime I'll work on some HSS.

 :ThumbsUp:
Stuart

Forging ahead regardless.

 

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