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Insert type tool holders (lathe) .. new and stupid.

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  • Insert type tool holders (lathe) .. new and stupid.

    Hi there, happy Saturday Morning to ya. 4:46am around here, meds keeping me up

    I've got this Bolton 12x24 lathe that I'm only just now getting around to setting up (health issues the last 14 months got in the way ... I'm sure some of you understand).

    It has a four-*slot* rotary tool post on it (NOT the aftermarket "quick change" type .. the one on my Bolton has four positions but you have to re-shim when you replace a tool). Bolton tells me it's set up for 1/2 inch holders. Fine, I got that part. What I'm going nutso with is the replaceable carbide (?) inserts for them. I wanted to use one of those for the "left cutting and right cutting" (sorry) holders and maybe for a cutoff tool as well. It just seems smarter ... no re-shimming just to replace the stinking tip, three cutting tips per insert, all of that stuff. I notice that one insert (three cutting points) is about the same cost as one brazed tool. So for a person like myself (sortof uninitiated to all of this) it seems like a good idea to go with the insert type setups on at least two or three of the four available "slots".


    I play around with streetbikes. I'm more of a chassis guy/tube fabber than anything. So please forgive my noobishness on the lathe. I'll need to make wheel spacers, threaded weld-n standoffs and such. Mainly working with 6061 and mild steel.

    I will be doing some prototyping of some suspension ideas with some of that "delrin" or "acetal rod" as well. It's a fork-air-volume spacer idea I'm working on. I'll also be making some simple aluminum knobs for the guitar pedals that I build to feed my family. (approx. .750 OD with a .250 hole in the center and a single set screw). So just simple things for now. (We know how that whole "just for now" thing goes goes, right? Heheh!). I would imagine some threading is in the future as well. Mostly tapping, but there may be actual thread cutting coming up. I would guess that the more I use the lathe .. the more I will use the lathe.

    (I have a mill too ... geez .. as if I didn't have enough to learn about already! Being 51 years old is kinda like a rebirth in many ways. Spent thirty+ years busting ass as an adult, now in our 50's my wife and I feel like we're kinda just getting started on OUR OWN lives now .... you know the rest. )

    The different "types" of these inserts is what's driving me nuts. I cannot seem to find any conventions or whatever that explain the different part numbers of the different inserts. Some look identical to others, for instance a few of the triangular types that have no center hole ... there seem to be several but I cannot distinguish one from the other. "TPG" ... "TPU" etc ...

    Or am I just better off using brazed carbide tools? I have one of those tool grinding grinders. It's nearly brand new, I've only used to it sharpen tungsten for TIG welding so far (Why on Earth does it have a two-way motor? You can switch the direction of the motor via the front switch! Seems kinda nuts to make it so easy to accidently reverse direction when simply shutting it off .. but hey what do I know .. obviously not much!).

    Anyhow, I just do general fab with non-exotics. SS is about all I'll get into. 300 series most likely.

    So ...

    ** Are the insert type holders worth it?
    ** Can they be re-shaped of needed for some other type of cut or use if need be? I have that tool grinder I mentioned.
    ** What are the different types of inserts for (is there a chart or something?)
    ** Am I just better off using brazed tools and resharpening them until they're shot to hell?
    ** Er .. doh! ... ??

    I'm currently in the midst of these things ...

    Gettin' there.

    I'm just another dumass looking through the Enco website.

    Thanks ... Brian ...
    I make messes.

  • #2
    The acetyl and delrin a insert or brazed tool is indicated the stuff dulls tools quick.The brazed tools are by far the most economical even by china import standards, insert tools are pricey.As far as regrinding you will find most carbide tools break and can't be reground most of the time it depends on the material of coarse.I find the use of 10-15% cobalt HSS tools to be the most versatile and economical.A low speed 1800rpm grinder helps keep your temper and tools sharp.The nice thing about HSS is you can shape it to most any form and it will take a beating and cut any material that can be cut and be reground time after time.I still have tool bits from my apprentice days 25 years ago.Learn to grind your own. Pat
    I never trust a fighting man who doesn't smoke or drink.
    William Halsey

    As a Machinist & Gunsmith I like to hear how to not can't do. P.A.R.


