Joe90's BIG RAT Build.

[joe.ninety]

Ok, on the advice of Jazz, I've decided to start a Build-Log. And those of you old enough will know why I've called it BIG RAT :joyous:

Anyway, I hadn't really thought of doing this as construction of anything still seems a long way off, but as Jazz said a BL is a good way of keeping all related content and stupid questions together, 'stupid' is my addition, not jazz's ;-)

Like most people, I've been lurking for quite a while and whilst I feel I'm starting to get an idea of what I want, it seems that my path diverges upon the turn of every corner and I'm left feeling overwhelmed at the complexity of making so many decisions.

I've been following AndyUK's build log with extreme interest and that seems to be the sort of machine I would be happy to end up with. Ideally, I'd like a machine that has a cutting capacity of 1.2m X 0.8m but I'm also looking at the possibility of using it for Aluminium (I'd like to be able to use it to machine any parts and plates for future machines/upgrades) but I'm worried that in trying to make the machine at this particular size, that I'll end up compromising things and that it will do neither well unless I throw a lot of money at it. Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good. More than that and it'll start to eat into my other interests.

So, off we go

For a floor standing machine, what sort of height should I be aiming for the main supporting frame/structure. i.e how far from the floor do most people make the actual bed of their machines?

Now I know that no 2 of us are built the same and what's suitable for someone who's 6'6" won't be approprite for Peter Dinklage, but I'm a pretty average 5'10" so what would be a good height to choose? What heights do those of you who are around that height use, and use comfortably?

Cheers

[AndyUK]

I've been following AndyUK's build log

Aww thanks. Definitely read through Joe Harris' build log. I based mine on his machine. His is better! More detailed log with videos on youtube and everything.


I'd like a machine that has a cutting capacity of 1.2m X 0.8m

Don't forget to factor in footprint size vs cutting size. My footprint is 1.2x1.0, I can cut about 0.90x0.65, but I haven't exactly tailored to maximum build size.


Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good.

I don't like to add up costs but we're probably talking about £3-4k for mine. Can certainly have been done a lot cheaper though. Worth factoring in that this build will probably take a year or more, and the expenditure is quite piecemeal other than the big ticket items.


For a floor standing machine, what sort of height should I be aiming for the main supporting frame/structure. i.e how far from the floor do most people make the actual bed of their machines?

Now I know that no 2 of us are built the same and what's suitable for someone who's 6'6" won't be approprite for Peter Dinklage, but I'm a pretty average 5'10" so what would be a good height to choose? What heights do those of you who are around that height use, and use comfortably?

As you say, depends what is comfortable for you! I have a standing work bench in the garage which is a really nice height to work at, so I just designed the frame to suit that same height. I think it was around 90cm, but I'll check later and edit this post.

[JAZZCNC]

I hadn't really thought of doing this as construction of anything still seems a long way off, but as Jazz said a BL is a good way of keeping all related content and stupid questions together, 'stupid' is my addition, not jazz's ;-)

Like most people, I've been lurking for quite a while and whilst I feel I'm starting to get an idea of what I want, it seems that my path diverges upon the turn of every corner and I'm left feeling overwhelmed at the complexity of making so many decisions.

Wise choice and over time you'll see why it's best to ask questions all in one place that relate to the machine your building.



Ideally, I'd like a machine that has a cutting capacity of 1.2m X 0.8m but I'm also looking at the possibility of using it for Aluminium (I'd like to be able to use it to machine any parts and plates for future machines/upgrades) but I'm worried that in trying to make the machine at this particular size, that I'll end up compromising things and that it will do neither well unless I throw a lot of money at it. Whilst money is not too much of an issue, if I can keep the overall spend under £2k that would be good.

With 2K you can just about do it but you will have to be very careful with what you buy and where from. First off forget buying things like Rails and ballscrews from inside UK or EU. They will need to come from China if you want to do it the cheapest way, but don't be put off by this because if you bought them in Uk then chances are they came from China anyway and marked up 300%.

