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  • Lazy newbie question

    I know there are undoubtedly print sources but does anyone know what the minimum total thickness of a faceplate would need to be if I want to cut a small "T" slot ..."small" being relative, how about "useful"...

  • #2
    Consider tapping some rows of holes. Less fuss. Can adapt later on.
    The thickness depends on the type of lathe and the work you want to do on it.
    You can keep it fairly thin when using tapped holes instead of T-slots.
    But beefier is better.

    Wer anderen etwas vorgedacht, ....... When you propose a solution for someone's problem,
    wird jahrelang nur ausgelacht. ....... you will be ridiculed for years.
    Begreift man die Entdeckung endlich, ....... When the discovery is finally understood,
    so nennt sie jeder selbstverstÙ†ndlich. ....... everyone will say it is obvious.
    -- Wilhelm Busch --


    • #3
      Direct answer to your question : I have a 4" rotary table and the plate is 14.5mm thick. This gives pretty minimal T-slots.

      Indirect answer : I haven't got around to making a proper faceplate yet, but for years I've got by with a 7.5mm thick disc of hot rolled with loads of holes and slots in it, some to a 60 deg pattern, some to a 90 deg pattern. I just mount on it, and then hold it in my three jaw. It'll hold anything that's not too enormous. The holes and slots just grew over time.

      All the slots are 8mm, and a lot of the bolts I use are 8mm coach bolts with the square part of the shank filed down to 8mm, so they slot in the slots, so's to speak.

      I make new centre bushes to centralise work as and when.


      • #4
        Err, Id wonder exactly where you plan to put these T slots

        If your making round T-slots all the way around, I think you'd seriously weaken the outside of the faceplate if you made it too thin.. And unlike a rotary table, a faceplate might be 10" around doing 2,000rpm.. Not something you want to let go, especialy if its made from chinese cast iron pea soup.

        If they where from the inside (leaving a decent 'hub) to the outside, you can probley get away with more since you still have a decent chunk of faceplate holding itself togethor...

        Also realise that at some point, you will be turning an offset load, and might suffer a tool crash someday, So stress on the faceplate could jump wayy higher then typical.

        Rohart: What size T-slots? kinda sounds like a 3/8" wide t slot or something. (1/4" studs?)
        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


        • #5
          Originally posted by RussZHC
          I know there are undoubtedly print sources but does anyone know what the minimum total thickness of a faceplate would need to be if I want to cut a small "T" slot ..."small" being relative, how about "useful"...
          You can always add tee slots to an existing faceplate as shown here:



          • #6
            BM: Yes, 1/2" deep, 1/4" studs. Radial slots of course. But that only leaves 2mm or 5/64ths under the slot. That's viewing it from the side. I haven't dismantled it (well I have, but I didn't check for thickness at the time) so the plate could be thicker than the 14.5mm I quoted.

            I find that if I draw something out on paper I usually decide pretty quickly if I think it's up to the job. The problem is that I usually end up weakening the job during the construction. Either I cut too much off somewhere, or I make it out of cold rolled and it warps, so I have to cut more off to straighten it out. So don't forget to add in a stupidity/safety factor when you're designing your faceplate, or any project for that matter.


            • #7
              A faceplate does not have to have slots at all. it can be loaded with tapped holes, dowels or any other bolt on fixture. I like a face plate thats nothing more than a circle of steel you chuck up and drill and tap holes for anything.


              • #8
                You don't need to cut into your faceplate at all. Get a steel disc the same diameter as the faceplate and about 1/4 to 3/8 thick. Mark the center, then using a compass draw a circle about 3/4 inch in from the outer circumference. If you want 4 radial slots, mark out 4 equally spaced holes on that drawn circle. Drill those and the center hole to 3/8 inch diameter. Insert a pin into the center hole, then another pin in one of the other holes. Holding a straight edge against both pins, scribe a line between them. Once you have all the slots marked out this way on both sides of the pins, you mount the disc concentrically to your faceplate using standoffs. These could be 3/8 long sections of round bar drilled to pass the mounting bolts through them. Use as many as you have to or are able to to support each pie shaped segment of the disc, leaving room either side of every slot for the t-nuts you will be using to fasten things with.

                Note that you will likely be running interference with any slots that might be on the faceplate already. Rotate the disc against the faceplate til you have the best amount of meat between the disc and the faceplate to give you lots of mounting bolts. A better idea- maybe you can use the existing slots and some custom spacers to mount the disc. Certainly, if you have the same number of slots in your disc as the faceplate has, this would be the way to mount the disc. If your faceplate has 8 slots, and you want 4 in your adapter, this will work also. If your faceplate has six slots, consider making the adapter jig with six slots as well. The center of each pie shaped segment of the disc will be directly over a slot in the faceplate. Under every slot in the disc there would be a flat metal bottom, which is the surface of the faceplate.

                Once each pie shaped segment of the disc is secured with at least two countersunk bolts, you can then turn the center hole out to what might be the size of your spindle through hole. You can also true up the OD of the disc, and turn the surface of the disc so it runs true. Clean all that up and then make some t-nuts to suit.

                Take care with the countersunk bolt heads when you're facing the disc. If you did your homework right, you'd have used some grade 8 hardware and you'd want them flush with the surface once you're done facing. You don't want them to be recessed, but you also don't want to be taking too much off the heads.

                If you put a center in the tailstock, you can use that to center the disc to position it against the faceplate when you are mounting it.

                I've suggested 3/8 wide slots so you can use 3/8 hardware to mount things with. There's considerably more meat on that diameter than on 1/4 inch bolts, but suit yourself.

                You have a couple more options- if you want this jig to be removable so you can use the faceplate as is, then you can epoxy the countersunk bolts and the spacers to the disc, which means it all stays together as a unit. The jig is then mounted by running up some nuts from the back of the faceplate. The bolts never turn from this point on. This is how I'd do it anyway. The custom spacers would have a turned down portion that fits in the existing slots of the faceplate. With care, and with mounting the jig the same way each time, you'll be able to remove and remount it and have it pretty much concentric with the spindle each time.
                Last edited by darryl; 08-04-2010, 10:41 PM.
                I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                • #9

                  Thanks for the ideas so far.
                  I received some blank plates, except for the spindle thread, meant for backing plain back chucks or at least that was the original intention but in looking at them there will need to be a fair bit of work done for that "custom" fit, as expected.

                  However given the meatiness of the plates as is, I began to wonder if removing a lot of the metal, in diameter as well as thickness in areas, to fit to chucks was necessarily the best or only use.
                  I have more than one and would consider getting more if an idea like "T" slots (or better Darryl's version ) gave me a lot of flexibility in terms of use...also recall seeing that older lathes had such as an accessory.