Hi all, I am new to openbuilds and to the CNC world. Now that the V-slot is getting back in stock I'm getting excited to start a project of my own. I have done some reading and have come up with a idea of what I would like to build. But before I go out and spend my hard earned money I would like get the thumbs up from you guys, who have more knowledge and experience. The general idea is that I would have an OX design but bigger (1500mmx1000mm), with the possibility to change the spindle with a printing head for 3D printing. To get more Z height I was thinking to increase the rail length on the Z axis for about 250mm. When 3D printing I would raise the whole machine and with the longer Z axis I would have cca 300mm printing depth. When milling the Z hight would be the same as in the original OX. A guide of 3D printing with mach3 is found here: http://www.shapeoko.com/wiki/index.php/3D_Printing_Mach3 Regarding the spindle it would be a brushless motor similar to the one from Robert Hummel, but with a few changes: Motor http://www.ebay.com/itm/141174603725?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 ESC http://www.ebay.com/itm/200597198227?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 Power supply: 2x connected in series to get 24v 55A http://www.ebay.com/itm/150833352692?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 Looking forward to your comments and critics. Sorry for the grammar, English is not my native language.
Hi Gvardo, Welcome to the forum - it looks like you have done a lot of research / homework before you start on your project and I am sure this will all be of benefit when you start the build. Thanks for the link for 3D printing and Mach3 - something I really ought to try, if I ever get the time to spare. Tweakie.
That motor will work fine, Gvardo. I have a very similar motor on my machine. The power supplies are a great price. I paid for one about the same as you'll be paying for two and my power supply only has 20A. But, truce to be told, I really don't need more amps. I control my ESC with a cheap servo tester that I got from China for a $1.50 or so. It's all that you need. No use of getting too fancy there.
Just my thoughts here, everything looks cool but I would just spend the extra 15 or so bucks and get a 24v power supply from open builds for the mill and 1 of them for your spindle. I just think in the long run you will be better off.
Yes I have seen the power supply from the store but taking in account the shipping cost and import charges it does not seam reasonable to pay more for less power and for the spindle I need as much power as I can find. Also I have read that server power supplies are high quality. Please correct me if I'm wrong. The only draw back I had was the serial connection, but then I found this tutorial and I think it will work fine. http://www.rcmf.co.uk/4um/index.php?topic=67706.0 Thanks for the tip, servo tester from china it is. Will do, but lately I have very little spare time, so this project will not be realized as fast as I hoped.
I only suggest it because if you plan to use an RC spindle ,12-14 vdc @10amps is optimal, running your spindle any higher will generate a lot of un-wanted heat in the motor windings. Also the RPM range for the ER11 collet tops out around 10,000 RPM so 900kv @ 12v = 10,800 RPM no load 900kv @ 14v = 12,600 RPM no load
@Gvardo, is Robert correct in his assumption that you are going to use the power supplies for both the stepper motors and the spindle? If so I would advise not to do it. First, I feel that each should be fed from it's own source. I had used from the beginning two 24v power supplies. One for the steppers and one for the outrunner spindle. I found out, as Robert mentioned, that the outrunner runs way to hot at these voltages. I changed the spindle power supply to a 12v power supply but I have it set to the highest output, which is about 14.5v. My outrunner now runs barely warm to the touch after two or more hours of cutting.
I plan to have two power supplies. A 24v one for the spindle and a 12v one for the stepper motors. As for the heat I really didn't think of it as a big problem till now. The efficiency is supposed to be very high on this motors so I assumed that there is not a lot of heat. But now I have ordered all the parts so lets hope my spindle will work well and not overheat too much. I was hoping to get a lot more then 140w out of my spindle, around 1000w for shorter runs and about 750w for longer runs. But reading your post I'm not that sure anymore. Regarding RPM the motor is 500kv, so running on 24v will do 12000RPM.
@Gvardo, I have my setup exactly the other way. I have the 24v for the stepper and 12v for the outrunner. Plenty of power from the outrunner at 12v, for my needs. I also prefer to have 24v for the stepper. Makes them run with more torque. At 12v they may be a bit too weak for the machine.
Thanks JustinTime, makes sense to go for 24v power supply for the steppers. For the RC spindle I will see how 24v performs, if it overheats I can still use 12v as I will connect the power supplies in series. I also have a dilemma regarding the controller board, as stated I would like to have multifunction machine(mill,printer, laser?) I have seen the Smoothieboard and it looks perfect for my needs. http://robotseed.com/index.php?id_product=11&controller=product&id_lang=2 Will it do the job?
I am too really interested in what you think about Smoothieboard. Any users that have tried it? What about a Beaglebone Black with Replicape?
If I understand Beaglebone Black is capable of running Ubuntu on its own and with a CNC cap all you need is a screen and you are ready to go? Here are some capes for CNC: http://blog.machinekit.io/p/hardware-capes.html#3D-Capes Still not sure which way to go Smothieboard(available), Beaglebone(powerful)?
