due to an experience recently reported here, I think it is important to also consider the accessories like compressed air. Compressed air is not only necessary for spindles with automatic tool change like the Jian-Ken JGL-80 or the Mechatron ATC-8022-42-HSK25 (Unboxing video), but also for sealing air, which is also available optionally on request on cheaper spindles like the Mechatron HFS-8022-24-ER20. A spindle with sealing air prevents dust entering the spindle body and damaging the bearings with time, and lives considerably longer. This is important if you are sometime negligent with using dust extraction and especially when milling soft metals without flood coolant. Soft metal dust can really damage the bearings quickly.
Of course dust can also enter the bearings of the hand trim router, and it does, like shown here.
Another use of compressed air is that you can clamp your workpieces with it. A web search for cnc pneumatics will show you some pneumatics actuators.
I have no experience with the PwnCNC spindle kit, but when people buy cheap chinese spindles from “manufacturers” that are not able to provide a serious spindle cable with it (as reputable spindle manufacturers do), but just a loose “aviation connector” to solder a cable yourself (which I don’t recommend to unexperienced users), I am always happy that I can link people to Daniel’s @PwnCNCspindle cables for cheap chinese spindles
Your video was interesting. I had no idea, and definitely know I am just a hobbyist tinkering around. I think the PWC for around a thousand or so will do me fine. Especially since I found out they go good with Onefinity. Thanks again for your time, suggestions, and great input and information. I’ll post if and when I go for the CNC world.
Just not sure what to do, the Axiom CNC AR8 seemed nice, but expensive. The Elite Onefinity looks good and sturdy, but not sure how to proceed. So many choices it seems, guess I’ll keep researching and see what transpi, Thanks a bunch
we also have more than one CNC manufacturers here, and I find it remains always difficult to find a decision. As for technical data, e.g. to know what is the difference between a ball screw and a lead screw, or an open-loop stepper and a closed-loop stepper, that are things you can research and learn. But how stiffy and sturdy the base and the bridge are, and how expensive the linear guides and bearings, is better to find out by knowing the machine, either by benefitting of experience shared by others, or by driving around to see some machines in action (if some friendly owners allow).
Thanks again, I actually don’t know anyone who owns a cnc. I did go to rockler and look at their shark cnc’s, but they weren’t able to turn it on and let me see anything. I am totally at the mercy of the good ol internet, and we know if it’s on the internet, it has to be true. I had no Idea there were so many different manufactures, or ways of making, using, sizing, ect, ect the cnc’s. Since I’ve retired, I just have way to much time on my hands. LOL…I guess I just need to make a choice, and see what happens. Thanks a bunch.
Or find a local Makerspace and go see them. Most makerspaces have CNC machines. You can get some hands on experience with both hardware & software for not a lot of money. That will give you a lot of information about getting your own machine.
There are lots of people here making amazing things with the Makita router as their spindle, any spindle will turn out projects of equal or better quality. Grounding and bonding of the parts is a concern with many of the low cost spindles out there but I’ve personally seen the same issue in a 5’x10’ brand name $25k CNC in a makerspace near me.
Sealing air was recommended when my Mechatron spindle got brass dust into the bearings. The simple concept is a continuous, clean source of air flowing into the bearing chamber, so debris nearby doesn’t enter.
After paying ~$300 for a Festo air filter and solenoid, the rebuilt spindle and new parts arrived. Then I started looking for an appropriate air source. I had no idea how expensive this could become.
The air flow is supposed to be 100 L/min (3.5 CFM), and the ‘input’ side of the filter is supposed to get 6-9 bar (70-90 PSI). If you’re running a carve for 3-6 hours, the air source can’t rely on a tank (unless you charge up one as big as a bedroom). It has to have a pump capable of those outputs continuously, and it has to be relatively free of debris AND moisture.
Wow. The units that can do all that cost $7,000 and up. Yes, you can buy a much cheaper air source, but your other expensive parts are going to bear the brunt. I suspended my efforts with brass while I think about this. I just can’t put that kind of money into CNC without a business reason to do so.
Aiph5u
(Aiph5u (not affiliated with Onefinity))
13
Hey David,
you can also start with a cheap compressor from the hardware store. They deliver easily more air flow and pressure and start at $150. They are just loud. You will pay more if you want an extremely quiet one, as the ones I mentioned in my post from the other day (45 dB). They are very expensive but do you know how silent 45 dB is? It’s considered as silence. It’s the noise that your refrigerator makes. A conversation between to persons in a room is already 60 dB.
Another solution to avoid brass dust, which cannot be extracted like wood dust easily, entering the spindle (and everything else like ball screws, linear bearing etc.) and damaging it, is to use a cutting fluid. Brass can be cut without, but all metals benefit of it when milled. But of course that is not compatible with MDF wasteboards .
