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OK, Convince me that A wedge Aloris type toolpost will work for me

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  • OK, Convince me that A wedge Aloris type toolpost will work for me

    Now, just to start with, I know hiow they work, I know the advantages, etc.

    This is a mechanical discussion, having to do with fitting it in place on the machine.

    background: I use HSS, brazed carbide, and carbide insert cutters up to and including 1/2" square, possibly a few 5/8". For ALL tools the cutting edge is at the TOP of the thickness, due to the type of 4-way post I use. I use some cutoff insert tooling that is 3/4" tall from bottom of shanks to the cutting edge, as well as whatever 1/2" HSS item looks like it will do the job of cutoff that I need done.

    here is the important part..... The distance from the spindle centerline down to the top of the compound is 0.912" on this Logan 200.

    AND, I already know that hanging the toolholder way out to the side so that it can go down next to the compound is a lousy idea, especially when I keep the compound at 29.5 deg. Because to clear the corner, it has to be just way way out off the compound.... even firther than if the compound were set with the travel at 90 deg to the spindle The thing that will be "compound" in that case is likely to be the leverage, particularly with a cutoff tool.

    So, is the thickness of the toolholder bottom going to preclude the use of the larger tools, and limit tools to just the 1/4" and maybe the 3/8" sizes? Are the 3/4" cutoff tools just too big, as it seems they must be?

    Because if so, that is a severe limitation that I would not pay money (i.e. buy a toolholder) to be subjected to. I have, and use, mostly the larger tooling, not because I really need the strength, but because that is what I have, lots of it, in HSS. brazed, and insert. Having to bin all that just to use a QCTP would not seem to be any great advantage.

    Hanging the holder off the side of the compound seems like a poor compromise, when it adds the better part of an inch overhang to the side. I prefer to have the center of pressure over the compound, even if there may not be actual direct-to-the-surface support under it. That keeps the "torque" applied to the compound to a minimum.
    1601

    Keep eye on ball.
    Hashim Khan

  • #2
    If you are most concerned about rigidity and don't need to use the compound too often, a solid tool post would give you the most rigidity. A quality QCTP shouldn't be a factor

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    • #3
      I didn't follow through and analyze all of the dimensions you gave; but yes, you can easily find yourself unable to lower the holder enough to get the cutting point of a tall cutter down to the center line.

      For a 13" lathe the recommended QCTP sizes (the B and C) overlap. I first bought a C size for my lathe and quickly found the lowest height to still be too high for some tool bits. My local source let me exchange for the B size.

      It's too bad they don't make the dovetails in the holders the same size for all. Or at least those two.
      Last edited by lynnl; 07-22-2019, 12:23 AM.

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      • #4
        here is the important part..... The distance from the spindle centerline down to the top of the compound is 0.912" on this Logan 200.
        I have one of the AXA wedge knockoffs. The 250-101-XL tool holders I bought have a slot that's 0.640" high and measure 0.418" from the bottom
        of the slot to the bottom of the tool holder. So with the tool holder sitting all the way down onto the compound, the top of a 1/2" bit will be 0.918"
        above the compound or 0.006" too high.

        Comment


        • #5
          Sounds as if the 1/2" would be a bit dicey, some probably would not work, others might. And the insert cutoff tools would have to be tossed because the holders would not even take them..

          Not sure I would see that as a win, overall.

          Originally posted by RB211 View Post
          If you are most concerned about rigidity and don't need to use the compound too often, a solid tool post would give you the most rigidity. ....
          That is what I have, basically, it is a solid block 4 way, not a ratcheting type, but the slots are each made up for a particular size cutter. There are 1/4", 5/16", 3/8" and 1/2", set up so the height is right, and there is no wobbly stack of packing needed.

          Some of the advantages of a QCTP could be of benefit, If I do not have to give up too much. But it seems from what I read here that I'd be forced to hang the holders off the side, and take the hit in overhung lever arm twisting the compound.
          1601

          Keep eye on ball.
          Hashim Khan

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          • #6
            Lantern tool post.
            With a threaded ring for tool location and height adjustment.

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            • #7
              I sat my tool holders on their side in the mill and ran a carbide cutter thru them to make the tool holder slots wider. Use carbide cause they are dang hard!

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              • #8
                Just a heads up Jerry. Both Shars and Precision Matthews list the dimensions of the 250-101-XL as follows:

                That suggests the distance from the bottom of the slot to the bottom of the tool holder is 0.938" - 0.625" = 0.313". Not even close to the 0.418" I measured.

                Here is someone who measured a pair of these holders in July of 2015:
                https://www.hobby-machinist.com/thre...97/post-319366
                Spoiler alert, they came in at 0.411" and 0.415".

