I am working on fitting the DRO for the Z axis on my mill at the moment. I am trying to reduce the rotary movement of the Quill. The quill has the usual vertical slot machined in it. There is a M10 threaded hole in the side of the head which had a grub screw in it which has the end turned down to match the slot size, almost. There is quite a bit of play.
I have turned down the end of a length of all thread to do the same job, but made it a closer fit. The all thread is long enough to extend outside the hole so I can fit a nut to lock it. This should prevent any movement from the thread fit. This is just a temporary fix, but has improved it a lot. The grub screw was only 25mm long total and just sat loose in there.
It was my intention to make a seperate piece to fit in the bottom of the hole which slides in and locates in the slot and is held in position with the all thread and locking nut. There is about 32mm of thread in the hole. The slot width is 7.32mm. As the thread is M10 which has a minor diameter of around 8.5mm there is a small amount of material which can be removed from the sides of the locating section. 8.5mm less 7.32mm. This will provide a bit more surface area to reduce future wear as apposed to the 7.32mm diameter round on the one I have made. I would make these pieces from high tensile bolts as they would be available locally. They way I see it I would make the bottom locking piece so it covered about 20mm of the thread depth leaving 12mm for the locking screw.
Any other suggestions about how I could improve on my ideas. The main reason for doing this is to reduce any sideways movement transferring thru to the DRO scale. I would like the rod that transfers the quill vertical movement to the DRO read head to be as solid as possible for accuracy, but this means that the head and scale will be subject to sideways force from the rotary movement. Is there any way to allow movement in the connection without sacrificing accuracy. The scale is a magnetic type so not super accurate.
Dean
I have turned down the end of a length of all thread to do the same job, but made it a closer fit. The all thread is long enough to extend outside the hole so I can fit a nut to lock it. This should prevent any movement from the thread fit. This is just a temporary fix, but has improved it a lot. The grub screw was only 25mm long total and just sat loose in there.
It was my intention to make a seperate piece to fit in the bottom of the hole which slides in and locates in the slot and is held in position with the all thread and locking nut. There is about 32mm of thread in the hole. The slot width is 7.32mm. As the thread is M10 which has a minor diameter of around 8.5mm there is a small amount of material which can be removed from the sides of the locating section. 8.5mm less 7.32mm. This will provide a bit more surface area to reduce future wear as apposed to the 7.32mm diameter round on the one I have made. I would make these pieces from high tensile bolts as they would be available locally. They way I see it I would make the bottom locking piece so it covered about 20mm of the thread depth leaving 12mm for the locking screw.
Any other suggestions about how I could improve on my ideas. The main reason for doing this is to reduce any sideways movement transferring thru to the DRO scale. I would like the rod that transfers the quill vertical movement to the DRO read head to be as solid as possible for accuracy, but this means that the head and scale will be subject to sideways force from the rotary movement. Is there any way to allow movement in the connection without sacrificing accuracy. The scale is a magnetic type so not super accurate.
Dean
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