First Build - Yet Another Alu Profile Router - 900 x 800

[CaptainBarnacles]

Just before I push the button on a transformer could I just have a quick sanity check please?

Here's my thinking:

I have 4 qty 3A max steppers and I've ordered 4 qty 2DM860H drivers. I reckon that it's highly unlikely to have all four motors chugging away pulling 3A each at any given time so I've assumed 10A as the max draw. The drivers will take AC so I won't have voltage drops and capacitance calcs to take into consideration. I am looking at a toroidal transformer with 2x35V AC secondary windings in series ie 70V AC (the drivers are rated up to 80V AC). Therefor 10A * 70V = 700VA (750VA is the closest standard size).

Am I missing anything?

[CaptainBarnacles]

I'm back!

It's been more than a year since my last confession. In that time I've moved house, changed jobs, started new projects and generally transitioned into a new life. The best part is that I now have a huge (but very cold) workshop in which to play and more time to play in it!

I have been slowly accumulating parts and ideas for my CNC router and I'm ready to pick up my project again from where I left off. I am currently pondering my motion controller choices (AXBB-E, Acorn, old PC with LinuxCNC or other - I think I've ruled out Mach3/4), sourcing some cheap aluminium plate (seemingly no such thing exists!) and refining my design (still struggling with Fusion).

When I get something that you won't laugh at I'll post my latest design for a bit of critique and guidance.

Cheers!

[Kitwn]

When I get something that you won't laugh at I'll post my latest design for a bit of critique and guidance.
Cheers!

That's exactly why there are no detailed photographs of my machine on the forum.

Re Fusion 360: I know it's very powerful, it's free and I would benefit significantly from mastering it, but every time I try to get competent in it's use I get frustrated instead and return to my old friend CamBam.

Kit

[Neale]

Personal view - F360 is well worth struggling with, although I'm not sure where you start. It is a steep learning curve at first and, to be honest, I suspect that personal tuition from a friend who knows it is the best way to go. Once you are off the ground, then the videos start to come into play. One problem is that based on reputation the best series of tutorials available online are those from Lars Christenson but they were made a couple of years ago and the F360 user interface has changed a bit since then. Not massively - an experienced user would very quickly see and adapt to the differences - but for a beginner, things like saying "Select the Model workspace" is a bit misleading when it is now called the Design workspace. I've done a bit of tuition for local model engineering club members so I'm aware of some of the problems beginners have and I'm not sure that they are addressed very well in the online tutorials. That's all true, anyway, for the CAD and modelling side of it. CAM and gcode production is a different issue where things are a whole lot more complicated but for design work, keep bashing at F360, get a bit of help if you can from someone you can actually ask questions, and you'll get there.

You will find a few photographs of my machine in a thread here somewhere. People did laugh. Nevertheless, the machine works, and it works better than i ever expected. I'm doing a fair bit of detailed machining in steel these days, which isn't bad for a machine designed and built for working with wood. Keep at it - you' ll get there!

[CaptainBarnacles]

Personal view - F360 is well worth struggling with, although I'm not sure where you start. It is a steep learning curve at first and, to be honest, I suspect that personal tuition from a friend who knows it is the best way to go. Once you are off the ground, then the videos start to come into play. One problem is that based on reputation the best series of tutorials available online are those from Lars Christenson but they were made a couple of years ago and the F360 user interface has changed a bit since then. Not massively - an experienced user would very quickly see and adapt to the differences - but for a beginner, things like saying "Select the Model workspace" is a bit misleading when it is now called the Design workspace. I've done a bit of tuition for local model engineering club members so I'm aware of some of the problems beginners have and I'm not sure that they are addressed very well in the online tutorials. That's all true, anyway, for the CAD and modelling side of it. CAM and gcode production is a different issue where things are a whole lot more complicated but for design work, keep bashing at F360, get a bit of help if you can from someone you can actually ask questions, and you'll get there.

You will find a few photographs of my machine in a thread here somewhere. People did laugh. Nevertheless, the machine works, and it works better than i ever expected. I'm doing a fair bit of detailed machining in steel these days, which isn't bad for a machine designed and built for working with wood. Keep at it - you' ll get there!

That's exactly why there are no detailed photographs of my machine on the forum.

Re Fusion 360: I know it's very powerful, it's free and I would benefit significantly from mastering it, but every time I try to get competent in it's use I get frustrated instead and return to my old friend CamBam.

Kit

Haven't heard of CamBam, I'll take a look. I like 'free' and open source software but I have no objection to paying for good software if it gets the job done. F360 is hugely frustrating at the moment, especially so as I normally pick up new concepts pretty quickly, but I would like to persevere and reap the rewards as I've seen just how great it can be. While I'm CNCing as a hobby (for the time being) I still value my time and if I just can't get the results I'm looking for in a timely fashion I may well look into alternatives.

[CaptainBarnacles]

I have two different Y axis arrangements which I'd be grateful for some input on please. I originally designed my machine with top mounted linear rails but then thought I would give side mounted rails a try in order to lower the gantry by about an inch. The trade-off is that my bed will have to shrink by about 80mm from side to side as I've already got the gantry profiles (I know, design first, shop later - I've now got this tattooed on my forearms!).

Any opinions about the pros and cons of either would be much appreciated.

[pippin88]

On top of the side beams is fine.

Using 2 separate extrusions for the gantry is a lot weaker than one big one. If you already have them, it is worthwhile using a plate on the back to join the two gantry extrusions.

[AndyUK]

Either of those two setups will work, but unlike pippin I'd favour the second one in which the gantry beam is bolted to the same plate as the bearing blocks. In the first you have an extra joint to complicate things.

Totally agree on the joining of the gantry beams though, they should be one solid unit, preferably in an L configuration.

[CaptainBarnacles]

Either of those two setups will work, but unlike pippin I'd favour the second one in which the gantry beam is bolted to the same plate as the bearing blocks. In the first you have an extra joint to complicate things.

Totally agree on the joining of the gantry beams though, they should be one solid unit, preferably in an L configuration.

I think that I am leaning towards the second option, it does make sense that the gantry beams and the bearing blocks being fixed to the same piece should be more rigid.

Great call on joining the gantry beams together, I hadn't considered that at all. I guess a few pieces of aluminuim plate or profile offcuts would do the job.

[CaptainBarnacles]

I've been paying some attention to my X and Z Axes design this week and I'm starting to question whether I have built my gantry too high. The fully extended Z Axis looks like it could be vulnerable to excessive deflection given the amount of extension from the gantry.




What I realised is that most of the work I'll be doing will be on relatively thin material (12-40mm) so the router will be operating at full extension most of the time. I also realised that this must be a problem for a lot of machines; do most people raise the bed in order to minimise the deflection of the cutter? I would like to work material up to 100mm thick and I currently have about 120mm clear travel on my Z axis.

Rather than compromise my design to accomodate thick material do you think I would be better to design a machine to work thin material well and accept that I just won't be able to work thicker material. Being able to work thicker material was a bonus rather than a necessity.