chip breakers for plastics (2025 Update)

I don't think any sort of classic chip breaker like for metal will work. The stuff is PLASTIC, of course, and therefore will just curl around anything like that. Some plastics also produce a HUGE static charge when cut, so the chips stick to everything.

Jon

Same thing I use for almost everything now. SC520 and distilled water. One of the very few things I use spray mist for. In fact the only thing I can think of in some years where mist is better than flood. (High (relative) rpm with no enclosure.)

Arthur R. Warner.

I don't want to get into any arguments but I grew up and did my apprenticeship in the High Speed Steel days and I must say that the way we were taught to grind high speed tool bits resulted in a substantially different tool than what I see used with "insert" type tool holders which I suspect might be better for turning something like plastic.

Hi John. HSS indexible inserts are available. Even Amazon has some. I've seen them offered with or without a chip groove and, IIRC, with a moderate amount of relief or no relief.

Granted, those variants were things I saw years ago, but I think you'll find that a few different types are offered, and some look exactly like typical carbide inserts.

Probably true as I've been totally out of the trade since 1972 and when I left we were still using HSS. In fact, thinking back, I can remember only one time we used a carbide tool to turn something and it was a hard valve insert in some sort of special valve and the HSS just wouldn't make a compete cut. (Damn! that was nearly 50 years ago :-(

But I think if I were to buy a hobby lathe today I'd still go for HSS if for no other reason than it lets you grind all sort of special bits for various projects. Back in the day a machinist would probably have ten or a dozen tool bits in his tool box that he had ground for some sort of special project over the rears.

And, if there was a bench grinder in the shop you never had to worry about dull tools :-)

My take on inserts is that they eliminate tool offset adjustments in high volume production. I'm with you on HSS but I make only one to maybe a dozen identical parts so one sharpening is enough.

The program was changed to include " pecking " and now the problem is manageable. The chips are maybe 2 feet long and can be removed by hand. Not a perfect solution, but as long as the chips are removed after machining each part, the chips do not clog the machine.

Peek is somewhat flexible and the chips can be cut with scissors. So it might be possible to make some sort of motorized cutter to cut the chips to a much shorter length, but it does not seem a high priority to do that.

Dan

Useful.

Yes, there are materials where carbide is the better choice.

There are tradeoffs. HSS for specialized tools/purposes.

Carbide inserts and a quick-change toolpost for repeated operations. The inserts can be rotated to give two, three, four, or up to six different cutting corners, depending -- and each time you do this, you don't have to re-calibrate the dial to the new length of the bit -- that is what "indexable" means. Especially useful with CNC and automatic tool changers, but useful enough with a lathe with a quick-change toolpost, and remembering the zero point for the tools where the diameter of the turned workpiece is important. And the inserts are made sufficiently precise so the zero is maintained when you finally wear out all the points on the insert and replace it with a new one. :-)

I use carbide inserts most of the time -- but still grind special tools at need -- including ones to cut ACME threads a bit too big for the insert tools which my lathe can handle.

Agreed -- but you did have to re-zero the dials after each re-sharpening. :-)

Enjoy, DoN.

Actually I was thinking of lathe tools and most of the lathes I ran, in those days, had cross feed and compound dials that could be "zeroed" to read zero (:-). Cutting threads for example you touched the tool bit to the work, to start, zeroed the cross feed and compound and then used the cross feed to retract the tool for returning to the beginning after each cut and reset to zero to begin the next cut and the compound feed to set the depth of cut.

I run a shop vac with a 2.5" line lock hose. Noisy, yes.

R Remove 333 to reply. Randy