[Dentedcrown]

Hello all,
One more thread about which stepper package to get...

OK, I am building a machine that I am going to upgrade a bit as time passes.

Initially I will running 2, 4' 1/2-10 acme leads on the x axis, 2' 1/2-10 acme on the y axis, and 9" 1/2-10 acme on the z. Spindle ti start will be a Porter Cable 690. Construction is all alluminum, 80/20 and plate, Thomson Accuglide 25 rails on all axis.

Eventually I will be getting ball screws for all axis to better fit the rail lengths I have. 6' x axis, 42" y axis with the same 6" travel on the z. And, dare to dream, a good machine spindle.

I am looking for a "all in 1" kit that will be able to grow with the machine as I upgrade. I want to mill alluminum and woods. I like the looks of the G540 as a driver but am not sure about how big the steppers need to be. Budget as allways is a concideration but I am willing to spend a little more for somthing I will get some mileage out of.

Any help making up my mind before my head explodes would be greatly appreciated....

Thanks
DC

[ger21]

What works best with 1/2-10 acme may not work well at all when you switch to ballscrews. The drive system all works together. When you pick a motor, you pick it to work with a specific machine configuration. With 1/2-10 acme, smaller motors will probably give you better performance. With ballscrews, depending on the pitch, larger motors may be better. A general rule, is that the bigger the stepper, the slower it spins. Since you have to spin 1/2-10 really fast to get any decent speed (1000rpm for 100ipm), the smallest motor that had the needed torque would give you the best performance.

For a screw driven router, 1 to 4 turns per inch will usually give the best performance.

[TOTALLYRC]

Hello all,
One more thread about which stepper package to get...

OK, I am building a machine that I am going to upgrade a bit as time passes.

Initially I will running 2, 4' 1/2-10 acme leads on the x axis, 2' 1/2-10 acme on the y axis, and 9" 1/2-10 acme on the z. Spindle ti start will be a Porter Cable 690. Construction is all alluminum, 80/20 and plate, Thomson Accuglide 25 rails on all axis.

Eventually I will be getting ball screws for all axis to better fit the rail lengths I have. 6' x axis, 42" y axis with the same 6" travel on the z. And, dare to dream, a good machine spindle.

I am looking for a "all in 1" kit that will be able to grow with the machine as I upgrade. I want to mill alluminum and woods. I like the looks of the G540 as a driver but am not sure about how big the steppers need to be. Budget as allways is a concideration but I am willing to spend a little more for somthing I will get some mileage out of.

Any help making up my mind before my head explodes would be greatly appreciated....

Thanks
DC

Take 5 and a cold beer for the brain melting.

As GER21 says it all has to work together. It is a very common thread that I will start out cheap and upgrade, but as he pointed out, it may not be that easy.
SO, work backwards from what you want to eventually have and get what is similar now. If you don't already have the acme screws, you can do something like this. I figure 200ipm as the minimum max speed an a machine that big and since you will be doing wood, the speed is a good thing.
If you plan on using a 5tpi ball screw in the future, get an acme screw with the same pitch, a 1/2"x10 2 start screw is 5tpi equivalent. now your motors that will work with the first screw will work with the upgrade screw. If you already own the acme screws, all is not lost. Use a motor that works with the tpi you currently have and then plan on using a belt drive for the new screw to match the motors speed to what is needed.
On a 10 tpi screw, you are going to want a nema 23, that will spin fast enough to get what you want. 200ipm x 10 revs per inch = 2000rpm, which is beyond what most steppers can do and have any meaningful power to do it.

Proofing this makes me think that even 5tpi is too fine of a pitch for a router of this size. Sounds like 2 tpi would be more reasonable. Or belt drive to overdrive the motrs output.

I normally figure 1000rpm as a reasonable max so it will only go about 100 ipm if you are lucky.
Search for other router builds and see what they are using with 10 tpi screws.

Just for more info, my z axis on the router has a nema 23 425oz from Keling on it. Driven by a G251 which has on the fly morphing, same as what is inside the G540. I can only go 13,000 steps per second before the motor will stall and become unreliable. I plan on testing with a smaller motor as I have several around, but it works fast enough at this point in time.
13,000step/sec / 2000steps/rev /5tpi = 78ipm.

Sounds pretty fast untill you drill 100 holes in as sheet of material, takes a long time for the z to move up and down. Of course it used to only go 20 ipm, so it is tolerable for now.

Hope I didn't make the brain melt any worse.

Mike

[Dentedcrown]

OK, Beer, check...

I didn't even think of doing a belt drive on this. I like the concept, could allow the use of 1 motor on the X axis. Couple questions though. Would it be better to get bigger motors now and gear up or the other way around? Where is a good place to get drive pulleys, what type would you recommend?

Many thanks guys, a little different way to noodle the issue.

DC

[TOTALLYRC]

OK, Beer, check...

I didn't even think of doing a belt drive on this. I like the concept, could allow the use of 1 motor on the X axis. Couple questions though. Would it be better to get bigger motors now and gear up or the other way around? Where is a good place to get drive pulleys, what type would you recommend?

Many thanks guys, a little different way to noodle the issue.

