Cutting - Sanding resin

[razordws]

So starting a new project that is all resin. I've dabbled in resin with short run kits before but this is my first all resin kit and I'm looking at this thing and there is one piece in particular that has a huge chunk of a pour block on it. I already did one that was a quarter of the size and it took me 20+ minutes to wet sand it by hand. So what's the scoop. Do I need an industrial strength respirator to go at this stuff with a dremel? Not interested in spending an hour plus doing it by hand plus it looks pretty fragile and I'm worried I'll break it if I do.

 

[moon puppy]

Short answer is yes. Respirator up and go at it.

What are you building all resin?

 

[Sherman 18]

MP is right. Don't mess around with your lungs.

 

[ausf]

I use a flex shaft dremel on epoxies and resins for hours on end with sculpting. Grinding, cutting, sanding, etc., you name it.

After a lot of sinus issues, I'm a bit of a nut in terms of lung safety, so after trying a host of different methods, I ended up installing a vented blower in the bench as a dust system. I'm not suggest you go that far unless you plan on serious use, but an alternative is either grinding in you spray booth or setting up a shop vac so it draws rigt at the point of the work.

Downside of the shop vac is it's loud and you'll need a good filter, but if you're only going for short spurts, it's tolerable. I grind stuff daily for long periods, so I needed something quiet and efficient. I ended up getting an ash vacuum for the shop, which made a huge difference too. My run of the mill shop vac was just re-broadcasting dust. I'd wheeze after a good cleaning session.

The main thing to realize is, even with using a respirator, the dust is fine and going everywhere. So you may not be breathing it right then, but you will be for the next few months every time you move something, that's why a collection methd is key.

I had the aha moment when I was gringing under magnification and saw how much stuff is getting airborne.

In terms of respirators, cured resin isn't an OV, it's just an irritant, so a good N95 particulate cartridge is all you need. Main concern is fit. If going long term, 3M makes a 6000 series that is real comfortable and relatively inexpensive (I think about $12 on Amazon), which you can add all sorts of cartridges to. I have one just for grinding with a dual N95. It's easy to breathe through, unlike the cheap paper masks.

 

[moon puppy]

Wonder if you could setup a wet sanding station. :hmmm

It'll be messy.

 

[jknaus]

I think its been covered but a few extra ideas. First is to see if you could score it at the joint between the plug and part. Thats not always possible but if it is it makes life easier.
Second, if you don't want to dremel and you don't mind a bit of work then sand under water. I use a tupper ware container or bowl and put a medium grade wet and dry paper on the bottom. Fill the container with warm water and then start sanding in figure eights. When you get close enough change to finer paper. This keeps all the dust in the water to be flushed after you are done.
James

 

[ausf]

Wonder if you could setup a wet sanding station. :hmmm

It'll be messy.

Stained glass routers are basically that, a wet table with a grinding wheel. I've used them in the past, but you still get covered it dust, it's just in a form of wet paste.

I agree with James, anything you can do to get the bulk off en masse is best, then work your way down. For large areas, I'll go outside wit a big container of water and coarse (100 grit) wet paper and work off most of the excess with that, constantly dunking and sanding. Then hose down the area when possible, otherwise the resin dries into a tenacious dust cover on everything, kinda what it does it your lungs.

 

[razordws]

Thanks for the tips guys. I think at this point my best option is to pick up some coarser wet/dry sand paper and continue by hand. Hopefully it will go faster. I don't want to get resin dust all over my model room (good point ausf) and I don't have anywhere else to work on it. I do have a shop vac but I doubt it will collect everything once I start cutting. Outside is not an option now that winter has set in.

Pup, the kit is for the goat build. The Planet models Faun tractor.

 

[sharkman]

Just be sure you get some kind of mask too!!

 

[Heavens Eagle]

One thing everyone else forgot, how about a picture of the part in question. I always use my jewelers saw to remove chunks of useless resin like big pour blocks.

 

[razordws]

Just be sure you get some kind of mask too!!

Thanks Warren, I'll be wet sanding but yeah should probably still mask up.

 

[razordws]

One thing everyone else forgot, how about a picture of the part in question. I always use my jewelers saw to remove chunks of useless resin like big pour blocks.

I tried my little hobby saw but it obviously is not up to the job. Works great on styrene but gets bogged down in the resin.

I'll post some pics in my build thread in a few days so y'all can see what I'm dealing with.

 

[ausf]

Resin is a tricky material to cover broadly. There are different types (urethane and polyester) and within those types there can be a whole host of different properties. It's much wider a subject than subtleties of styrene. Even within brands; Smooth-On must have a dozen different resins all with their individual strengths and weaknesses and within the different types there are three different set speeds, all which effect the end product.

Then there is whether it was vacuumed, under pressure or both and the actual conditions on the day it was poured.

Bottom line, each model has to be approached individually. If this particular resin is fairly hard and brittle, you can score and snap off the gates. If it's soft and pliable, you can cut and bend away. Best practice to avoid dust is to remove as much as possible with blades or cutters before you break out the sandpaper, even carving excess away once you get the gates out of the way.

I'd play around with some scrap of it to get an idea of what you're dealing with. Pay attention to the thickness of where the gate meets the model. Some guys are really good and the attachment point is impossibly thin and breaks away. Some guys attachment points are hideously wide.

If you have a hard, bubble free resin with small attachment, it's a breeze.