Power Supplies

Are you searching for a new, cheap power supply for your CNC project? Well, here you have two options for a 24V / 8A supply.

supply-comp_2I bought Sonyang for $35 just here. I don’t remember how much I paid for the MW one, but for sure it was in the same range. So here are the guts, Sonyang on top, MW below.

supply-comp_1

Some things to point out:

  • Yellow plastic cover on MW is not well designed: can’t be fully opened (I will just remove it).
  • Soldered fuse on MW, socket fuse on Sonyang.
  • Dual output 24V terminal on MW; triple on Sonyang.
  • Way better output rectifier heatsink on Sonyang.
  • Overall larger components on Sonyang.

Of course a visual inspection of the boards doesn’t tell the full history, but to me, there’s a obvious choice.

Update: Second power supply brand is “Meang Wel”, not “Mean Well” as I thought. Real Mean Well power supplies seems to be a lot better.

 

Posted in All, CNC, Electronics | Tagged , | Leave a comment

Nema23 mounts

I’ve got these motor mounts from rattmmotor88 ebay seller for just $15.67 each one, shipping and hex screws included. Shipping was really fast (fedex), just eight days (I use to wait 30 to 50 days for items from china).

IMG_2908

Packaging could be better; there are some scratches, but nothing you can’t fix with a file. Internal milling is great. External sanding finishing looks nice, but flatness is somewhat compromised; milling finishing for mounting surfaces would have been great. I don’t understand why they make motor recess 42mm diameter when it should be 38mm; anyway this is not a serious issue. Of course a critical parameter in these mounts is the space they add between motor and mount surface; 40mm in this case.

As this kind of mount allows a lot of play between leadscrew axis and motor axis, you should be careful every time you install X or Y motors, especially if you’ve got heavy motors and/or your couplings are “flexible type”.

Posted in All, CNC | Tagged , | 2 Comments

CNC6040Z

This gallery contains 16 photos.

Cheap chinese routers: will be worth? That’s the question (or was, for me). So here’s my new machine; well, just a frame. US $1040, shipping included. Here’s the link. I’d rather choose this machine instead the most popular chinese router … Continue reading

Gallery | Tagged , | Leave a comment

Things you don’t know you need

I’m quite tidy. But when I’m working, I should move from my chair to get any tool. So every tool I grasp ends on my table (because I’m too lazy to put it back), and after some days my work area turns into a mess, so later I should spend a lot of time putting everything in its place. But now I have this:

IMG_2787

This is a really cool tool organizer: compact, cute, wheeled. Having your tools at hand, fast and easily, makes a difference. I’m in no way associated with Keter, and for sure there’re another brands similar products, but this is a great product.

Posted in All, Comercial Tools | Tagged , | Leave a comment

Learning the hard way

When I was a CNC girl, I thought things like “Once you make one, you can do thousands, easily!”, “Acetal is the perfect plastic for precision parts and cuts like butter!”. OMG I was so naive. Making these parts were really a pain in the ass. That’s why.

IMG_2782


IMG_2774

Acetal has internal stresses. This mean that if you remove a significant mass from a block of acetal, the final shape will warp a bit. I knew that. But what I didn’t know was that sometimes this natural “stress relief” can take hours. So one day I was turning a lot of these parts, everyone having a perfect bearing fit. But then, on the next day, the bearing fit was really tight; the parts have had shrank a little bit. May be acetal I got wasn’t annealed? Or may be I should anneal these parts? (yes, plastic annealing is a topic).

BTW, in this specific case, a bearing housing should, ideally, not divert more than 5-7um from the nominal size: 10um less and the bearing will not fit; 10um more and the bearing fit will be too loose.

Now the other issue: long aluminum crosslide = noticeable thermal expansion. So the table temperature will change after stepper warm-up. And, it will change again after some machined parts. From what I remember a machined radius can easily divert 0.03um because of thermal expansion. And rehomming after temperature changes can be a bit misleading.

The good thing is that, once you understand these issues, making something to avoid or reduce them is not too hard. The bad is that now I have a full bag of black plastic decoracion parts (not the ones in the pictures, of course).

Posted in All, CNC, Sherline | Tagged | Leave a comment