For a corner or arbitrary angle. What is the way to do it ? It doesn't have to be very accurate. I have got a hobby-grade Emco indexing table ( no ball bearing ) which can be used as an unprecise rotary table but I can't figure out how to set it up.
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How to round a corner to a wanted radius ?
- Thread starter compact8
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Find the center of t!he radius. Then center that point in the center of the rotary table. Next off set the spindle by the amount of the radius. If there is a hole in the center of the radius ,put a shaft through the hole that has a slip fit . Put the piece in the vice with the shaft resting on the top of the vice jaws. Make a series of cuts moving the part a little each cut around the shaft axes. It will produce facets that can be smoothed over with a file
This is the hardest part. If the workpiece does not have a hole, how can the center be found ? The angle to be rounded off may not be a right angle.
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- Jul 29, 2014
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If I understand your question, it’s a geometry problem. If you have any two lines, say the edges of your part, you want to draw a circle or arc tangent to both lines. The center of that arc is placed over the rotary table and proceed as Nutfarmer fully explained.
Draw the lines, extend to where they cross, then move back the same distance on each line, draw perpendiculars and where the perpendiculars cross, that’s your center, and from there to the lines is your radius. If you don’t like the way it looks, move back either more or less and repeat. This works no matter the angle the edge lines intersect at.
If there’s no hole, then the challenge is in figuring how to hold the part on your rotary table. That depends a lot on what you have available and how clever and inventive you need to be.
Draw the lines, extend to where they cross, then move back the same distance on each line, draw perpendiculars and where the perpendiculars cross, that’s your center, and from there to the lines is your radius. If you don’t like the way it looks, move back either more or less and repeat. This works no matter the angle the edge lines intersect at.
If there’s no hole, then the challenge is in figuring how to hold the part on your rotary table. That depends a lot on what you have available and how clever and inventive you need to be.
Finding the center of the arc is no problem on the drawing as I use CAD. The challenge is to locate the center on the workpiece and place it at the center of the rotary table. If the radius is large enough may be I can scribe some lines on the workpiece, align the center of the rotary table with the spindle and use a pointed tool to line up with the spindle with the arc center marked on workpiece. However if the radius is relatively small that will not be doable.
The workpiece can be held down with normal clamps so thats not a concern.
The workpiece is a polygon plate. Some of the angles are not right angle.
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- Dec 23, 2019
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Grab a pin the size of radius you want, put it in and accurate chuck.
Center the table under the spindle.
Indicate a parallel in on top of the table some distance away from where the workpiece will be and clamp it.
Place the workpiece on the table and bring the pin down to just above it.
Use an adjustable parallel between your fence and workpiece to bring one edge inline with the edge pin.
Slide it in the other direction to bring the other edge inline with the edge of the pin.
At this point, the pin should be perfectly describing the radius you want to create.
Clamp your workpiece.
Offset your table in the same direction as the fence an appropriate distance for the cutter you're using, remove the adjustable parallel and have at it.
The key here is having that fence on the table, it gives you a zero degree ref to place the part against and the rest falls into place. Joe Pi has some great RT videos that go into more depth.
Center the table under the spindle.
Indicate a parallel in on top of the table some distance away from where the workpiece will be and clamp it.
Place the workpiece on the table and bring the pin down to just above it.
Use an adjustable parallel between your fence and workpiece to bring one edge inline with the edge pin.
Slide it in the other direction to bring the other edge inline with the edge of the pin.
At this point, the pin should be perfectly describing the radius you want to create.
Clamp your workpiece.
Offset your table in the same direction as the fence an appropriate distance for the cutter you're using, remove the adjustable parallel and have at it.
The key here is having that fence on the table, it gives you a zero degree ref to place the part against and the rest falls into place. Joe Pi has some great RT videos that go into more depth.
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- Apr 22, 2016
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So put it on your rotary table (location is not critical) and attach a DTI to the locked spindle or mill head. Now sweep the DTI along one edge using X or Y travel and turn the RT till there is no deflection in the DTI. Mill that corner. Move to the next edge and repeat.
Aaron
EDIT You could also save a little time by using the parallel as Lo-Fi stated above if there are very many to do.
Aaron
EDIT You could also save a little time by using the parallel as Lo-Fi stated above if there are very many to do.
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- May 27, 2016
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- 3,479
From about 6 days ago, Quinn has been showing how on this very thing. She was after losing most of the setup time.