Has anyone built their desktop cnc with a drain pan below? I cut mostly aluminum and i have to actually stand there while I cut everything so i can spray wd40 as the spindle is cutting. The aluminum gets really hot and at times you can hear the spindle sound like it wants to stall. then I have to spray wd40 to keep it going. About a couple weeks ago I was cutting some aluminum and the spindle got stuck in the material and as the gantry was moving -Y it jammed into the material and bowed forward a bit. I fixed the problem and I noticed that the machine does not cut as it did before. I am thinking that it went out of alignment and I just don't want to get it aligned until my project is complete (its 99% right now). If I were able to pour some sort of coolant on the bit and material while its cutting I dont think I would have that experienced the machine binding. Also, second question on this one. When the machine bind into the material and the gantry tilted forward I am guessing that it did that because of the 20x40 aluminum that I used to hold the top frame where the gantry sits. How would you make this a lot stronger so there is no flex? The top of my machine looks like this. When the spindle gets stuck in material it actually does flex forward, right now I don't think my bed is level anymore.
Also checkout section 3.7.4 of docs:blackbox:connect-coolant [OpenBuilds Documentation] - if you have a compressor at hand, fitting a misting kit is a simple solution and less liquid to deal with than flood coolant. Also (and sometimes more important) - make sure you are using the right bits! Uncoated bits literally weld aluminum chips into the flutes. Using proper coated bits (CNC Router Bits - OpenBuilds Part Store for example) makes the world of difference with this. I've not had the WD40 at hand in a while (; Consider your old frying pan, vs modern non-stick - and frying eggs on high heat...
The three flute works great for aluminum. If the aluminum is getting really warm, something is wrong. I have been cutting a lot of aluminum lately, and I have used the 1/4" 3 flute mentioned above and the 1/8" two flute so I do not have to change collets when a tool change is required.
Hmm, I use uncoatd bits for aluminium - cheap 3mm single flute, spiral upcut from Ebay. RoutER11 at 13K rpm, 0.5 mm doc/woc (I'm sure I could increase that), 2000 mm/min. That's on a workbee with linear rails upgrade, with V wheels feedrate was much reduced. I found I needed coolant with the wheeled workbee (alcohol - not WD40 - I found that caused the chips to clump around the cutting area), with linear rails I don't use coolant at all - the downdraft from the RoutER11 is enough to keep the area clear of chips (which take most of the heat generated with them). Alex.
Alex, appreciate this info. This is very interesting as I do not like using the wd40 since it gets the entire work area oily and the chips do clump up in the cutting areas, looks like I will have to try the alcohol to see what happens. My build is all linear rails as I don't like the wheels, seems there is a lot of drag when it comes to the wheels. I am currently using a 1.5kw water cooled spindle, my spindle is always cold. I store some 16oz bottles of water in the freezer, then whenever I have to do a cut I take one of those bottles from the freezer in the garage and place it in the container with water and that keeps the water running through the spindle really cold. Once done I just put that bottle back in the freezer to get frozen again. What advice can you guys give me regarding the feeds and speeds when cutting aluminum. Right now I am doing no more than the following DOC: .50mm spindle speed: 20k-21k (I have gone down to 18k and that works too) recent binding made me up the speed since I think my machine needs to be realigned after my first bind which threw my machine out of whack. I don't remember the rest of the settings, I think I just went with whatever plunge and feedrate that Estlcam had. I want to switch programs but I really don't want to take 10 years to learn something new,
I quoted my speeds and feeds above - with linear rails, 3 mm single flute spiral upcut, 13 K rpm, 2000 mm/min, 0.5 mm doc/woc. At 0.5 mm doc plunge rate is not really significant. No coolant apart from the downdraught from the fan in the RoutER11. I did try a collet mounted fan but took it off to make some videos and decided it didn't really make any difference. I used alcohol before I upgraded to linear rails because it seemed to reduce chatter, but haven't found any need for coolant other than air now. It's really important to clear chips away from the cutting area - especially if you are cutting a slot - most of the heat generated goes with the chips. One important point is the grade of aluminium - I use 6082T6 - very similar to 6061. Alex.
Just be careful of alcohol and flash fires - stalling a job with the spindle running, overly hot chip, endmill too hot... You do get proper water based cutting fluids...
As @Peter Van Der Walt said - caution with alcohol - I don't find I need it now, but when I used it I used tiny amounts which evaporated almost straight away. Alex.
Alcohol based coolants have flame retardant in it, don't go out and just use regular alcohol, which can have a low flash point. That is just a fire waiting to happen.. especially if the vapors/mist somehow get drawn into the spindle....
Yeah, I don't use wd40 either, or anything with a propellent that is flammable (what makes WD40 so explosive). I have this aversion to bursting into flames
I have a cold gun but I am using a very small quiet compressor and its not pushing out enough air, I need to get a bigger quiet compressor as the larger compressor I have is way too loud.
You don't really need lots of air or high pressure - the main aim is to clear the chips away - most of the heat generated goes with the chips. Alex.
Alex, I just wanted to say thank you very much for this info. When I got home this evening I started working on my project with your info and I was totally surprised at how everything worked out. I didn't need to use any lubricant to get my cuts going, I also noticed that my pieces came out a lot smoother than before. Also, I was able to touch the aluminum and it wasn't hot, just a little warm. I guess my settings before was running too fast and the material was getting really hot, I mean hot since I wasn't able to hold the pieces after the cut was complete. I can now touch the material while its cutting and its just slightly warm. I have looked at tons and tons of videos trying to learn about feeds and speeds but I guess you just have to experiment. Unfortunately you don't know what to experiment with since you have zero experience. Remember, this is all new to me. I just finished building my machine a few weeks ago and that is the extent of my cnc cutting experience (3 weeks). Any more knowledge you want to pass on to me? Thanks LP
Ok, so now I have got to try this. I am more aggressive with the 6.35mm endmills. The 1/8" have always scared me too cut more than about 0.3mm deep and only at 900mm/min. I guess I will have to find out this weekend.
Alex, Quick question. I am going to be cutting some Plexi to help me with prototyping my project today. Would you happen to know what feeds and speeds to use on material like that? Thanks
Only a suggestion - I cut a fair bit of polystyrene sheet but that's the limit of my experience with plastics. Lowest spindle speed you can manage, about 2000 mm/min and a shallow doc - don't exceed ½ the diameter of the bit as a starting point. You will need to experiment though - problem with all plastics is avoiding heat build up and melting the plastic onto the bit. Alex.
Also, a single flute upcut endmill has worked the best for me. Acrylic seems picky to me. HDPE is so much easier and forgiving. It is one of my favorite materials to cut.
Okay gotcha. I do have quite a few single flutes that I can use. I tested last night at a starting spindle speed of 10k and all went well. Today when I get home I am going to try at 8k and if that works I will stick with that. I really like how nothing gets hot anymore when cutting , everything I cut now is cool to the touch thanks to you guys.
