1000*1200 build log.

[m.i.k.e]

Hi all,
New year's resolution – Get a build started! I joined the forum over four years ago and designed numerous machines In cad but never started a build so I hope to change that, the design is nothing new and just ideas copied (stolen) from other forum members great machines with my own twist thrown in. I would welcome any input as I'm sure I will need it.

Rough working area -
X- 650mm
Y- 900mm
Y- 170mm

The frame will be made of 90*5 square tubing and the gantry 45*90 aluminium extrusion arranged L shaped.

I am hoping to use it for wood/aluminium and tiling larger wood/ply/MDF jobs through the Y-axis hence no Y bracing (I will be fitting a bolt-on brace on the Y when not tiling.)
pictures to follow.
Any thoughts on the design are deeply appreciated
Cheers Mike.

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[m.i.k.e]

Maybe a stupid idea but just trying to make it versatile.


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[m.i.k.e]

For the drivers, I was thinking of DM860T

https://www.omc-stepperonline.com/digital-stepper-driver/digital-stepper-driver-24-72a-18-80vac-or-36-110vdc-for-nema-34-motor-dm860t.html

And the steppers 23HS33-4008S

https://www.omc-stepperonline.com/nema-23-stepper-motor/nema-23-bipolar-1-8deg-2-83nm-400-oz-in-4a-2-26v-57x57x84mm-8-wires.html?mfp=149-step-angle-deg%5B1.8%5D%2C145-holding-torque-ncm%5B250%2C280%2C283%2C300%5D

And for the power supply I will be using is a toroidal transformer, how many volts for the DM860T they are rated for 36-110VDC?

Cheers mike.

[m.i.k.e]

I have a load of 63mm od galvanized pipe 3.2mm thick I would like to use for the stand but looks a touch undersized - what do you reckon?

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[AndyUK]

Hi Mike,

You've clearly got a reasonable design going and have done a decent amount of reading up. That's probably why you haven't got a lot of replies making better suggestions!!

The first thing I'd say is go for closed loop steppers rather than open loop. The cost increase is minimal but should prevent lost steps. I'm not even sure the drivers you linked have the (not perfect but better than nothing) stall detection. If you can get AC powered drives it also saves you a lot of PSU hassle.

I'm not overly keen on the lack of central Y axis support but give it a go and as you say you can always use braces or add them in later.

How are you planning to level the two sides of the Y axis and flatten the steel surfaces?

I'd also recommend an extra plate on top of the Y carriages to separate the linear motion components from the gantry itself further. This gives more adjustability to square the two axis to one another.

Keep up the good work!
Andy

[JAZZCNC]

Not sure how I've missed this and do agree with much of what Andy says.

#1 Closed-loop steppers are the way to go, far superior, and given the amount of work that goes into building a machine like this, it's just silly not to pay the extra.
Voltage wise it will depend on the motor but on the machines we build we use 4.5Nm and 5.5Nm closed-loop motors using AC drives with 50 or 55Vac toroidal transformer.

#2 If you use a thick enough tube the Y-axis support isn't a great loss for a wood router, but if you are wanting this machine for mostly cutting aluminum then support is better. The idea regards making it removable won't really work very well because it could affect the linear rails by pulling or pushing on the top tubes.
Now the idea of feeding through from the side is not too daft but I don't think it's worth leaving the brace out for when you could easily feed it through the other way if you just made it slightly wider.

#3 The extra plate is a good suggestion and you kind of do already have it, but I will go further and suggest you change the gantry sides and how it mounts to the ball-screws. I would shorten the gantry side to the level of the top plate and have it bolt into the top plate, this plate would also fasten into the gantry profile on the underside, this would then make the gantry a one-piece unit that bolts into the bearing plate.
The ball-nut mount drop plate would fasten into the lower bearing plate, this then makes each ball-screw and linear bearing a separate unit and much easier to align. The gantry then just bolts into the bearing plates and makes squaring the gantry much easier and without affecting the ball-screws. The way you have it now if you try to square the gantry at one side it will twist the screws unless you shim the end bearings accordingly.

#4 Check your holes..:hopelessness: What I mean is some of those plates won't allow you access to the bolts for the linear bearings so can't possibly work. Same on the Z-axis, make sure you can access the bolts and the bearings don't conflict with each other.

Other than these things it's looking good and your nearly at the build stage.

[m.i.k.e]

Hi Andy and Dean,

Thanks for the kind words and great suggestions.

As for the closed-loop steppers - I realize they are the way to go but I am trying to keep the costs down, They seem to be a decent price for 36v-48v but any higher and they shot up in price. I will have another look and do the maths.

