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threading the shank of a router bit

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  • threading the shank of a router bit

    Hi, I have a router bit with a 1/2" shank. I am not able to attach a collet adapter to my 30mm shaper spindle. But the spindle has an internally thraeded hole. So I want to cut the proper thread to the router bit shank. But how can I hold the router bit in the chuck?

    Here is the picture of the bit:

    Last edited by taydin; 01-13-2011, 07:00 AM.

  • #2
    I am contemplating the following scheme:

    Turn a disk out of 10mm thick steel. The ID will be about the shank diameter of the router bit, the OD will be larger than the router bit cutter diameter. Then cut the disk and use a screw to secure the disk around the shank. Then chuck the disk to the lathe and use a dial indicator to verify that the shank is concentric to the chuck axis. Then cut the thread. Will this work?

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    • #3
      You should probably first find out if the shaft is even going to take a thread on your lathe. If the shaft is hardened, cutting that thread will be difficult at best and if it's very hard it might be impossible to do on a home lathe.

      The other concern I have is the spindle rotation of the shaper verses the router bit cutter orientation? I have understood, possibly incorrectly, that shapers and routers turned in opposite directions.

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      • #4
        Originally posted by BillDaCatt
        You should probably first find out if the shaft is even going to take a thread on your lathe. If the shaft is hardened, cutting that thread will be difficult at best and if it's very hard it might be impossible to do on a home lathe.
        The shaft doesn't seem to be hardened. I will do the file test to double check ...

        Originally posted by BillDaCatt
        The other concern I have is the spindle rotation of the shaper verses the router bit cutter orientation? I have understood, possibly incorrectly, that shapers and routers turned in opposite directions.
        The shaper spindle is reversible, so that won't be an issue. The reason I cannot use a collet adapter is because even at the lowest position of the spindle, the bit would be too high on the table.

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        • #5
          shim

          Could you just shim the top of your table with a thicker board to get the height correct?

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          • #6
            OK. One last concern. You should verify that the thread is oriented so that the bit will tighten, rather than loosen, when it makes contact with the workpiece. Otherwise the bit will unscrew itself the first time it grabs.

            edit: I like Snipe's idea of using another board as an auxiliary table to raise the surface of the table. One or two scraps of plywood should do the trick. No machining needed.
            Last edited by BillDaCatt; 01-13-2011, 08:41 AM.

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            • #7
              If you elect to use a supplementary table, Arborite or similar countertop surfacing material makes a very slippery and durable surface. Sticks to plywood or MDF or chipboard with contact cement, (or yellow glue but you have to clamp.)
              Duffy, Gatineau, Quebec

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              • #8
                Originally posted by snipe
                Could you just shim the top of your table with a thicker board to get the height correct?
                Hmm, haven't thought about that. Very good idea! The shaper fence is plenty high, so I will be able to use it as is.

                My only concern now is the top speed of the spindle, which at 10,000rpm is kind of low for a router bit. I will have to experiment with various woods and a low feed to see how it will work out...

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                • #9
                  Originally posted by BillDaCatt
                  OK. One last concern. You should verify that the thread is oriented so that the bit will tighten, rather than loosen, when it makes contact with the workpiece. Otherwise the bit will unscrew itself the first time it grabs.
                  That thread is used to tighten shaper cutters with a 30mm bore. There is a ring and a bolt that presses down this ring. I am wondering how this isn't an issue with the standart setup...

                  The same problem will happen if I build a collet adapter. The threaded part of the ER25 collet will have to be tightened to the spindle using this thread and a bolt.

                  Comment


                  • #10
                    Speed

                    You can run some bits at 10000 and get decent results - usually bits of a largish diameter.

