Insert IC size selection

[Ischgl99]

I need to get an SCLC toolholder since the tool I have now isn’t offset for facing cuts on anything larger than about 1.5”. I use an AXA size post, so will be ordering a 1/2” toolholder and it is available with insert IC sizes of 1/4 or 3/8” depending on the brand. I have a lot of 21.5x inserts for my existing turning and boring tools and would have to buy new inserts if I went with a 32.5x sized toolholder.

Does the 32.5x insert size offer much, or any advantage, over a 21.5x insert for a 2hp 1236T lathe? The smaller inserts are a bit cheaper, but not enough that it really matters in the long run. I already have a hodge podge of toolholders and inserts I bought over the years that I am working on dwindling down to only what I really need, so it would be nice if I could stick with the smaller size inserts to reduce the variety of what I have on hand, but if the larger ones have an advantage, then I would go with them.

 

[mksj]

I would stick with the 21.5X inserts if that is what you mostly use. Not much advantage to adding 32.5X other than being able to take a deeper cut, and you will be Hp limited for some materials. The 21.5X also works well for many boring bars 1/2" or smaller, 5/8 and 3/4" I would use a 32.5X. Not sure there is most of a difference in cost between the two sizes, there does seem to be more insert options in the 32.5X but not really relevant for a hobbyist.

 

[Ischgl99]

Thanks Mark, that’s what I was leaning towards, but you make a good point that I would need 32.5x inserts if I wanted larger than 1/2” boring bars. I was looking at latheinserts.com at the insert prices, it’s a $2 different between the two sizes, I haven’t checked prices at other places yet, but the inserts I got from them for my DCMT holder are working very well and planned on getting some CCMT from them as well for whichever size I decide on.