Announcement

Collapse
No announcement yet.

QCTP string gasket - whats its purpose?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • QCTP string gasket - whats its purpose?

    So I've got myself an Aloris wedge style QTCP clone as an upgrade for the lathe. Following standard procedure I stripped it down to clean and deburr, but wasn't expecting to see what appears to be a string gasket on the rotating body part of the toolpost, it only goes around 3/4 the length of the slot and fits completely in the slot depth.

    Any idea what function it serves? Is it just a case of badly copying a feature without understanding function?

    Thanks - Andy

  • #2
    You don't say whether your clone was new or used. My guess is that it should be felt and its function is as an oil holder. Or, some knitting yarn got in and found a neat niche to hide in.

    Comment


    • #3
      I did a brief write up on the one I bought here:
      https://bbs.homeshopmachinist.net/fo...qctp-from-cdco

      Mine also came with a flimsy gasket that goes in the groove of the drive screw as shown in the picture. The drive screw has some up/down play
      depending on whether the wedges are being pulled loose or tight. I suspect the gasket is meant to keep debris out of the threads of the drive screw.

      Click image for larger version

Name:	qctp6.jpg
Views:	398
Size:	57.8 KB
ID:	1837495

      Comment


      • #4
        Felt oil / dust seal that was either too short from the start or moved. Poor design if it doesn't stay in place. May have been cut short from the start. With "clone" Aloris tool posts who knows.

        JL...............

        Comment


        • #5
          Thanks guys,

          It was new "from the factory" so to speak, so unless there was some part time knitting going on...

          RichR, I did have a vague memory of having seen a similar image before, I'm pretty sure I must have seen your write up when researching what to buy. I think there has been further cost savings, mine is without the hole on the side.

          I'll replace it with something full length that is a better fit.

          Andy

          Comment


          • #6
            I have seen references to a piece of felt that creates a light drag on the handle. Maybe that is the function? Or is it to keep coolant and chips out?

            Comment


            • #7
              I found the same thing on mine. I assumed it does the same job as felt way wipers: keep the swarf and gunk out of the mechanism. Mine was a wee bit longer than necessary. So I was pleased.

              Best Regards,
              Bob

              Comment


              • #8
                I have never seen one of those tool posts taken apart before. The bloody thing is hollow - no meat to it. I assumed that there were moving parts inside them, but it is far worse than I could have possibly imagined. No wonder people complain.

                Make yourself a real man's tool post. One that is rock solid.



                This tool post offers:

                Rock solid stability: the post is solid steel with only a central hole for the mounting stud.
                And the tool holders wrap around the post with a very large area of contact: the post and tool holder are like one, solid piece of steel.

                Excellent repeatability: There is a large flat and height adjustment screw that provide repeat positioning that is well better than 0.001" in all three axis.

                Fast, One Hand Tool Change: This design offers a very fast tool change. A tool holder can be removed with ONE hand, NO TOOLS, and using ONE continuous motion. The installation of the new tool holder is equally fast and easy. Quick tool changes are the essential idea behind a QCTP and this design offers the fastest possible tool change.

                Independent Adjustments: Tool height, angle, position, all adjustments are independent of each other to the maximum extent possible.

                Self Cleaning: There is virtually no place for chips or other debris to hide. The action of installing a tool holder wipes the mating surfaces clean. And if you insist on cleaning them, those surfaces are readily accessible so cleaning is a matter of a fast wipe. There are no hard to reach corners.

                No Dovetail: The dovetail of many tool posts offers a very small area of contact between the post and the tool holder. This can have negative effects on the positional accuracy, repeatability, and rigidity. And it is harder to make. This design offers an easy to machine, round post with a generous flat for accurate positioning and rock solid rigidity.

                Here are several ways to obtain the article with photos and drawings:

                Original Article:
                Quick-change Tool Post, Feb-Mar 2010 Machinist's Workshop
                https://secure.villagepress.com/stor...oup/319/page/4

                Free Download of later version:
                https://groups.yahoo.com/neo/groups/MachiningTips/files/Lathe%20Accessories/

                Latest version:
                https://www.homemadetools.net/forum/...st-lathe-52118





                Originally posted by RichR View Post
                I did a brief write up on the one I bought here:
                https://bbs.homeshopmachinist.net/fo...qctp-from-cdco

                Mine also came with a flimsy gasket that goes in the groove of the drive screw as shown in the picture. The drive screw has some up/down play
                depending on whether the wedges are being pulled loose or tight. I suspect the gasket is meant to keep debris out of the threads of the drive screw.

                Click image for larger version  Name:	qctp6.jpg Views:	115 Size:	57.8 KB ID:	1837495
                Last edited by Paul Alciatore; 11-08-2019, 06:38 PM.
                Paul A.

