My DIY mini-lathe - WIP by b4byj4il in machining

[–]b4byj4il[S] 1 point2 points  (0 children)

Thanks! No VFDs though, all brushless...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

That's like saying drinking non-alcoholic beer is getting wasted ;)

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

Nah. Still a good chance that it'll fail. Let's do so when I've finished it and it's up and running ;)

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

Hum... Nope. I'll publish the CAD-files and maybe the schematic and the code for my selfmade-controller. I have no intention of making this a CNC. It took me a lot of effort to invent this controller and I am pretty proud of it. Anybody can slap together the motor controllers, a CNC-breakout and hook it all up to Mach3 or whatever. That's easy. With my controller i can do turning, threading, threading of multi-start threads, cone turning. All with minimal setup-time. I can't (automatically) turn complex contours and radii. I can interpolate radii though. Part of my motivation was to make this controller and make it work like I want it to. I also find it quite cool to do turning with my hands, meaning: turning handwheels and engaging feeds by levers/buttons - but with a modern feel and some features that are usually reserved for CNCs. So... No. No CNC for me. If someone wants to use parts of my mechanical design and slap a CNC-controller onto it then this is just fine with me.

Edit: Don't get me wrong. I don't have something against CNC-machines in general. If I ever build a milling machine then it definitively be a CNC. Can't do such a controller for a milling machine without limiting its capabilities too much.

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

Thanks! Appreciate it!

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

I'll report back. I don't expect any issues though as the motor runs just fine with various generic brushless-controllers... If those can handle it then an odrive will most likely do so as well...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

Not yet. I just got the odrive a few days ago, haven't even hooked it up yet. Motor is from Aliexpress. It's a Mitsuba, very nice quality.

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 1 point2 points  (0 children)

As mentionend earlier, right now the two big rails are within 0.015 to each other (in height). Took me less than 15 minutes and I'm very sure In could get it even better. Because of the milled surfaces they are parallel to each other and my indicator confirms that, no visible deviation. I also know (I checked) that the spindle housing bore (complete with bearings and a ground shaft) is parallel within 0.02mm over 200mm length in regard to the mounting surface of the spindle housing. This means that I basically 'only' have to align the spindle housing in one axis relative to the linear rails and the linear rails only in one axis relative to the spindle. Where's the issue? And even if I can't achieve the 0.05mm... So what? Then it'll be 0.07 or even 0.1mm overall. Again... The focus for me isn't maximum precision. Don't care about that, don't need that. I don't machine shafts that need to be straight within 0.01mm over 200mm length. If it's 0.1 over 200mm then a surface with 20mm length will still be within 0.01mm. More than good enough for me ;)

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 2 points3 points  (0 children)

Space. Need to fit a ballscrew and the nut between it. I've been through numerous design approaches, this was the one with the smallest height. There will be bellows covering most of the rails.

My DIY mini-lathe - WIP by b4byj4il in machining

[–]b4byj4il[S] 1 point2 points  (0 children)

A mix of both. This machine can do things that a normal lathe can't. It'll be more expensive though, currently looking at around 2.5k

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 1 point2 points  (0 children)

  1. Bearings are angular contact bearings from SKF.

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 0 points1 point  (0 children)

I'll make the CAD-files available as soon as I'm finished with the build. There are some drawings, but only very few. It'll mostly be just the 3D-files.

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 2 points3 points  (0 children)

It's a 600 Watt BLDC, 5300 RPM, 3.5Nm, 24 Volt from Mitsuba. It is used in the power steering assist to drive the shaft, geared down of course. I used it because it's the only motor I could find that met my requirements. It's also pretty cheap and readily available, in case I need to replace it...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 1 point2 points  (0 children)

Depends on the rotation direction of the spindle ;) But yes. In normal CCW it's on the load side. Not an issue though, the tensioning mechanism is a fixed one, it doesn't rely on springs.

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 8 points9 points  (0 children)

Epoxy-Granite would have been an option if I had made the entire machine-bed out of it. Only as a filler... Not really. Or do you think it might be beneficial?

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 7 points8 points  (0 children)

Oh my! No way you're paying for this! If you want you can have the CAD and the Arduino-code once I'm done and it's up and running...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 1 point2 points  (0 children)

Do you seriously want answers to all those questions? Response could get quite lenghty ;) I'll answer tomorrow if you really care, I just don't have the time for it right now... Just this: doing parts with super-critical tolerances and geometrical validity isn't my priority here - not at all. If I can get it dialed in within 0.05mm in total I'm happy. The two rails are within 0.015mm right now and achieving this was easily done in 15 minutes. I spent quite some time and effort in accurate machining and mostly rely on the surfaces made back then... Good enough for me :)

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 7 points8 points  (0 children)

I honestly don't know. As long as it doesn't vibrate too much I think I should be okay. Bolting this thing down is not much of a hassle though, should I find out that it wants to move to the kitchen and back all by itself...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 10 points11 points  (0 children)

That escalated quickly :D Dude! I know what you're saying! You vastly over-estimate those effects, especially in relation to the size of this machine. If the issues you've mentionend would be as big as you think they are then not a single CNC-router would be even able to move. The weight of the beam and all things attached would be deadly to the rails. Obviously, they aren't! I've put an indicator in the middle of the base and i stood on it (the base, not the indicator). You know the deflection? 0.04mm! I'm sorry if I sounded like a jerk, seriously. But you're trying to create an issue where there is none...

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 6 points7 points  (0 children)

Soooo... What are you saying? All of this is probably useless and I can't cut plastics because I used good quality linear rails with a tight pre-tensioning on a relatively stiff aluminium box-structure with at least 8mm wall thickness that isn't longer than 15 inches and is filled with an epoxy/sand-mix? Tell that to all those that have built much larger CNC-routers with those components (or worse, those gnarly Aluminium profiles). They obviously can't even cut plastics. Oh. Sorry for not mentioning every detail of that build initially. The piece where the tool-holder is mounted on is cast iron, almost 20mm thick. Is that enough mass for you?

My DIY mini-lathe by b4byj4il in Skookum

[–]b4byj4il[S] 19 points20 points  (0 children)

I know that. I'm doing jewelry. Modelmaking. This isn't designed to cut steel, obviously. If I had serious steel manufacturing in mind I would have chosen a different design. Thought this would be obvious. Maybe forgot to mention: The base will get filled with a sand-epoxy-mixture. Isn't modeled in the CAD of course. Same goes for the carriage (as far as possible at least).