18987RE: [SherlineCNC] RE: Another new addict
- Nov 14, 2013
I just finished a PC to dedicate to my Sherline 4100 Lathe, woohoo! It’s a Frankenstein made from three old pc’s but it turned out REALLY well. It’s a Dell 2350 (found on roadside dead) the case was perfect and motherboard was good so I chose it for the ‘base’ platform and filled it with parts from the ‘heap’! It is the true Pentium 4 model (not a Celeron) 1.8 GHz single core with 500 Megs of ram and a 40 gig IDE hard drive. I just sings along with a fresh install of XP Pro and a Linux CNC partition.
I’ve always wanted to try Linux CNC (formerly EMC2) and have looked at and played with it (studied) it many times but this is the first time I’ve finally been able to test it on a machine. I must say it seems a bit faster and smoother than Mach3. Bit strange to get used to though and a quirk causes me to have to press the e-stop button (physical) then the reset button (on screen red power button) then release the e=stop. This is required to activate the charge pump output for my BOB (C11G). I read that there is a way to modify the INI file to ‘fix’ this?? It also appears that backlash compensation must be done in the INI file as well (Backlash=x.xxxx) , though I don’t know how to fix either one yet. Also PWM is being a real monster as it was in Mach3. What settings do you Linux guys use for Base frequency and other tips for calibrating PWM? I never did get good power curves in Mach with PWM either so I’ve told it to use Step\Dir spindle control with ‘DIR’ routed to a false pin on a false port(2), works a treat and very accurate.
If I work out these few little issues it may well be Mach3 for Mill and Linux CNC for the lathe!
Still trying to get Partmaster lathe working with Mach3, no luck yet (all arcs are crazy spirals), anyone willing to share a working post, and maybe a small sample file?? How about a Post for Linux CNC??
Most people here use Mach CNC software running under Windows and are very happy with it. In the hobby end of CNC, I've even seen people say that you can start with other options but you'll probably end up with Mach. It certainly has much to recommend it, but I use LinuxCNC and have found it to be very easy to configure, particularly for a simple stepper motor based system like we're discussing for a Sherline CNC machine. You can download the free ISO and burn it to a CD or thumb drive and install it from there. Run the StepConf program to tell it the number of steps per revolution for your motor (probably 200), the inches per turn of the lead screw (probably .05" for the Sherline, unless you got the metric version), etc. Installing the operating system, CNC program, help files, web browser, etc., all at once, is a fast and easy way to get a system up and running. At first, I'd take the bootable thumb drive to a Craig's List PC seller, boot from the read only media and run the latency test. There's no rhyme or reason to which old PCs work well and which have latency problems, but there are "known good" LinuxCNC PC lists online. A $100 or less used PC runs LinuxCNC just fine. Lately, I just buy one of the several known good Intel Atom based PC boards and a 64GB solid state drive and compatible PC power supply and Logitech K400 wireless keyboard (doubles as a CNC pendant) and I'm good to go for about $200 or so, brand new.
I've bought some Gecko drivers and they're top notch, but lately I've been going on eBay and buying the parallel port I/O interface, motors, drivers and DC power supply as a single kit from importers like Longs Motor, etc. Search eBay for "NEMA 23 kit" and you'll see a lot of choices. You can probably buy all of the motion control for $300 or so. I prefer the versions with one stepper drive per axis. They're a little more trouble to mount the three drivers and wire them, but if I ever blow one up (haven't yet!), I can quickly and cheaply replace the one drive for $40 or so rather than replacing all axes at once.
Something like this: http://www.ebay.com/itm/190649299152
I recently bought the Sherline mini lathe in the CNC configuration and had it up and running in a total of 15 hours. I could have done it MUCH faster if I wasn't so fussy about making it look pretty. I did a lot of custom stuff like assembling a couple of cabinets (electrical panel and tool storage), assembling an aluminum frame, painting and drilling and tapping a plate of steel to securely mount the lathe, making a custom clear acrylic chip guard, etc. It was a fun project. I need to upload the 15 minute time lapse video that shows the 15 hour build. There were no snags or complications. Just bolt it together, wire it up, install the software and configure it (30 minutes?) and it's making chips.
YMMV, but that's how I roll.
Hello all I'm Paul and I am addicted to machining... Lol! New to the forum and interested in converting my 2000 mill to CNC and I'm looking for info. I am not against building my own controller as long as I can get some plans or does anyone know of a good one to start with? 4 Axis Paul
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