                    The threads on my shaper spindle are quite coarse and I would think, less than ideal for what you're proposing. These threads were not machined at the factory with any intention of holding close concentric etc. etc. tolerances for the application that you are thinking of - are they even up to the task? Also you'll need to come up with a scheme to lock the bit in position as I think that you'd want to run the threads up against a shoulder as opposed to just winding the threads in as far as they go. Could you do the threading and get a bit that ran true enough to be useful? That bit will be difficult to hold and be secure enough for threading on the lathe.

                    The table shimming ideas seems like the way to go!

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                    • #11
                      Taydin- a couple of basic questions- why not use a router table? If you do not have or want spend time to make a nice one, just drill a hole in a piece of mdf and screw the router to the bottom. Clamp the mdf to a table-done. 15 minutes. And you can run the bit at the correct rpm.
                      Spacing the work up with a piece of mdf on the shaper table is a good suggestion also.

                      or- you did not specify the cut, but given a choice, I would always use a shaper cutter over a router-faster, cleaner, less chipout, less burn, etc.

                      And no, the reversing the shaper spindle will not help you, the router bit cuts in one direction only-and you can't flip it over-so if you do thread it, get the direction right!

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                      • #12
                        Originally posted by taydin
                        The shaper spindle is reversible, so that won't be an issue.
                        It will be an issue if the direction you need to run the shaper to prevent the bit from unscrewing runs the bit backwards

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                        • #13
                          Originally posted by stoneaxe
                          Taydin- a couple of basic questions- why not use a router table? If you do not have or want spend time to make a nice one, just drill a hole in a piece of mdf and screw the router to the bottom. Clamp the mdf to a table-done. 15 minutes. And you can run the bit at the correct rpm.
                          Spacing the work up with a piece of mdf on the shaper table is a good suggestion also.
                          I need to make dados, so the shaper doesn't help there. Well, it would help if the dado is very close to the edge of the board. My saw doesn't have the dado arbor (was an option I didn't buy), so unless I make one, I can't use dado blades.

                          I am very tight in space, so a router table isn't an option really. The shaper table is quite large, so if I can run a router bit there, I will be able to cut dados even in the middle of a large sheet.

                          Here is what I will try to do based on the responses: I have an ER25 collet sleeve and a number of different collets for it. I will just have to make the threaded part where the collet sleeve is tightened to. The bottom of this part will be attached to the shaper spindle using a suitable bolt. Then I will use a 18mm or 25mm sheet stock to shim the shaper table.

                          If this works for dado purpses, I'll be fine. Otherwise, I will try attaching a 20mm thick aluminum plate with a hole in it to the edge of the shaper table and then attach a high speed router to this aluminum plate. If nothing works, the final option is building the dado capable saw arbor. I have all the dimensions and with the help of the experts here, I feel confident that I can make it

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                          • #14
                            Ah- I see now- the picture of the router bit is not the bit you will use-it was just to show the idea (no way to cut a dado with a bit that has a bearing on top! )

                            What sort of saw and shaper are you using? I am running a Felder saw/shaper combination machine on one of my shop setups. That one has a special router bit spindle as an option.

                            I assume you are clamping the work to a sliding table to pass it through the router bit?

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                            • #15
                              Originally posted by stoneaxe
                              Ah- I see now- the picture of the router bit is not the bit you will use-it was just to show the idea (no way to cut a dado with a bit that has a bearing on top! )
                              Oh, OK, sorry for the confusion... I didn't notice the bearing at the top

                              Originally posted by stoneaxe
                              What sort of saw and shaper are you using? I am running a Felder saw/shaper combination machine on one of my shop setups. That one has a special router bit spindle as an option.

                              I assume you are clamping the work to a sliding table to pass it through the router bit?
                              It is a hammer c331 combo. It was an exhibit machine, so I got a very nice deal on it. But the downside was, the machine was sold "as is". No further options etc. At this point, getting the high speed spindle or the dado arbor will be very expensive. The local Felder dealer isn't very helpful.

                              Actually, there is one other option: Remove the existing shaper subsystem entirely, build a suitable flange to the table and mount a high speed router to the table.

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