Raised Y Axis Plywood CNC Router Vol.2

[mactec54]

Thanks everyone!

It will likely be the red breakout board:
https://www.ebay.com.au/itm/30460439...frcectupt=true

Will step the voltage down from 24V to 12V+ to be safe.

Are you using any fuses in some places?

Cheers
Dan

That is not a normal Breakout Board you have the link too; and they require a 24v supply that is a USB 100Khz Breakout Board and are not easy to setup

Most all good Power supplies have a fuse inside, so they are protected, you normally would not use a fuse from the DC output to the Breakout Board unless it is high voltage being used

[peteeng]

Hi Dan - Re voltage. I'm helping setting up a dual voltage system at the moment so took the time to flip the Z axis to 48V and see how fast I can get it to run. I ran all the motors on 48V and they all reached 3000rpm no load before becoming unstable. I then flipped the Z back to 24V and it reached 3000rpm as well so the drivers are doing a great job on each voltage. The motors are not low inductance either with 3mH &2mH. The driver is a DM542. Peter

[mactec54]

Hi Dan - Re voltage. I'm helping setting up a dual voltage system at the moment so took the time to flip the Z axis to 48V and see how fast I can get it to run. I ran all the motors on 48V and they all reached 3000rpm no load before becoming unstable. I then flipped the Z back to 24V and it reached 3000rpm as well so the drivers are doing a great job on each voltage. The motors are not low inductance either with 3mH &2mH. The driver is a DM542. Peter

Yes, the speed may not change even if you used 12v, 48v to 24v will have half the torque, and holding power.

[OZ_Dan]

Hello everyone!

Pete - Thanks for testing!

Well, if torque and holding power is halved when dropping from 48V to 24V, wouldn't that be an issue especially on the Z axis where the stepper has to carry and hold a significant amount of weight all the time?

[peteeng]

Hi Dan - I have made 12V systems in the hope of running demos in trade shows with a car battery but 12V was atrocious totally unworkable. I've made a few with 24V and they have worked fine, one with all 48V and its was fine. The latest is 48V/24V and it works fine on the bench have to marry it to a machine in the next week to really know. Its sister machine is 24V and its great so the 48V will be a bonus... My main reason for the dual voltage is the brake on the Z axis is 24V. I used to use gas struts, but the brake is so much easier and betterer...

But I doubt 24V is half the torque of a 48V. Torque has to do with current not volts. But you should be able to get torque curves from the supplier. I did a quick look at stepperonline and found this one 24V-48V comparison. Peter

re Z weight - a 5mm pitch screw will provide over 300kg of force at slow speed so if your Z is over that weight then your in trouble. Its also typical to set steppers to 50% amps when stationary this may not be the correct setting for the Z axis. So at 500rpm you have about 150kg of force available to you... 500rpm is 2500mm/min which is quite fast for a hobby Z axis.... So usually the z axis holding is not an issue. Falling when no power is an issue so balancing or braking is recommended...

[mactec54]

Hi Dan - I have made 12V systems in the hope of running demos in trade shows with a car battery but 12V was atrocious totally unworkable. I've made a few with 24V and they have worked fine, one with all 48V and its was fine. The latest is 48V/24V and it works fine on the bench have to marry it to a machine in the next week to really know. Its sister machine is 24V and its great so the 48V will be a bonus... My main reason for the dual voltage is the brake on the Z axis is 24V. I used to use gas struts, but the brake is so much easier and betterer...

But I doubt 24V is half the torque of a 48V. Torque has to do with current not volts. But you should be able to get torque curves from the supplier. I did a quick look at stepperonline and found this one 24V-48V comparison. Peter

re Z weight - a 5mm pitch screw will provide over 300kg of force at slow speed so if your Z is over that weight then your in trouble. Its also typical to set steppers to 50% amps when stationary this may not be the correct setting for the Z axis. So at 500rpm you have about 150kg of force available to you... 500rpm is 2500mm/min which is quite fast for a hobby Z axis.... So usually the z axis holding is not an issue. Falling when no power is an issue so balancing or braking is recommended...

The current (Amps) would have to be higher for the 24v than the 48V to give you the same performance, there is always going to be a tradeoff, lower voltage =more current (amps) to get the same performance as what a 48v would give you

12v would work fine if everything was designed to work with 12v if you only had a choice of 12v to take a machine to a show, then you would use an inverter that would give you 230v Ac power to run your machine, this is what is normally done, they have many options to do this, so no one is restricted to having just a 12v supply anymore

[mactec54]

Hello everyone!

