Help with turning resin

[Mitch schiffer]

I was turning some resin and It broke apart on me. Im pretty new to turning and very new to turning resin. Can anyone provide some advice on how this may have happened. I was using a carbide finishing tool from easy wood tools with a fresh edge. The second it touched the resin this happened. I did have a face shield on and was not injured. I was using a vacuum chuck turning at about 1000 rpm with the tool rest about a 1/2" away and about a 1/2" below center. I was pretty sure the the tool was in contact with the rest before the workpiece.


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[David Walser]

Been there. Done that. Didn't get a t-shirt.

Mitch -- There are a lot of possible causes for what happened. Some resins are more brittle than others. Polyester resins are notorious for being chippy. Alumalite Clear and Clear Slow are urethane casting resins. They turn well and are less prone to chipping. There are a number of different epoxy resins that are used by one or more turners. Each turns differently.

In addition to the resin type, the quality of the mix and pour can alter the way the resin will turn. Generally, waiting until the resin has fully cured -- which may be days after it has hardened to the touch -- is a good idea.

Next is the way in which the resin is turned. Resins, in general, respond very well to scraping cuts made with a negative rake scraper. You can try to make a bevel supported cut, but, in general, the friction from the bevel will heat up the resin, softening it. That can cause poor cut quality, but not the kind of chip out you're seeing. So, use a negative rake scraper (which includes Easy Wood Tools new carbide inserts with a negative rake profile), take very light cuts, and cut on center. That will give you the best chance for success.

One last tip: Chatter is one of your enemies when turning resin. It can cause the kind of blow-out that you're seeing. There is no grain supporting the resin surrounding the area being cut. Thus, even a small catch can cause the resin to fracture well beyond where the tool is in contact. This is why light cuts, with the tool rest close to the work, and cutting on center are so important.

HTH

[Mitch schiffer]

Thanks for the tips. I was using super clear 2.0 deep pour. I had started turning it 2 days earlier and ran out of time so I'm thinking it was fully cured. I did notice some chatter. I was taking light pases as I was almost done with the outside. Is there a different type of resin I should try? And is there anything I can do to help limit the chatter in the future

[Steve Eure]

I would suggest not turning 1/2" below center. You need to have it centered as best you can. Light cuts also. I never turn anything with a vacuum chuck at that speed. 600-800 maybe, but even at that I try to have the tailstock on the piece. Even with good vaccum, a light catch can make the piece lose suction, and away she goes, especially at that speed. Keep trying. It gets better with practice.
BTW, there are some good videos out there that are helpful. Some good content. but the individuals are a bit chatty and it takes a while to get to the meat of the subject, but good content none the same. Good luck.

[guy laizure]

Deep pour is a epoxy resin.It takes 1 to 2 weeks for epoxy to fully cure.

[John K Jordan]

I was turning some resin and It broke apart on me. Im pretty new to turning and very new to turning resin. Can anyone provide some advice on how this may have happened. I was using a carbide finishing tool from easy wood tools with a fresh edge. The second it touched the resin this happened. I did have a face shield on and was not injured. I was using a vacuum chuck turning at about 1000 rpm with the tool rest about a 1/2" away and about a 1/2" below center. I was pretty sure the the tool was in contact with the rest before the workpiece.


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I have no idea what an Easy Wood "finishing tool" is. I turn all plastics with either spindle or bowl gouges or Hunter carbide tools, all in a cutting mode rather than a scraping mode.

[Pat Scott]

I don't turn resin like this, but I think some general guidelines still apply:

1. What size is the bowl? 1000 rpm is too fast unless the bowl is 6"-9" diameter. Dale Nish came up with a formula years ago for a safe turning speed (Diameter x RPM = 6,000-9,000). Note that 6,000-9,000 is just a number, not the RPM!

2. I wouldn't trust a vacuum chuck either for this, don't you still have the tenon or recess?

3. Your tool choice is fine.

4. The tool should be cutting on center, not 1/2" below.

[Jim Tobias]

As others have said, it could be any number of things with resin....1) not fully cured 2) a heat fracture from it being a deep pour 3) definitely I would (use negative rake cutters on anything that is mostly resin( it just cuts better and smoother and safer) 3) did it cure under pressure (pressure pot) to reduce bubbles ( I always to work the outer edges to completion before taking material from the middle of the bowl( less vibration on edge).
Good news is with resin, you can get creative and tape off that area and repour it and just turn that area again. Kinda like a resin graft. Just rough up(sand) the smooth areas where it fractured and have at it. This is, unfortunately, from experience that I am speaking about repairing a fracture.:o

Jim

[Mitch schiffer]

I have no idea what an Easy Wood "finishing tool" is. I turn all plastics with either spindle or bowl gouges or Hunter carbide tools, all in a cutting mode rather than a scraping mode.

Easy wood is a brand of carbide turning tools. Their finishing tool is a round negative rake carbide scraper.

[Mitch schiffer]

I should have probably specified by the tool rest was about a 1/2" below center which puts the cutting edge pretty close to center. I was using the tail stock with a live center in combination with the vacuum chuck, and the work piece did not become dislodged when this happened. The reason I was using the vacuum chuck is I turned the bowl back around after turning the inside, since I changed my mind on the profile. Would I be better off using a different way to mount it after the tenon on the inside is turned away? Also what would be a good speed? The piece is about 12" in diameter. Is it a general rule to turn slower with a vacuum then with a regular chuck given the same diameter?

[Pat Scott]

The reason I was using the vacuum chuck is I turned the bowl back around after turning the inside, since I changed my mind on the profile. Would I be better off using a different way to mount it after the tenon on the inside is turned away? Also what would be a good speed? The piece is about 12" in diameter. Is it a general rule to turn slower with a vacuum then with a regular chuck given the same diameter?

A good speed is 500-750 rpm (dia x rpm = 6000 to 9000). I generally turn around 700-750 for a 12" bowl but will go lower if the bowl has distorted as stress is relieved. It also depends on what tool I'm using, for example if using a NRS on a distorted bowl I turn the speed down to 200 rpm or whatever speed is necessary so the tool doesn't bounce.

It's never a good idea to try and recut the outside after cutting the inside! Get the outside the way you want before doing the inside, and if you change your mind after doing the inside oh well too bad. Let it go and try for a better shape on the next bowl. Chances are the bowl would have moved some after removing the inside and now it's thinner and more fragile. A "regular" cut at this stage can be disastrous, especially on the rim.

Your tenon is on the inside? If you have removed the tenon/recess then the vacuum chuck is how I would remount it (but again not for reshaping the outside). The speed should be turned down as well, I never run my vacuum chuck the same speed as a 4-jaw chuck even with a good vacuum.

[Mitch schiffer]

Thanks for all the tips. I don't think I will try to fix this one. Hopefully I can do better on the next one.

[John K Jordan]

Easy wood is a brand of carbide turning tools. Their finishing tool is a round negative rake carbide scraper.

Thanks. I'm familiar with the Easy Wood brand, long time ago I bought two of their first tools, roughers, large and small, to try. I tried them and gave them away. I haven't tried any of their newer tools.