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I saw the lack of decent draw slide builds on you tube prompted me to make one better than whats currently on offer on you tube so here it is... unfinished of course !!!
cutting area should be 260mm x 350mm once finished
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ROTATING IMAGES
@steel: "Again pics are rotating somehow when i upload them anyone got a fix for that ?"
My way may not be the easiest way, but to fix this from the laptop I use an excellent and free product called IRFANVIEW http://www.irfanview.com/ and use function Image>Rotate Right (Clockwise) and then save the modified image, as I've found that the Windows Explorer function Rotate Clockwise/Counter-Clockwise is not honoured across different software apps.
Thanks Andy managed to rotate them in preview on the mac strange though as i rotated them 360 deg and there the right way up this time. !!
Well thats day of your life you'll never get back.!!!
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Just a few photos of the z axis, shafts are 12 from some old rear shocks from a car, bushes are nylon diy held down with u bolts
Just a few more photos of the z axis, i will fit the lead screw tomorrow if all goes well.
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finished off the z axis today, i finally gave up on having supported bearings on the lead screw and mounted it directly to the motor as ill only be using this machine for wood/plastics it wont be a problem
https://youtu.be/cj665WQhmYU
So today I made some progress...
I mounted x axis to the base
I updated z axis face plate to alloy insted of ply
I decided I didn't want the y axis motor sticking out the side so
I mounted it inboard
Im using my cheap ebay router
overall Dimensions are as follows...
Length of base 550mm
Width of base 500mm
Height overall 800mm
cutting area...
X 400mm
Y 260mm
Z 90mm
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Sorry to sound negative, but you will kill that Z stepper very fast if you start using the machine. The screw seems to be hanging on the motor axis, which is a VERY bad idea, since the motor and the motor bearings are not designed for that heavy job. Same on all the other axes as well, but the Z is probably the most critical, and at least one end of the screw must be fixed. I also don't understand why use drawer slides. Those have just too much play and are not fit for the purpose. But OK, if learning is the purpose then fine, but considering the time you must spend on this, I am sure that real parts are better investment than parts which later on must be replaced, especially considering that replacing and squaring will be very difficult since you have welded everything possible to weld.
Don't be sorry the world is full of negative people !!! the stepper bearings will cope no problem,I am using heavy duty draw slides as i wanted to build a machine that uses alternative components as much as i can
Can you do me a favor and start a thread on your machine that way you can remove your links from my post and place them on your own post
cheers Dave
He hasn't placed any links on your post. They are part of his Signature and are on every post he makes which is perfectly fine.Quote:
Originally Posted by Steel
He's also correct in what he says and I don't see it as being negative.? What your doing is joke in terms of real cnc machine and these Important things should be pointed out for the sake of others who are new and thinking this is acceptable way to do things. It isn't correct or accurate and it will cause problems or fail so he's perfectly correct to point it out.
End of the day this is forum for debate and if you post something then don't get upset when someone disagree's with how your doing things. Either explain why done this way or choose to just ignore the poster or better still accept and learn from them. But don't tell them to go away just because they are not blowing smoke up your arse or not saying what you want to hear.!! . . :thumbdown:
Why do you think its not acceptable to be creative, innovative, and experimentative and do things differently ? after all there's more than one way to make a chocolate cake right !!!Quote:
Originally Posted by JAZZCNC
Don't worry, experiment and be creative, nobody wants to prevent you from that, but the solution you came up with is not very experimental or innovative at all, been tried many times before and there are plenty YT movies about it as well. I was there once as well, thinking that it may be possible (but quickly realized it won't fit my needs), and yes, it is possible to do the way you want to do it, but like I said, depends on what your goals are. For learning (the hard way) is fine, for making things with it, it is not. At least not if precision is part of the equation...and you are wrong about the motor bearings, they are NOT made for this sort of job, they are just made for supporting the rotation of their own shafts, not the huge forces a CNC is putting on them, so they will fail pretty fast. But of course, you don't have to believe me, I am just an amateur just like you... I also like to experiment and like innovative solutions, and I learn something almost every day and not always listen to what others have to say, so just continue with your project. I just thought that you may be interested in what others may see but you don't. Of course it is acceptable to be creative. Don't be so childish.Quote:
Originally Posted by Steel
please show me one youtube video of a fixed gantry draw slide build made of steel please, you wont find one !!!
your right us armateur's are just that I got no idea how much a thousands of an inch is in mm i have to google it !!
I can tell you none of my stepper bearings will fail due to direct mount and do you want to know how i know ?
