BusyBee tool -- what inserts?

[trlvn]

Hi:

I bought a couple of lots in an auction this week. Included was a used set of BusyBee tool 3/8 inch holders:

I have zero experience with carbide tooling on my tiny Atlas 618 lathe. But I'm wondering about trying. If these holders are the same as the ones BusyBee currently sells (B1278), then they offer 3 inserts for $20:

https://www.busybeetools.com/products/carbide-insrt-c6-for-b1278-tin-coat-3pcs.html

If I wanted to buy elsewhere, how do I determine exactly which inserts to buy? Taking a rough measure on the existing inserts, I get 10.x mm long on each side and 3.0 mm thick:

A specific recommendation would be much appreciated.

Craig

 

[Alexander]

I know the insert is called a TNMG. The size is measured by the inscribed circle. calculate the largest circle that fits inside the triangle and that will help you pick the right size.

 

[YYCHM]

I have that same set. The inserts are identified as TT-221.

Craig

 

[PeterT]

Here is an ID chart that breaks down the parameters (although vendors can still vary a bit with their own lingo, coating, chip breaker, nose radius designations...).
http://www.mitsubishicarbide.com/en.../tec_turning_guide/tec_turning_identification

I would check out Ebay or AliExpress. That is a very common size & lots to choose from at lower cost. I cant imagine BB is stocking anything special.
https://www.aliexpress.com/item/400...chweb0_0,searchweb201602_2,searchweb201603_55

 

[Dabbler]

I cant imagine BB is stocking anything special

How true. and what they do stock is usually quite spendy, compared to aliexpress or banggood.

 

[trlvn]

I have that same set. The inserts are identified as TT-221.

Any idea how this relates to the coding shown on the web page that @PeterT linked to?

Could you perhaps post a picture

Craig

 

[trlvn]

Here is an ID chart that breaks down the parameters (although vendors can still vary a bit with their own lingo, coating, chip breaker, nose radius designations...).
http://www.mitsubishicarbide.com/en.../tec_turning_guide/tec_turning_identification

I would check out Ebay or AliExpress. That is a very common size & lots to choose from at lower cost. I cant imagine BB is stocking anything special.
https://www.aliexpress.com/item/400...chweb0_0,searchweb201602_2,searchweb201603_55

Thanks!

The inserts that you linked to on Aliexpress are: TNMG160404

G = zero relief angle? This seems to be common but I don't understand. Every HSS needs relief; why not carbide?

0404 = The first 04 is thickness. Does this mean I can choose the thickness? The existing inserts appear to by "03" which is 3.18 mm. "04" would be 4.76 mm which is quite a bit thicker.

The second 04 is tip radius. "04" means 0.4 mm radius. Is this a good general purpose radius for my tiny Atlas 618 lathe (with 1/2 HP motor)?

Thanks again,

Craig

 

[Brent H]

Hey Craig

these would fit your tools

Check here for the code explained:

http://www.carbidedepot.com/formulas-insert-d.htm

 

[PeterT]

Sorry Craig. I just inserted a random example just to illustrate price, not a specific recommendation. I remember flipping catalog pages on these triangle inserts before trying to find equivalent designations and it can be confusing. I don't use these particular ones myself, but similar issues regardless of inserts. Some parameters (like size) you have to get correct, others are more preference.
I'll try to point out a few things to get you going.

I think you are nominally T-C-M-T-11-03-08-F-N-MP. The 11 indicates 6.35 mm inscribed circle. The NAm? equivalent is when you see TCMT 21.5 like these.
If you look at the breakdown sheet, it lists all the corresponding parameters
https://www.traverscanada.com/terra...ndexable-carbide-turning-insert/p/22-100-132/

So sometimes entering 'TCMT 21.51' in the search bar will turn up lots of hits on NAm sites whereas TCMT 1103.. in offshore.
https://www.ebay.ca/itm/TCMT-Insert...396147?hash=item2acbf40ff3:g:YnAAAOSwMM1c2N3o

 

[PeterT]

Using the designation chart just as an example, here is how the breakdown would work. And remember, other vendors or standards may have variations to this. So its just to get you going.

