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Messages - vre

Pages: 1 2
1
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: April 01, 2014, 02:41:56 PM »
thank you!
i will go with 3210 ballscrew

2
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: March 24, 2014, 06:04:15 PM »
My lathe is the same with this http://images.ua.prom.st/28306498_w640_h640_27032013431.jpg
but has 400mm more z axis length mine is 1400mm between centers
and the lathe in photo is 1000mm between centers but all the others are the same
My lathe has total weigth 1250kg

(to correct my previous post 40mm ballscrew has x1.6 inertia of 32mm ballscrew not tripple)

3
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: March 24, 2014, 03:46:45 PM »
I measured again and the shortest length of screw i can put between bearings in my lathe and is 1750mm.
I will put 10mm pitch ballscrew but i have not decided for diameter 32mm or 40mm.
32mm has lower column strength but has lower inertia so better acceleration also is cheaper.
40mm has better column strength (almost double) but much higher inertia (almost tripple) so worse acceleration also is more expensive.
Critical speed is ok in both cases.
In Z axis i will use 1.8kw servo 3000rpm with reduction 1:3 so i will have max 1000rpm to ballscrew with 10mm pitch rapids will be 10m/min.

If it was your lathe what diameter would you install 32mm or 40mm ?
Because this size ballscrew has some cost i dont want to make a false selection.
I want just your opinion 3210 or 4010 ballscrew ?
thank tou! 

4
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: March 24, 2014, 11:07:33 AM »
Hood
From this calculator http://www.nookindustries.com/EngineeringCalculator/MetricCriticalSpeed with 2000mm length 4005 ballscrew (36mm root diameter)
with type c end support the critical speed is 1600rpm so 1600rpm x 5mm = 8000mm/min.
How you get 10m/min and 15m/min rapids without whipping problem ? Maybe the calculator is wrong and calculates with big safety factor ?

5
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: March 24, 2014, 01:22:00 AM »
thank you!
I have checked the rotating nut mechanism it can give better column strength and better critical speed with the
caveat that the Z axis servomotor must be fixed to carriage and move together with carriage.
(I also found that some high end machines use hollow shaft servos for direct driving the ballnut )
My Z axis servo is 8kg so it is too much to move x & z axes motors with carriage.

So I have 2 solutions remaing
1) Bigger diameter Z axis ballscrew (40mm) to overcome column strength and critical speed.
I have a dilemma if i would use 32mm or 40mm diameter ballscrew because both ballscrews fulfill the critical speed but the 32mm has about 2900kg column strength and my servo can give force about 3500kg the 40mm fulfills both critical speed and column strength force but has about triple inertia of 32mm ballscrew and this will degrade much the performance.
 
2) Do not use a ballscrew but the rack pinion mechanism that lathe has for semi-auto feeds.
This would be inaccurate and will have a lot of backlash but it will not have the the problems of critical speed & column strength
From that i can see this lathe which is very long uses this method http://www.youtube.com/watch?v=E-F5vgQnKVg
(or uses a ballscrew ? i can't see clearly)

Your Z axis ballscrew is 900mm and 10mm pitch but what diameter ? 20mm 25mm or 32mm ?

6
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: March 09, 2014, 11:58:38 PM »
My ballscrew is 2m 32mm diammeter and from this calculator http://www.nookindustries.com/EngineeringCalculator/MetricCriticalSpeed (30mm root/Length 2000mm/type B fixture)
the critical speed before ballscrew begins to oscillate is 907 rpm so would be better to take 10mm pitch ballscrew to get the desired rapids without the risk of oscillation ?

Also what end supports do you have for Z and X axis ? Iam planing to put for Z bk25/bf25 and for X fk12/ff12 is that ok ?

7
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: February 22, 2014, 05:10:15 AM »
The 10mm pitch ballscrews have good accuracy from your testings ?
Or would be better with 5mm ballscrews and 1:2 reduction ?

With this setup you have 15m/min rapids  is this speed in usable range or it is so much for conventional prismatic ways ?

8
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: February 19, 2014, 04:28:04 PM »
What type pulleys/timming belts have you used ?
Have you any backlash with these pulleys/timing belts ?
Finally reduction is 1:2 and ballscrews 10mm pitch on both axis ?

9
Finished Plugins for Download / Re: Huanyang VFD controller plugin
« on: January 17, 2014, 05:14:37 AM »
I got a Huanyang SL-440EE 380V 4KW and some componets are missing.
I have marked the the missing components with red color in photos.
I know in 1 photo that the missing ic is a max485 but what are doing the other missing parts ?
Also what doing the missing components in 2 photo ?
thanks.

10
Show"N"Tell ( Your Machines) / Re: Prima Lathe conversion
« on: December 28, 2013, 07:51:02 AM »
I see that you have a big transformer in the box.
What doing this transformer ?
If the drivers are 3 phase 230Vac and my supply is 3 phase 400Vac or 1 phase 230Vac what can i do ?
3 phase transformer 400Vac to 230Vac of 1 phase 230V conected L1-phase L2-neutral L3-phase and add extra electrolytic caps after the bridge in driver ?

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