Okay... so this one may be a bit out of most lanes, but if anyone has any suggestions I'd love some help here. I have a 1515 that we just got set up to do some milling in of all things, vulcanized rubber. It does a terrific job of it, the rubber is quite dense and mills very nicely. But the rubber dust and vapor (which is toxic) are a bit of a problem so I bought a large dust collecting system hoping it would help with the lightest dust (I didn't expect it to be able to pick up the heavier stuff) and vapors coming off the rubber. I've been waiting for the dust shoe in the parts store to become available again as it is currently out of stock, so I bought a rather cheap one off of Amazon hoping to tide us over until the larger one in the Part Store is available again. The one I bought is much smaller, round instead of the large oval, and utilized a 1 1/4" port which is very small but I was able to adapt it to my shop-vac for a test. My dust collector is a 4" and the number of adapters to get down to 1 1/4" was a bit dizzying. Anyway, I got it all hooked up and it seemed like it was going to work well enough for the time being when my router started literally screaming. It freaked me right out and of course, I shut it down to try to ascertain what was happening. After a while without the shoe on, it seemed to quiet down and over time it got better almost back to normal. What I am assuming is that the dust shoe was maybe causing the finer rubber dust to get sucked up into the router? Is that possible? It kind of makes sense to me since it got better the more I ran it without the shoe on. I don't know if the larger shoe would work better or not, but the port in the small one to the shop-vac was very, very close to the bottom of the router since the overall size is so small. Plus, the shop vac would have had much better suction than the dust collector would, which may have overpowered the fan blowing down from the router. I don't know, and am kind of stuck. Any suggestions? We have a lot of work ahead of us with this, and I hate the idea of having to manually hold a shop vac in front of the router to capture the worst of the atomized rubber coming off the router. We do have an air filtration system for the shop which works great, but it takes time to clear the air and we need to be working while the router is. Thanks, Derek
You could consider a water bath - typically used for Carbon Fiber where the dust is absolutely carcinogenic, might fit this use well too? https://www.youtube.com/results?search_query=milling+water+bath+carbon+fiber
I don't think so... aside from a gooey mess, the rubber sheets we're cutting are way too big, 4' x 2'. I'd have to build a hell of a bath for it. This dust isn't as bad as the carbon dust (or as fine) I'm mainly looking for something that can suck up the vapor like the shop vac does when we just hold it in front of the router bit. Because of the router speed, it's just on the verge of melting the rubber a bit. But if we try a slower rpm, the bit just stops before completing the cut. (we're using several pecks to avoid this, but the diameter of the bit is 7/8") Is there any kind of attachment for a collector hose that doesn't involve a shoe, and maybe just places the hose relatively close to the cutting surface? I'm wondering if the shoe is what's causing the dust build-up in the router. Also maybe too much suction with the shop-vac, pulling larger bits than a regular dust collector would. I had thought the router fan would prevent this if this is indeed what's happening. Thanks for your super fast reply as always though!
since you have a CNC router why don't you just make a bigger shoe to do what you need? plenty of pictures online to get ideas from (-: as to air flow, which way does the router feed cooling air through itself? my Makita blows down onto the workpiece so any vacuum shoe would aid the airflow but it seems to me yours is going the other way, in which case I would design the shoe to separate the vacuum flow from the cooling flow so the router gets no dust at all. The design of the shoe makes a big difference too, there are 2 basic designs: the one where the shoe is attached to the Z/router such that it moves up and down with the router. the one where the shoe is attached to fixed part of the Z (actually the X I suppose) and is fixed at a suitable height and does not vary with Z motion. This by far the better design since the guard bristles can be set at a good contact pressure and thereafter it does not vary during the cuts. Then there is the direction of flow, I would make it so the air flow circles the bit in the direction of bit rotation rather than trying to buck the trend.
I'd consider making my own dust shoe if the router had survived, but it didn't. I have no idea what caused the meltdown... we haven't put that much of a load on the router. We got rid of the dust shoe and made sure there wasn't any build up in the router. There really wasn't that much when we looked closely. But for whatever reason, the thing started making a noise like dropping a fork into a garbage dispenser and will only run for a few seconds and then just dies. I can't imagine this router wasn't up to the task, we were only doing counter-sink mills (about 2/10ths of an inch) and then 1/4" straight mills all the way through. Easy peasy, right? Is that asking too much from this router?
was it running at a low speed? they tend to overheat if they run at the lowest speed setting for long periods, since there is not enough airflow.
