George's 8x4 router-me-bob

[georgetheforge]

ohh a bit of time on google turns out bought ones are hideously expensive-!

so now am looking for some (i assume) zero backlash ballscrew in maybe a 16mm? was gonna do 20mm hiwin type with the carriages fixed and the rail sliding to give more slide,

so i figure i need a motor mount, a flexi couple, the ball screw support, the nut, the nut housing, and the end support?

whats the best pitch?, and will 16mm be ok-

also anyone know of a supplier that has decent drawings/ downloads available?

getting there- only problem is work getting in the way-!!

George-

[JAZZCNC]

Here you go George have a look at these. This is one way and my prefered way to build them.
The Obviously the gantry is not showing but the Y axis rails could go either way like I have them or both on front or 1 on top 1 on front but this way I prefer because it brings Z axis closer to gantry, increases travel and is very strong. The belts help with resonance and allow gearing up or down if needed.
I use 16mm screws with 5mm pitch, sometime I use BK/BF bearing blocks some times FF/FK just depends on what I'm building and have even been knownt tomachine my own blocks but can't be arsed anymore as the chinese prices are so low it's not worth the trouble.

These are just reference models so not 100% accurate regards alignment etc but all materials and linear rails, motors etc are the correct and actual size and match whats available.

Hope this helps.

[georgetheforge]

ohh nice drawing Jazz-

see what you mean re the linear rail placement/ getting the spindle as close as poss-

what reduction did you do on the belt-? 2:1?

saw one from marchant dice for £1400....!!

Thanks again for all your help- it's really appreciated-!

now that i basically know what i'm gonna do will do a bill of materials to see what the damage will be-!

Thanks

George

[JAZZCNC]

Hi George,

There's no reduction it's 1:1. The main reason for the belt is to reduce resonance and also allow easier positioning, the gearing is just a bonus if needed.
The previous drawing shows the motor up high but I also make them with the motor reversed, it just depends on the gantry design really. If possible I use the other position as it keeps the centre of gravity lower(no big deal) and it looks neater. I'll let actual real picks explain they show it better, ignore the bracket that looks like num 1 thats machine specific.

Tip regards material be very carefull when selecting or buying the Ali plate that it's perfectly flat. . . It's often not.!! Often it's cupped across it's width or even twisted in it's length.
If you look close at the pics you'll see I machine all the bearing mounting surfaces. I do this for 2 reasons.
#1 It gives me a register for the master bearings and rail to butt against which makes setting rails parallel easier and allows for easy replacement/setup if stripdown/cleaning required.

#2 Very important.!!. . If you try to bolt rails or bearings to material thats not flat then you get binding in the bearings increasing friction and causing premature wear, if bad it will lock them up soild when tightening.
Linear profiled rails are by far the best for performance and longevity but like all high performance things are tempromental and in tolerent of shoddy inferior material or poor workmanship so therefore require higher accurecy.
If you don't have the capabilty to machine surfaces flat then I strongly urge you to buy ground flat plate like the ECO CAST from Alu warehouse it's more costly but will save you a world of pain and give much less friction and smoother action. This is what I do now as the little extra it cost's is worth the expense as it saves me many hours machining and I just machine insert pins for master registers and machine the edge.

Making one with linear profiled rails, 16mm ballscrew and 20mm ground flat plate along with pulleys etc will cost you around £310 and will handle anything you throw at it for millions of years at DIY level.
Skimping on a Z axis is just plane dumb IMO if you want a accurate machine as it handles all the cutting forces.!!

[Jonathan]

When I started out with my machine I did have issues with motors stalling on the X-axis, but really that was just me trying to push it too much. Now I've been a bit more conservative (still 10m/min which is fast by most peoples standards) the machine hasn't stalled for several months so that's not an issue.

I'm going to be making a couple of rotating ballnut mounts soon, so let me know if you're interested and I'll work out the price as it'll be more efficient to make several at the same time. I've updated the design to be fully enclosed with aluminium such that no swarf can get in. Something like this, can of course modify it to suit / aid mounting:

[C.AlveSilva]

...I'm going to be making a couple of rotating ballnut mounts soon, so let me know if you're interested and I'll work out the price as it'll be more efficient to make several at the same time. I've updated the design to be fully enclosed with aluminium such that no swarf can get in. Something like this, can of course modify it to suit / aid mounting:

Hello,

I'm probably interested ... I am considering using this system instead of the traditional.
In my project I'm planning to use 2005 Ballscrews with Nema 23, (3.1 or 4 Nm).
Already know something about the cost?

[Jonathan]

I'm probably interested ... I am considering using this system instead of the traditional.
In my project I'm planning to use 2005 Ballscrews with Nema 23, (3.1 or 4 Nm).

If the machine is big enough to consider rotating ballnuts you do not want to use less than 10mm pitch screws.
I can make some more, however I'm currently busy making another machine and other parts so it's a matter of how soon you need them?