Molding toolpath in PVC - what bits to use ?

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FabLab Wageningen
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Molding toolpath in PVC - what bits to use ?

Post by FabLab Wageningen »

A client of our makerspace asked whether we could make him something in PVC.

Now we have done PMMA (acrylate) with good results (after a pretty steep learning curve), but PVC is totally new to us. It is also pretty undocumented on the 'Net. What he wants is simple in design: a kind of bowl with a hole in the middle, cut out of a solid slab of 40 mm PVC. Designing a molding toolpath is simple enough, but my question is: what bits would give the best (= smoothest) surface in the bowl ? It is for a bioreactor, so smoothness is paramount.
PVC_test_1a_screenshot.jpg
This is a rough indication of the request: I know, PVC does not look like wood....

kind regards,

Marcel.

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Re: Molding toolpath in PVC - what bits to use ?

Post by ohiolyons »

As a general rule O flutes bits do better in any plastic.

FYI Your are running 11.013 and 11.5 should be a free upgrade.

FYI There are plastic material types to pick from, if your color isn't there you could add them.
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Re: Molding toolpath in PVC - what bits to use ?

Post by dealguy11 »

If you're doing moulding toolpaths that means you're going to be using ballnose bits for the profiles. There are spiral o-flute ballnose bits listed on toolstoday.com. I've never used them so can't say whether they're better or worse then regular ballnose bits. I've always used my usual ballnose bits the few times I've done PVC work that required ballnose bits, and didn't have any particular problem.
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Re: Molding toolpath in PVC - what bits to use ?

Post by adze_cnc »

And as the dish is so shallow you might want to use as large a round bit as you can to lessen "cusping".

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Re: Molding toolpath in PVC - what bits to use ?

Post by FabLab Wageningen »

thanks all,

Thats an 'ordinary' O-flute I use for acrylate for the rough work and a ball-nose for the fine part then, as a first test. We will see next week. I'll check the O-flute ballnose in the meantime, but as I'm located in continental Europe delivery might take some time.

John: I use the special 'Makerspace edition' - Vectric warned us not to migrate yet. Don't know how long it will take.

thanks again,

Marcel.

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Re: Molding toolpath in PVC - what bits to use ?

Post by tomgardiner »

PVC is gummy but cuts easily with sharp regular wood bit geometry. No need for O flutes. The key is to keep the cut cool and evacuate the chips. Air blast will help. PVC generates static charge so the chips will stick to everything.
I would do a fine finish pass of 1mm depth to ensure a clean cut.

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Re: Molding toolpath in PVC - what bits to use ?

Post by jerry carney »

Tom is right on + 1

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Re: Molding toolpath in PVC - what bits to use ?

Post by sharkcutup »

+2 tomgardiner's post

I have had several projects carving HDPE using a vacuum and for chip removal and yes the chips stick to everything due to static especially during the cooler weather months. So yeah either a vacuum or air bursts can help in keeping the bit cool along with chip removal during the carving process.

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Re: Molding toolpath in PVC - what bits to use ?

Post by FabLab Wageningen »

Thanks all for your feedback.

This is the result of a first test on reduced scale. Clearance with an extremely sharp 6 mm O-flute (for acrylate) - so sharp that I cut myself when removing the bit from the collet. Fine work done with an 'ordinary' 1/8" ballnose.
20230405_140216_resized_2.jpg
It needs some refining, but it is an encouraging start. Client and I were seriously impressed with the result.

kind regards,

Marcel.

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Re: Molding toolpath in PVC - what bits to use ?

Post by Mikehell »

sharkcutup wrote:
Sat Apr 01, 2023 3:42 pm
+2 tomgardiner's post

I have had several projects carving HDPE using a vacuum and for chip removal and yes the chips stick to everything due to static especially during the cooler weather months. So yeah either a vacuum or air bursts can help in keeping the bit cool along with chip removal during the carving process.

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Re: Molding toolpath in PVC - what bits to use ?

Post by sharkcutup »

:lol: :lol: :lol:

Yup!!! Interesting Tip!!!

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