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  • steady rest idea

    Just wanted to run this past you all. I found the steady rest I had made some years ago. I don't like it now- it's corroded and hard to adjust, besides which it doesn't line up all that well behind the cutter. That depends on the tool holder geometry, but in any event, I'm going to make a more suitable one. Here's a sketch of what I had in mind.


    Two ball bearings mount on a fork which slides in a groove. The fork is clamped in position wherever it works. The vertical plate is attached to a bridge which mounts to the carriage, and clears the crosslide. The plate can be positioned anywhere on the bridge that lines it up where it's wanted. The ball bearings can be mounted in any of about four holes each. I've shown only one extra hole for the sake of clarity. When set in suitable holes, the slide can be adjusted so both bearings come to bear on the workpiece at the same time. The groove is set at 45 degrees and is centered on the spindle axis. The fork is likewise marked and drilled to place the bearings in precise spots such that the only adjustment required is to slide the fork till both bearings touch, which they should simultaneously. Each position of the bearings would accomodate a range of workpiece diameters, with the idea being that it's not critical that they touch only at the exact side and top of the workpiece.

    I think that by making the groove at precisely 45 and aimed directly centered with the spindle axis, plus careful layout of the bearing locations, I can avoid having to make individual bearing placement adjustments when the workpiece diameter changes.

    Comments, ideas-
    Last edited by darryl; 01-30-2010, 10:28 PM.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    That is called a follower rest. A steady rest has three fingers and wraps around the work.

    The follower rest in the photo mounts on the carriage and runs behind the cutter or leading it. The two rollers need to be independent of each other so they can be adjusted for small to large diameter work.

    I missed the extra holes for the rollers and that may work but the long arms may get in the way of the work. You also need more clearance under the bottom roller for bigger work.
    Last edited by Carld; 01-30-2010, 11:44 PM.
    It's only ink and paper

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    • #3
      I've never seen a follower rest with both bearings mounted on one slide. There's probably a good reason for that.

      Rotating bearings will cause problems when chips are caught between the outer race and the work. They will deflect the work and ruin the surface, get stuck in the finished surface, or cause loads high enough to push the follower rest out of position. Brass inserts are much more forgiving on all counts.

      Google "follower rest" and look at the images for some better ideas.

      I wouldn't worry too much about accomodating large work. You won't need a follower for that, unless it's very long or very flexible.
      Any products mentioned in my posts have been endorsed by their manufacturer.

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      • #4
        I wonder if an adaption of a knurler might be a reasonable tool - in particular, a scissors type tool with smooth rollers, of course.

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        • #5
          Oh, sorry- I mistyped. I meant follower rest, not steady rest. I did realize a while ago that mounting the bearings in farther would leave a finger sticking out- as I was just in the shop measuring things out, it seems they will get in the way, and if I accomodate that, it will severely limit the diameter of workpiece I could use it for.

          I've just been tinkering with another layout- same plate with angled slot idea, but with the bearings on arms which pivot, and are locked to each other with gear teeth. (there's the scissor idea). Playing with some parts on the bench, it looks like I can accomodate a 6 inch diameter workpiece, and go down to less than 1/4 inch diameter, while only having to move the slide about an inch to match that range. If I don't move the slide at all (or don't have it at all) it can handle a 4 inch diameter workpiece and go down to about 1 1/2 inch. (mistyped again, edited dimension) While doing this, the contact points vary from top and side somewhat. I'm not sure that's going to work, but it would be nice if I didn't have to use a slide mechanism at all.

          That idea is intriguing- I'll have to lay it out in cardboard to see how well it might work. The diameter of the bearings is very important- seems that 3/4 inch would work just about right. On the subject of bearings, yes I have felt that it's not ideal because of the chip jamming factor.

          Yes, I do realize that the plate has to clear the workpiece- my drawing could have but didn't show that. I'm off to get a sandwich now and think about this some more.
          Last edited by darryl; 01-31-2010, 01:20 AM.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Well, the tuna sandwich worked! I got some other ideas. I laid it out using some gears I had that I'll use to sync the bearing arms together with. Using available materials I can build it to get a 3 1/2 inch diameter capacity, and I can use brass discs or blocks in place of the ball bearings if I want to. If there's a lot of one diameter that I would need to do for some project, I can always mount a cutter in the chuck and bore the two blocks in place for the exact diameter of the workpiece. I will be using a groove to guide the sliding bearing holder- it appears that's the only way I'm going to get a good geometry between the bearings and the workpiece, especially to include diameters down to 1/8 inch or so. If I use brass blocks instead of ball bearings, I can fully surround a 1/16 inch wire if I wanted to.

            I'll start by building the mounting base to fit the carriage, then work out the fastening of the upright to the base. After that, I'll put a center drill in the chuck, then run the carriage up to it to get a mark for spindle axis. With that as a guide, I'll mill the groove for the sliding part, then mark the spindle axis on the sliding part with it in place. Locating the bearing stud centers will also be done using the center drill in the chuck, and mirror image symmetry will be used to get both bearing arms drilled exactly the same.