    • #3
      Up too, left over effects from meds over the years (and its not really early by now so getting some "sleep" )

      Others way more knowledgeable will be along shortly but a place to start furthering knowledge of inserts is here:

      that's home page, "inserts" on the left column (I'd go there second), "technical resources" in the right column

      Not saying buy from them but as they carry a number of manufacturers, you get to see selections, if you want


      • #4
        Good morning Farndurk, it's 5:30 am where I'm at,
        About your inserts - there is a desigination chart.
        you can find an online copy here:

        I also found a copy in my J&L Industrial Supply catalog ( #74) and Travers tool show one in their catalog also.
        There is also a metric designation that I haven't had reason to research yet.
        While insert tooling is good, I think you'll find occasions when just a regular HHS tool will give better performance and finish on some materials (plastics, AL, soft gummy types of metals like CRS, etc)
        HSS is the prefered tool for making interrupted cuts as they handle shock better than carbide due to it being less brittle.
        It takes a little practice to learn how to properly shape and sharpen HSS
        but it's well worth the effort. Once learned, you can make your own custom form tools.
        Keep in mind that the silicone carbide and diamond grinding wheels used to sharpen carbide are not for use with HSS, just a regular, good quality grinding wheel will suffice.
        I've always considered inserts to be a consumable, and once the edges have been used up, I just toss'em. But I think there are some folks on this site that have resharpened them.
        I'll leave the tool grinder question to others that have them (it is on my list)
        Just my 2 cents worth, Happy Saturday
        I cut it twice, and it's still too short!


        • #5
          You have a grinder. Been said on other forums, learn to grind your own HSS tool bits first. Learn from what works and doesn't. Much cheaper than chipping a $12 insert. Won't work well for all materials, but for turning mild steel, they are fine.


          • #6
            PERFECT answers! I'm a total believer in DIY stuff and grinding my own HSS sounds like the shtoof.

            I took machine shop in High School in 9th and 10th grade until we moved ... AGAIN! .. this time to a rural pig-patch with a crappy school and NO vocational classes other than "general auto shop". I went to a total of twelve public schools between K and 12. (Nomadic/remarrying mom). Her and I held twenty mailing addresses between my birth and me leaving home at 17. So my education was terribly fragmented.

            Anyhow, Mr. Sigerstrom (machine shop teacher at Santa Rita) did manage to penetrate my dirtbike enfortressed brain with at least a little knowlege. I seem to be remembering a few bits and pieces about tool grinding, cutting reliefs under the edge etc ... This was 1975 when people actually had to learn artisan skills instead of more computer programming. I actually passed those two years in that class ... I think I have a c-clamp and a plumb-bob that I hade to fab for grades to show for it

            Oh yea, I'd be all about tool grinding. For instance even though I own a great 25 yr old transformer TIG welder (Miller Dialarc HF), and a 25 yr old transformer MIG welder (Lincoln SP200), I prefer to o/a bronze-weld if that is any indicator of where my head lives.

            So alright then, just google the crap out of "hss tool grinding" then? You Tube and all of that?

            I R.E.A.L.L.Y. like that idea ... I live in the desert and I am kinda into self-sufficiency (no I don't live in a missile silo ... yet).

            Although I DID spend six years working in Titan II ICBM silos when I was enlisted in the USAF on a Nuclear Security Team as a "fire team leader". No I didn't fire the missile, I just protected them and everything that had to do with them. Bla bla .. sorry ... I tend to babble. (I'm certain you haven't noticed because I do such a great job of hiding it ... )

            Anyhow, thanks for the dope. High Speed Steel tool grinding .. right? I'd bet there is an absolute shyteload of dope on that on the web ... tons of older artisans showing off their chops on the tool grinder.

            Right on then. Thanks folks.

            Farny ...
            I make messes.


            • #7
              Originally posted by Farndurk
              I'm just another dumass looking through the Enco website.

              Thanks ... Brian ...

              Brian - Can't help a bit with your stuff but had to reply when I saw the above comment. I'm 52 and have recently acquired a little mill I am rebuilding. Never touched a machine tool other than a drill press, hacksaw and file before that. I never seem to be able to spend a lot of time in the ENCO site as my head starts to spin too much - ha.

              As an electronics guy by profession, I'm used to detailed things but the sheer volume of "I never knew that" stuff starting out in machining is pretty overwhelming. Still though, I can say that it's extremely enjoyable and rewarding and forums like this are loaded with people who have a lifetime of experience and are also willing to help a new guy out. I'd be lost without it.

              Anyway, welcome to the club of 50+ characters learning new stuff !



              • #8
                A couple of books that will really help to flatten the leaarning curve.

                A used copy of "Machinery's Handbook".

                And a copy of South Bends "How to run a lathe" avalible from places like lindsay Publications.

                The Machinery's Handbook isn't really designed to be read from cover to cover, It's a referance manual. Far too many topics in it to list here. But there's real good information in it about carbide and HSS. It's also FULL of industry standards that would be very helpful to you. You could probably pick a used one up for about $20 from Ebay. The new ones are over $80

                Some real good info about HSS tool shapes in the South Bend book.

                Last edited by uncle pete; 10-22-2011, 03:55 PM.


                • #10
                  Hey, I recently hit fiddytoo myself, but I'm unlucky enough to have worked in the machining business all of my adolescent through adult life. This means two things: I never made much money, and I know far too much about all kinds of tooling.