Regards the structure then cheapest way to build a strong machine is to use steel for the mainframe and epoxy the rail mounting surfaces for accuracy. The gantry can be built from steel but it's simpler to use Aluminium Profile and makes mounting rails etc very easy.

The best advice I can give you don't buy anything until your ready to build and don't buy any electronics until needed.

Next would be don't try to reinvent the wheel. Machines like what Andy and Joe Harris built which use the L shape gantry design and high frame sides work very well, I know this because they are mostly based on my original design which I've built dozens of machines using that are used to cut all materials up to aluminum and brass. Often by users running a small business.

Finally don't be shy or worried about asking what may feel like stupid questions, they will have been asked before.

Good luck.

[joe.ninety]

Ok,

Just trying to come up with a list of possible suppliers for bits,

So far I've got the following...

Linear Motion & Ballscrews etc. etc: - Fred @ BST Automation

Aluminium Proflies: KJN

Aluminium Tool Plate: Seems like lots of possibilities.

Steppers: Undecided - But I'm assuming that I'll be using the Closed Loop variety

As far as motors are concerned, what do people think of the kit that Stepperonline sells. They seem to be very competitively priced, and I've seen that they have been mentioned in previous threads towards the start of last year. Are they a good supplier of decent kit or to be avoided.

Cheers

[AndyUK]

I think some people use Motedis (https://www.motedis.co.uk/shop/index.php) for Profiles. StepperOnline / CNC4YOU / Zapp for the steppers & drivers.

[joe.ninety]

Am I correct in thinking that

BK/BF12s are for 1605/1610 Ballscrews

and that

BK/BF15s are for 2005/2010 Ballscrews

Also, I don't see many builds using the other variety... the FK/FF type. Is that because the BK/BFs offer better performance or is it down to costs?

[JAZZCNC]

Am I correct in thinking that

BK/BF12s are for 1605/1610 Ballscrews

and that

BK/BF15s are for 2005/2010 Ballscrews

Also, I don't see many builds using the other variety... the FK/FF type. Is that because the BK/BFs offer better performance or is it down to costs?

Yes BK12 = 16mm BK15=20mm

Regards the FF then they are a different fitment where they don't actually use a block that you bolt down. Instead, they bolt directly to something which is usually machined.
For instance, you would use them in situations like where you would machine a hole in the gantry sides and bolt the FF block thru the hole directly to the gantry side, you can gain a little extra travel this way. The downside is you have very little room for adjustment or error so require careful planning and accurate machining.

I use Motedis for my profile, they are cheaper than KJN, esp in regards to T-nuts, etc and usually quicker also a lot more accurate cutting.

Regards the motors and drives then I'd definitely suggest going with closed-loop but you need to pay careful attention to the Max voltage as a lot of the NEMA 23 sized kits use 50Vdc drives which means running around 45vdc which doesn't make them overly fast. Ideally, look for drives that allow 80-100Vdc or 50-70Ac.
AC drives are simpler and cheaper because you only need a transformer, where a DC requires a Transformer. Capacitors and Bridge rectifiers to make up the PSU.

I use Lichuan closed-loop systems on all my machines now.

[joe.ninety]

In regards to carriages, I understand that Hiwin is the brand of choice but I just wondered when you would chose to use the W kind, with the side flanges as opposed to the regular square type? So when for example you'd chose to have HGW15CA or HGWCA20 instead of the what seems to be the more common choice of HGR15CA or HGR20CA.

Also, is it common to have the 20s on the X & Y Axis' and have the smaller 15s on the Z? This seems to be quite a common choice

I've been watching this video series on YT and that was what got me thinking about the 'W' carriages, as he uses the 'W' variety on his Z axis and his Y, but the 'R' variety on his longest X axis...

https://www.youtube.com/playlist?list=PLx3FKzVphd7cRb9nwFMyCkJLcRBChdojC

Finally, are people happy to go with the self-made ball screws that Fred @ BST supplies, or do people still stick to Hiwin branded wherever possible?