            There will likely be a small error when swinging the arms against a workpiece. One bearing will touch and the other will have a small gap, most likely. I can accommodate that by moving the mounting base fore or aft by some small amount. I could either drill for a locating pin at this point, or just use it like that.

            Sound like a plan?
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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            • #7
              I like the concept of the follower rest your building. Last night after shutting the 'puter off I was thinking about it and thought if there is some way to pivot the bearing holder on the sliding finger you may have a good tool. Today you posted just such an idea.

              Having the bearings open and close and pivot as well may be a great idea and as said by another, you don't really need a follower rest on large work but it never hurts to be able to go to 5-6".

              Post your tool as it progresses, I may like to copy it .
              It's only ink and paper

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              • #8
                Having the relative positions of both fingers fingers fixed will require you to make it to a much higher degree of precision than two separatdely adjustable fingers.

                Phil

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                • #9
                  Originally posted by Carld
                  . The two rollers need to be independent of each other so they can be adjusted for small to large diameter work.
                  Carl is right.

                  With both rollers on the same mount there will always be a diam. that is to big or to small to fit this devise, maybe OK for in between sizes. The roller will also limit the smaller size diameter's that can be held against them as opposed to small bronze bearing surface's.
                  The shortest distance between two points is a circle of infinite diameter.

                  Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                  Southwestern Ontario. Canada

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                  • #10
                    I think you have something there, how about something like this coming in straight from the back, You wouldn't use it for large dia. work anyway.

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                    • #11
                      The job of the follower rest is to keep the work from rising from the force of the cut. For that reason one roller has to be on top of the shaft. Where the rear one is located can vary as long as it keeps the work from going to the rear.

                      The modification darryl described in an above post may be the solution as it will allow adjustment of where the rollers touch the work. Whether it proves better than the style currently used will be seen when he makes one to test.
                      It's only ink and paper

                      Comment


                      • #12
                        Originally posted by Carld
                        The job of the follower rest is to keep the work from rising from the force of the cut. For that reason one roller has to be on top of the shaft. Where the rear one is located can vary as long as it keeps the work from going to the rear.

                        The modification darryl described in an above post may be the solution as it will allow adjustment of where the rollers touch the work. Whether it proves better than the style currently used will be seen when he makes one to test.
                        As in my drawing I don't beleave the shaft can move up down or towards the rear IMO

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                        • #13
                          First let me point out that I am an amateur and maybe that is why I tried what I did. I thought the brass points on my followers were kind of crude and wondered why they, and others I had seen, were not bearings instead of the brass rubbing on the surface, just cheaper to build that way I reasoned. Simple enough to remedy so I ordered some small roller bearings from Enco and made up a set of 3 "fingers" (don't know what to call them, I told you I am an amateur ) for my steady rest using the bearings on the tips. What I soon discovered was exactly what was mentioned a couple of posts back and that is the problem of chips getting under the bearings and causing problems. I did this on my steady rest and intended to do the same to the follower rest but decided against it, I can see where it might cause more problems there than on the steady. Just thought this might be of interest but I guess it is entirely possible I did something wrong like maybe the bearings were too big, I have since tossed them aside and replaced the brass pieces which don't seem to be a problem anyway.

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                          • #14
                            I'm thinking to install a wiper which would come up from the bottom and spring load against the workpiece to help the bearings out. I can see it being likely that I'll scrap the bearing idea and just use blocks. This can all be after-the-fact changes and won't affect the way the mechanism works.

                            I just spend the afternoon so far trying to come up with a mount arrangement to hold the bridge plate above and parallel to the crosslide. The carriage has enough flat spots in somewhat suitable areas to bolt things to, but I have to clear the gib screws and the way wiper area on one side. So far that is the most complex piece of the base, and it's now pretty much done. After I mark the locations for mounting holes, I'll prop up the apron and remove the carriage to drill and tap the holes. It's work, but it's time again anyway to clean and inspect the 'guts'.

                            The last time I removed the carriage, I wanted to install a way oiling system, but I didn't do it then. If I can prepare for it by drilling and tapping some holes, maybe I'll get that done this time.

                            Once again, I've nearly lost track of the the little project that started me on this follower rest, and now there's another 'little' project mixed in with it all

                            Must be coffee time. Yep!
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                            Comment


                            • #15
                              digr, the top roller needs to be on the top of the shaft or very near it. On the small shaft you show it may work but on the larger shaft the force of the cut will push the shaft back and the top roller may tend to force the shaft back forward again and set up an oscillation or vibration in the cut. You need a roller to stop the shaft from lifting and a roller behind to keep the work a set distance from the cutter.
                              It's only ink and paper

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