Web Goblin cnc has begun

[Jonathan]

How are you finding the High power kinco drives? I can't decide between those and the normal DC powered variety, any reason you chose those?

The 2M2280 drivers run on 240VAC they run the motors at a high voltage, not sure if it is actually 230*2^0.5 as that seems a bit much. This get much much higher speed from the motors than the 'normal' 70V (or so) drives, however it will make the motors run hotter. That's not necessarily a problem - as long as the case temperature is not above about 80-90C it's fine.

I'm thinking of getting a couple to use on either my lathe/mill or router. They're only suitable for Nema 34 (or 42) motors, not 23/24. A Nema 23 motor with high inductance might be ok... but with how much those drivers cost that's probably not the best option.

[Web Goblin]

Again I have not had much time on my build lately but I have managed to get afew things done. My workshop pc died a couple of weeks ago but I have now managed to get another one up and running. I have had the machine moving about with it again. I have started to get some work done on the spindle wiring.



I need to get this finished and get the interlock from my cooler done as well before I try to run it.

I had also been looking at a way to protect the linear rails from cuttings so this is what I came up with.



Nice and simple idea. The perspex should keep the worst of the cuttings away from the rail and it will also let me see if anything gets in there.

Ian

[Web Goblin]

I had finished connecting up my cooler last night and did the first version of my interlock circuit between the pump flow switch and the vfd. The circuit worked fine so I decided to run the pump and check it all out properly. So connected up the 110V supply to the relay and turned the pump on. The pump ran great for about 5 seconds then burnt out! I cant see any reason for it so it looks like I just have a bad one. I need to get this repaired before I can get anything else done.

Ian

[Jonathan]

That's a shame, what pump was it? Something like this one would be more than adequate to replace it:

http://www.ebay.co.uk/itm/Submersibl...ht_2753wt_1139

[Web Goblin]

Its a Shurflo pump. The good thing about it is that its Americam made and still available. I have disconnected the cooler from the machine and am going to take it to work tomorrow for a bit of surgery.

Ian

[luke11cnc]

Ian How stable is your gantry ??

I've only just seen you CNC Machine looks good

If you had to start again would you do anything different ??

James

[Web Goblin]

James.
the gantry seems stable enough but I have not actually cut anything with the machine yet.. I have had some problems with the USBCNC software and hardware and cant get any feedback from the supplier. He doesnt want to answer emails so I had had to try to sort them out myself. I think I have most of the problems sorted but time will tell I suppose. My workshop pc died as well and it took a couple of weeks to get another. I had gotten hold of a Lincoln Electric welding torch cooler to use as a cooler for the spindle but this had quite a few problems as well so it has now been scrapped.
I dont know if I would change anything yet except the Z axis screw. I am currently using an acme screw but I think it would be much better with a ballscrew. I may change this in the future. I also have an extra section of alu extrusion to fit across the front of my gantry but this has not been installed yet until I see how the machine runs without it. If there is any play in the gantry I will fit it.

A picture of the lincoln cooler is below.


After powering this unit up I found the motor only ran for a few seconds then died.
I stripped the motor down to find the brush gear had collapsed and part of the brush holder had vanished.


The comm is badly carboned up and needed a good clean.



It turned out fine after a good clean up as did the motor casing and permanent magnet.
The motor was re-assembled with new brushes and springs and seems to be running ok.
I have decided to make a new cooler unit from scratch using some of the parts from the old cooler.
I have fabricated a new tank from 3mm stainless steel. Then fitted the pump.


As usual just need some more time to get it finished and tested now.

Ian

[luke11cnc]

ok

but can I ask a question

what is wrong with a plastic box and a pond pump delivering 1000l/m ??

James

[Jonathan]

what is wrong with a plastic box and a pond pump delivering 1000l/m ??

There is nothing wrong with that setup as far as I know. I'm using an extremely small pond pump that is probably less than 1l/m. Before I had an 8l/m pump and that was plenty...I would say that overkill is good to be safe, but if you're transferring the heat away fast enough anyway then all a bigger pump achieves is to heat the water up more itself. Pond pumps, such as this one (which is plenty), are also brushless:

http://www.ebay.co.uk/itm/Aquarium-P...#ht_2736wt_905
These spindles don't need much cooling as most of the time we're operating them at nowhere near full power/speed and they are inherently quite efficient so the heat generated is not that great. This means that especially if you use a metal container the natural conduction of heat into the atmosphere is enough to keep it stable as long as you have a reasonable amount of water.

[JAZZCNC]

There is nothing wrong with that setup as far as I know. I'm using an extremely small pond pump that is probably less than 1l/m. Before I had an 8l/m pump and that was plenty...I would say that overkill is good to be safe, but if you're transferring the heat away fast enough anyway then all a bigger pump achieves is to heat the water up more itself. Pond pumps, such as this one (which is plenty), are also brushless:

http://www.ebay.co.uk/itm/Aquarium-P...#ht_2736wt_905
These spindles don't need much cooling as most of the time we're operating them at nowhere near full power/speed and they are inherently quite efficient so the heat generated is not that great. This means that especially if you use a metal container the natural conduction of heat into the atmosphere is enough to keep it stable as long as you have a reasonable amount of water.

You dont need high flow or pressure just good head height. . . . The thing to watch with these pumps is the Head height, this pump can only pump 1.85mtr max which if like me your using the simple pump in a tank under the machine then it's not quite enough. Even thou they say it will pump 1.85 meters this a max and puts the pump under too much stress if run for long periods. Try to aim for one in the 3mtr range and you wont have any trouble, mine's been going now for 3 yrs with out trouble and it's 2.5mtr head height. I've just bought a spare 24v 3mtr head height off ebay thou because it's starting to struggle so time to retire it to just pumping coolant on my lathe.!!