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

[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

[Desertboy]

Can I mix stepper drivers temporarily? I budgeted it out and can afford 3 Am882 and the power supply today and can borrow a DM542T for a couple of months of my mate.

Could I get away with this setup use the AM882's for X&Y and the DM542T for the Z? I would power the DM542T with the 24v and the AM882 with the new build PSU.

I'd buy another AM882 ASAP obviously but would like to start playing.

[Nr1madman]

Can I mix stepper drivers temporarily? I budgeted it out and can afford 3 Am882 and the power supply today and can borrow a DM542T for a couple of months of my mate.

Could I get away with this setup use the AM882's for X&Y and the DM542T for the Z? I would power the DM542T with the 24v and the AM882 with the new build PSU.

I'd buy another AM882 ASAP obviously but would like to start playing.

This should work without a problem ;)

Skickat från min SM-N910C via Tapatalk

[Neale]

No problem with that - I use EM806 for X and Y, and a recycled M752 from my old router for Z. I was able to use the same 68V PSU for all of them but it's fine to run them off separate supplies if needed.

[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.

[Zeeflyboy]

Absolutely... you can theoretically detect around 15 seconds of arc with callipers that have 0.01mm resolution using a 100mm square.

That's about 0.004 degrees

If you nail it to within a couple of hundredth's of a mm then you have a pretty damn square machine. Depending on where I do the square on my machine mine it will be anywhere from about 0.02 to 0.09mm out iirc.

[Desertboy]

Poor photo's but got the final plate today all lines up ;)

I must have made one of the tightest Z axis ever lol





One more plate to collect tomorrow morning (Needed to have 4 10mm holes enlarged got an engineering firm to do it) and we can finally put it all together.

Been very happy with my nema to ballscrew alignement 3 of the 4 are perfect not tried the 4th one yet (Gantry motor) but I'm hoping we got 4 for 4.

The bolts in the Z axis top plate are 1mm too long at moment so need to cut them down as well.

I was worried about the Z plate most of all and it all seems good there's a couple of holes to counterbore in the Z axis but simple job.

I was going to chop my Hiwin's down for the Z axis but I'm going to leave them sticking over the top of the Z axis so if I do want to rebuild the Z I can get more travel, my travel is just over 8cm at moment.

When the top plate was being made an end mill broke hence the nasty bit on the top where the scratches are. The part is functionally perfect and the spindle mount is bolted onto this plate so it's also not visible so it would be pointless to remake and a waste of money.

The scratches I made when I was filing down round where the end mill had broke.

Big thanks to Chaz for making the plates and it was a pure pleasure to see Thor and an experience to feel her move lol, Thor truly is something else.