                If you want to make this work for 1/2" tooling, I would suggest removing 0.030" to 0.050" from the bottom of the tool holders. It's a non-critical surface
                and you are only trying to gain a little clearance. If you want to make this work for 5/8" tooling, I think the amount of material you need to remove may
                start to compromise the tool holder (my opinion, no facts to back it up).

                Comment


                • #9
                  Just to keep the "noise" down, this is the current toolpost, which is very solid and quite adaptable to most any task. The only reason I would change is to get an advantage in convenience without giving up much if anything in rigidity or size of tooling. (I use a different block for the insert cutoff tools or boring bars).

                  The insert tooling shown in the post in the pic is 1/2", and the HSS in the other is also. I have lots of that size.

                  I have no idea why I would change from this to anything other than some workable form of QCTP. This is stable, solid, and fits all sizes of cutters with no "packing". It does all the things that are needed for the "TP" portion of "QCTP", the part lacking is the "QC" part.



                  1601

                  Keep eye on ball.
                  Hashim Khan

                  Comment


                  • #10
                    I ran into a lighter weight version of the same problem with my own lathe and an Aloris style holder. My 12x36 has just 1.18" from center axis to top of the compound. So a slightly scaled up version of your problem.

                    In a weak moment when I found a BXA sized Aloris clone piston tool post on sale for very cheap I also dove in and bought it. While it is listed as being the proper size I find it quite clunky and boxy. It's just visually in the way and when I use it I find myself always rubbernecking to see around it.

                    And my buddy I'd reported on here earlier with a South Bend 9" has an AXA. On a smaller scale I again find that to be a bit clunky and boxy for the size of the machine. But it doesn't visually get in the way as badly.

                    Like you're saying I'm also a big fan of keeping the cutting tip of the tool as close to being located over as much metal of the compound as I can. Likely for the same reasons. Those being reduced chatter risk and just a more solid and precise cut.

                    My thinking is that for a Logan and similar size lathes that I think I'd go primarily for a maximum of 3/8" for cutting tools with square shanks used in the normal holders..

                    For the bigger inserts and given our home shop options I think I'd go for custom made dovetail holders that directly mount the inserts. I'd either machine the insert pockets myself if the insert shape is not too extreme or I'd look at making holders without a lower shelf and attach cut down square shanks into the corner notch directly. Options for securing the square shanks to these open bottom holders would be silver solder, brazing, a bit of delicate TIG or screws.

                    Due to how hard some shanks are screwing them into place would likely require buying a couple of solid carbide drills or drills and counter sink. For up to 1/2" shank I'm thinking a couple or three 10-32 screws. For larger I'd go with 1/4-28.

                    Comment


                    • #11
                      Hi,

                      Choosing a tool post, no matter the size, is going to constrain tooling size. And for what a Logan 200 is capable of, 3/8" tools are plenty large enough, (just because a 1/2" tool will fit, doesn't mean you need to or even should). And 1/4" or 5/16" HSS tools are large enough. For carbide insert use, 10mm insert holds are plenty fine. And if you buy a "kit" tool post set, you will get a cut off tool holder properly sized, use that.

                      Worrying about the "extra" stress of hanging the tool post over the edge some, is somewhat misplaced. Your machine is perfectly capable to handle the stresses of a tool post that has a bit of overhang. It's not like you are taking .2"[email protected]"Rev. In 30 years I've seen a whole bunch of stupid, (sometimes me), and never have I seen a worn or broken compound because the tool post was over hanging a bit. If there was damage it was caused by a crash.

                      For your lovely little Logan, get either an AXA size and use a riser under it or get a BXA and mill the bottoms off of you need a bit more clearance. Or turn your compound parallel to the ways. It ain't no big, lots of ways around this.
                      If you think you understand what is going on, you haven't been paying attention.

                      Comment


                      • #12
                        Seems like a lot of trouble and compromises in order to pay money for a QCTP......

                        Normally, when I buy tooling, I expect it to make life easier, not involve me in a big project, not force me to abandon the tools I have and buy new, etc.

                        Sounds as if I just to not need a QCTP for this machine. Maybe for one of the others.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          Hi,

                          Perhaps you don't need a Aloris tool post. Nothing wrong with that, not everything is for everyone or instance. That's why there are so many different types to choose from. So look for something else instead. But understand, ANY tool post you choose WILL lock you into a particular size and type of tooling. Ain't no "One Size Fits All" here.

                          As far as tooling size, well to be blunt, you perhaps chose poorly. Commercial shops are awash in such choices that no longer fit they way they work. Why do you think you got to buy all that "cheap" tooling off of ebay? Needs change and if things aren't working the way you want, cut your loses and change.
                          If you think you understand what is going on, you haven't been paying attention.