 

[PeterT]

Note that your tool set has left hand, right hand & neutral tool holders. What I think most people do is use a neutral cutting direction (the 9th designation) as a jack-of-all-trades. But you can see where problems can arise. You get a smokin deal on 50 triangle inserts that happen to be left hand factory leftovers & you get strange cutting results wondering why.

You asked about nose radius. I tend to favor about 1/32" (0.8mm) or 3/64" (1.2mm) but it really depends. I do more aluminum & they hold up well with decent finish. In aluminum I also use smaller radius like 1/64 (0.4mm) good for sharp shoulders, bit less cutting force but a slightly duller finish & bit more more fragile. A wider radius like 1/16" (1.6mm) looks very shiny, takes a bit more power... & basically the tradeoffs go in the opposite direction. Dont confuse shiny with accurate, its a sequence of scallops under a microscope. You'll find whats right for your machine. Steel really isn't much different but you have to be careful about interrupted cuts & mill scale. Some people use their old tool on the first passes & save the inserts for actual cutting. Coatings & chipbreaker... its a rabbit hole & so dependent on what you are doing, speeds & feeds. I tend to buy whats cheap but in the ball park designation wise.

Yes I think its best to have back relief like the 7-deg example. I don't think you will find a lot of thickness variation once you get the other parameters fixed but just be aware if you replace an insert to re-check center.

Some of the toolholders have gone their own way on the insert fastener in terms of torx head & screw pitch. Just be aware. Whats important is the head angle. Most seem to work, just dont gronk on it.

 

[YYCHM]

Any idea how this relates to the coding shown on the web page that @PeterT linked to?

Could you perhaps post a picture

Craig

TT-221 is on the label of my BB inserts. Google TT 221 insert

https://www.traverscanada.com/borit...ndexable-carbide-turning-insert/p/24-772-468/

Craig

 

[PeterT]

Yes but on the Travers link you provided, see how you can see the ISO equivalent

 

[PeterT]

Unrelated but to make life confusing I have seen very similar triangle inserts used on milling cutters. I never got along with them very well myself, but after experimenting with other variants & gradually improving results, I started to question if the (typically offshore) toolholder maker even knew what they were doing. They generally copycat 'real' tools, but sometimes they go off on a tangent or take shortcuts. Or they find a more obscure insert designation specifically so you have to go back to them to buy replacements. Again, nothing wrong with BB if you got a deal, but you can find those toolholders dirt cheap on Ali & Ebay.

 

[trlvn]

Wow, what a can of worms!!

So I've checked the existing insert closely. Using my drill index, it most closely fits a 1/2 inch diameter hole so that makes it size "22". Also, the screw is tapered and the insert has a cutting face (+ chipbreaker) only on one side so that makes it a "T". Based on all the other postings (thanks everybody), I probably want:

TCMT220308 F-N-MP

I'll check Bangood and whatnot for some inserts to try out.

Thanks again,

Craig

 

[PeterT]

Just to be clear, on the triangular inserts its the inscribed circle (IC). 6.35 mm (1/4") agrees very well with your 10-ish mm accross an edge

 

[PeterT]

Drawing to verify. If by 1/2" you mean the insert would fit like like so. But the designation goes by (smaller) inscribed circle 6mm, not connecting the points with large circle (12.7mm = 0.5")

 

[trlvn]

Drawing to verify. If by 1/2" you mean the insert would fit like like so. But the designation goes by (smaller) inscribed circle 6mm, not connecting the points with large circle (12.7mm = 0.5")

Aha! I had totally misinterpreted that!

Trying again, it appears to be a 1/4" inscribed circle (6.35 mm) which which would be size "11". However, when I search for TCMT11, there seem to be very limited choices. None, in fact, for TCMT110308.

My head hurts. Maybe I should just stick with grinding my own HSS.

Craig

 

[YYCHM]

My head hurts. Maybe I should just stick with grinding my own HSS.

Craig

I hear you bro, I gave up trying to figure out those designations to.

TT-221 should get you what you need.

Craig

 

[Brent H]

Hey Craig,

refer to the site I posted before:

T= Triangle
C= 7° clearance
M= is the tollerance
T= tapered through hole

2= 1/4” inscribed circle
2= 1/8” thick
1= 1/64” radius on the cutter