DIY pizza pan drill, for small series production

[Vekke]

Hi you all,

I was wondering how to manufacture different diameter smooth hubcabs from ABS sheets. Quality needs to be good, so jigsaw is out of question. Different sizes you need because not all rims are the same diameter and the size can differ lets say in 14" rims -+5 mm easily what will fit... Max rim diameter I need would be 22.5" so guite big and the smallest pieces 10". It is not wise to order 4 pieces cutted with CNC every time you need custom hubcaps...

Idea comes from regular Google-kuvahaun tulos kohteessa http://home-decor-store.biz/pictures/SHELVING/adjustable-carbide-hole-drill.jpg

Now that wont work because we dont want a hole to the center. We need to build 4 supports to the sides of the drilling area. Supports need to have slides so the drill can go up and down straigth. You will need footholes for you support to push this big drill to ground.

Now the drill needs to be with two blades to be in balance. Both blades need to be adjustable. Power to machine would come from big electric hand drill. What you think could this work?

[Rokeby]

Longish post follows.

I am a boat builder/wood worker, but from time to time I get involved with
working sheet plastics, mostly for instrument panels, small windows, etc.
So,I have some limited experience here.

What you've shown is typically called a "wing cutter." I would be reluctant to
use it, especially where a smooth, finish is desired on the cut edge. The
difficulty with the wing cutter is that almost inevitably as the cutter gets to
the bottom of the hole it "breaks through" and then twists/tears/breaks the
hole edge somewhere along the circumference. Damn!

In general, it is recommended that holes in Plexiglas at any rate be made
with a course toothed hole saw in a sturdy drill press. Typically something
like this:

They are available in sizes from ~1/2 inch up to :

(If that saw catches on something and stalls, the operator is risking one
or even two sprained wrists. For uses like this the drill motor should
have two directly opposed handles on the sides of the drill body.)

The hole will be somewhat ragged, showing tooling marks from the drill's
teeth. To get a really smooth, finished look/feel, I have heard that you first
cut a slightly undersized hole with a hole saw, and the re-cut the hole to
desired/final size with a router with a spiral cutter. Something like this,
where the amount of material to be removed, ~1/8 in., 3 mm, is less than
the diameter of the cutter:


You'll need to make custom sized jigs for each hole size to be made
The router doesn't have to that powerful, a laminate cutter or RotoTool
should do fine:

For a more formal discussion of these matters from pro's, here's a good
place to start, See especially the PDF download at the end:
How to Fabricate Plexiglass - cutting plexiglass from ePlastics.com

[EDIT] You may also want to consider a small CNC machine to do this.
Here's one that is designed solely for sheet goods that comes as a kit
for ~$1000 USD. It may not be quite wide enough for what you need :

(I'd kill for one of these!)

Phlatprinter 3 Kit

Best of luck to you.

[Vekke]

Thanks for the info on that cutter i was planning.

Gen II idea follows also a long post

Use similar is it "uppercutter" in english also. I have one of those...

Build a sturdy table for that.
Under that sliding axis centered to the milling drill, which can be locked to correct length/radius. on top of that axis rotating table from Ikea, where measuring will start.

1. To attach the plastic sheet to rotating table use some sticky "gum" or twosided tape etc.
2. Now first you need to measure radius from the drill centre to rotating tables centre.

3. After this you can start the uppercutter and lower it to the sheet. Lock it
4. Start rotating the table.

If everything goes as planned you would have a round pizza pan cutted smootly at correct diameter.

This should be even more easier to built than that evo1
I knew that first setup was really bad for wrists, but that was first thing what came in to my mind.

Any thoughts on this setup?



Yes some cnc machine is on planned shopping list, but at the moment no 1000€ to invest one. So I have to figure something out to work things around... Also this might help someone else who is struggling to find correct size pizza pans.

[Rokeby]

I think I misunderstood what you wanted to do.
I thought you wanted to cut holes inside the disc. Oops.

Swinging either the router/cutter or the material in a circle isn't
that hard to do. It sounds like you're on the right track. The trick
is to hold the material securely so that it doesn't vibrate or shift
away from the cutter.

On simple CNC machine cut routines, the cutter doesn't completely
cut around the item as it cuts. Little tabs about 2-3 mm are left
uncut at 2 or more places on the perimeter. This way the piece
does not move relative to the material outside the cut and the cut
is accurate.

The tabs are removed by hand later.

When making a circle, the radius of the cut has to take into
account the diameter of the cutter. The set-up radius needs to be
the desired radius + .5 cutter diameter. (On cut routines involving
both inside and outside cuts, convex and concave curves, the .5
cutter diameter shifts and can be a source of inaccuracy if not
tracked carefully. First rate cutting programs take this into
account.)

[Vekke]

First pizza pan made with my own cutter . Tolerance is +-1mm at the moment, but I have to make better thing to hold the sheet on place than that two sided tape. Its not holding strong enough.

DIY Pizza pan cutter.jpg - Windows Live

Havent installed the radius gauge/tape yet, but that should not be a problem. cutting quality is the same as my subcontractors CNC milled FleXcaps. It should be because I am using the same 6mm milling head as they do .

Maybe I will even build a electronically rotating table then it will be really pro machine