                          Comment


                          • #14
                            Originally posted by dalee100 View Post
                            Hi,

                            Choosing a tool post, no matter the size, is going to constrain tooling size. And for what a Logan 200 is capable of, 3/8" tools are plenty large enough, (just because a 1/2" tool will fit, doesn't mean you need to or even should). And 1/4" or 5/16" HSS tools are large enough. For carbide insert use, 10mm insert holds are plenty fine. And if you buy a "kit" tool post set, you will get a cut off tool holder properly sized, use that.

                            Worrying about the "extra" stress of hanging the tool post over the edge some, is somewhat misplaced. Your machine is perfectly capable to handle the stresses of a tool post that has a bit of overhang. It's not like you are taking .2"[email protected]"Rev. In 30 years I've seen a whole bunch of stupid, (sometimes me), and never have I seen a worn or broken compound because the tool post was over hanging a bit. If there was damage it was caused by a crash.

                            For your lovely little Logan, get either an AXA size and use a riser under it or get a BXA and mill the bottoms off of you need a bit more clearance. Or turn your compound parallel to the ways. It ain't no big, lots of ways around this.
                            I agree with much of this. But not with some other things.

                            On the overhang issue I'm sure no one is expecting the tool post to lever the compound so hard that something breaks. But having the cutting point cantilevered out away from the direct line of support does introduce a lot of flexing issues through the parts and dovetails trying to lever up against the required play so they can move. So smoother cuts with less risk of chatter are going to come with the cutting tool being directly above the main body of metal. And on lighter lathes (the Logan being at the upper end of what I'd consider "lighter") this is very much something to be avoided.

                            On the sizing issue an AXA would not require a riser. But a BXA would be not only incredible overkill but I'd venture the thought that the tooling would often get in it's own way. The distance of a cutting tip from the center support axis compared to the cross slide travel would often mean that some of the cross slide travel would not be usable. A tool post that keeps the cutting tip of the tool in closer to the pivot axis of the tool post reduces this issue. I'm sure we've all had examples of this when we needed to shift the tool post around to make a particular cut and found that the cutting tip is now a good 2 inches or more further in or out and have to crank the cross slide to compensate. That's cross slide travel that is "lost" due to the tool post arrangement. Normally not a big deal. But now and then on bigger facing cuts it's caused me problems and having to shift around the compound to compensate.

                            For this and the cantilever issue and the smaller visual "brick" in front of my face I'm a fan of a shorter design with a smaller "swing diameter" . That is provided the tool post does not become so small that it starts to be a source of flexing of it's own.

                            Comment


                            • #15
                              Originally posted by dalee100 View Post
                              Hi,

                              Perhaps you don't need a Aloris tool post. Nothing wrong with that, not everything is for everyone or instance. That's why there are so many different types to choose from. So look for something else instead. But understand, ANY tool post you choose WILL lock you into a particular size and type of tooling. Ain't no "One Size Fits All" here.

                              As far as tooling size, well to be blunt, you perhaps chose poorly. Commercial shops are awash in such choices that no longer fit they way they work. Why do you think you got to buy all that "cheap" tooling off of ebay? Needs change and if things aren't working the way you want, cut your loses and change.
                              Actually, I LIKE the size tools I have. I CAN USE the little minilahe 1/4" bits. I have a slot for them. I have them, and I even use them.

                              I have other sizes also, with slots for them also, and I do sometimes do a parting-off operation, where the typical tool is just about ALWAYS 5/8" or 3/4" tall, at least for the insert tooling types. Likely why I often use ground HSS blanks for parting off.

                              I have never bought item #1 off ebay..... And the most trouble I have with size is caused by more modern insert tooling, much of which was bought new. not too much available in the 1/4" shank size with insert tooling..... the action is in the 1/2" and above, some in the 3/8" 10mm.

                              What is arguable is that if I can be said to have "chosen poorly", it is in buying too small a lathe, I ought to have bought something in the 14" area. I'd not argue with that very much. One might blame the relatively tall compound of the Logan for causing the problems.

                              Options are to hang the toolpost off the edge of the compound, taking the added flex as a cost of doing business, or remove the compound and crosslide and replace it with a t-slot crosslide intead, using a block of appropriate size as the replacement for the compound, or perhaps putting the block on the existing compound mounting and crosslide. That way I could make the toolpost fit the machine. I have a t-slot crosslide, although I do not know that I wish to do any of the above just to get the use of a QCTP.
                              Last edited by J Tiers; 07-22-2019, 03:38 PM.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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