Let the fun begin !!! ???

[PAULRO]

originally i designed around 16 mm x 10 mm ballscrews for X (1440 long) and y ( 1395 long) and 16mm x 5mm for z . i know from reading your previous posts that the length is critical or rather going over a certain length will almost certainly introduce whip at high speeds. i would like at some stage to tackle a Mayan calender and so i'm curious about resolution if i go with a 20 mm pitch. I'm not sure also about the amount of clearance i should leave between ballnut and bearing blocks either end. is there a standard clearance that i should factor in ? i have left 15mm either end but i'm not sure if this is enough.



i could also use nema 23 4Nm motors instead of 3Nm. (courtesy of Eddycurrent ) would the same psu ,motor drivers , smooth stepper, break out board etc. do for both? just trying to get a handle on the cost of everything required is a job in inself!!!!

[JAZZCNC]

At this length then go with 16mm you'll be ok, 16mm will allow slightly faster acceleration due to less inertia. Resolution with 20mm isn't a problem because the ratio effectively makes it same as 10mm and even with 1:1 ratio 20mm res you'd still have enough to cut the mayan calender.

There's very little between the 3Nm and 4Nm motors in terms of performance so you wouldn't really see much differance. Either will work fine with what your planning to use. Just run them around 70Vdc and you'll be fine.

With bearing blocks/ballnut then all you need is to leave a enough clearance in case you over run limits. In which case the limits should stop the machine so you need enough clearence for the over run. That said your better fitting hard stops in case of over run and have the bearing blocks just past these.
To be honest I wouldn't sweat over it you can control this with adjusting limits and they take a fair old bang to damage anyway so worst you'll do is knock something out of alianment.

Let me just say if your at the point of planning in cad to this level of detail then your wasting time that could be better put to use building the machine because in reality you'll more than likely to see a better place to put them on the actual machine.!! . . . . . Time to put the pencils down and pick up the tools.

[PAULRO]

it's time to put the overalls on o.k i should have steel middle of next week so i'll be fighting iron the following weekend. i'm just gathering the most info before i start into the build. i will be missing in action in the near future for a couple of weeks so i'd rather take time at this stage and plan it out . having said that i have enough info to get me up and running.

[EddyCurrent]

Just for the crack, keep a spreadsheet of everything you buy and the cost, maybe categorise as 'mechanical', 'electrical', 'sundries'

[PAULRO]

it time to source linear rails, ballscrews , ball nuts , bearing blocks etc. so i'm looking for contact details for chai. i have found an email address for him but i'm getting no reply. i have looked at zapp but want to do a compare & contrast before i purchase. so if any body has his web address can they send it on?


cheers Paulro

[EddyCurrent]

please check your pm inbox

[PAULRO]

i have touched base with chai and just need to work out the 16mm ballscrew lengths. i also notice that the bearing shaft diameters for BK and BF are different and am curious to know why this is.



this is my z axis end view, it has 20 mm rails and a travel of 160 mm. i'm thinking of a z axis ballscrew length of 400+ 30 for for a timing pulley. i'm sure this is enough or should i go more?