Might be good with Armorite MDF - it’s an exterior grade moisture resistant MDF. Depending on the cutting fluid, a fine mist might have a fairly high evaporation rate and not a lot ending up on the wasteboard. I’ll be playing with this when I move into the new house (shop).
I’ve milled a hundred or more brass blanks as wax stamps and brands using an air blast nozzle with good success so far, no damage to the spindle (maybe just luck. It requires far less air at low pressure than the air seal to be effective. You can still use the air dryer and solenoid you purchased for the setup too.
I’m no expert, but I can repeat what others have been telling me:
The compressor has to deliver 3.5 CFM (100 L/min) at 6-8 bar (70-90 PSI). If the CNC project is a long one (hours) then the compressor has to have an output AND tank that allow it to run 30% of each hour. (The tank has to have enough volume & pressure to deliver while the pump rests 70% of the time).
Compressors of all qualities (and costs) are available. The sales representative who made the most sense to me happens to use compressors for her side-job (car repair). For the specifications above, she suggested:
DeWalt DXCM60; 60 gal, 220 V machine ($900) Generates 14.6 CFM at 90 PSI
These two are not “oil-less”. In the US, there are high-volume, low quality sources like “Lowes” and “Home Depot” which are much like “Obi” in Germany. The compressors at these are almost disposable.
There are sources that sell to businesses, where long-lived, low-maintenance machines cost far too much for me. A surprising source (to me) is a US company called “Tractor Supply”. Their market includes farmers and small businesses, which are at neither of the above extremes.
Aiph5u
(Aiph5u (not affiliated with Onefinity))
18
Hey David,
are you sure about the amount of air flow (CFM) necessary at the input? Where does that information come from? Your Festo MS4 DS5 is for regulating 0.8…4 bar at its output. Mechatron said that at the output, you only need 1-1.5 bar for spindle sealing air.
In my planning for a workshop, I always reserve a certain amount of money for compressed air. When I had my last big workshop, I had a big and good compressor because I had more than one uses for it. Regarding the plan for my next workshop at the moment, I plan for an ATC spindle and pneumatics for clamping workpieces, and also a vacuum pump for a vacuum machine table. All that is usually not really cheap. I understand if you are reluctant to spend more money.
For milling non-ferrous metals like brass or aluminium, most people have a different, smaller CNC machine, with an aluminium or steel base that can withstand cutting fluid. Also usually machines for this purpose are much smaller. I think sealing air on the spindle is especially of value if you mill brass without cutting fluid, i.e. dry, but switching to using a cutting fluid could make a difference.
As already mentioned above, I could imagine that using a cutting fluid that is applied to the workpiece with the M7 or M8 commands would prevent the brass dust going everywhere. Besides traditional flood and mist coolants pumps and nozzles, which spray more or less amounts of liquid onto the workpiece (which must then be collected somewhere on or under the machine bed), so-called minimum quantity lubrication (MQL) has become increasingly widespread in recent years. This method only uses the amount of cutting fluid that is needed to just cover the cutting edge of the bit and the area of the chip. There are even spindles and bits with channels so that the liquid comes from the inside, but you can also realize a minimum quantity lubrication if you spray with a nozzle, but can adjust the dosage very finely and reproduce it very accurately. I could imagine that this would make the situation with the brass dust better while at same time not necessitating the effort to catch the large amounts of superfluous cutting fluid like with traditional flood and mist coolant pumps, so could work on a machine that is also used for wood with a MDF wasteboard, i.e. by putting an aluminium or steel base on top of the wasteboard that prevents cutting fluid (should there be any excess fluid at all with minimal quantitiy lubrication) reaching the MDF wasteboard.
May I suggest you a very ingenious MQL device from a German, Sebastian End, the → ColdEND from end-cnc (video ) (complete kit). While other cutting fluid dispensers use a normal pump that uses a needle valve for fluid dosage, which brings problems because a needle valve cannot easily be adjusted to very minimal amounts of fluid and lacks good dosage repeatability, the ColdEND uses a peristaltic pump. This means, no valve at all! The amount of fluid is regulated only by the speed of the stepper motor that drives the peristaltic pump.
When I had my last big shop, I used the compressed air for car repair too, and also for house renovation. I had pneumatic screwdriver, impact wrench, sandblaster, paint spray gun, chisel hammer, etc. Of course, such tools need much more air flow than pneumatics for CNC. I think I would buy a compressor that just fits the needs of pneumatics on the CNC.
We have such suppliers too, and often they have the things “in the middle” , between hardware store stuff and super-professional machines. I think it’s because farmers are usually very careful about what they spend their money on, but they also don’t like to buy cheap junk.
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