Cheers

[JAZZCNC]

In regards to carriages, I understand that Hiwin is the brand of choice but I just wondered when you would chose to use the W kind, with the side flanges as opposed to the regular square type? So when for example you'd chose to have HGW15CA or HGWCA20 instead of the what seems to be the more common choice of HGR15CA or HGR20CA.

Ok well first HGR is the rail. HGH15CA or 20CA are the Slim carriges.
When to use the W or wide carriage depends on the design. Personally I always use the W on the X & Y axis when ever possible and Slim type on the Z axis to save room. If I have plenty of room on the Z axis I'll use the W type again because being wider gives that little more support.



Also, is it common to have the 20s on the X & Y Axis' and have the smaller 15s on the Z? This seems to be quite a common choice

Regards 15 or 20mm on the Z-axis then I strongly urge you to go with 20mm. The 15mm is fiddly and mean you have to have big standoff spacers or machine deep into the rear plate. 20mm rails and bearings give you much more support which you need in a Z-axis.

To be honest, only partly watched the video and didn't see his other machine but he made comment to the rails on the front plate being stronger.? This isn't strictly true and it does depend on the type of cutting your doing and the length of the tool being used and the machine design.

I've built machines small and large using both methods and there's very little difference between them when using short tools, as the tools get longer the rails on the front start to have a slight advantage because the Z-extension reduces. However, this only applies up to a point because it also limits the length of tools and the material height you can use. Whereas the other method with rails on backplate allows much longer tools to be used, it allows much taller material to be used and still use long tools or drills.

So here's where machine design comes into the mix. With the rails on the front plate then because it limits material and tool size due to the fact it can only lift the spindle up until the rails reach the bearings, meaning the tool and spindle hang below the gantry. This means the gantry sides need to be taller if you need to cut taller material with longer tools. This weakens the machine and takes away any advantage it offers over the other method, which as I say isn't a great deal.

Whereas the rails on rear plate mean that the spindle can be lifted high up the rear plate so the tool clears the bottom of the gantry giving the full height from bed to underside of gantry even with a long tool. This means you can make your gantry lower and still have the same material clearance as the other method but it makes a much stiffer machine and better cutting so eliminates any advantage the rails on front plate offers.

So as you see there's more to it than just bearing type.!


Finally, are people happy to go with the self-made ball screws that Fred @ BST supplies, or do people still stick to Hiwin branded wherever possible?

Fred is a great guy to deal and I fully recommend him, tell him Dean sent you and it might help on the price. Also, I suggest you invest in some C5 grade ballscrews and ask for the Better BK/BF bearings which I believe are C3. These are more in line with Hi-win grade ballscrews.

[joe.ninety]

Do the external dimensions of BK/BF blocks vary by manufacturer or are they standard dimensions dependent only on rail diameter?

Cheers

[JAZZCNC]

Do the external dimensions of BK/BF blocks vary by manufacturer or are they standard dimensions dependent only on rail diameter?

Cheers

Yes they can do slightly. The internal will be all the same as it's a standard but the externals can vary in size but in my experience they are very close in size.

[joe.ninety]

Whereas the rails on rear plate mean that the spindle can be lifted high up the rear plate so the tool clears the bottom of the gantry giving the full height from bed to underside of gantry even with a long tool. This means you can make your gantry lower and still have the same material clearance as the other method but it makes a much stiffer machine and better cutting so eliminates any advantage the rails on front plate offers.

Does having rails on the rear plate also mean that you can have a smaller plate on which the spindle mounts? Thereby saving on material costs?

Cheers

[Andrewg]

Hi Joe,
Thanks for asking many of the questions I need answers to as well!. I am currently trying to start my own design from the Z axis out. You would think this would be the simplest axis with least design options, but still the choices come. I had also picked up the tit-bit about rails on Z plate for stiffness, so grateful that Jazz has spelled out the trade offs.

