Triac Z axis counter-balance
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- Roy
- CNC Expert
- Posts: 104
- Joined: Tue 30 Jan , 2007 20:20 pm
- Hardware/Software: 1986 Triac modified & running Mach 3
- Location: Bucks, UK
Triac Z axis counter-balance
Below are a few pictures of the counter balance i have made for my Triac.
This is to ease / equal the load on the z axis stepper and ballscrew, thus reducing the chances of the stepper stalling when moving in the Z + direction.
The counter-balance weight is 20kg. This is an estimated weight of the head and motor.
This is to ease / equal the load on the z axis stepper and ballscrew, thus reducing the chances of the stepper stalling when moving in the Z + direction.
The counter-balance weight is 20kg. This is an estimated weight of the head and motor.
- Attachments
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- framework/pulleys
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- wire attachement studs and plates
- Pc270827.jpg (58.79 KiB) Viewed 25318 times
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- 20 kg counter-balance weight
- Pc270828.jpg (71.26 KiB) Viewed 25318 times
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- framework
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- sneakym8
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Hi roy
I am going to do a similar thing to my triac , I am retrofiting dc servo's so the balance is needed to,
A. stop the servo drive burning out just sitting holding the axis up.
B. stop the z axis shooting towards the table when the drive is switched off.
Thanks for the look at yours, i might do something similar.
I put a spring balance on my z axis with no motor connected and it took about 28 kg to get the balance .
regards colin
I am going to do a similar thing to my triac , I am retrofiting dc servo's so the balance is needed to,
A. stop the servo drive burning out just sitting holding the axis up.
B. stop the z axis shooting towards the table when the drive is switched off.
Thanks for the look at yours, i might do something similar.
I put a spring balance on my z axis with no motor connected and it took about 28 kg to get the balance .
regards colin
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I would never thought something so simple would have worked.I got an adjustable gas spring off ebay and balanced the head perfect
(Certainly my favourite method, just for ease of fitting)
How did you balance/setup up the gas spring ?
Did you monitor motor current going up and down ?
Is average motor load higher now its having to drive(ie not drop) down as well ?
- sneakym8
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Hi
The gas spring I bought was a stainless steel adjustable pressure spring, The pressure is at 640n when bought and you can let them down, being very careful not to go too far as you can only go down not up,
Go too far and your looking for another one.
When I first fitted the spring I disconnected the motor and the head went up
so I held the pulley at the top of the lead screw and released some gas, just a little at a time until the Z axis was in perfect balance.
The balance does not seem to alter very much at all, if the z axis is at the bottom or the top of its stroke it is still in balance.
I think that it is preferred to have the head slightly negative (pushing down)
But for the time being I left mine in perfect balance
So the motor has very low load when travelling up or down !! Good eh.
The gas spring I bought was a stainless steel adjustable pressure spring, The pressure is at 640n when bought and you can let them down, being very careful not to go too far as you can only go down not up,
Go too far and your looking for another one.
When I first fitted the spring I disconnected the motor and the head went up
so I held the pulley at the top of the lead screw and released some gas, just a little at a time until the Z axis was in perfect balance.
The balance does not seem to alter very much at all, if the z axis is at the bottom or the top of its stroke it is still in balance.
I think that it is preferred to have the head slightly negative (pushing down)
But for the time being I left mine in perfect balance
So the motor has very low load when travelling up or down !! Good eh.
Re: Triac Z axis counter-balance
Hi
Not sure if you are still on here Colin but I have your machine!
I bought it as a project as it had some issues which I am keen to sort out.
The guy I bought it from was up-front and said there were issues with the machine and may need a new Z axis ballscrew...
Did you ever measure the force to turn the Z axis.
I had a look and found in both directions (the gas strut must still be working) it was 2.2lb at 3 inch which is: .75 Nm or .55 Lb Ft
Cheers
Dave
Not sure if you are still on here Colin but I have your machine!
I bought it as a project as it had some issues which I am keen to sort out.
The guy I bought it from was up-front and said there were issues with the machine and may need a new Z axis ballscrew...
Did you ever measure the force to turn the Z axis.
I had a look and found in both directions (the gas strut must still be working) it was 2.2lb at 3 inch which is: .75 Nm or .55 Lb Ft
Cheers
Dave
Re:
Guess I need to disconnect the gas spring...sneakym8 wrote:Hi
When I first fitted the spring I disconnected the motor and the head went up
so I held the pulley at the top of the lead screw and released some gas, just a little at a time until the Z axis was in perfect balance.
Dave
- sneakym8
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Re: Triac Z axis counter-balance
Hi Dave
Nice to know its still around it was a good project. I never did measure the force on the z axis although it was very light to move , with the gas strut in place and with it removed the axis ran away on its own . If theres anything i can help you with i will although its a while since i did it.
Nice to know its still around it was a good project. I never did measure the force on the z axis although it was very light to move , with the gas strut in place and with it removed the axis ran away on its own . If theres anything i can help you with i will although its a while since i did it.
Re: Triac Z axis counter-balance
Hi Colin - great to see you are still here and I'm sure I'll have plenty of questions for you if you are happy to answer?
I think the z -ball screw will need replacing - the pulley needs grasping with my hand to turn it and it does feel a little notchy. The guy I bought it from said he reckons it needs replacing too. I found the nut that secures the z screw to the top bearings loose and the screw itself was moving up and down as you turned the pulley causing a lot of resistance.
