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Davo242
06-01-2016, 12:02 AM
Can anyone help me find out the volts Dec I can turn my power unit up to that my stepper motor will take all it says on them is 3a 2.4nm no volts. As far as I can make out the drivers will take 50vdc. I have attached a photo. Hope fully someone can help.

Clive S
06-01-2016, 10:12 AM
Can anyone help me find out the volts Dec I can turn my power unit up to that my stepper motor will take all it says on them is 3a 2.4nm no volts. As far as I can make out the drivers will take 50vdc. I have attached a photo. Hope fully someone can help.If you are using the drivers in you picture then 36 V would be a max and the power supply you have will only give 36V. What is the actual problem you have. Pictures of the setup would be a good starting point.

Davo242
06-01-2016, 10:30 AM
The motor on the y just seems if it's not getting enough power to drive the gantry the motor gives the odd shudder also I think the problem could be that it's only driven on one side and I'm just trying to tell myself I don't have to hand out anothe 200 odd to drive the other side to. I will upload some pictures this morning.

Clive S
06-01-2016, 10:45 AM
The motor on the y just seems if it's not getting enough power to drive the gantry the motor gives the odd shudder also I think the problem could be that it's only driven on one side and I'm just trying to tell myself I don't have to hand out anothe 200 odd to drive the other side to. I will upload some pictures this morning.
If you are driving the gantry from the side then it will rack. So lets see the pictures

Davo242
06-01-2016, 01:42 PM
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routercnc
06-01-2016, 01:55 PM
For a single CENTRALLY DRIVEN gantry I would not go wider than 600mm. Any wider needs to drive systems (one on each side). Yours looks considerably wider.

Furthermore, and critically, for your design it is very unusual to try and drive a gantry from one side only. It is very likely to rack / judder, plus give poor accuracy when cutting further from the driven side.

I expect that if you grab hold of the non-driven side you can push it back and forth several mm, maybe more ? If so racking is a the likely cause of the judder.

This can be reduced by spacing the X axis bearings further apart fore/aft, but I suspect even this may not be enough if you are still driving from one side.

Davo242
06-01-2016, 01:59 PM
yea its what i have been thinking all along. its nearly 1600 on the x axis so i was just pushing my luck. to add another drive on is that the A axis that is used???

Clive S
06-01-2016, 03:14 PM
yea its what i have been thinking all along. its nearly 1600 on the x axis so i was just pushing my luck. to add another drive on is that the A axis that is used???I don't think you will ever get it working with those drives and a 36V power supply and one motor on the long axis. Also do you have a gearbox on the rack & pinion what is the ratio.

Davo242
06-01-2016, 03:44 PM
no gear box just a direct drive at the min for testing. its a 59 tooth sprocket on a mod1 rack. 4:1

JAZZCNC
06-01-2016, 07:21 PM
no gear box just a direct drive at the min for testing. its a 59 tooth sprocket on a mod1 rack. 4:1

What you mean 4:1 if it's direct drive there's no ratio.? 59T direct drive means 185mm pitch.!!!

Anyway I strongly advise you to STOP and have re-think because your wasting your time on several fronts.
#1 No way can you move gantry that wide with one motor.
#2 Ratio of at least 5:1 will be needed with that size pinion.
#3 The drives are rubbish and even with 36V if they survive long enough they will run so badly and rough you'll struggle even with 2. This is because resonance will cripple them and turn them into horrible stalling nightmares. These cheap nasty drives have no way of dealing with resonance and with machine being all steel and not exactly HD the motors/drives will be affected.
#4 Looking at the Z axis unless your going to use for just Plasma then No way is that Z axis going to be upto cutting anything but foam. Certainly won't cut wood very well.

So again please don't take this wrong way I say it for your own sake and your wallets sake. You'll be wasting good money and time if you continue as you are.!

Davo242
06-01-2016, 08:24 PM
what do u see wrong with the z axis jazz??

Jonathan
06-01-2016, 08:39 PM
what do u see wrong with the z axis jazz??

Single bearings on the rails. Rails not on front plate so bearings are miles from the cutter. Spindle mounted at wrong end.

In fact simply taking the Z-axis front plate off with the bearings and turning it upside down would make a difference...