It seems to come down to how to sandwich rails/bearings and ballscrew/ballnut between two plates neatly and compactly.
A 16mmm ballscrew nut and holder is 40mm high, so that is the minimum distance between plates,
However BK12 are 25mm from base to ballscrew centre, and ballscrew holder is 20mm, So using these simple components, plates must be 45mm+ apart
If you are going to have to pack up rails or bearings to span this gap, then 20mm rails are far from too big, as at 30mm combined height, you will need a 15+mm space. FK bearings and clever design might make it possible to pack things a little tighter, but I am still looking around for a reference design that solves all this with minimal parts and machining.

Good luck with your design

[Neale]

My approach to this problem was to use 20mm rails, and 20mm Ecocast plate. This gave enough depth of material to be able to pocket the plates for clearance around the nut holder. The important point here is that the pocketing is for clearance and is not super-critical in terms of dimension. This means that you can use a woodworking router to do the job. I actually used my vertical mill, but if you search the forum for (from memory) Joeharris's posts he talks about how he used a conventional handheld router successfully to machine aluminium. Might be worth a look and a few back-of-emvelope sketches. I know that I spent a long time on the details in this area; apart from anything else you have to be able to assemble the Z axis and I ended up doing things like drilling access holes in the moving plate to be able to get to a few allen bolts going into the fixed plate. All good fun!

[JAZZCNC]

My approach to this problem was to use 20mm rails, and 20mm Ecocast plate. This gave enough depth of material to be able to pocket the plates for clearance around the nut holder. The important point here is that the pocketing is for clearance and is not super-critical in terms of dimension.

This is the easist and best way to build a Z axis. Packing rails off or bearings off is a fiddly bodge. 15mm rails while more than strong enough are fiddly things and make it awkward.
You could go with 25mm rails and get away with no machining but then it gets tight with space and really requires a wider Z axis, plus there's more mass to deal with.

Hand machining isn't difficult provided your comfortable using a large router. I did several of the parts for my first machine this way and was the one who talked Joe into giving it a go, however Joe cut far more parts than I did using this method and made a very nice job of it so I'd advise anyone thinking to do this to go check out how he did it.!

[Andrewg]

Yes, as you say Joe Harris's videos show simple routing of Aluminum is doable if high precision not required. However looks from video that he actually used 15mm+ spacers under his Z bearings and flat plates.

Neale, presumably you have to recess one plate for the ballnut holder, and the other for the BK/BK bearings....or go another way? What am I missing?

[JAZZCNC]

Yes, as you say Joe Harris's videos show simple routing of Aluminum is doable if high precision not required. However looks from video that he actually used 15mm+ spacers under his Z bearings and flat plates.

Neale, presumably you have to recess one plate for the ballnut holder, and the other for the BK/BK bearings....or go another way? What am I missing?

Just because Joe did it that way doesn't mean it's a good way. He did it because it was the easiest way, I'm telling you the other way is better from experience. Those building have to make there own minds up which to route to take based on there own abilty's and equipment just like Joe did.!

This might help with the confusion.

27879

[Neale]

Neale, presumably you have to recess one plate for the ballnut holder, and the other for the BK/BK bearings....or go another way? What am I missing?

As per Jazz's picture, you need a recess in both halves. As I remember (and I can't find a drawing of it to hand) the recess was wider somewhere around the middle of the plate to give space for the ballnut mounting bracket. As ever, make sure that your design allows adjustment to align the ballscrew and nut in two dimensions - well, I needed to as my machining ain't that accurate...

[CNCRY]

Andrewg - I went through this same thinking, and am in the process of building it now. I'm using the spacer method, it's requiring 15mm spacers with the 20mm hiwin rails to get enough clearance with no pocketing. My thinking is that if I can get the CNC up and running I can then pocket out a new piece if needed, as I'm more likely to mess up the plate routing by hand (and no access to mill anytime soon). I'm offsetting the overhang by using 15mm thick tooling plate instead of 20mm. So saving 10mm but spacing 15mm.
Mine is untested so far though! - so I'd go with Jazz's and others advice any day if you are happy to pocket them.

[joe.ninety]

I've been doing a lot of reading about PSU design but there are still a couple of issues I'd like help with.

