Thread: Definately a scrapyard challenge
Hey I enjoy seeing people put their theorise to the test. I have a budget but I also like do the best I can. As I already have the screws then thats fine. The upgrade to a water cooled spindle was good advice and still stays , just, in budget. If I cannot afford it then as you say I will save. Biggest problem is deciding in what order to buy stuff.
I will do a sketchup of my gantry redesign and get some coments. probably at the weekend.
Right...cough... remember when you were a young engineer you always had to know how things worked. I remember taking a clock apart, and my electric train, my mums iron. Then I got into motorcycles and that was great fun. been doing it for 45 years with varying degrees of success. Always have to find out how they work and maybe put them back together. Well.. oh dear I am not sure how to say this....I was very interested in exactly how the ball screw worked. You guessed it. I unscrewed it and the balls fell out. After spending the last hour trying to rebuild it I realised that the plastic bungs are where they put the balls in and then press hot plastic in to close it off. Is this now an ex ballscrew system or is it fixable? Thankfully it was the shorter one if it has to be replaced.
On that high note of failure goodnight
Bruce (yes i am going to spend the night standing in the corner)
Just to be clear, all my previous comments about 10mm over 5mm pitch were referring only to X and Y. Also a 5mm pitch screw can still backdrive on Z (mine does) if it's aligned well.
I took the ballnut off once just to see what all the fuss was about. I spend a while trying various methods of poking the balls back it which didn't really work. The easiest way (other than buying just a new ballnut) is to get a very strong magnet and stick it to the side of the ballnut. then you can carefully place the balls back in one after the other as they'll stick to the nut inside. Then you machine/find a bar that's just under the pitch diameter of the ballscrew minus the diameter of one ball so it just slides in (doesn't have to be accurate as long as the balls can't fall out). Introduce the ballscrew into the nut allowing it to push out the bar as you turn it on. Only took about 10 mins once I'd found the magnet (2"x1"x0.5" neodymium).
You can also try putting grease on the balls so they stick to the nut inside, but that's not as effective as the magnet. I think you should demagnetise the nut afterwards.
You university boys so darn clever. This is definatly something to tackle at the weekend.
Good night all
Yes jonathan's correct when he points out that the calculated physics way of looking at it that 10mm pitch wins for a router!. . . BUT. . . I can tell you because my machine use's 5mm pitch geared 2:1 it's absolutly no problem and in no way limits the performance. Actually IMO it's a bennifit because it's just a simple belt/pulley change to gain resolution.
That said I agree that 10mm pitch (except Z axis then 5mm) would be better choice for a router which mainly cuts wood or plastics. Anything harder IE Ali etc and then extra speed 10mm pitch gains is wasted as the feed rates dictate. 99.9% of the time you'll be lucky to cut any where near quarter the speed 10mm pitch allows.!
An often over looked and misunderstood area which Jonathan touched upon earlier is acceleration.!! . . . IMO and experience for most jobs (Esp 3D) that don't need high feeds (2mtr/min or less) then your much better off tuning your motors to give higher accel than velocity. . . Often less is more.. . Like in the Aztec case where there are lots of short moves it can and does often make job's faster. 3D and v-carving really see the most increase's from high accelleration.
I use Mach3 and it's such a simple job to create profiles that you can easily tailor for specific job types or conditions. IE I have 3D profile tuned for Accelleration. 5mm pitch profile (pulley/belt change)for when resolution needed. I also have profiles for Inch units for each so when I get given code that use's imperial measurements I don't have to fanny about changing settings or code.
Doing it this way makes it very simple and quick to change from one to the other.
So Like 2eOpoz I 100% agree 5mm pitch will be fine in your case.!. . . . BUT . . . 100% Agree with jonathan 10mm pitch rules for a wood/plastic router.
Anyway the screw pitch or speed will be the least of your troubles if you don't beef that gantry up.!!
Last edited by JAZZCNC; 05-01-2012 at 11:04 PM.
Ok Ok I promise to do a redesign on the gantry. I have learnt more in a few days here, mainly how little I know but I am so grateful for all your help.
I get the impression you think I'm saying 5mm pitch won't work, seeing as you say "it will work fine". I agree with that, but when designing a machine I think it's foolish to aim for it working fine, you should aim for it to work as well as possible, not just well enough and 5mm pitch screws will simply limit the potential of your machine.
I'm not going to say anything more on the subject since apparently it provokes a particularly strong reaction, I think motoxy has all the info to make an educated decision. Good luck.
Motoxy: There's a quote for that - The more I know, I know, I know the less. (John Owen)
Dog with Bone? :rofl:If the nagging gets really bad......Get a bigger shed:naughty:
Jonathan . . .My point was that 5mm pitch geared 2:1 works fine because I use it.!. So all your bullshit spouting about K:E means sweet F:A whether nema 23 or 34 because for 99% of DIY use both are far more than good enough.
Also If you look again ya touchy lickle git you'll see I agreed with you on the 10mm pitch.!!
Presumption is the mother of all F:U.!! . . . SO NOW. . How the F~@K do you know what I've done or not done with my machine.? Or any other machine for that matter.:exclaim: . . . . . reading a few old post's don't make you Physic Sally.
If you want to get into machine design and foolish ness. My approach is that you build a machine to be strong and accurate as possible to do the best it can at it's intended purpose.! .. . To build with just speed in mind at the sacrifice of accurecy, repeatabilty resulting in poor quality in-accurate work.!!. . . is plane stupidity IMO.
Now wasn't having a go at you or saying what you said was wrong or wouldn't work so suck your petty lip back in and drop it.!:tup:
ok but no kissing please:heehee:If the nagging gets really bad......Get a bigger shed:naughty:
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