All axis's moved when I went to look at it but it would trip when moving the X and Z. The guy who sold it to me said he thinks this was because the screws have had it. I got a new X screw and ball nut with the buy so I'll fit that and see if it stops the X tripping.
It's had new spindle bearings too so hopefully once the screws are fitted/replaced it will be up and running nicely.
Really like the fact it is on servo drives![Smile :)](./images/smilies/icon_smile.gif)
I don't suppose you know how the Z axis screw is removed? It looks tight. I'm guessing the bottom single bearing retainer plate it removed and the screw and the bottom bearing move down far enough to remove the top of the screw shaft from the two top bearings?
Cheers
Dave
I think the z -ball screw will need replacing - the pulley needs grasping with my hand to turn it and it does feel a little notchy. The guy I bought it from said he reckons it needs replacing too. I found the nut that secures the z screw to the top bearings loose and the screw itself was moving up and down as you turned the pulley causing a lot of resistance.
All axis's moved when I went to look at it but it would trip when moving the X and Z. The guy who sold it to me said he thinks this was because the screws have had it. I got a new X screw and ball nut with the buy so I'll fit that and see if it stops the X tripping.
It's had new spindle bearings too so hopefully once the screws are fitted/replaced it will be up and running nicely.
Really like the fact it is on servo drives
![Smile :)](./images/smilies/icon_smile.gif)
I don't suppose you know how the Z axis screw is removed? It looks tight. I'm guessing the bottom single bearing retainer plate it removed and the screw and the bottom bearing move down far enough to remove the top of the screw shaft from the two top bearings?
Cheers
Dave
- sneakym8
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Re: Triac Z axis counter-balance
Not sure how the zaxis ballscrew comes out i never had to remove any of the screws, it sounds like its been in a damp place if there's trouble with all the screws as they were mint. If the shafts are ok you can re-bal l
- sneakym8
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Re: Triac Z axis counter-balance
Re -ball them . You can buy selectiv size balls so you can eliminate backlash.
Re: Triac Z axis counter-balance
Thanks Colin - I will look into re-balling the Z ball nuts if I can.
Interestingly I disconnected the gas strut. The force required to lower the Z halved and doubled to raise it - i'd say the strut is still working perfectly.
I did have a feel of the Z servo motor - it is very notchy. I checked the X servo and that is lovely and smooth. I'm guessing the Z axis not running free has possibly damaged the servo? I'll have to look for another![Sad :(](./images/smilies/icon_sad.gif)
I took the table off tonight to get to the X ball screw - as I loosened the nuts it freed off and the screw turned a lot easier. As the guy who I bought it from said the nuts just need shimming so they run free when tightened.
I think I am derailing this thread now so I will start a new one tomorrow and stick a few pics up. I'll try to update so there is a record of what I do.
Cheers
Dave
Interestingly I disconnected the gas strut. The force required to lower the Z halved and doubled to raise it - i'd say the strut is still working perfectly.
I did have a feel of the Z servo motor - it is very notchy. I checked the X servo and that is lovely and smooth. I'm guessing the Z axis not running free has possibly damaged the servo? I'll have to look for another
![Sad :(](./images/smilies/icon_sad.gif)
I took the table off tonight to get to the X ball screw - as I loosened the nuts it freed off and the screw turned a lot easier. As the guy who I bought it from said the nuts just need shimming so they run free when tightened.
I think I am derailing this thread now so I will start a new one tomorrow and stick a few pics up. I'll try to update so there is a record of what I do.
Cheers
Dave
Re: Triac Z axis counter-balance
Just found this thread with contact info of a company that does re-ballingsneakym8 wrote:Re -ball them . You can buy selectiv size balls so you can eliminate backlash.
![Smile :)](./images/smilies/icon_smile.gif)
viewtopic.php?f=47&t=4714
Dave
- sneakym8
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Re: Triac Z axis counter-balance
Dave
I don't know who you got the machine from but when i sold it there was a spare motor with it , as i was going to put a 4th axis on it . I saw some similar motors on ebay last week .
I have just bought a denford microrouter and was thinking about converting it to servos.
I don't know who you got the machine from but when i sold it there was a spare motor with it , as i was going to put a 4th axis on it . I saw some similar motors on ebay last week .
I have just bought a denford microrouter and was thinking about converting it to servos.
- sneakym8
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Re: Triac Z axis counter-balance
Dave the reballing is really easy to do and costs pennies . I will have a contact for the balls if you struggle to findsome.Rgvbaz wrote:Just found this thread with contact info of a company that does re-ballingsneakym8 wrote:Re -ball them . You can buy selectiv size balls so you can eliminate backlash.
viewtopic.php?f=47&t=4714
Dave
- sneakym8
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Re: Triac Z axis counter-balance
The motor probably just needs new
bearings
bearings
Re: Triac Z axis counter-balance
Colin - sorry I missed this post.sneakym8 wrote:Dave
I don't know who you got the machine from but when i sold it there was a spare motor with it , as i was going to put a 4th axis on it . I saw some similar motors on ebay last week .
I have just bought a denford microrouter and was thinking about converting it to servos.
There was no spare motor with it
![Sad :(](./images/smilies/icon_sad.gif)
Is there any way of servicing these. Not had a look inside yet but I will.
Dave