I don't think it's unacceptable to be creative, innovative or experimental. However your not being creative or innovative.? You are being Tightfisted and cheap which are not to be confussed with the latter.! . . . . . If you took the same approach in baking Cake the outcome would be the same.? . . . It would taste Shite and end up in Bin.!Quote:
Originally Posted by Steel
Experimenting is fine and something I fully encourage. But your not inventing or creating anything that hasn't been tried before by others dabbling in CNC. So please don't try to tell others that what your doing is OK and will work fine for CNC machine.! . . . It's not, it's complete rubbish and by the very nature of innapropriate components used along with piss poor engineering is doomed to fail.
So when experienced builders comment don't take it as being negative because they are actually trying to advise YOU and OTHERS against making big mistake.! . . . The time you have wasted on this crap would have been better spent reading the forum and then searching Ebay or selling sites for deals on suitable components. Just like if can't bake Cake better going to ASDA.!
Quote:
Originally Posted by JAZZCNC
Do you even know why im building this machine and what im using it for ?
Icing Cakes.?Quote:
Originally Posted by Steel
keep guessing, do you think there's a cnc machine that's capable of surface accuracy of 1 micron over a 12 inch disk ?Quote:
Originally Posted by JAZZCNC
No thanks got better things to do and couldn't give a shit anyway. To answer your question then yes provided you have enough money. High end CNC grinders work in Nanometers not micrometers.Quote:
Originally Posted by Steel
https://youtu.be/sicrx7QlRF8Quote:
Originally Posted by Steel
https://youtu.be/9pKzInAQ7Dc
https://youtu.be/_A4Q3w-pt2c
That's just three, but there were many in my list when I made a search just by entering "CNC drawer slides" in the search text box. Perhaps I am just lucky, I don't know, but if I say this is not new and not an innovative idea at all, or that there are plenty YT video examples I mean it. As you can see, more than one of those three links are about 5 years old links.
The only reason I commented your build was that you seem to have spent time in making a rigid frame, which is very good, and then weld the drawer slides on that frame, which in my opinion is not a good idea at all, since even if you have some exceptionally well made slides with zero play, you will not be able to square your machine properly.
BTW, I seriously doubt you will achieve 1 micron over 12" and can repeat that over and over again. Perhaps you meant 1 thou (0.0254mm), which if you lucky, you might be able to achieve and if you get that you can count yourself really lucky. More likely, you will get 1mm accuracy or even worse, especially over some time of use, when things start to wear out. I think that 1 micron (0.001mm) is a dream for any home made CNC, even more so for one which is welded at home using drawer slides and lead screws hanging on the motor without properly fixed bearings and curtain rods with delrin slides as Z. I know you won't believe me, but like Jazz said, you are not the only one reading this post, so it is important to point out some facts. Even measuring at that accuracy accurately requires better instruments than most DIY CNC builder can ever dream of. I have 0.02mm (20 microns, worst case) on my machine and I think that is excellent, considering the materials I have used and is definitely more than enough for my needs. But of course, I would not say no to 1 micron... if I could make that for a reasonable cost and in reasonable time (maybe when I retire in a few years time). Having that accuracy on each component is one thing, but once everything is assembled and you start to square... well, that's a completely different thing all together.
Again, that's just my experience and don't let me discourage you, but others who consider making something similar and expecting getting 1 micron accuracy should know that it will be a real challenge with those parts.
Edit:
One link was pasted twice, so only three links are unique so I removed one of the four.
I think you have one one vid repeated so three shown.:whistle:
Fixed. Thanks.Quote:
Originally Posted by Clive S
What has been pointed out is entirely correct.
If you are just looking for a cheap machine to mill e.g. foam or something then this probably works fine, as pointed out though the bearings on steppers are radial bearings designed for radial loads. They will be experiencing axial loads when trying to drive the screws which is something radial bearings aren't particularly great at... That will result in excessive play, premature wear and eventually failure.
Given that the drawer slides won't allow you to machine anything hard anyway, you will probably be ok on the X and Y (although they will still wear out and develop slop more quickly, and are more difficult to replace than in a separate fixed bearing block for the screw), but given the weight of the router being pulled up repeatedly the Z-axis will probably suffer more.
It also means you are relying on a rigid coupling between the motor shaft and screw, which translates vibrations and resonance into the motor, which again isn't great news. With direct drive really the idea is to have a jaw type coupling with a rubber/flexible insert that provides some protection to the motor. You can't do that however unless the screw is supported by its own bearing set.
I know you think people are being negative or crushing your creativity but there's a reason why things are done a certain way, and it's not creative to go and do things the wrong way just for the sake of being different. To come up with a new solution that actually addresses the reason why things were done in a certain way (e.g. the fact that radial bearings aren't designed for axial loads, and vibration decoupling) whilst doing it better/cheaper/differently is what being creative or innovative would be... just ignoring the issues that cause things to be done a certain way and then doing it poorly to save money is not innovative, it's poor engineering.
