Plastic cutting - thread frizzy

[mischmerz]

Just got into cutting plastics with myshank's styli and blanks. I don't use stylus heat (yet) because I have no experience with that and want to learn step by step. I am working with a Rek-O-Kut Master Pro and a Grampian head with a long shank stylus.

Here's my question:

While cutting, the swarf thread is nice and smooth and my suction has no problem taking care of it. However and for some weird reason, the swarf sometime gets frizzy .. for the lack of a better word. It gets curly and immediately becomes an entangled ball that can't get sucked away anymore.

Static has been removed after the blank has been placed on the lathe, I am heating the blank to about 100 degrees (F) , the blank has been treated with turtle wax, the suction tube is grounded and will be treated with powder before every cutting.

The suction is 1/4 inch aluminum.

Any ideas?

Michaela

[Gridlock]

It's so fascinating how different drum beats and guitar solos make different shaped swarf

[mischmerz]

It's so fascinating how different drum beats and guitar solos make different shaped swarf

I see. I am going to give it a try. Thanks.

mm.

[mischmerz]

There is *no* way my suction will be *ever* able to handle this.

swarf.jpg

This reminds me on entangled fishing line. My 1/4 inch suction tube had no problems with anything a "normal" lacquer disk would produce. But it's simply overwhelmed by what plastic cutting produces.

May I ask what suction line sizes you guys use? And what kind of vacuum device?

Michaela

[mischmerz]

Well - like I said - my current vacuum is unable to reliably handle plastic cutting swarf. This is how the suction tube is installed currently

suction_left.jpg

There is one problem with that kind of a setup that I will fix shortly: The suction tube angles upward pulling the thread over the heating coil. Not good. Has to be straight. The second problem: Not enough air flow. I am using this kind of a pump

sucker.jpg

I don't know much about the tech specs but I assume this pump has an air flow of maybe 30 or 40 Liters per minute. This may just not be enough. So I went ahead and ordered a pump able to pull 120 liters/minute. I also ordered 1/2 inch OD aluminum tubing to replace the 1/4 inch vacuum tube.

Here's what I am going to do:

First try to run the pump with the 1/4 inch vaccum tube. If this still gives me grieve, I am going to replace the tubing. Will report back. Meanwhile - any suggestions or hints are welcome.

Michaela

[Soulbear]

Hi Michaela,
The trials and tribulations of getting a good vacuum set-up eh? I'm currently mulling over some similar design issues and what I can tell you for sure, is that if you double your pipe diameter, as a rule of thumb, you would quadruple its volume and ergo reduce the flow velocity by a factor of 4. If as you say you are going to up the flow rate with a bigger vacuum pump then this wouldn't matter too much, and all may be well, but with your existing pump you might want to consider this reduction in flow velocity when upping the pipe diameter. I'm following this thread with interest Soulbear

[mischmerz]

Hey Bear:

Yes .. i already made a few tries with the current pump and larger diameter tubing which lead - as you might imagine .. to nowhere. I am not even sure if I can get a 1/2" tube under my cutting head - I would very much like to continue to use 1/4 " if only because its easy hand bendable. I already built a new tube that ends up horizontally. Can't wait to try it with the new pump. 120 Liters per minute should give a lot of improvement.

mm.

[mischmerz]

OK - Step 1: New suction tube. This pulls the swarf horizontally.

suction_left_new.jpg

The image looks like the tube touches the head - but it's just a bad perspective - there is plenty of room. Now we wait for the new pump.


mm.

[rsimms3]

So, the issue isn't frizzy swarf, it's the inability to consistently vacuum it away, correct? You mention the thread itself but don't mention the quality of the cut. Is the cut okay? How are you addressing inner groove distortion without heat? Sloped EQ?

As for your pump, I use the same type pump that you have cutting both Laserdiscs and lacquers with few issues. I also notice that you are using plastic tubing still instead of rubber tubing for at least part of your suction chain. Your new suction tube looks better in that the opening is parallel to the needle. As SoulBear mentioned, if you increase the size of the tube to the same diameter all the way through you'll loose air velocity. Think of a vacuum cleaner and adding the crevice tool, you get increased velocity through the more narrowed and tapered tip.

[mischmerz]

Well, the "old" system works fine as long as the swarf is undisturbed and smooth. Depending on the frequencies cut the tread get's frizzy, entangles and won't get sucked in anymore. That's my main problem. Teh cut is fine.

Michaela

[rsimms3]

Well, since you've already ordered a bigger pump I guess the next step would be to incorproate it into your vacuum chain. Outside of that I would recommend getting heat up and running. That will introduce a whole new set of challenges keeping everything close but adequately spaced. Your frizzy swarf might get better and you might have better results with a slightly warm swarf off of the needle.

[mischmerz]

Thanks for the tips. I'll report back, when I have the new pump up and running.

Michaela

[Gridlock]

You should see my vacuum it's a wreck but what the hell. Try acoustic folk instead of grindcore

[mischmerz]

You should see my vacuum it's a wreck but what the hell. Try acoustic folk instead of grindcore

LOL .. good one. Though my test is a early 60s version of Benny Goodman's "Sing Sing Sing" .

Michaela

[pellegrino707]

Hi Michaela,

I cut plistic with a VinylRecorder, and the only issue sometimes si still annoying me is the suction.
I think with plastic this is a reallly problematic thread, mostly for static charge, and i found out during the winter it is even worse, because the heating is making the air dry, and the static charge increase in dry ambients.

I suggest you to use the MyShank antistatic wax instead of turtle wax, in my case made the difference, Myshank is the specialist for plastic cutting.

I also get sometimes that kind of frizzy swarf, usually when the suction tube is too close to the stylus or the stylus heating too high, so the swarf build up in the space between stylus and tube, and with the heating it becomes like in the picture you show.


PS: the stylus you are using doesn't look diamond, what material is it?

[mischmerz]

I also get sometimes that kind of frizzy swarf, usually when the suction tube is too close to the stylus or the stylus heating too high, so the swarf build up in the space between stylus and tube, and with the heating it becomes like in the picture you show.
PS: the stylus you are using doesn't look diamond, what material is it?

Howdy:

You're right *that* stylus is not a diamond. It's one of my "bad" styli (ruby with bad tip) I use to adjust stuff - it has about the same size as my diamond. I don't use heat yet, I heat the blanks up to about 100 degrees which gives ok results. As to the swarf: It all depends on the weight of the cutter head and the music I am cutting. To little weight and the swarf is very fine and my suction pump not strong enough to pick it up. Cutting strong base will produce a zigzag swarf that, if it is not removed right away, produce those darn swarf balls.

I am pretty sure my suction pump is the main problem. I ordered a different one and I'll see if its going to get better.

Michaela

[jeffandthom]

hey there, i know this is an old thread - no pun intended - but did you ever figure out how to stop these swarf balls from happening? i've been getting them on silent groove (and with audio) with a brand new diamond with weight and angle set