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Slotters and Their Tooling

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  • Slotters and Their Tooling

    I was looking at the UK site at different shapers and noticed references to slotters.

    So many tools and so little time....;< )

    Since I have not seen one in person, I have some questions.

    For the small home shop, how useful is a slotter?

    Were there small slotters made that would fit in a home shop?

    What tooling and accessories does a slotter use?

    Are the cutting tools the same as a shaper?

    How does one set up a slotter so the tool doesn't bottom out on the work platform but yet still maintain a rigid setup?

    There seems to be many more shapers around than there are slotters...why?

    If anyone has a slotter, I would like to hear more about it and how you use it.



  • #2
    Rhodes sold small shapers and vertical slotters that shared the same basic machine design. The shaper was rated at 7" and the slotter at 3", I think, both referring to ram travel.

    I have the Rhodes 7" shaper and scored what looks like most or all of the parts to convert it to the slotter. I'd guess that the slotter uses standard HSS bits ground to the desired form for the application, mounted in an extension holder, and that the work would be clamped to the table on relatively thick parallels or 1-2-3 blocks. I've no real clue there, though.

    Mike Henry near Chicago


    • #3
      Thanks for post.

      Any idea if there were other small slotters like the Rhodes built?

      Considering how common shapers were, I would expect more slotters to be in use.,,,kind of like horizontal versus vertical mills.



      • #4
        Generic post on slotters.

        Roughly speaking they can be divided into attachments and machines but someone will pull me up on this, rememeber, Generic.

        The attachments were made to fit horizontal and vertical mills to increase their capability.
        They drove off the main spindle of the machine, some had an adjustable stroke and were limited to about 3" or 4" stroke.
        Many could be inclined to do tapered work.

        Main uses of these were splines and internal keys with a bit of external work where shart corners were needed.
        Aimed at R&D, repair and toolrooms more than production work.

        Later came the free standing attachments that are commonly seen on the rear of Bridgeport rams. Also made by other manufacturers these were the next step up in that they supplied their own motive power from a their own motor.

        Next generation was the dedicated slotting machine.
        Not in a time scale but as an upgrade.
        These evolved as the beeds for slots and keyways above what the attachments could do meant they had to be far greater in mass to cope with the tooling loads.
        You only have to swop a single point tool on the lathe for one with a large radius to realise the greater forces and rigidity needed.
        This is why many people have problems parting off, the fact that the machine isn't rigid enough for the tool width.
        Noe transpose this to a long bore that needs a 3/8" wide keyway thru it.

        True many operation can be done on a shaper, after all a slotter is only a vertical shaper but by transposing the work ram thru 90 degrees you gain a lot of advantages. Rigidity and ease of use being the greater two.

        If you compare a slot put in on a shaper you have two main problem areas. One is the work is supported on an angle plate or similar and is therefore relaint on the stiffness of the plate and the fact it trying to work at 90 degrees to the slide movement.
        The second is you are workig blind as the tool is entering the work from the opposite side to which you have access.
        If it's a blind bore this is even worse.

        Now that same slot done on a slotter is working to push the work down vertically onto the largest mass of the machine, the base.
        At the same time you now have a clear access to the work and tool entry.
        This swapping of the axis now means you have the facility to mount a rotary tabel with proportions and mass far greater than a shaper can handle.

        Now to the questions.
        Slotters are usefull, just how much depends on your work and range of work.
        Small slotters start at about 4" but that transposes to about a 12" or 14" shaper size.
        Unlike shapers with grow in proportion slotters grow out of proportion by a factor of 2 or 3. An 8" sloote can be twice the size of a 4" one, some even bigger.

        Most slotters have an inbuilt rotary table so other than a chuck or other clamping means there isn't a lot more needed,

        Tooling is the same as a shaper and is cheap home ground HSS bits.
        Shapers like slotters don't like carbide because of the interupted cut althoug there are now some grades that can handle this.

        The ram is adjustable on a slotter so you can adjust both stroke and position.
        It's normal to set this at the bottom of the stroke so you tool is either claer of the work or enters a run off groove or drilled hole.

        Slotters can be defined as a specialised form of shaper hence their rariety.
        For many uses a shaper can be used but for specialised slotting and spline work then the slotter rules.

        Again only generic and doesn't cover high speed production methods like internal and external broaching.

        John S.


        Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


        • #5
          Very good posting John...thanks

          What you cover in your discussion corresponds with what I have seen in the marketplace including the scaling up in size.

          How well does the slotting attachment to the Bridgeport work? I would think having the slotter and its motor hanging out on the arm of the Bridgeport would not be very stable.

          I would imagine that a slotter attachment on a horizontal mill would be more rigid.


          [This message has been edited by Too_Many_Tools (edited 03-20-2005).]