Thread: New CNC Mill on the horizon
so a bit more research, how about the cold air gun approach? I have a decent compressor with plenty CFM output. If the temp is right would the aluminium cut well with a cold air system? this would remove the need for coolant.
The machine will primarily be cutting ally plate I would imagine but it will be used to cut hardwoods as well and I know of the evil wood snot you speak of when mixing wood and coolant as I have had it before on my lathe! its worse than concrete.
Failing that then think about system that use's coolant that evaporates quickly like ethanol, good but expensive.!
One problem with coolant or should say small amounts of coolant is that it Can shock tooling and cause micro cracks in certain tool materials like Carbide. So it's often considered better to have No cooloing at all or Go large and have full flood cooling.
With Aluminium I find Air alone isn't enough and it needs just a small amount of lube to help with any hard Sticky spots and melting to tool, which happen often in lesser grade Ali like 5 series.
This is why I like the idea of John's system in the Mister thread because it would mean having full control of the squirting but mainly use air for clearing chips. This would work well if your mixing materials.!
One day I will get round to finishing a directional Air & coolant squarting ring around the base of spindle which follows the inverse of Axis movement and squirts air or coolant as required, Bit like Datron system does.! . . . . Just not enough hours in a life time.!!
Thanks for that, I love the datron machines they are great, I have not looked closely at the accessories but the coolant head you mentioned looks cool I just checked it out.
I had a word with my friend who is building this with me who also designs all the electronic wizardry in our other projects and we are going to have a crack at something similar. I have a bit of background in pneumatics so I am hoping if we put our heads together on this we could come up with a neat solution that maybe others could use as well.
so in terms of the fogless mister am I right in thinking there is an air supply that can run independantly and the air supply also feeds a pressurised container (regulated) full of coolant which has its own control valve to allow the oil to be introduced into the flow?
Air supply pressurizes at 2 bar the container which is just about right for the air flow needed, so no need for super precise separate regulator at the end, one normal regulator with filter before the container is enough. There is a second precise valve that regulates the coolant flow in the nozzle. 4mm OD tubes each are enough for the flow both for air and coolant. 0.8-1.5 mm nozzle at the end depending what exactly you want to do, i would say 1mm is perfect flow wise and control wise. Polycarbonate containers are rated 6 bars usually. the precise air flow formation depends on the outside angle + inside angle combination /of the nozzle tip/.
Hope that helps and clears the basic principles of the design.
Last edited by Boyan Silyavski; 26-03-2015 at 07:22 PM.
Thanks Silyavski, that certainly does.
I like the idea of using a system like this but the worry is still even if we are really over the top at cleaning the machine after its been used for the odd bit of hardwood are we likely to still get a build up of "woodcrete" as I shall refer to it as from now or is it likely to be far less due to there not being flood levels of coolant involved?
Certainly I will be trying to deveklop something that directs the air flow relevant to the direction the cut is going that should not be a problem at all given the projects we (the guy building with me/my business partner) have going on I believe we already have something we can just reuse for this anyway
Until sec 15 on the video you could see nothing, but the flow is there just enough to cool it. Then i decided to give more flow so it could be captured on the video.
For the sake of using the camera the nozzle was pointing from right to left and as you could guess cooling the back instead all, whencut was going left-right , but even like that it worked. How i know? We did not break a bit and the cut was good. Ideal is when the flow comes from our point of view, when we are in front of a mill.
Another thing i learned yesterday is that to clamp the goose neck at the dial hole on the mill is good and easy, but best would be a thin collar clamped directly at the lower part of the arbor/??/ , so it moves always with the bit and always cools where necessary.
As you see there is no mess, we were using the bigger 1.5mm nozzle at minimum adjustment. According to Jeff he could cut say 1/3 faster at least and he is using typical HSS cutters/not sharp to my standard / next time i will bring him brand new USA made micro grain carbide cutters that are ultrasharp and polished, so we could see how much we can push that thing. Anyway i soon am finishing my machine so i hope to see what happens with cooling and me taking 16k rpm, deep, fast passes in ali, checking my setup rigidity.
PS. After reading about the pulsing, yesterday had to test how good my setup leans chips. I will make more test and video but the size chips you see on the video, it blows them easily away,without any problem . tested it on the bed where there were mountains of them, 15cm away which is a longer distance than usually. So no worry there, i believe i will have no need for pulsing. Will have to check for steel.
Last edited by Boyan Silyavski; 27-03-2015 at 06:07 AM.
Thanks for that video it looks good im going to look into it further.
In the meant time I've got the y axis moving now, it's great in one direction so with the flanged edge of the ballnut leading. However in reverse back end of lead screw leading it sounds like a wood pecker. Click click click every rotation. Any ideas? It's all greased up with lithium grease, not enough grease? Crap in the nut? Don't get it on the z axis
Wood pecker issues seems to have been relegated to a random peck every now and again. I fill the ball nut with some more grease and ran it up and down so I'll keep going and see what happens.
My next question is about series or parallel connection of the x axis motor? Which should I do? It's a nema 34 motor with 8 wires rather than 4 as per the nema 23. I've read about the two but just want people opinion as to what's best for this machine?
No brainer go with Parallel.!! . . . .In series you'll need a lots of volts for any kind of speed and torque. Parallel gives you more torque at higher Rpm.
Series is good if your not going too fast Ie: on Mill as it gives more torque lower down but soon as Rpm start to rise then torque drops rapidly.
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