Ball Turning Attachment

[bug_hunter]

Hey Guys,

Working on a ball turning attachment, and need a little insight. I'm working on a attachment similar to the Holescreek design, but for a smaller lathe. It will go on a South Bend 9c. I presume that I should be working around a carbide insert cutter, but know nothing about carbide inserts as everything I turn, I use HSS. The turner will use a triangular insert, and I will be cutting aluminum, mild steel, and acetal. Can someone out there give me a little direction on an insert to choose? Seems like there are a large number of letters and numbers in each manufacturers selection of inserts. I am looking for a relatively inexpensive box of ten, that will most likely last me near eternity. Most likely will go the ebay, aliexpress, or "from a friend" route. Doubt I'll go to MSC or McMaster as quality level and shipping are above where I need to be.

Any help would be appreciated.

Thanks,

Greg

 

[extropic]

Carbide is not a magic solution in all circumstances. In general, to get the best performance out of it, carbide requires a stiffer machine and higher speeds and feeds than HSS. If you are comfortable with HSS and can sharpen it, I recommend you stick with it.

HSS can be had in indexable insert forms. Also, just because it's an indexable insert doesn't mean you can't resharpen it.
The supplier linked below specializes in HSS. Browse the catalog and see what you think. There may be other brands available also.

Standard and Specialty Inserts

Here is a link to a breakdown of insert nomenclature that may help find what you're looking for.

Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle,

Carbide Insert Designation Chart

www.carbidedepot.com

Also,

Insert Templates

 

[mksj]

You need to determine the size insert if using carbide, so most likely either a 1/4" inscribed circle 21.5X (TCMT11020X, TCGT11020X) or 3/8" inscribed circle 32.5X (TCMT16T30X, TCGT16T30X), M = molded, G = ground, X is the nose radius. I use a different style of carbide insert, but I find that the ground edge inserts with a slightly rounder nose radius (CCGT 21.52 or TCGT110208; CCGT 32.52 TCGT16T308) work best in my ball turner. If you go more steel, then you may want to look at a molded type insert TCMT rated for steel/stainless steel or cast iron, as these type of inserts tend to have a sharper positive rake edge. The Korloy are pretty cheap in a ground edge profile, so might be a good starting point, otherwise the Seco listed below may work ok. Ball turner you tend to want a sharper positive rake edge, and a bit more nose radius so it does not dig into the material when turning.


Korloy TCGT110208-AK H01 TCGT21.52-AK H01

10Pcs Korloy TCGT110208-AK H01 TCGT21.52-AK H01 CNC Aluminum Inserts | eBay

Find many great new & used options and get the best deals for 10Pcs Korloy TCGT110208-AK H01 TCGT21.52-AK H01 CNC Aluminum Inserts at the best online prices at eBay! Free shipping for many products!

www.ebay.com

SECO TCMT21.52-MF2 TCMT110208-MF2 New Carbide Inserts 49683 Grade TP3501

SECO TCMT21.52-MF2 TCMT110208-MF2 New Carbide Inserts 49683 Grade TP3501 10pcs | eBay

Quantity: 10 Inserts.

www.ebay.com

Korloy TCGT16T308-AK H01 TCGT32.52-AK H01

Korloy TCGT16T308-AK H01 TCGT32.52-AK H01 CNC Carbide Inserts for aluminum | eBay

Find many great new & used options and get the best deals for Korloy TCGT16T308-AK H01 TCGT32.52-AK H01 CNC Carbide Inserts for aluminum at the best online prices at eBay! Free shipping for many products!

www.ebay.com

SECO TCGT32.52F TCGT16T308F AL KX EDP 15875

SECO TCGT32.52F TCGT16T308F AL KX EDP 15875 (Lot of 10 Inserts) | eBay

Find many great new & used options and get the best deals for SECO TCGT32.52F TCGT16T308F AL KX EDP 15875 (Lot of 10 Inserts) at the best online prices at eBay! Free shipping for many products!