Davo242
06-01-2016, 08:56 PM
I can see what your saying about the bearings but why the rails on the front plate and not the back.???I think the spindle will be ok there is still another bracket to go there yet the same as the top to hold it in place.

JAZZCNC
06-01-2016, 09:59 PM
what do u see wrong with the z axis jazz??

Jonathan said everything that needed to be said so I won't repeat.

But I will say this.!!. . . The fact you have asked this question to me and query what jonathan points out plus the fact you have bought TB based drives and no clue about voltage shows me you haven't done much research so I suggest you start doing some.
We can tell you this and that, answer a query or two but you really need to read up on it and under stand why things are done like they are. Doing so will save you money and time in the long run.

Davo242
06-01-2016, 10:24 PM
Ok you maybe right in what ur saying jazz but I started this project a while back and I'm only getting back to it now. Up until recent I didn't know this forum existed. But yes I have been looking threw posts on here to find info and guidance

JAZZCNC
06-01-2016, 10:57 PM
Ok you maybe right in what ur saying jazz but I started this project a while back and I'm only getting back to it now. Up until recent I didn't know this forum existed. But yes I have been looking threw posts on here to find info and guidance

Dave don't get me wrong I'm not having a go at you and anyone around knows I'm 100% supportive but end of day your the one doing the work and if you don't research you will get it wrong.
The mistake you made and many others is by not asking before starting and with not enough research. It's recipe I see and deal with all the time so my advise is based on experience and with genuine intent to help not offend anyone.

While building a good CNC machine isn't exactly difficult it is very easy to build a lemon if you don't go about it in the right way.!!

Davo242
06-01-2016, 11:08 PM
Your ok I do see where you are coming from and I'm grateful for all the advic that yourself and others give . As for the gantry I have another motor ordered for the other side so I prob will need some help on getting the wiring sorted for it. Also you have mentioned the drivers are no good, which ones do you recommend if theses ones blow.

JAZZCNC
07-01-2016, 12:07 AM
As for the gantry I have another motor ordered for the other side so I prob will need some help on getting the wiring sorted for it. Also you have mentioned the drivers are no good, which ones do you recommend if theses ones blow.

Dave this highlights my point perfectly.? . . .One mistake people often make is just rushing out and buying parts without really knowing what there buying.

For instance you say you have ordered another motor but I bet you have no idea other than probably the Nm rating to the spec of the motor.?

Not all motors are equal even if they have the same Nm rating. There are specs that make a huge difference to how motors perform and 99% of time Cheap motors, like those supplied with cheap drives like the TB based drives are perfect examples of this.

The relationship between Motor spec and Drive spec is critical to good reliable system. Cheap motors, well actually no cheap is the wrong word because you can buy motors that are cheap and still good.! Poor spec motors is better word. These motors typicly have high inductance which massively affects how they perform and impacts on the whole system, voltage required, affects of resonance everything. This follows into the drives and affects how they perform and deal with things.
So it's very important Motors, drives and voltage are all balanced and suit each other.

For this reason I won't recommending any drives without knowing more about the motors. No point having Great drives if your running high inductance motors with only 36v. Best drive in the world won't make much difference other than reliabilty.

My suggestion is if, well when, the drives blow up you do a complete upgrade and re think of the machine electronics because better drives won't do much for performance if your running high inductance and low volts.

Better still bite the bullet now and do it right from the start. This will save you money long term and pain in the short term because that's all that's in store for you now with these drives and low voltage. Which you will endup replacing sooner or later and often they are dead so have no resale value.!

This size and style of machine needs good electronics sized correctly other wise your always going to be smacking your head against the wall.
The fact your using R&P with no ratio complicates things further and makes it difficult to advise until you come to better setup with a ratio.

All I can say with certainty is that those crappy drives and 36v won't be much use for R&P and better drives won't help unless the rest matches.

Jonathan
07-01-2016, 01:00 AM
Better still bite the bullet now and do it right from the start. This will save you money long term and pain in the short term because that's all that's in store for you now with these drives and low voltage. Which you will endup replacing sooner or later and often they are dead so have no resale value.!

Agree entirely. Whilst they still work the drives have some resale value (e.g. to people making 3D printers who don't require better), but once they blow up ... I got 25 per tonne for a heap of old circuit boards and bits earlier this week.