                Make it fit.
                You can't win and there is a penalty for trying!

                Comment


                • #9
                  Originally posted by Paul Alciatore View Post
                  I have never seen one of those tool posts taken apart before. The bloody thing is hollow - no meat to it. I assumed that there were moving parts inside them, but it is far worse than I could have possibly imagined. No wonder people complain.
                  ....
                  Once it is tightened down, the "hollow" deal is probably much reduced, as a lot of it will be compressed together by the clamp force on the holder, And the holder becomes part of the structure.

                  Is there not a heavy duty type with just one dovetail? Seems like I remember that.
                  1601

                  Keep eye on ball.
                  Hashim Khan

                  Comment


                  • #10
                    This may be silly , but does tge string maybe hold some parts together while you assemble it ?

                    Comment


                    • #11
                      Click image for larger version  Name:	Aloris Thread.jpg Views:	0 Size:	154.7 KB ID:	1837606
                      I don't criticize Andy for his purchase ( you do what you do or can sometimes) but His photo
                      shows the kind of quality that most Aloris impersonators have.
                      Here is a genuine Aloris worm. Sorry for not getting all the grease off, but you can see the
                      beautiful ground surfaces on the thread on this hardened part. No dings or roughness
                      The low pixel count on the photo may not show how smooth it really is

                      The string ?

                      The shouldered tube which clamps the worm within the body , is about .001 to .002" longer than the worm when fully tighened
                      and the groove to prevent chips from entering the assembly is packed with lubricated packing as seen here.
                      The material is similar to graphite yarn used in steam valve and piston packings. It is very dense and smooth
                      Rich

                      Comment


                      • #12
                        Thanks Rich for that picture of the "real deal", makes sense seeing the "proper" gasket there.

                        Yes the quality is no-where near the Aloris, but I wasn't expecting it to be for the price, a little fettling has been applied to remove some of the burrs and dings and its definitely functional for my shop.

                        Comment


                        • #13
                          A real Aloris will repeat a tool within 0.0001". Easily proven by cutting multiple parts moving only the tool on and off the post. Years ago I had a pile of Aloris holders from an auction and was starting up a new business. I didn't think I could afford an Aloris so I bought a Yuasa set. Then I found out the Aloris tools wouldn't fit the Yuasa post but the Yuasa tools would fit an Aloris! That pissed me off so much I sold the Yuasa and bought the genuine Aloris. It was still on my last lathe that I sold two weeks ago after 30 years.

                          Comment


                          • #14
                            Yeah Gary, Aloris is neat. Most folks don't know the rule that you need to control " Six Degrees of Freedom"
                            When you do that effectively, you gain repeatability and Aloris has done that amazing well
                            Rich

                            Comment


                            • #15
                              Originally posted by Paul Alciatore View Post
                              I have never seen one of those tool posts taken apart before. The bloody thing is hollow - no meat to it. I assumed that there were moving parts inside them, but it is far worse than I could have possibly imagined. No wonder people complain.
                              -Complain? I'm not sure I've ever heard of anyone complain about an Aloris-style toolpost, apart from complaining about the quality, when they buy the absolute cheapest bargain-bin twelve-for-a-dollar-off-Bangood copy. I have never once heard anyone complain about a Phase II or Shars copy, apart from the usual gripe about soft setscrews on the toolholders.

                              Make yourself a real man's tool post. One that is rock solid.
                              -While that's still a nice toolpost (and has been in each of the 276 times you've posted it ) the fact is, the Aloris style, even a cheap copy, is more than sufficiently strong to hold up to whatever we can throw at it. Virtually all the cutting forces are straight down, in compression, and the 'wall' of the post is plenty thick for that. Really, the adjusting nut stud, generally being in tension, is the "weakest link" in the system, and I've never heard of anyone so much as bending one of those studs, let alone breaking it. (I'm sure it's happened, but it's rare- a nasty crash situation, etc.)

                              Most of us here use the AXA size on a lathe with an average of about 1 HP. We simply don't have the power or rigidity to damage even a cheap import of at least moderate quality

                              I've had Phase II AXAs on both my small lathes- the Logan starting around 2000, and the Sheldon came with one in '08. I use one or the other damn near daily, and have been ever since I got them. I've never had a single problem with either one- they're repeatable enough for the now-CNC-converted Logan, strong enough to take the biggest cut I dare on the 3HP Sheldon, and, of course, if and when I've needed more tool blocks, I can get them for between $9 and $15 each by mailorder.

                              Yes, yours is a neat design, but there's a reason- several reasons- the Aloris style has lasted so many decades, and is still so popular today- and it ain't because of, or despite, any weakness.

                              Doc.
                              Doc's Machine. (Probably not what you expect.)

                              Comment

                              Working...
                              X