New build with recycled parts on a ridiculous budget 120cm*60cm work area

[Desertboy]

OK still need to source the drivers, would using

4 of these
https://www.omc-stepperonline.com/st...or-dm542t.html

with 2 of these (2 per motor)
http://www.ebay.co.uk/itm/Universal-...YAAOSwaMpZno1f

be suitable for my machine

3 of my nema 23's are 2.8amp (X&Y Axis)
the other one is unknown but based on shaft length, size and weight it's 2 amp (Z Axis).

I was going to go with AM882's but seems overkill for my application and it's unlikely I will make major upgrades down the line to my machine as it makes more sense to build another one and then sell the first one.

[Clive S]

OK still need to source the drivers, would using

4 of these
https://www.omc-stepperonline.com/st...or-dm542t.html

with 2 of these (2 per motor)
http://www.ebay.co.uk/itm/Universal-...YAAOSwaMpZno1f

be suitable for my machine

If you are using a slaved axis arrangement then ideally you will need stall or fault protection to stop the gantry racking the AM882 will provide that.

The drives that you linked to seem to recommend 36V.

You could built a toroidal for not much more that would work better.

[Desertboy]

If you are using a slaved axis arrangement then ideally you will need stall or fault protection to stop the gantry racking the AM882 will provide that.

The drives that you linked to seem to recommend 36V.

You could built a toroidal for not much more that would work better.

So what you're saying is stop being a tight ass and do it properly lol, ok point taken!

When it comes to building the PSU will need help :)

[Neale]

I use 2 motors for my X axis, and I bought EM806 drivers primarily because of the stall detect. The EM806 is a later version, effectively, of the AM882. That stall detect has saved my machine from potential damage on a number of occasions when I've got something wrong. Typically, I've hit the e-stop because of some silly setup or gcode issue, and as a result the gantry has gone out of square. Not a lot, but enough to cause one end or other to bind on rapid feed somewhere along the rails. I've wired the fault signals from the stepper drivers into the motion controller and the whole machine then stops before any damage is done by one motor continuing to drive. Resetting and rehoming is a small price to pay. I reckon that if you are going two-motors rather than one-motor-and-a-long-belt, stall detect is pretty much essential.

Have you worked out how you will home the gantry so it is square?

[Desertboy]

I use 2 motors for my X axis, and I bought EM806 drivers primarily because of the stall detect. The EM806 is a later version, effectively, of the AM882. That stall detect has saved my machine from potential damage on a number of occasions when I've got something wrong. Typically, I've hit the e-stop because of some silly setup or gcode issue, and as a result the gantry has gone out of square. Not a lot, but enough to cause one end or other to bind on rapid feed somewhere along the rails. I've wired the fault signals from the stepper drivers into the motion controller and the whole machine then stops before any damage is done by one motor continuing to drive. Resetting and rehoming is a small price to pay. I reckon that if you are going two-motors rather than one-motor-and-a-long-belt, stall detect is pretty much essential.

Have you worked out how you will home the gantry so it is square?

I was going to assemble it first then fit (High quality) microswitches both sides of the gantry I need to work out where to fit them because I want them drilled into the aluminium so they can never move, had issues with 3d printer microswitches but they were super cheap, plastic printed mounts a nightmare on the Z. Conversly it's the X&Y that are the hassle with cnc with 3d printing they're nowhere near as important.

I've not looked at Mach 3 or linuxcnc but I have assumed that the microswitchs have some software adjustment to compensate for inaccuracy when fitting the microswitchs I know grbl (And even Marlin for 3d printers both Arduino based) does so would be shocked if they don't.

I figured one step at a time lol make router move and learn Fusion (These are at same time) then start with linuxcnc if I really struggle buy Mach3 but I'd rather use Linuxcnc been a linux used since 2005 big believer in opensource.

I did also consider inductive sensors like I set up on my printer for the Z axis but the microswitchs I'm looking at have very high repeatability and the difference in accuracy between them is marginal, when I checked the datasheets the inductive sensors had a slightly higher accuracy but lower repeatability and in the end they were both in the 0.01mm range with is probably better than my router will be lol.

I have no idea how to make sure the gantry is properly square though in the first place, pretty certain a set square isn't going to cut it lol.

[Neale]

From what I hear, you are probably on a winner with the LCNC approach. When I built my first router around 5 years ago, it had single motors on each axis so gantry squaring wasn't an issue. Just as well as I was using LCNC which had no capability to home each end of the gantry separately. I ended up going to Mach3 and a CSMIO/IP-M motion controller for the Mk2, with twin X motors. This combination works really well - except that it doesn't home each end of the gantry separately either! However, I understand that this is functionality that is now in LCNC so you should be OK when you get to that point. I have a manual process to get round this but it would have been nice to just press a button and have it all happen automatically.

I've had Z axis microswitch issues on my 3D printer - I know what you mean!

[Clive S]

I understand that this is functionality that is now in LCNC so you should be OK when you get to that point. I have a manual process to get round this but it would have been nice to just press a button and have it all happen automatically.

Yes you are correct but it is only in the master branch (version 2.8) at this time and you can also alter the homing position on each axis in software just by changing an offset in the Machinexxx.ini file

When it comes to building the PSU will need help

Have a look at Joe's excellent vids on building one.
https://www.youtube.com/playlist?lis...zD30sZjtp_VyqY

[Zeeflyboy]

I have no idea how to make sure the gantry is properly square though in the first place, pretty certain a set square isn't going to cut it lol.

Machinist's square is one option, but they are expensive. I got a 200mmx130mm one (square to 0.005mm/150mm or better) from starret for about 80 quid with a 20% off code.

You can make a less perfect square work by flipping it and averaging the results, but once you get into the lower ranges of measurement just the flatness of the edge can become problematic and that's harder to cancel out.

You can also drill a square with diagonals that you can measure with eg a digital calliper (100x100mm square will give an easy to measure distance that your typical digital calliper will reach). Insert some dowels and measure the corner to corner distance. If both corners are equally spaced diagonally then it's square, if one is longer than the other then it's forming a parallelogram and is leaning towards the top corner of the longer diagonal...

One problem you'll probably encounter, which I also have on my current machine, is that your extrusions aren't particularly flat or straight. You will have varying curves along the axis rather than a perfectly straight line which makes fine tuning the squareness extremely difficult if not impossible as it varies from one section of the bed to another... so you just have to do the best you can.

[Neale]

I used the holes-at-corner-of-100mm-square technique to set up my gantry, and it's surprisingly sensitive to small errors. We're not talking super-accurate toolroom standards here, but for woodworking use it's more than good enough. I used a 6mm drill to make the holes and then 4 more with shanks inserted in holes as dowels. A digital caliper is pretty much essential for this as it's difficult to read a vernier caliper when it's in the middle of the bed.

I wrote a little bit of gcode to drill the holes so that I could guarantee approaching each hole in the same direction to take any backlash out of the equation.