www.ebay.com

SECO 2960407, TCMT32.52-F1, TCMT16T308-F1 TP1501, Carbide Inserts

***Pack of 10, SECO 2960407, TCMT32.52-F1, TCMT16T308-F1 TP1501, Carbide Inserts | eBay

Find many great new & used options and get the best deals for ***Pack of 10, SECO 2960407, TCMT32.52-F1, TCMT16T308-F1 TP1501, Carbide Inserts at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Search results for: 'tcgt'

tormach.com

 

[bug_hunter]

Thanks guys. Things are getting a lot clearer. Couple more questions:

When using a ball turner, should I expect to need to use a different insert for aluminum versus mild steel (different relief angle)?

Does the "inscribed circle" go to the flats of the triangle or the points of the triangle?

Thanks again!

 

[bill70j]

Greg:

I built the Holescreek model several years ago for a 13" lathe, so copied his design pretty much verbatim, except for the center height difference of my lathe which is slightly different than his.

I attached a copy of the Fusion 360 drawings that show detailed dimensions of the tool holder, the insert supports, and the inserts themselves. Pages 6, 7, and 9 show details of the holder, supports, and inserts. Maybe these drawings will be useful in some way.

I have used the tool with good success on stainless as well as aluminum, brass, and Delrin - all with the same insert.

I used TNMG322 carbide inserts, but for your 9" lathe, you could probably go smaller, and scale the tool holder and insert supports proportionately. You can use the chart that @extropic shows above to pick a different insert. The TNMG insert has a zero deg relief so the holder is milled to provide a "general" 5 deg relief. This allows for six cutting edges.

Here is one suggestion that might work. Look at this TCMT11 . It is smaller than the TNMG3 (11mm cutting edge length vs. 0.375" IC), but also has a 7 deg refief, so you would want to machine the holder or the insert supports to achieve the refief you're after. You get 10 for $9.00. They will last for your eternity (and mine).

HTH, Bill

 

[bug_hunter]

Bill,

Thanks a lot for the insight. Also, thanks a lot for the drawings. Did a lot of searching for them, with very little luck. Also contacted "Holescreek" with no luck. His website is there, but none of the download links work. The drawings came over as ,pdf's. Any chance you have the .dxf's of the 2D set? If not. no big deal, I can do some "to my scale" redrawing. I'll probably not use the dovetail, as I think that is beyond my skill level.

Thanks again,

Greg

 

[bill70j]

Bill,

Thanks a lot for the insight. Also, thanks a lot for the drawings. Did a lot of searching for them, with very little luck. Also contacted "Holescreek" with no luck. His website is there, but none of the download links work. The drawings came over as ,pdf's. Any chance you have the .dxf's of the 2D set? If not. no big deal, I can do some "to my scale" redrawing. I'll probably not use the dovetail, as I think that is beyond my skill level.

Thanks again,

Greg

Greg:

I use the free version of Fusion, so don't believe I'm allowed to export the model files. If you are a Fusion user, I believe you can access my files through sharing.

Bill

 

[great white]

Bill,

Thanks a lot for the insight. Also, thanks a lot for the drawings. Did a lot of searching for them, with very little luck. Also contacted "Holescreek" with no luck. His website is there, but none of the download links work. The drawings came over as ,pdf's. Any chance you have the .dxf's of the 2D set? If not. no big deal, I can do some "to my scale" redrawing. I'll probably not use the dovetail, as I think that is beyond my skill level.

Thanks again,

Greg

if you want the originals: https://web.archive.org/web/*/http://www.shinyobjectdesign.com/staff/paul/holescreek/downloads/*

 

[bug_hunter]

Greg:

I use the free version of Fusion, so don't believe I'm allowed to export the model files. If you are a Fusion user, I believe you can access my files through sharing.

Bill

Bill,

Thanks, but I use NanoCad. Looks like Great White posted a link to the original drawings.

Greg

 

[Parlo]

I would use a round insert for better finishes and easy to locate.