Dome fixturing tips?

Hi.
I have encountered a slight “problem” that I wondered if any bright minds could help me solve. I started playing disc golf last summer, and during the off season I figured I should make myself a mini marker. Maybe even sell some to the locals if they want :slight_smile:
My problem is the small area for holding the piece down to the waste board while cutting.
I wish to add a “pistol grip” pattern to the edge of the disc, without tabs like I tried while testing. I’m thinking of vacuum, but I haven’t really got a clue where to start. Shout out all obvious and rare suggestions please!
Edit: The disc is 98mm (4") wide, the top of the “dome” is close to 65mm (2,5"), and the rim on the bottom is 7mm (1/4")
Top:


Bottom:

Pattern side:
Pattern

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If I understand correctly the bottom surface in contact with the wasteboard is 7mm wide ?
I would use tape & glue (in that specific case, probably multiple strips laid out all around the perimeter on the bottom)
7mm x the circumference makes for a reasonably large contact surface, and carving a pistol grip texture on the surface is not going to put huge efforts on it anyway. Pretty sure this would work.
And you’ll probably fall in love with tape & glue workholding in the process (but I’m biased)

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The “top” circle looks flat enough for tape & glue.
I would try cutting the top first, do all the checkering and then flip it over to hollow out the underside.

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It’s 7mm wide, so 23,145*0,7 would give me aprox. 22cm^2. Didn’t think it would give me that much surface… I’ll give this a go tonight! Had some issues with the painters tape and glue I have been using, so I might try another brand of both. It’s from a cheap store for a fraction of the price.

Yeah, it’s probably flat enough, but it give me an issue with getting the piece in the right place after flipping it over. Then I would have to make some sort of “cradle” to align it.

I use cheapo painter tape too

(“Dexter” is our local brand for “chi**** cr**”, several times cheaper than 3M/Blue tape)

The key for me is to use a wallpaper roller when applying the tape on each side:

image

You can get surprisingly good grip from surprisingly little surface.

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Alternatively, make the concave feature of that part 2nd. (thought process in development here).

  1. Modify the initial design such that the side that would eventually have the concave is initially an extrusion that terminates in a planar circle form. This extrusion would have tab features that would lock into a work holding jig, which you would also need to make for this crazy idea to work.
  2. After making the work holding jig, make the domed side. This would have tab features past where the original edge transitions to the concave.
  3. Separate your part from the stock, preserving the tab features. Flip it over and secure the domed side into the work holding jig that you created first, tabs would be securing the part at this point.
  4. Create tool paths for the concave feature and tool paths to remove all material up to the original edges of the concave side of the part.
  5. I’m not sure yet how to secure the dome side of part at this point… thoughts?
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I like your thoughts outside the box! I had an extrusion like you are thinking of as a part of my initial the design, and then I could add tabs who could easier be removed then as a part of a sharp edge. I guess I could do super glue and tape to hold down the finished dome in some sort of holder like you say.
I’ll have a go at it, for science :wink:

Didn’t cut all the way through on my depth, so I had more surface then I was aiming for, but I’ll go again some other night this week :slight_smile :slight_smile:

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