Comments sought on new build: A CNC Router for RC Gliders and Planes

[njhussey]

I was lucky, not complaining as I've always had the fee (which I don't mind as it's the law) on imported stuff so a bit of a change. You got your steppers and drivers yet? Which ones you going for? I was thinking of the Leadshine AM882 from Zapp and the Nema 23 3.1Nm stepper motors from cnc4you...plus looking at making my own (gulp...) PSU.

[Wobblycogs]

Erm, snap on all items (even where I was planning on buying them) . From what I've read they seem like a good combination of parts. I'd probably have made some purchases by now but I've been looking into getting one of these PMDX-107 for spindle control. I doubt I'll set up spindle control straight away but if I can order the part at the same time as the BOB that would be good. I take it you've seen this thread about building a PSU?

[njhussey]

Sounds like yours and my machines electrics will be the same I was going to look into the closed loop system but for what I'll be using it for I couldn't really justify the extra. I've also been looking at that as I was wondering if I could use the PWM output to control my RC Speed Controller which will be powering my spindle. Sounds like some combined purchases could be made here!!! Yes seen a few threads, I'm fine mechanically but anything electrical leaves me cold...

[Wobblycogs]

I own a soldering iron and I even switched it on once...

I'm actually quite interested in the electronics I just don't really have time to learn as much about it as I would like. I think I'll probably build the PSU as it's only a dozen or so components, more complicated magic will have to wait.

If you want to get together for a brain storm on the electrics or to put together a combined purchase just give me a shout.

[njhussey]

More than happy to get together for a brainstorm on the electrics, would be good if we both have the same as then we can help each other out (seeing as we only live a couple of miles apart!) in case of problems. I'm definitely going to build my own PSU but will need to check from the experts on here that I'm getting the correct parts.


Will give you a shout when it's time to get the electrics, in turn give me a shout if you're ready before me to get them as I'm going to concentrate on the build of the frame first as the electrical bits have a 12 month warranty and I'll want that to be as near as possible to the end of the build...

[njhussey]

OK Dean, switched the gantry around again to how it was before. Have put a folded aluminium enclosure over the Z axis, on the bottom of the Z there will be a rubber cover (5mm thick rubber with cut outs for the rails) to stop chips going up into the bearings. Have put deflectors on the X axis to stop chips hitting the linear rail, also put a deflector down the bottom so chips slide into the bin. Have altered the ballscrew mounting so it's on 20mm block and not the aluminium box section as I'm not using that anymore. I will also put a cover over the X axis belt and steppers.

Couple of questions now...

1. I'm going to use 1 stepper and belt (T5, 15mm wide) and pulleys to drive the X axis, what number teeth pulleys would you recommend? I take it that it's worth getting spare pulleys and belts so that the option of 1:1 and 1:2 (stepper to ballscrew) is available?
2. For the belt idlers/tensioners I was going to use skate bearings (as I've got sh*t loads of them) and penny washers, I couldn't see any specific idlers for the belts?

[JAZZCNC]

Couple of questions now...

1. I'm going to use 1 stepper and belt (T5, 15mm wide) and pulleys to drive the X axis, what number teeth pulleys would you recommend? I take it that it's worth getting spare pulleys and belts so that the option of 1:1 and 1:2 (stepper to ballscrew) is available?
2. For the belt idlers/tensioners I was going to use skate bearings (as I've got sh*t loads of them) and penny washers, I couldn't see any specific idlers for the belts?

Depends on how your having belt system.? My machine is setup with 2 pulleys bolted together on one screw with a single pulley on other. A short belt goes from motor to first pulley then connecting belt goes between screws. The ratio is 1:2 motor with 40T and first pulley 20T Connecting pulleys are 36T. I then have 2 spare pulleys for 1:1 or 1:3 ratio 20T & 60T.
Connecting pulleys could easily be 20T for simplicity sake but I just happened to have spare 36T so used them.

Don't go smaller than 20T other wise you don't get good tooth engagement and the belts wear quicker or worse they can jump. I'd also use HTD belts/pulleys not T5 has thou they are very similar the HTD just seem better fitting belt.

Yep skate bearings and large Penny washers work fine for idlers.!!