You clearly aim to create a cheap machine, on that front you are succeeding. Though how anyone on here is supposed to know what your end goals are when you haven't stated them is ridiculous. Hopefully it's just a fun project for you, and you enjoy making stuff - which is great imo. If you are expecting any sort of accuracy or ability beyond carving some foam into interesting shapes then you are probably going about it in the wrong way.
By the way were you actually trying to infer that your creation will be capable of holding 0.001mm over a 12 inch disc or did I misunderstand that?
For all those who don't read entire threads and have no idea what this machine will be used for, I posted this 2 weeks ago
"finished off the z axis today, i finally gave up on having supported bearings on the lead screw and mounted it directly to the motor as ill only be using this machine for wood/plastics it wont be a problem"
Wood and Plastics !!!
A_Camera, I asked for you to show me a draw slide cnc machine made of STEAL and all you posted was videos of ones made of wood !!!
"BTW, I seriously doubt you will achieve 1 micron over 12". It was a question not a referral to my cheap draw slide build.
Zeeflyboy, "You clearly aim to create a cheap machine, on that front you are succeeding" "Hopefully it's just a fun project for you, and you enjoy making stuff - which is great imo". yes your 100 % correct,
This build is not about saving money its about making something off the top of my head no plans to follow just using parts you wouldn't use in a high end cnc machine.
"Though how anyone on here is supposed to know what your end goals are when you haven't stated them is ridiculous". read the 5th post i made it clearly states I'm going to cut wood and plastics.
"By the way were you actually trying to infer that your creation will be capable of holding 0.001mm over a 12 inch disc or did I misunderstand that?". No i was just asking a question if there was a cnc
machine capable of .001mm as I make telescope mirrors for a hobby and i can produce by hand mirrors with a surface accuracy of 0.000125mm so just wondering if a machine could get anywhere near that.
As to the Axial loads in Nm on my z axis can anyone tell me what you think it will be lets say cutting pine at a feed rate of say 700mm pm with a 2 flute 6.35mm end mill and a pass depth of 4mm ? just a approximate estimate will do
Please explain/show the equipment you use to measure to that level of accuracy.!Quote:
Originally Posted by Steel
It's no that simple. To calculate accurately you need to know the bearing type and arrangment. Also just saying pine isn't enough as there are many species of pine so each will cut differently and be different Density/Dryness.Quote:
Originally Posted by Steel
However I wouldn't worry about the bearings failing, which they will sooner rather than later, because this will be the least of your troubles. Between resonance and the shity engineering they'll hardly be working much.
Jazzcnc just the other day you said "No thanks got better things to do and couldn't give a shit anyway" in referral to my cnc draw slide build so my question for you is why are you still posting on this thread ?, since you are then give me a ballpark figure in Nm of the axial load range i can expect.
"Please explain/show the equipment you use to measure to that level of accuracy.!" https://en.wikipedia.org/wiki/Foucault_knife-edge_test
Because it's Free country and Forum so I can and there's sweet FA you can do about it other than not reply.! . . . . . . But It's true I don't give a shit what your doing however I was intrigued to how some one who thinks draw runners are suitable for CNC would go about measuring such fine tolerences.?Quote:
Originally Posted by Steel
Oh and if going to quote try using the "Reply with Quote" button it's much clearer.
Regards Axial loads then like I say depends on lots of factors and lifes too short to waste time working it out plus I'm not that clever.:whistle:
Ok so you don't really know about what axial loads i will encounter ok fair enough maybe someone else has some idea ?
Axial force from the plunge is I would say largely irrelevant in the materials you are using and is probably the least of your worries. The weight of the router/mount and travelling parts of the Z-axis are probably higher than the force required from the motor as long as you aren't plunging crazy fast.
Typical max axial rated load for a double bearing nema23 is in the region of 1.5kg-f (e.g. see data sheet here, last page at the bottom specifically) https://www.anaheimautomation.com/ma...ec%20Sheet.pdf
So your biggest problem (in terms of Z-axis axial load, I think Jazz would probably contend that it's not your biggest problem lol) is that unless your screw, nut, router, router mount, and all "hung" mass of the mounting plate is less than 1.5kg, you are already exceeding the axial load before you even start moving.
Let's say you are using a small router that weighs about 3kg, add the weight of the screw, router mount, etc etc and what, maybe 5kg? Simply hanging there before taking into account any dynamic acceleration loads during retracts you are exceeding the rating by over 3 times.