                  You can ping me with any questions about carbide insert tooling, but no matter what do not buy any of those cheap made-in-China sets of carbide insert tooling. Do learn about and use HSS tooling first and then make a rational decision as to whether or not it does everything you need. When you can't get a task done in a time reasonable to YOU, and you have the money to invest in carbide insert toolholders and inserts, then I can help you.


                  • #11
                    I am very new to machining myself. I have been around it most of my life.

                    I started using HSS and then cheap brazed carbide tools bought on Ebay. Recently I made the jump to very good carbide insert tooling. All from Walter.

                    Unbelieveable is all I can say. The difference between quality tooling and cheap tooling is amazing as to how easy and fast it is to turn out good work.

                    This week I needed to part off a 90mm diameter part on the lathe. Put in my Walter tool and set the blade out 50mm and bam, part cut off. That was at 800rpm and power feed with me dripping on oil.

                    I just wish that the box was bigger that my tooling came in for the amount of money I spent!!!!! It sure was a small box to have 2000 Euro's of tooling it it!
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!


                    • #12
                      Holy cow, BF! A 90mm (3-1/2", approx.) cutoff at 800rpm? That's 742 surface feet per minute, or (in metric) 226m/min cutting speed. What kind of material was that, and was was the feed per rev? Width of insert?

                      I think the comparison video of that vs. yours with the reciprocating saw would be quite a contrast.

                      That 2000 Euros is more than most folks pay for their whole machine, so it's not right for everyone. However, if there's ONE tool that should be considered for switch to carbide insert tooling, it just might be the parting tool.
                      Last edited by PixMan; 10-23-2011, 09:14 AM.


                      • #13
                        Pixman, that was 90mm in diameter. So it was only a 45mm depth of cut! The material was steel.

                        I willhave to look at what the feedrate was. I just used whatever the lathe was set on at the time. The chips were flying!
                        Location: The Black Forest in Germany

                        How to become a millionaire: Start out with 10 million and take up machining as a hobby!


                        • #14
                          Originally posted by Black Forest
                          Pixman, that was 90mm in diameter. So it was only a 45mm depth of cut! The material was steel.

                          I willhave to look at what the feedrate was. I just used whatever the lathe was set on at the time. The chips were flying!
                          I do/did understand the diameter/depth of cut thing. I wrote 90mm cutoff because I always think in terms of the diameter of a part. If that was a 2mm wide parting insert & blade for a 45mm depth of cut, that's a VERY long length-to-width ratio for such a thin tool. Even if it is a 4mm wide insert, that's quite a good achievement.

                          Can you just imagine how long something like that takes with a HSS parting blade, or worse, a power-reciprocating or hand saw? I'll bet you got nice curled-up clockspring chips!


                          • #15
                            Getting back to the tooling etc......

                            You say you have a 4 way block toolholder..... OK. You can have a problem with "packing up" the tool to the right height. There IS a solution, per a ways below.

                            The GOOD thing about insert tooling is that the cutting edge is always on top, at a consistent height, so it is on-center if the block is made for the shank size of the insert holder.

                            The bad thing is that they are often the wrong thing to use, and shape is limited, etc. You will use something else to thread, etc.

                            The good thing about any carbide, insert or brazed is that it keeps an edge with 4140PH and other materials that wear down HSS.

                            The BAD thing is that it chips, is harder to grind, etc.

                            The good thing about brazed is that it too has a consistent height of edge, barring any chipbreakers etc.

                            The good thing about HSS is that it can be made ANY shape that fits inside the raw metal.

                            The BAD thing about HSS cutters is that there is a temptation to grind down the top to sharpen, which moves the edge down. Or if there is a chipbreaker, that can move the edge down, as they are often ground-in by lowering the edge. And you DO have to grind it, unless you can go to tool tag, garage, and estate sales and make a habit of buying odd shaped HSS cutters if available. And some materials wear it down so fast that you may only get one pass before you have to sharpen.

                            But generally HSS is good for the run of lathe work.

                            So, what about the 4-way toolholder?

                            So, you measure the distance from the bottom of the 4-way slots up to the spindle center. Now subtract the height of the edge on the cutters you want to use, each shank size. For HSS this will just be the cutter size, 1/2", 3/8", 5/16" or whatever the standard in your location.

                            For the brazed, probably the same. For inserts, very likely the same, but check. Typically you will need just a few shim sizes, one size per shank size.

                            The difference is the thickness of one-piece shim that you need to raise up the cutter. Make two or three of each size you need, and you will never have to fiddle with a stack of "packing" shims.

                            Someone was intelligent with the 4-way I have, and milled it with a slot for each common size from 1/4 to 1/2". Makes it easy, except that if I want to use a couple cutters of the same size, I may have more hassle, but only if both are 1/2" is there a real issue..

                            Keep eye on ball.
                            Hashim Khan