The lack of Y support brace - Yes this is a suck it and see, I deliberately made the frame from 90*5 to compensate for this. I think it would take all the fun out of building my own machine if I just copied yours and other members machines lol, If it doesn't work out I can always add Y bracing later.

As for leveling the Y-axis surfaces - I think I will just use shims because of the uncertainty above ( could also level with epoxy at a later date)

Gantry side plate adjustment - That makes so much sense, I will re-design that.

Check your holes - Yes I think I was guilty of that in my first design a couple of years ago ha-ha.

Thanks for all the input - cheers mike.

[JAZZCNC]

The lack of Y support brace - Yes this is a suck it and see, I deliberately made the frame from 90*5 to compensate for this. I think it would take all the fun out of building my own machine if I just copied yours and other members machines lol, If it doesn't work out I can always add Y bracing later.

Wheels are round because they work best which is why everyone copies them, no shame in copying if it's what works best.!! Adding at a later date never works out well or like you expect and is certainly not fun when it affects sensitive surfaces which are important to machine accuracy.

Also, why 90x90.? That is an odd size for steel which I think you will probably find more expensive than 100x100 as it's less common.!

Last it's false economy buying steppers or drives because they are cheap because you'll only end up eventually buying them again and before that time comes you'll probably pull your hair out chasing issues or spending more money because the machine doesn't perform like expected so buy other things to try and make it better when all along it was the drives or steppers holding it back.
Better to wait a few weeks longer to finish it and do it right the first time, you'll have a far better machine with less stress for the sake of an extra £100 or less.

[Neale]

My own support frame is made of 50x50x3 which seems to be fine, so in principle your round tube should be OK.

However, the frame doesn't just keep the machine at the right height, it also has to withstand surprisingly high loads as the gantry in particular accelerates and slows down. Corner joints need to be strong, with plenty of triangulation. Round tube is more difficult to join to achieve this. And please remember that you need to remove zinc from galvanised areas before welding as the fumes are toxic (although maybe you know this already).

[m.i.k.e]

Wheels are round because they work best which is why everyone copies them, no shame in copying if it's what works best.!! Adding at a later date never works out well or like you expect and is certainly not fun when it affects sensitive surfaces which are important to machine accuracy.

Hi Dean, I'm on with a new design - I understand the points you are making are valid.


Also, why 90x90.? That is an odd size for steel which I think you will probably find more expensive than 100x100 as it's less common.!

I agree there are certain places that work that way but I have found plenty that charge by weight and 90mm is cheaper than 100mm.


My own support frame is made of 50x50x3 which seems to be fine, so in principle, your round tube should be OK.

Hi Neale, That's good to know, and yes you are right I do need some triangulation in there.

Cheers Mike.

[m.i.k.e]

Getting closer to my final design hopefully with the help of your contributions, I have made the central rail support permanent and widened the x-axis. The stand may need a little more bracing yet tho.

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Am I right in thinking I need 8 proximity sensors for the limit/home switches?
Cheers Mike.

[JAZZCNC]

Coming together Mike got just a couple of suggestions.

#1 Build in more adjustment, for instance at the moment you have no way to adjust the alignment of the Y-axis (long axis) ball-screws up or down, in and out you can shim but because it looks like you plan to bolt directly into the steel tubes then you have no up/down adjustment. It would be better to make those spacer plates wider so you can machine slots into them on either side of the BK block and make the BK bearings bolt directly to these, then bolt the spacer plates into the main tubes.
Balls-screw misalignment is the #1 cause of missed steps and stalling motors at high feeds and if too badly aligned bent screws so having plenty of adjustment will pay back big time when setting up the machine.

I can't see the X-axis clear enough but I suspect you could have similar issues there as well, esp around the ball-nut mount area.?

#2 Similar and related to adjustment is the motor brackets would be better bolted to the frame rather than welding which is how it looks like you plan on doing it from the pics.
A bolted setup also gives you more choice on belt lengths and again alignment, plus if you ever want to fit larger motors ie: Nema 34 then it's easy to swap out the bracket.

Other than those couple of things it's looking good.

[m.i.k.e]

Cheers Dean, I will look into your recommendations :beer:
Mike.

[AndyUK]

Am I right in thinking I need 8 proximity sensors for the limit/home switches?
Cheers Mike.

You can get away with four if you use traveling switches on Z X Y and A.

I use 5, travelling Z and X, then a fixed sensor on Y- and the slaved A-, then another fixed on Y+ which also covers A+.

[m.i.k.e]

Thanks Andy, that really helps :encouragement:
Cheers Mike.