Reply with QuoteWell, left the project a little appart but made some progress today. I started the Z carriage and the ballscrew i ordered was quite short so i'll keep it for the base and order a largar one.
Hope you enjoy!
Thanks Mactec, going to try tomorrow and see what happens... Rocketflyer, my mobile phone decided it was hot and decided to stay in the pocket of my swimsuit in a friend's pool, sorry. If i do more mix for the next parts i'll take shots!
Cheers.
Well, left the project a little appart but made some progress today. I started the Z carriage and the ballscrew i ordered was quite short so i'll keep it for the base and order a largar one.
Hope you enjoy!
Very Nice man..!! was it easy to machine the EG, can you tell some more about that?
Hi
I'm quite interested in your build, pretty much the kind of thing I'm about to build in a few weeks, just a bit more sturdy for me. I'm student in college as well
By the way, what are you planning to machine ? I see some high end components here but a not-so-stiff structure - no offense, but there could be some ribs, unless you plan to add some. Even though a gantry is a pretty beefy structure by nature, the 20mm ballscrew and the massive Hiwin guideways would take muuuch more than the structure itself.
That taken appart, I am also interested in knowing how well the e/g mix can be machined. I would probably do most of the mill out of e/g and thus would have to surface guideways beds and assembly surface.
BTW, where did you get the guideways and particularly the ballscrew ?
Thanks
Rather then trying to machine the e/g, you are better off casting in steel or cast iron bars for those surfaces Epoxy-Granite machine bases (was Polymer concrete frame?)
bob
Yes, but as our friend here has attempted to do so, I wanted to know if it can be done easily. As I'm selling my machine to build the new one, I won't be able to machine except if I pay for it, so I'd rather avoir anything but to auto-surface the table once done.
yellow_submarin~
Machining E/G for flatness is not easier than machining cast in place steel. Assuming your recipe is optimal, it would be similiar to polishing a quartz countertop like Caesarstone.
Here's an interesting implementation: http://opensourcemachine.org/files/G...%20Machine.pdf
The Anorad gantries from Rockwell Automation are worth a look too. Find them using Google Images.
rowbare is giving you good advice.
~john
For those interested in EG machining, i'd not recommend to do it, it was hard and costed me lots of inserts, time and worries, but the result is a perfectly squared structure!Originally Posted by yellow_submarin
Hi
I'm quite interested in your build, pretty much the kind of thing I'm about to build in a few weeks, just a bit more sturdy for me. I'm student in college as well
By the way, what are you planning to machine ? I see some high end components here but a not-so-stiff structure - no offense, but there could be some ribs, unless you plan to add some. Even though a gantry is a pretty beefy structure by nature, the 20mm ballscrew and the massive Hiwin guideways would take muuuch more than the structure itself.
That taken appart, I am also interested in knowing how well the e/g mix can be machined. I would probably do most of the mill out of e/g and thus would have to surface guideways beds and assembly surface.
BTW, where did you get the guideways and particularly the ballscrew ?
Thanks
Anyway, i guess that using tooling for stone or quartz (i know nothing about it) would be less time and money consuming.
As Robware advised, it's best to use steel bars with all the features pre drilled and ready to use after casting so you are shure that the planes you are using to attach linear guides or anything are flat and square, rather than facing an error in the mould feature or a bad mould wall that could lead to an error.
I did it like this because i thought it would be easyer to machine (note that the photo of the machining part i posted is only resin from the back of the machine, that had no stone or sand, just added some resin into the mould when the important mix was dry to get better finish).
Anyway, why are you saying that a gantry is a beefy structure?, of course if it was only for me i'd have done something more like a small VMC, but as i hadn't enough money to do the project by my own, i joined a couple of classmates that wanted to develop their "things" and had to make a machine with a bigger table.
So what would you suggest to get a more stiff structure? i'm now making it so any suggestion to improve the whole machine would be appreciated.
Cheers!
A bit more progress today, i guess i'll finish the Y axis carriage on friday.
Nice work !
I'm taking the steel inserts advice seriously, I was just picking up information.
I had first planned to build a steel plate structure for accurate positionning, but as I'm selling my SX3 in order to buy the supplies, I'd like to stick to what asks for few milling operations.
I think I'll have them waterjet cut and surfaced, it will cost me some bucks but as I'm planning to build a premium quality machine there (ac servos, 5 axis, ...) it would be quite stupid to ruin everything with a warped structure.
