Starting Over

[Clevelander]

I'm just setting up a machine shop and could use some direction on my tooling. Do I go primarly the carbide insert route our primarly the HSS route.

I'm going to be doing a fair bit of 6061-T6 work and I see the Carbide will cut a lot faster than HSS, the down side is there is no resharpening. If inserts are the way to go which particular type(s) would you recommend.

Also I'm interested in knowing why you'd use a spotting drill in place of a center drill. While talking about center drills..are the cheaper ones OK or do I need a better grade to ensure concentricity or improved tool life. Any recommendations?

And last but not least for now....tool holder for the lathe, piston or wedge type and why?

Thanks

[The Artful Bodger]

Hi, my experience is only about two years since I set up a home shop with almost no earlier experience.

I started with inserts etc then 'reverted' to HSS as I can grind the tools myself and hopefully learn something in the process plus the price of inserts became quite impractical for me.

No doubts inserts are the preferred tools for serious machinists but for a home shop, especially for someone with little or no experience I highly recommend starting (at least) with HSS. Having said that there are doubtless many old hands and professional who use HSS where appropriate.

IMHO.

[gizmo2]

I'm only repeating what I've heard, but it seems to hold true. If you have older machines they do not turn fast enough to take advantage of carbide tooling. Since I use quite a bit of scrap metal, carbide is good for cutting off the crusty stuff. I get much better finishes with hss, and have more flexibility with cutter profiles since I'm grinding my own.
The other issue, which I haven't seen discussed as much, is the QCTP's holders that are available commercially are usually set up for carbide. HSS needs more relief angle, and those holders aren't as easy to find. Easy enough to make; it's hard to have too many tool holders! I've got a wedge type Dorian tool post, like it alot, but see no reason why a piston type wouldn't serve you equally well.

[Black Forest]

I'm only repeating what I've heard, but it seems to hold true. If you have older machines they do not turn fast enough to take advantage of carbide tooling.

That is not true with the modern carbide tooling.

[Tyro 001]

Start with HSS. It's a lot cheaper and it seems like we home-shoppers are always needing a special cutter. HSS is a lot more newbie resistant; the inserts are easily broken. Inserts are great once you learn how to use your lathe, but they do work best with higher speeds and pressure than HSS.

I went with Dorian tool holders. Pricey, but almost indestructible.

Spotting drills are more durable. It's easy to break the little lubricant reservoir part of the center drill. However, if you're drilling a hole for use with a dead center, use the center drill; that's what they're for.

[Arthur.Marks]

I as well started out with the carbide inserts. I have since 'reverted' like The Artful Bodger. I have found manual machines are more accommodating to HSS. This is a result of not only speeds, but usually a lack of programmable feeds. Even with HSS, you can see a major difference if you are doing a set, defined operation a whole lot rather than onesie-twosies. Carbide's benefits are largely in the former. That said, don't discount that each has their place in a manual shop. I still keep some carbide around for things that it can only do---but the majority of my use nowadays is HSS.

[EDIT:] a response to Black Forest, yes, it is true. Carbide in 2012 is not the carbide written about in books from the 50's. That said, the material is inherently brittle. Even if the cutting edge can deal with much lower SFM or hold up incredibly under good conditions, as you lower the SFM on the cutting tool the brittleness becomes more of a factor, IME. All too easy to chip even if you are familiar with its properties. Unless you're working with a very hard material or other such, I see HSS offering more benefits than carbide in my own shop. Not least of which is price/performance ratio.

[EDIT 2:] Also worth pointing out that all the more likely purchased by a HSM, lower cost carbide-insert toolholders don't really perform that well (read: they don't support as well and exacerbate the chipping issue with carbide). The name brand ones are quite impressively priced in comparison. I guess what I am trying to say is that I found myself feeling like I was throwing money at a problem that was so simply solved--with so much more versatility offered--by switching to HSS for my primary cutting tools.

[Black_Moons]

I use HSS mainly, with carbide when its a tough job. Cutting though abrasive skins on hot rolled, roughing large quanitys of mild steel, Or trying to get a fulgy finish with a insert endmill so that I have a texture to make a clamp work better.

[rohart]

I used HSS for ages, grinding my own all the time. When I got a larger lathe, I was never very happy grinding larger tool material.

Then I came across a complete kit of carbide inserts and holders. This worked very well with the larger lathe, and I use carbide for all bulk work.

I still use HSS for boring, and for special shaped cutters, but my goto tools are carbide inserts.

So I'd advise you to get a (wedge type) post, with a lot of holders. Get a basic set of HSS tools, for cheapness, and then look for some insert holders and inserts at your leisure.

Beware carbide spotting drills - they can chip easily IMO.

[Black Forest]

I find carbide insert tooling is the most practical for me. I find the tooling I use from Walter to be very durable. The biggest plus for me is the repeatability. When HSS gets dull you take it out of the tool holder to sharpen it. Then you have esentially lost your place regarding distances. Inserts you just loosen the the insert rotate it to a new edge and go on. The only grinding I do is for the cutting tools for my shaper.

I have had no luck with brazed carbide tooling especially threading. I had much better results with HSS threading on the lathe than with brazed carbide. The inserts I bought for threading are great and give me repeatable results.

I use a Multifix tool post and think it is great.

[Carld]

Actually the small diameter tip on a center drill is for the tip of the live or dead center to have clearance, it has nothing to do with lube. Buy a 1/4" and 3/8" spot drill and it will cover most jobs.

Your better off with HSS for turning aluminum. You will need about 15 deg back rake on the cutter for best results and front clearance can be 5 to 10 deg. the side clearance depends on the feed rate. You may be better off with a lantern tool post rather than a QCTP.

If you don't have one buy an older Machinery's Handbook, preferably a #15 to #24 issue because the older ones cover things more for manual machines.