[ledaero]

Hi,

I am building a router of 1500mm x 1500mm to cut ply, mdf and acrylic. It has leadscrew Nema 17 Z-axis, belt-drive X, Y axes and Nema23s (Dual steppers on x-axis).

I have all my mechanicals sorted, but wondered what kinds of speeds I should expect/build to (if that isn't putting the cartesian before the horse...).

I am at the stage where I need to spec the motors, drivers and control system, but things like IPS (mm/sec in my case, being one with the 21st century) mean nothing to me. I have no reference.

I hope to be making small plywood toys, dolls houses, some v-carving cutting acrylic to complement my 3D printing (small boxes, etc.). And while time IS money, I am not at the stage where I need to make a certain number of units a day to keep the wife in the manner to which she has aspired...

I can take a wild stab in the dark and look at some of the figures others are saying they are using - but I've seen some numbers up over 100mm/sec for 1/4" MDF, single pass, and that seems quite high.

So, where to go from here? To say I was on a budget is not too far from the mark, but I'm at the stage where the important bits get decided and so I'm prepared to spend a little now to get the desired effect.

A Gecko 540 is out of my price range, but something like a TinyG isn't. So, that means I am looking at around 2-2.5A per winding.

Any advice gratefully received.

[ger21]

For a machine that size, I would think that a nema 17 motor would be much too small for a Z axis, unless your machine is incredibly lightweight.

Do you have any pics or drawings of the machine?

What are you using for a spindle?

Typically, speed is specified in units/min. I would probably want a minimum of 5000-7000 mm/min rapid speeds.

Are the X and Y axis direct drive?
Direct belt drive, can give very high speeds, but low power and poor resolution.

If you go with a TinyG, I'd get the biggest motors with the lowest inductance that will work with it. Probably something in the 270oz range. I'd recommend the same for the Z axis.

Be aware that for the extra $150 that the G540 costs, it's capable of about 5x better performance, with the right steppers, and higher voltage power supply.

[ledaero]

It's the openbuilds Ox. A nema 17 is what's spec'd on all their builds. I was going to start of with a small Makita trim router as a spindle, as funds became available, upgrade to a DC spindle with better collet and speed control.

As to accuracy, I am cutting ply to make boxes and model aircraft parts, not milling metal. Half a mm is accurate enough. I think GT3 20 tooth belts and high resolution steppers will give me enough accuracy for what I want.

I hear what you are saying about the Gecko... It was certainly on the bucket list, but money's tight. Being such a critical component, I guess if you are going to spend money, that's the place not to skimp. It isn't just $150, though. By the time you have bought d9s, cables, etc, it's significantly more than that, but I appreciate that I should probably start off on the right foot

Looks like I need to do more research on motors, too. Thanks for the help.

[ger21]

I would consider that type of machine to be a very lightweight hobby machine. The G540 is probably more than you need, as there are too many other weaknesses to really take advantage of the G540's power.

[ledaero]

I would consider that type of machine to be a very lightweight hobby machine..

Correct.

Not everyone is a master machinist or needs .0001 accuracy while cutting 12 hours a day.

Some of us just like to make things for fun.

[ger21]

Has anyone built one of these 1500 x 1500??
The website I looked at said it can be built as large as 580 x 1219.
Let us know how the machine turns out, and if your still happy with it after a few months. We don't see many of these lightweight machines here at this forum.

Good luck.

[ledaero]

Another bloke on the Openbuilds site has just about finished a 1500x1500 machine and another guy has done a 1500 x 800 one. In some respects a500 square is easier, as there is no large-scale alloy cutting involved. I understand the issues with deflection on a 4ft span, and if it becomes an issue, I will just have to upscale the y-axis. It being an open source project, there are a lot of variances in machines already and there has been a bit of chat about beefing them up. There are no illusions that this is just for making lightweight sheet-goods projects, maybe a bit of v-carving, some light alloy or acrylic, but not to close tolerances.

And 1500 x 2 is the span dimensions, the maximum cutting area will be a bit smaller, obviously, but for what I want I think it will do as a start. If I can cut a half a sheet of MDF/ply, I will be very happy.

If things go well, a more robust steel 8x4 unit would be on the cards - but then I would need to buy a container or rent a unit to house it in. I don't think the missus would be happy with an 8x4 on the downstairs bedroom

To get my feet wet, for under $2k, it's a fun project.