Beefy was not the appropriate word. I meant they are stiff by nature as the spindle is not operating in a cantilever configuration. But I must say some people ruin this advantage by building weak Z axis. There was a very neat build of a similar fixed gantry on the french forum usinages.com . Even though the gantry was massive and pretty well built, the Z axis only consisted in an aluminium thick plate to which a homemade spindle cartridge and an ac motor were bolted. This is a shame, as opposed to conventional mills where the cantilever configuration shows weakness in column torsion following Z axis, a gantry is, when working close to the table, suffering from a strong moment as well but following the Y axis. And this is where a beefy Z axis can make a huge difference.
By the way, I remember seeing the first steps of your builds, and I must admitt I liket your Z axis configuration because of the generous spacing between the rails as well as the 90° tilt. I just hope you plan to ehnance your Y-axis shuttle with some EG for instance so as to reduce the stress caused by the fully extended Z axis. And additionnal mass never hurts, it actually helps ! The same way, a strong Z shuttle is required there, but seeing your design, I suppose you intend to build something strong enough ! I might just add ribs at the bottom of the gantry legs to increase stiffness as it's the maximum momentum point, but nevermind, your setup is probably strong enough there.
Some other questions : what type, size and preload are your Hiwin blocks ? I've been looking around for the last 2 weeks and only recently noticed that 90% of what is for sale is not suitable for machining, even though heavy duty rated, because of the light preload used in automation. Seems that only a few dealers such as Zapp Automation have the proper blocks (super heavy duty, heavy preload). I guess a 25mm light preload block is not even close to a 15mm heavy preload block.
One last, what spindle have you planned to install ?
Cyril
My rails and blocks are 20mm light preload, the preload thing "for what i've read" stands for the tolerance to accept positioning errors, i mean, in a diy machine is comprensible to commit little deviations and the lighter the preload, the more error the blocks accept.
I buy directly from an industrial supplier wich cuotes really cool prizes;
- 20mm ballscrew: 54€/m
- Ballnut FSI 16/05: 80€
- HGH 20(block): 32€
- HGR (rail): 59€7m
That is for sure worth the price ...
I was about to buy a LG set from a surplus, but seeing the preload rating, I doubt they're the good choice.
I think preload has an important role to play as much as preload in ballscrews.
It for sure doesn't change the load rating of the block, but it will probably change the deflection. If a block is preloaded, it will take more effort to distort it, and considering the amount of effort and vibration milling causes, I think it shouldn't be neglected. I might be wrong, but I think most people using linear guideways use them on routers that clearly don't stress even a zero preload block. But for a mill cutting steel, I don't think I would risk using a light preload. IMO there would be some undesirable amount of vibration ruining the damping ability of the granite epoxy. Yet I suppose eve light milling in aluminium is not enough to expose it.
Though, if anyone has an experience that would invalidate my previous statement, I would be more than glad to hear it, and my credit card as well.
Cyril
I'm shure you're right, but talking to the salesman he advised me to go for the zero preload blocks to avoid misalignment issues.
However, i think you're going for a higher end project, my goal is to make things at home, prototype my school jobs and just... have fun and experiment. My real challenge is not getting a high end machine, my goal is just to know that i'm able to think and somehow create a machine. I'm putting on it every cent i get and every free minute of my time, and i'm really learning lot making it, that's the important point, learn.
It'd be great if somebody has experience with linear motion components to expose their thoughts in the issue. The main concerns i got right now is getting a good result with my machine and my motors, it scares me if they are not powerful enough.
Precisely, you're right about that, and that's quite what I'm busy doing at the moment
Misalignment cas actually be a concern with rigid rails, I'll make sure to take care of that. Besides, I intend do cut steel and some serious speed in aluminium, so I'd rather stick to the heavy preload. Unless I get to know that zero preload 25mm are as rigid as heavy preload 15mm, but I doubt that. As I said, it must be stiffer, but shouldn't handle vibrations as good.
Nice build anyway ! Mine should be on the way soon !
Here is a link to a THK mounting guide. It is good to know this stuff when you are designing.
https://tech.thk.com/en/products/pdf/en_b01_089.pdf
bob
I've read a similar documentation for Hiwin rails.
Thanks for the link.
Hi, if you want, i could ask the supplier to quote the rails and blocks you want, maybe your're lucky and find a good deal!
Anyway, Y axis DONE!
Continuing next week, cheeeeeeeeers!
Excellent photos love the build progress looking very very nice
Eoin
Thanks Mad Welder, you build is awesome too!
Milled the front plate today, still need to make the motor mount and order a steel bent part to reinforce the long Z plate but using a dial indicator, Z to maximum travel and pushing really hard, i got only 0,2mm flex. With the parts i need to order, i guess i would make it much more stiff!
Well thank you very much
Eoin