Pete - Thanks for testing!

Well, if torque and holding power is halved when dropping from 48V to 24V, wouldn't that be an issue especially on the Z axis where the stepper has to carry and hold a significant amount of weight all the time?

Yes, that is correct, you can overcome that by having more Amps from the lower voltage supply if needed, this can create more heat in the motors though, and if the system allows you to use higher Amps.

[OZ_Dan]

Hello everyone!

Thanks for the info Pete and Mac!

Some more stuff has happened. 90% of the parts have been cut and the assembly of the torsion box has started. It's sitting on a sheet of laminated blockboard which is the flattest surface I had available. Photo attached is a first rough layout. The spacing will be properly adjusted and all the ribs be glued and screwed in place.
I also ordered all the HGR20 linear rails yesterday after they have been out of stock for ages as well as limit switches, wires, ON/OFF switches and an emergency stop button. Currently waiting on the 1605 400mm Z axis ball screw getting back into stock, they seem very popular.

I got to try out the little jig for my drilling guide I 3D printed and it seemed to work quite well. The jig centres the drilling guide to the side/thickness of the plywood sheets, letting me drill holes for the threaded nuts exactly in the middle
PS: Ignore the sticker on the guide - we are not in California so it doesn't apply lol

Next up is ordering all the bolts and washers. Accumulating up to over 500 pieces...

Cheers
Dan

[LorenBMS]

Looking good

[OZ_Dan]

Hello everyone,

Thanks Loren!

Quick update:
HGR 20 Linear rails and the ~500 bolts and washers have arrived. Now there's no going back anymore haha
Will need to cut 100mm off the 1700mm long Y rails as they didn't have any in 1600mm. Gotta be careful not to heat them up that much!

The torsion box is in it's final steps. Takes quite a bit of time to make one as only one section at a time can be assembled due to glue needing 24+hrs to dry!

Currently figuring out a table to mount it on. I found a 1500mm square solid timber table which would be perfect but it doesn't fit in my car - bummer!
Anyway, will keep you posted!

Cheers
Dan

[mactec54]

Hello everyone,

Thanks Loren!

Quick update:
HGR 20 Linear rails and the ~500 bolts and washers have arrived. Now there's no going back anymore haha
Will need to cut 100mm off the 1700mm long Y rails as they didn't have any in 1600mm. Gotta be careful not to heat them up that much!

The torsion box is in it's final steps. Takes quite a bit of time to make one as only one section at a time can be assembled due to glue needing 24+hrs to dry!

Currently figuring out a table to mount it on. I found a 1500mm square solid timber table which would be perfect but it doesn't fit in my car - bummer!
Anyway, will keep you posted!

Cheers
Dan

You can use a disc grinder with a cutoff wheel or a chop saw

The heat won't bother the rails unless you go past the annealing temperature and that is a cherry red color, where you are cutting them is not a working area so nothing to worry about

The main thing is that you deburr them where the cut edge is like it is on the original ends

[OZ_Dan]

Hello everyone!

Have shortened the Y Rails 100mm with a disc grinder and deburred them nicely with a dremel without any issues

Also, I ended up getting the 1500mm square table I saw on FB and luckily it was located just down the road because there was some dodgy transportation going on late at night haha
But it fits very well in my workshop, might have to end up stiffen the legs a bit as the table tends to get a bit wobbly already with only the machine base on it - which was another big act getting it on the table on my own...
Received the 6mm aluminium plates and some electronics (48 + 24V PSUs, cables, switches) and also bought some cheap extension leads to cut up which will serve as the power cords for the PSUs.
Furthermore I started assembling the X/Y Axis. Most of it from now on will be bolted together, not glued, as I need it to be adjustable for when the rails go on.

Next step is ordering the stepper and drivers and also the BOB.
I read somewhere that the inductance of the stepper motors play a big part and it should be as low as possible. The NEMA23 I picked have an inductance of 3.4 mH. Is that acceptable? I can't seem to find any lower on NEMA23. Will they work fine with DM542T drivers on 48V? Anything to watch out for?