Firstly, I've seen some people say that that the current drawn by a stepper is per phase? So if a motor is rated at say 4A per phase its actual requirements might be as high as 8A? Presuming it is of course a 2 phase motor. Whilst I've seen lot's of drivers that can happily supply that amount of current, it does seem to have an enormous impact on PSU requirements, which brings me neatly to my second question...

I've seen differing percentages quoted regarding exactly how much of that current a driver actually uses, AndyUK talks about it being 60-70% but I've read elsewhere that it can be as high as 80%. Obviously this has a significant impact on the design of the PSU, not just on the actual tranny itself but also on the size of the capacitors needed for the smoothing function.

So can some kind soul clear this up for me... when calculating motor current draw, do we calculate the A per phase or not, and what is a good % figure to use for actual driver current draw? OR does this last point very much depend on what drivers you actually end up using? So some might use 60% whereas others will take 80%.

On another note...

I sunk a big chunk of my CNC budget into one of my other loves and bought one of these babies...

https://www.brewuk.co.uk/grainfather-g70.html

It does mean that my hopes for my CNC will be knocked back a bit further but I'm saving a fortune by not going to the pub so the CNC kitty should be back to pre-lockdown levels soon.

Cheers

[AndyUK]

Wow that's some serious brewing activity...

Don't worry about phases in your calculation. Just take that single phase value, 4A or so and go with it.

If your Calcs end up needing more than 1000kVA you're probably not quite right, or you're building a beast. Most builds here use around abouts 500kVA.

I won't comment on the information you've already seen from my build log - no point hearing the same persons opinion twice. Although I will add that I think I was a little conservative with my secondary voltages in retrospect, and could have gone higher.

[Neale]

It's easy to get too wound up about these things. Whether you should use 60%, 70%, or 80% really doesn't make a bit of difference - if you are using a linear (i.e. toroidal transformer, etc) anyway, in practice, the average load will be way lower. Doesn't matter to the transformer - as long as it's rated for the average load with a bit left over, its thermal mass is so great that a few seconds a bit over rated current won't worry it. The rectifier is coping with short high-current pulses anyway as it charges the capacitors towards the peaks of the cycle. And capacitors aren't that critical as regards value as this is a CNC machine, not an audio amplifier. Ripple is not an issue. My drivers, for example, are rated for something like 20-80V input. A few volts more or less ripple ain't going to bother them any. I use a 650VA transformer that gives me around 67V and it doesn't even get warm.

Different case if you are using a switched-mode, stabilised, power supply. They are much less tolerant of peak loads and you might be safer over-specifying if you use one of those. Which is why linear PSUs are generally recommended!

[JAZZCNC]

As the others say don't get stressed over it and just build to give the required amps plus a few spare. Work on 60% of the total Motors rated amps and it will be fine.

Don't go crazy OTT with the amps because you will end up with a large Va rating and the inrush will bite you. 500Va does most 3 axis machines and 625Va for 4 axis running typical 4.2a steppers with 60-70Vdc. These are tried and tested values on 100's of machines.

[Clive S]

Wow that's some serious brewing activity...

Don't worry about phases in your calculation. Just take that single phase value, 4A or so and go with it.

If your Calcs end up needing more than 1000kVA you're probably not quite right, or you're building a beast. Most builds here use around abouts 500kVA.

I won't comment on the information you've already seen from my build log - no point hearing the same persons opinion twice. Although I will add that I think I was a little conservative with my secondary voltages in retrospect, and could have gone higher.

That would be some big machine :whistle:

[Muzzer]

Yes, 1000kVA would be about 750 hp. You'd need your own substation to be installed. Even 500kVA / 380hp would be pushing it. You can safely drop the k....

[joe.ninety]

That would be some big machine :whistle:

Yes, I think there's been a of 'k' inserted where it shouldn't be. Lol

Can you imagine the size of the donut for a 1000kVA toroidal... Probably about the size of a truck tyre inner tube blown up to its max.