You could bodge your way around it by counterweighting the Z-axis, but you'd still be subjecting it to axial loads when it does actually hit the material by doing it that way, and it would also be more complicated than just giving it a proper bearing setup which would be superior in every way.
edit - actually are you using a nema17 there? in that case it'll be more like 1kg-f axial load rating which would change the equation to being 5 times over load just hanging there.
double edit - I'm not sure why you think a steel framed build like this is innovative or indeed preferable to any of the other extrusion or wood based drawer slide builds? Indeed the only point I can see of doing a drawer slide build is that it's cheap and easy to build without access to any special equipment, which you kind of ruin the point of when you start talking about welding a steel frame. The components you are using don't have the accuracy or rigidity to benefit from the more sturdy steel frame, so it actually seems to be slightly defeating the point of these designs in the first place.
To me it seems like you're wasting what could be quite a nice little steel frame by then going and fitting it with sub-par components. assuming you've done a semi-decent job of alignment on that frame, if you took that same frame and fitted it out with some proper linear motion components (and stopped hoping that radial bearings could take thrust loads) you'd actually have a half decent machine there.
I just looked at the z axis on my 3020T and the lead screw is supported with one bearing on the top plate and either a bearing or sleeve on the bottom plate and the motor is connected with a flexi coupler so those bearings are being used to support axial loads even though there radial bearings. I cant see the difference by using the stepper bearings to replace that type of set up. Im using a 420oz nema 23 fitted with 6000z bearings.
I think i will make a stand to hold a nema 23 to replicate a z axis position with a 10kg weight mounted to a shaft hanging from the motor shaft to replicate what my setup and run the motor till the motor bearings fail !!
Again the point is to build this machine using using draw slides, I have a new set of 20mm supported rails with ball screws but i dont want to make a mid end machine. If it works great if it doesn't then ill make changes but for now ill do it how i wanted to do it and see how it turns out
Yes, Nema 23 max axial load is 15 N. This means -
For Z stepper motor:
This has to react the Z axis parts which move up and down - if 3 kg then this is 30 N down
When plunging / drilling into wood this is typically 60 N up (giving 30 N in the other direction)
Drilling holes repeatedly takes the force from +60 N to -30 N which will work those bearings
Machining with helix cutters will also apply axial loads (due to the helix) - up to 20 N from memory
For X and Y stepper motors:
These have to react the horizontal cutting forces which for wood can be up to 50 N
All of these loads are well over 15 N so this is why everyone is recommending that the leadscrew has it's own bearings.
I seem to remember that steppers can have a bit of axial play in them, even when brand new. This means that there will be positional accuracy limitations. Angular contact bearing blocks on the ballscrew can be tightened up to remove this.
The final comment to make is that the leadscrews are usually not perfectly round, plus it would be difficult to align them perfectly with the axis of the motor shaft. This means there will be fluctuating forces being applied to the bearings each time the shaft rotates.
Finish the machine, run it for a month or so and report back how you get on, what worked, and what didn't.
References:
http://www.motioncontrolproducts.com...tors.php?cat=1
(max axial load)
http://ac.els-cdn.com/S1877705812021...5afb04f23aa36d
(drilling force in wood 4th page)
Thanks for the comments and info in the linksQuote:
Originally Posted by routercnc
cheers Dave
And two wrongs don't make it right.!!Quote:
Originally Posted by Steel
Quick google brought this up.....found one :yahoo:Quote:
Originally Posted by Steel
https://www.youtube.com/watch?v=dY10zIMaCmI
Question....if you've got decent linear components, why are you making this one?
Fun video to skip through.
Look at how much the motor wobbles at 4:34 - that's a great example of what routercnc was saying about alignment causing extra load on the bearings!
Ok so maybe ill try this setup ? this is not the finished setup but you can get the idea.Quote:
Originally Posted by Zeeflyboy
Attachment 20985
That's a just a set of 2 thrust bearings I assume? Which end are we talking there?
Ok i was wrong there are a few out there after all :dejection:Quote:
Originally Posted by njhussey
In answer to your question I saw one on youtube and thought to myself I want to make one of those and so here i am, Since i cant seem to sell my rails and ball screw kit maybe one day i will have the space and time to turn it into a decent machine but for now this build and my aluminum melting barbecue i put together on Saturday i should have enough to keep me busy in my free time.
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My very first machine, made from bits I had laying around to see if I was serious about building a cnc machine, used something like that. A pair of thrust bearings either side of a plate to resist the axial loads. The stepper was then connected to the ballscrew using a very stiff and tight fitting piece of rubber tube to act as an alignment coupling. Something off a car engine cooling circuit ?
The coupling worked fine for many months, but the thrust bearings became noisy and needed regular adjustment. I think this is because they were held there by a locking collar and did not apply a preload. Your picture has a preload nut so this will be better. By all means try it as it is much better than using the stepper bearings.
Quote:
Originally Posted by Zeeflyboy
Top end, i think ill put a radial bearing in the middle to keep the shaft centered plus some sort of aluminum cap on both thrust bearings so i can bolt everything to the plate.