DC

I think you really need to figure out how fast you need to go first and then buy the motors once.
You also need to figure out how big and how heavy this is going to be to be able to size the mtors correctly. It seems to me that the smallest motor that will do the job is the way to go.

If you go with the g540 and the 387 from keling or similar sized package, and then build the machine based on those capabilities, then you can work backwards. The g540 is a great package and it would run my ~42 x 36 router quite well as I am only running on 50v and as I have said have a g251 driving the z. I am using 425's for motors at the moment. I have rack and pinion on the x and it is way overdriven it is less than 1 motor rev per inch. 1575 steps per inch IIRC. 2000 is one motor rev. I paln on trying to increas the gearing some to get it to at least 1 rev per inch. This will allow me to actually run faster as I am running the motor well below it max torque.

SDP/SI has worked for me in the past, although there are other places.
I have also used MSC because we use them at work and we get a good discount from the book prices.

If you setup for belts from the begining, you can always fine tune the drive ratios whenever needed, and would allow you to go servo in the future if desired.

Question, Do you already have the screws mentioned? Because if you do, we could figure from there. If not, then getting a more appropriate pitch might be better.

[Dentedcrown]

I do have the screws at present. Got them with end bearings and motor mounts, 1/4" ends for coupling.

So, with the pulleys I would want to step down like 4 to 1 giving me the equivilant of a 2.5tpi screw? Depending on any # of things...

I am not sure how fast I need to go, don't want to wait forever but with the PC router as spindle not sure how fast I can go. When doing alluminum/light brass it would be more engraving type stuff with passes no deeper than 1/16" or so. With wood I want to be able to cut 3/4" hardwood ply and do some carving stuff/sign work. I am hoping I can use the machine for both applications, I have NO experience with milling so the spindle speeds/feed rates are an unknown to me as of yet.

More info...

The gantry should come in somewhere around 70-75 lbs I think, the rails are kinda heavy.

More beer, man you have great ideas...

[TOTALLYRC]

That must be the reason for the headache I have, not enough beer.

Onto the machine.

My gantry with spindles is easily 75lbs, as it was a bear to assemble by myself and I had one of the children give me a hand, Since you are going to belt drive this, the gecko G540/387/power supply package from keling or the new motor package from Keling is a nice option.

Mariss from Gecko recomends a vexta pk268??? as one of the smothest motors he has ever test run. Geared properly, they would be great if you can get them at a good price, as they are about double what Keling charges for his motors of a similar size.

If you search the Zone for it you will find the exact number he recomends.

A rapid of 200ipm would be a good starting place.

The X axis is going to have the toughest time as it has to move all the weight. On the Z axis, a smaller motor might be in order as you will want it to rapid quite fast if you do hole drilling or some such thing.

I am sure that other people will chime in with there suggestions as to which motors will do well.

1:4 overdive might be a bit steep, and since I am a trial and error kind of guy,(nuts) mostly error my wife says(nuts), I would consider setting up the X axis and experimenting a little bit with ratios. Get the large pulley for 1:4 and then a couple of different pullies for the small. A few extra dollars spent now will insure that you have the correct ratio for the performance you want and that it will be as closely matched as possible to the components that you have.

[Dentedcrown]

Awsome, progress...

I like that kit from Kelling, simple...

Should I run both x axis screws off 1 motor with the belt drive or get a 4th motor and run them independant?

Looking at pulleys the MXL pitch .25" belt pulleys at SPD-SI look like a winner. They have tooth counts that will go to 1 to 4 ratios. The belts are available to around 40". Hmmm, strong enough???

I am starting to get more excited than confused now...
DC

[TOTALLYRC]

Awsome, progress...

I like that kit from Kelling, simple...

Should I run both x axis screws off 1 motor with the belt drive or get a 4th motor and run them independant?

Looking at pulleys the MXL pitch .25" belt pulleys at SPD-SI look like a winner. They have tooth counts that will go to 1 to 4 ratios. The belts are available to around 40". Hmmm, strong enough???

I am starting to get more excited than confused now...
DC

I think L would be better, mxl is awfully small. I have L on my router in the .500 width. XL might work but I prefer a little bigger than too small.

2 x axis motors will give a lot of power and allow for aggresive acceleration with a lot less chance of stalling.

Hopefully someone will chime in if I am way off base.

Keep up the good work.

Mike

[jschmitt]

I would be careful overdriving a 1/2-10 acme screw because of the whipping action you could get. There is a calculator on Nook's site to help out.

[ger21]

I would be careful overdriving a 1/2-10 acme screw because of the whipping action you could get.

But if it does start whipping, you can just limit the speed in the software.

Definately go with two separate motors. Slave them in software.

[BobF]

Have you bought the screws?
If not, look at the multi start acmes that are available.in 1/2"-10. You would probably get better results with 2 start or 5 start.

[Dentedcrown]

I allready have the screws so I am kinda stuck for the meantime...

I will be going for the 2 motors on the X.

I was looking at this spindle

http://www.littlemachineshop.com/pro...ory=-269978449

Has anyone had experience with this set up? I am thinking that I might be able to fit the z azis to change out between it for metals and the PC 690 for the wood???

Thanks
DC