I was shooting for the lowest speed I could so the rubber wouldn't melt... at lower speeds, the bottom-cleaning mill would just stop after a peck or two. So we gradually increased the speed until it seemed happy, which on the Router 11 was about 4 or so. What I wondered was if the little dust shoe was preventing the fan from working well enough to blow away the rubber particles and they ended up getting sucked in somehow. But when we looked inside, there wasn't much of anything around the fan. So I have no clue. We weren't trying to get all the rubber bits up with the shoe anyway, I'm sure they're much heavier than typical sawdust... but I did want to remove as much atomized rubber particles and vapor as we could because that stuff is toxic. I just ordered another router and by dumb luck, the OB dust shoe just came back in stock, so we'll try again with a bigger shoe but I'd love some guidance about milling rubber so we don't have this happen again. We're a small manufacturing company, and we were hoping this machine would transform our workflow. Each file is about 50 countersinks about .2" deep with pecking a 7/8" bottom cleaning bit. and then a second run in the exact center of each countersink with a 1/4" end mill all the way through 3/8" vulcanized rubber. (minus the .2 already removed) It was doing that with no pecking before, but after the router started making the horrible noises, we needed to set pecking even on that bit for it to make it through without stopping. None of this seems like it should be too much for a 1HP router to me. We have been doing this for months by hand with power drills (albeit at MUCH lower speeds) and a dremel (at router speeds) with no issues at all. I have checked for heat many times during our test runs, and never seemed to notice excessive heat. The bit does get warm as you'd expect, but not too hot to touch. On our last run before the router completely crapped the bed we were spraying a bit of water during each countersink to help cool it just in case that was an issue, and running a shop vac ahead of the bit to clear up what we hoped the dust collector would. I'm also wondering if maybe we had the plunge rate set too high? I could see that the gantry was flexing ever so slightly on the countersink plunges... I don't imagine that should be happening? But we're really new to all this, so it's all a bit overwhelming, to be honest. When the test runs worked, they worked beautifully and we spent a bit of time just dialing in the files for precision. We feel like we just got there when this happened. The machine is calibrated to within 1 mm on both x and y.
my guess is that the brushes were worn out. pecking straight down with a' bottom cleaning bit' is something you want to avoid. while they are called 'end mills' and they do cut on the end, they are not drills and don't like plunging straight down at all. many of them do not cut in the center at all, and many center cutting types only have 2 flutes on the end no matter how many side cutting flutes they have. I would do the entire cut with a smaller bit using a spiral bore tool path so the bit never plunges straight down. You say countersink but I think you mean counterbore, countersink would have sloped sides (as for a countersunk screw) while a counterbore is straight edged as for a bolt head to be recessed. anyhow, if you can bore the 1/4" hole with a 3/16" bit first, then work outward to make the countersink or counterbore, working up the slope if a countersink so the bit is always cutting on the side I believe you will have better results. even better if you can chill the rubber before and during cutting, cold rubber it harder and cuts easier. you will also get less dust and more chips which is a much more effective cut in all materials.
Yes, you're correct that it's a counterbore. We need a clean flat bottom. We did try doing this with a 1/4" end mill, and it didn't work out as clean and took a very, very long time. The bottom clearing bit worked perfectly though... don't you think it would be okay for something as shallow as .2" and pecking? We could certainly do the 1/4" bore first and the counter bore second if you think that would help. I'm afraid if we have to start with a 3/16" and then switch to a 1/4" we're going to lose a lot of the time savings we were hoping to achieve with the machine. I did check the brushes, and they looked fine to me. There was quite a bit left to them. I don't know how long they are to begin with, but these looked like probably 1/3" or so left. I have new brushes that came with the router, I can put them in and see if it makes any difference.
Here is my stab at Gcode for a single 1/4" hole with 7/8" counterbore 0.2 deep with a 3/16" bit. 17000 rpm at 30"/min but of course you can search and replace the feedrate to suite yourself. using 0.2" per pass it will do the counterbore in one outward spiral, climb cut, 40% stepover. first it will spiral bore the 1/4" hole to 3/8" depth then it will spiral down doing 2xbitdiam then spiral out for the counterbore. This code was generated using SketchUcam plugin for Sketchup Make 2017
Hello! Okay, so after much trial and error, we have tried what you suggested. We're using a 3/16" single flute in a spiral path for both the counterbore and the 1/4" hole. It seems to work okay, but not nearly as clean as what we were doing by hand with the Forstner bits, or even when we tried the bottom-cleaning bit on the CNC. But it looks like it will work and the router seems happy enough. However, this has created two new problems. One, since each path involves over 50 counterbore/holes, this is taking a LONG time. Close to 2 hours to run one path! Should it take this long? We assumed this would save us time, and not take even longer than by hand. It is more precise though. The other issue just happened today. I was running a 'real' path (after a successful test run on a scrap piece of rubber) and things were going well albeit super slow. Since it was taking so long, I did some other work and at one point noticed the spindle wasn't moving. I checked on it and the router was spinning away, but my interface had lost all information about the file. I couldn't even abort out of it because it didn't know it was supposed to be in the middle of a path. I had no choice but to load the file again, and start over. This was about 90 minutes into the run, so I don't know yet if it'll stop at the same place but I'll update once it either completes or bails again. Any idea what could have caused this?
