Today in the computer room (holey disk)

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reible
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Today in the computer room (holey disk)

Post by reible »

I working on a project that might seem a bit odd at first. A holey disk. It might be though of as an indexing disk but it will serve me as a step towards a drilling jig that I want to make.

It will be 10" in diameter with 360 holes, ie one for each degree of a circle. So any angle that is a whole number would be possible. Depending on how this goes I might make another disk with say divisions of 7, 11,13,14,16,17, and 19 or perhaps some sub set of that.

The center hole is 5/8" and the other holes are 1/16" arranged as 2 arrays as seen here:
ScreenHunter 159.jpg
ScreenHunter 159.jpg (91.48 KiB) Viewed 22891 times
I plan to use my Shaper to cut the whole thing. It is going to be a lot of effort with that many holes.

The results should be reasonable but I don't expect the accuracy to be perfect, but it doesn't need to be either.

Material will be what ever plastic I might find in my collection in the 1/4" thick range.

No time table but I will try and make some time to do the whole project at one time. Really hot this week so maybe next week?? Longer away if I can't locate any suitable material and have to order something.

Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
masonsailor2
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Re: Today in the computer room (holey disk)

Post by masonsailor2 »

Interesting project Ed. The SO should be able to do that with pretty good accuracy. It will definitely take some time !
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Re: Today in the computer room (holey disk)

Post by sehast »

I think you can do one quadrant (maybe even half) and the center hole very accurately with the SO. Then you might consider doing the rest on the drill press by rotating about the center and using a peg to reference off the holes you have cut with the SO.
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reible
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Re: Today in the computer room (holey disk)

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I'm thinking I will do the whole job using the SO, but yes if it were years ago I would have used the drill press and tried to make an accurate layout and then see how well it went by drilling and then indexing. I hope the SO will yield better results with the added time being the down side.

Here is a bit more information on how I want to use this. Perhaps a sketch or two might be useful. First this is disk will be used to make other fixtures hence the large number of holes. An example might start with conversion of the hole pattern for jig that could be used in a horizontal drilling operation.

The first task is using this disk to make a jig for say 8 holes. The set-up would look something like this:
ScreenHunter 161.jpg
ScreenHunter 161.jpg (91.19 KiB) Viewed 22764 times
The resulting jig could then be used for a vertical drilling operation as seen here:
ScreenHunter 162.jpg
ScreenHunter 162.jpg (71.18 KiB) Viewed 22764 times
It could also be used to generate index disks for lathe work. Hence the mention of adding a second disk with the "odd" numbers of segments like 7,11,13....

Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
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Re: Today in the computer room (holey disk)

Post by masonsailor2 »

The SO should be able to accomplish this disc without too much problem. I used it to make an 18 sided turntable and the accuracy was pretty impressive. I did two turntable platters that were about 40” in diameter that were 18 sided and the facets were dead on to the point that I was able to mass produce the 36 pieces of edge banding using a stop block and they all fit perfectly the first time.
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Re: Today in the computer room (holey disk)

Post by sehast »

The accuracy of the SO is very much dependent on the size of the profile to be cut due to the computer vision algorithms it uses and the limits of the camera and markers on the tape. I have made some fairly rigorous measurements to determine what I could expect in accuracy. For joinery where the span is 1-2 inches I measured a repeatable accuracy of .002"-.003". For profiles out to 12" it holds to about 1/64". For profiles out to 48" it holds to 1/32". Over a full 96" it can vary from 1/8" to 1/16". Those were accuracies achieved by taking the utmost precautions during the cut. That is using a steady feedrate, keeping the tape meter full and most importantly keeping a constant orientation. If you allow the SO to change its orientation with respect to the tape these accuracies will quickly deteriorate. In this particular case of just drilling the holes it should be easier to achieve good accuracy but over 10 inches you may see as much as a 1/64" error. Cutting that in half to a 5 inch span would significantly reduce the error.
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rpd
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Re: Today in the computer room (holey disk)

Post by rpd »

A different way to achieve indexing for any desired number of segments.

[youtube]https://www.youtube.com/watch?v=PBlBJ5RWTSk[/youtube]
Ron Dyck
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reible
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Re: Today in the computer room (holey disk)

Post by reible »

361 holes in 1 hour 4 minutes according to my stopwatch.

I had planned to use a plastic but the only piece that I had that was of the correct size turned out to be less then wonderful to work with. Can you say it melted??? I can. I played with router speed, plunge speed and after very poor results I moved on. So it's BB plywood.

The other change I made was to change to a larger hole but I did that by telling the SO I had a smaller bit and it believed me silly machine. I will not get into this other then to say it worked.

And so you know it really happened:
holey1.jpg
holey1.jpg (119.95 KiB) Viewed 22427 times
This is when the holes were finished and I stopped the stop watch. I still needed to make it into a disk. And yes that happened too:
holey2.jpg
holey2.jpg (121.85 KiB) Viewed 22427 times
This part of the project is done. Not sure when I will get back to the next project where I use this but for now I'm glad to have this part done.

Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
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algale
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Re: Today in the computer room (holey disk)

Post by algale »

Amazing what you can do with that thing, Ed!
Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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