[Doddy]

I think you're all missing the important part of this thread. How's the beer? (if you don't mind I might PM you over this - I've a similar interest, or at least an interest in getting the missus interested).

[Kitwn]

I'm with you Doddy! There's a definite new social possibility in this thread... "come round for a free beer and have a look at my home-made CNC machine". I might be abe to make some friends!

It is something of a minefield trying to understand what the ratings of various components mean and how they need to be interpreted when designing a machine from scratch. Best thing is to just do what Dean says, as usual!

Kit

[JAZZCNC]

Best thing is to just do what Dean says, as usual!

Kit

Not quite sure how to take that.? I just offer advise based on experience and people are free to take it or leave it.!

[Kitwn]

Meant as a compliment! Your range of experience is unique among forum members and as a professional machine builder your customers would have told you loud and clear about anything that didn't work effectively and reliably.

[AndyUK]

That would be some big machine :whistle:


Yes, 1000kVA would be about 750 hp. You'd need your own substation to be installed. Even 500kVA / 380hp would be pushing it. You can safely drop the k....


Yes, I think there's been a couple of 'k's inserted where they shouldn't be. Lol


Ooops. :)

Force of habit I'm afraid... work requires kV / MV... You know what I meant!!

[joe.ninety]

I think you're all missing the important part of this thread. How's the beer? (if you don't mind I might PM you over this - I've a similar interest, or at least an interest in getting the missus interested).

Well it would probably be a case of the blind leading the blind, as I've never attempted an all-grain brew before. To be honest, it's typical of me to go out and splurge instead of dipping my toe in slowly. Some people start with large pot/pans and commercial tea kettles/boilers but that would have meant too much time in the kitchen and under SWMBO's feet.
I only made the plunge last week and it hasn't even been delivered yet. It'll have a decent sell on value so it I decide it's not for me then I'll just stick it on fleabay.

I've done plenty of home brew but only from kits, nothing where I've made the wort from scratch. In fact a good deal of enthusiasts don't even consider that home brewing, I guess it's the male equivalent of making a sponge cake from a mix rather than individual ingredients.

Getting the missus interested is a bit of a double edged sword... It helps with approval for financial outlay, but I've now found mine drinks too much of the stuff I make and I've had to take to hiding it :beer:

Anyway, give it a couple of months and I'll probably be in the position to offer some advice. In the mean time check out this guys channel on YouTube...

https://www.youtube.com/channel/UCb3HYxTpCaVDeulH1mZGW1Q

One of the best I've found, an English guy living in Denmark who works in the industry. Really informative without all the added guff... Not like a lot of the US brewing channels you find.

Cheers

[joe.ninety]

Ooops. :)

Force of habit I'm afraid... work requires kV / MV... You know what I meant!!

I think everyone knew what you meant, even me. When I joked about it, I'd missed the fact that Muzzer had already followed up on Clive's original subtle highlight of it, otherwise I'd have said nowt.

Cheers

[Kitwn]

Ooops. :)

Force of habit I'm afraid... work requires kV / MV... You know what I meant!!

KV (Strictly NOT kV if I'm correct) and MW is one thing, I do those every working day. But MV (as opposed to mV)... That really is fun and games! :eagerness: The trick is keeping it in the wires.

[joe.ninety]

Is the choice to design a machine using belts and pulleys between the stepper and ballscrew down to the size of the machine or due to what materials you intend to cut and the ability to control the speeds better.

So would a much smaller machine, say a 6040 be more likely to be driven directly than by belts and pulleys?

Cheers

[AndyUK]

Is the choice to design a machine using belts and pulleys between the stepper and ballscrew down to the size of the machine or due to what materials you intend to cut and the ability to control the speeds better.

So would a much smaller machine, say a 6040 be more likely to be driven directly than by belts and pulleys?


Its a combination of both. Lets start a pros/cons list! Hopefully everyone can add/remove. I don't think you can make a general statement about what sizes of machine would be more or less likely to have belts and pulleys?

