How NOT to make blanks

[jesusfwrl]

There is many ways in which you can make blank records. I will demonstrate some ways on which you probably shouldn't attempt to make blanks and save the effort for a more efficient way...
Feel free to contribute your own methods of NOT making blanks!

My most impressive attempt involved a 130000 euro water jet machine....

https://www.youtube.com/watch?v=ESeMqqLjkgo

On this video you can observe the waterjet machine destroying a perfectly good sheet of polycarbonate!
The result:



Good looking and perfectly unusable records!

This CNC waterjet machine takes a CAD drawing and cuts it into any material using a jet of water with sand mixed in.... It is meant to have great accuracy, but for some reason, the cuts are not straight and the angle means that although the accuracy is good on the top, its off at the bottom. These blanks wont even go on the spindle. Apart from this, the sand goes everywhere finding its way under the protective coating and effectively sandblasting the surface of the blank.



They might actually be good for a harsh noise project but not for much else.

I have a feeling that this guy holding the polycarbonate sheet should be wearing a respirator but I guess he thinks respirators are for the weak...

Another method of not making blanks would be using a press with a cutting die originally meant for cardboard or leather. Result:



The only thing it does it putting a tiny dent in the plastic without being really able to cut it. I did not bother making a round die for records, I just used a scrap die that someone gave me to see if it would work, which is why the shape is this trapeze of straight lines, cutting into the recorded surface of this piece of plastic. The press and die method could potentially work if one would machine a die with a suitable cutting angle for this material, but this is far too expensive just for experimenting.

Tin snips and drill:



This is by far the best result I've gotten so far. Nothing technically wrong with this method. The blanks are sort of round and it sort of works. Apart from the fact that it takes ages, gave me friction burns on my fingers and aching muscles for the next days.

My attempts were not intended for the commercial production of blanks, but merely to have some material to experiment with... I thought this might save people some time and give you a bit of a laugh.

[Bahndahn]

Holy smokes man, thanks for sharing!

I'm planning on using a standard palm-router and a circle arm/jig. Drill a hole where the center of the record should be, put in a pin that connects to the adjustable-length arm that is hooked up to the router, then plunge to router in and swivel around the center pivot.

Havent bought sheets of poly yet, so I have yet to try it but making the adjustable arm was easy enough.

[jesusfwrl]

Would a router be faster than a jig saw in the same arrangement? Or would it just produce a clearer cut?

[ROLANDJAYS]

In my opinion the best way is to cut them.
Whether its a cnc mill or router table its the best cut and pretty quick.

[Bahndahn]

Would a router be faster than a jig saw in the same arrangement? Or would it just produce a clearer cut?

Consider the blade of a router and a jig saw: the jig saw has a blade that will always have a straight section, or its 'width' from the cutting side with the teeth to opposing side without teeth. This element makes it not ideal for cutting circles. The blade would always be a little twisted as you turned around the circle. The blade of the jig saw is typically quite thin and fragile so its certainly not a great option for doing this.

The router has a circular, more robust cutting member that can cut in any direction, even downward into the disk ["plunge", provided you have a center-cutting endmill/router bit in it]. This makes it optimal for is cutting task.

[tragwag]

I used to use a band saw and home made spindle situation, imminent danger at all times, not suggested.
then I modified a router table to have a movable center pin, fairly clean cuts but hard work.
now I'm using the CNC router in a local workshop, great results, fairly easy working, though small issues appear from time to time.

they're working on getting a laser cutter going, that will be my next choice

[jesusfwrl]

Laser really seems to be the most effortless way of doing it, but for some reason the local laser cutting places tell me their machines cannot cut plastic....

[rsimms3]

Makrolon brochure recommends circular saw with "triple chip" tooth design (obviously only good for straight cuts). Provides guidance on other methods like band saws, routers, and laser cutting. Some good information overall in the brochure including cleaning recommendation using Isopropyl Alcohol for removal of any residue from the protective coating and to eliminate static from removing the coating.

http://www.curbellplastics.com/technical-resources/pdf/polycarbonate-fab-guide-makrolon.pdf

[dimi751]

Hi Jesus

I bought some makralon from the hardware 2mm clear a while ago used a hole saw

http://www.ebay.com.au/itm/110-200mm-Bi-Metal-M42-HSS-Hole-Saw-Cutter-Drill-Bit-Set-For-Aluminum-Iron-Pipe-/141767982002?var=&hash=item210207bbb2


Bad points

Cut was too rough at the edges had to smooth out

Largest size I could cut was 200mm


Good points

Quick and easy just clamp your sheet down on a thick block of flat wood and make your disks

The records were not damaged at all plastic coating seemed to protect the record very well.

Again cnc or laser is the best option I only tried above this method once then gave up and bought some records from my shank.

Dimi

[Fela Borbone]

Hi,
  I tried with rotatory blades attached to a drill. I'm lucky enough to survive! I made a stand that fitted 12" but the thing came very easily  out of control, both blades and plastic. The "blank" breaked and projected violent to anywere around.... dismanteled the thing after first try!!!!....
  But scaled down can be usefull to make big holes in CDs. Leather gloves and safety goggles are a must, sometimes the CD breaks and flies around, even at low speed!

 

 My plastic supplier don't have CNC tools, so I do it by hand,with this setup:


  First I punch the two holes (against a hard wood yields better results),and then turn the stick with blade at the edge around the centre pin... a great way to train Karate Kid!
  0.75mm.thick  cuts  easy , 1.5mm. is better do one side and then the other. T he central pin can be set for 7" , 10" and 12"... and to cut the labels too!!

[Ciuens]

cut using a dremel and a compass


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[ROLANDJAYS]

I think I have a great idea for all you guys who need to cut your own record blanks at home.
get a hot foam knife,
and get a lazy susan turntable,
drill a center hole in the turntable, to accommodate a screw to clampo the record,
attach the hot foam knife to a fixed position on the outer edge of the turntable and as you heat it up you can turn the record to make a cut ,
hows that sound? cheap, easy, can be made at home out of wood.