Cheers
Dan

[peteeng]

Hi Dan - 3.5mH is Ok. Lower is better but hard to get sometimes. The 542T will drive them easily. If the 542T are the newest version they can use a 24V or 5V control circuit. 24V you have so this will save having a 5V circuit. Peter

[OZ_Dan]

Hello everyone!

Thanks Pete - have ordered all steppers and drivers. Let's see if they make it up here or if they go under with all the flooding on the NSW/QLD border...

Some more stuff has happened! The machine bed walls have been added as well as the Y linear rail mountings and also, with only 1 screw for now, the Y linear rails! Pre-aligned the Y axis carriers on slid it on the rails - it's moving, yay! Lots of means to adjust everything - which I reckon I need!
Been busy with the X/Y saddle. Takes a long time making it fit AND adjustable with all these bolts from both sides. But it's looking good so far, hope I can finish the saddle tomorrow.

The X and Y ball screws have also arrived but haven't unpacked anything yet. Still waiting for the Z ball screw to come back in stock...

Snatched a cartridge of lithium polymer bearing grease from work haha. Now I just need a grease gun!

[peteeng]

Hi Dan - Is the machine going to be safety orange? If you use acrylic paint dilute the first coat 1:1 with water, it gets into the timber much better. Peter maybe British racing green with a red stripe?

[OZ_Dan]

Hi Pete,

Probably will paint it red, because we all know, red makes everything go faster! Jokes aside, I don't actually plan on painting it any colour as this process takes a huge amount of time (and money) and doesn't add anything of value but looks.
I'm more concerned about moisture proofing the wood. I likely will go with PVA glue for the end grains (as I have some left) and thinned linseed wood oil for all the surfaces as it is quickly applied with a rag.
Stuff like this:
https://www.bunnings.com.au/diggers-...trate_p1670039
Will make the timber look a tad darker which is fine by me.

I thought I share a quick insight into budgeting. Aim was to build the machine for about $2000 AUD. In my spreadsheet I'm currently up to 2126.88 AUD for everything which also includes small things like cable conduits, tool setter, screws and wood sealant. Am expecting it to not grow more than $100AUD unless something absolutely doesn't wanna work together... Can share the excel spreadsheet once the machine is kinda finished

Cheers
Dan

[peteeng]

Hi Dan - I'd use PVA for a snader/sealer but not exposed to moisture. Several of the brands will go fungusy if left to the environment. One of my routers has done that on the ply ends. I'd go to a local hardware and asked for expired/old acrylic paint they usually sell it off cheap. Water it down 2 parts paint one part water gets good coverage and penetrating. 3 coats doesn't take much time and I'd rag it on although a brush is fast as well when diluted. I wouldn't use oil. When you start cutting aluminium and use a lub you will need to protect the timber. Use a plastic sheet, if the lub gets into the timber it will ruin your timber jobs plus slowly degrade the machine. The diggers oil seems like a good idea but you will have to reoil occasionally and the cost will add up. Plus its difficult to paint over an oiled surface even though it's supposed to cure when you decide to do the stripes. If your near a fiberglass supplier polyester resin is cheaper then paint and will be hard and impervious to lubs. If the budget is there vinylester resin is one step better. Peter

[peteeng]

Hi Dan - Started assembling my new Z axis today. Its red must be going to be fast!! Peter

[OZ_Dan]

Hi Pete!

Thanks for the options!

If I can't get acrylic paint, how about clear varnish?
https://www.bunnings.com.au/bondall-...rnish_p0079567

I do not have any fibreglass shops near me but I read up on different resins and found this stuff. Would this work too?
https://www.bunnings.com.au/protite-...resin_p1560653

Assembly looking good!

Cheers
Dan

[peteeng]

Hi Dan - the monocell is $25/l the polyester resin is $37/l at bunnings way too expensive. Something like this is <$25/kg
Surfboard Laminating Resin + Catalyst – Trojan Fibreglass Online

check if it requires wax additive. If some PE and VE resins are unwaxed they stay sticky on the surface as the styrene evaporates and there's not enough left to cure at the surface. So either get a waxed resin or ask about some wax to add yourself... So first coat unwaxed so surface stays active then final coat use waxed resin...

cheers Peter

https://www.bunnings.com.au/spring-4...paint_p1400910 cheap acrylic paint is going to be your cheapest option. Bunnings will tint it RED for free. Dilute 25% and 4 liters will cover a lot of territory. If you have a small spray gun even better... I like brushing. Peter