Advantages are:

Ability to gear up/down, particularly relevant with servos I believe.
Ability to position motors more flexibly, potentially reducing the footprint.
Can drive multiple screws per motor.


Disadvantages are:

Potentially more complex system, especially if needing tensioners?
More opportunities for backlash.


? Finger-trap potential?
? Replacement requirements?
? Expense?

[joe.ninety]

Been doing some serious thinking over the past week or so and have decided to scale back my ambitions considerably. Was stuck between going for a 8060 or a 6040, then thought a 7050 might be the ideal compromise.

With that in mind, if I wanted to use profiles for the frame of the machine, what would people consider the minimum size of profile to use? I'm assuming that 4590 in an L configuration is fine for the gantry, but just wondered what I'd need for the long sides... I'd originally thought I'd use 80160s with the rails running along the top and the screws on the sides, now I wondering if that's a bit overkill and if I could get away with something smaller and obviously cheaper.
As stated ages ago, the design would be based off of AndyUKs but obviously using profile instead of the steel Andy used.

Cheers

[joe.ninety]

When selecting aluminium plate for gantry sides etc. do people tend to use the most expensive Ecocast variety, or is the the 6082-T6 type OK to use instead?

Are you more likely to get perfectly flat pieces with the Ecocast?

Cheers

[JAZZCNC]

When selecting aluminium plate for gantry sides etc. do people tend to use the most expensive Ecocast variety, or is the the 6082-T6 type OK to use instead?

Are you more likely to get perfectly flat pieces with the Ecocast?

Cheers

You only need Eco cast or ground plate for critical surfaces like bearing plates or Z axis etc that require parallel surfaces. Gantry sides are not so critical in terms that they need to be perfectly flat or parallel surfaces. Thou I find the difference in prices isn't always huge and the cast plate is so much nicer to work with so I just use it for everything.

[Muzzer]

JAZZCNC - I've never knowingly used cast plate - where do you get yours and what grade is it?

Recently bought some 15mm plate from Poland and assumed it was rolled. That was EN-AW 2017 T451 and it machines very nicely. Also pretty flat.

[JAZZCNC]

JAZZCNC - I've never knowingly used cast plate - where do you get yours and what grade is it?

Recently bought some 15mm plate from Poland and assumed it was rolled. That was EN-AW 2017 T451 and it machines very nicely. Also pretty flat.

Cast plate tends to be mostly tooling plate and is very flat with a shiny machined surface or ground surface in most cases. It's easily identified from a rolled plate which tends to have a dull finish and is rarely flat.
Also, Cast plate is heat-treated and annealed to relieve stress as part of the casting process so it's very stable and cuts completely different to rolled plate. The chips that come off are like little balls rather than stringy chips because of the grain structure which is much finer, it also doesn't have hard n soft spots as the rolled plate does.

I buy mine locally and the grade is 5083. You can buy Cast plate from Aluminium warehouse and Ecocast is their trade name for cast plate but I believe it's 5083 grade.
You will also find it under the name Mic5 or Mic6 which is basically 5083 or 6082 grade. 6 series cast plate isn't so common and much more expensive usually and to be honest I find little difference between the two in machining terms, obviously, if you need the 6 series properties then that's different but I find 5 series more than good enough for any CNC use.



I buy mine locally and it's 5083

[joe.ninety]

Jazz, what's you recommendation for plate thickness for a standard z axis build? Is 15mm thick enough? I'm talking about for a desktop machine and not something huge, so say a 6040 cutting area.

Cheers

[JAZZCNC]

Jazz, what's you recommendation for plate thickness for a standard z axis build? Is 15mm thick enough? I'm talking about for a desktop machine and not something huge, so say a 6040 cutting area.

Cheers

Personally I use 20mm mostly but 15mm would work for a lighter Z-axis. Just remember the Z-axis is handling all the cutting forces so if it vibrates then the tool vibrates with it and you get a shitty finish, excess tool wear and even breakages if bad.! . . . Some areas you don't want to skimp on and Z-axis is #1.

[joe.ninety]

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