Giant 20' x 3' x 2' router build

[charlieuk]

There's nothing between the motors. I would definately go with the digital drives thou in My experience I'd go with EM806 rather than the DM856 as they are worth the extra. They have better resonance handling and stall detection and just seem to run motors that bit smoother than the DM856.

With the rack I'd go with sprung loaded as it keeps backlash to a minium and lowers rack wear. Problem with fixed is you need to be very precise with rack alignment and pinion tension/engagement otherwise it wears quickly and can stick or bind causing motor stalls.
Sprung loaded is more work but more forgiving and if done correctly gives better backlash and longer life.

Cheers thanks for that, are the digital drivers cnc4you good alternatives to the em806 only that they have been super helpfully through my build and
offer great backup and support from them so far.

I will do a little more searching to see what I can find for the rack and pinnion and come up with some sort of design unless zany one knows of something avalable for mod 1 rack? Many thanks

[JAZZCNC]

Cheers thanks for that, are the digital drivers cnc4you good alternatives to the em806 only that they have been super helpfully through my build and offer great backup and support from them so far.

I understand what you mean regards supplier being helpful and it goes along way in my book too but you have to remember with any supplier they are always going recommend and Big up what they sell for obvious reasons. Helpfullness does also needs to be factored in but must say from folks I help and my own experience Gary and staff at Zapp are not unfriendly or awkard.!

Regards the drives then Honest answer is I haven't used those drives so can't comment on them. What I will comment on thou is the things they don't have compared to the Leadshine EM806 or DM856 which can become a major issue in some machines, esp large steel machines and machines with slaved axis.? . . . Resonance handling and stall detect.!

Most decent drives, inc the CW6060AC will have Resonance handling features built into them and some like the CW6060 will have more advanced algorithms to deal with resonance than others but essentially they still do the same in that they use a fixed frequency range or field of view along the motors speed curve.
The Leadshine drives come with a COM port so you can connect to them via software and adjust the drives resonance parameters. This can be priceless if you have a machine that is resonant and happens to be producing resonant frequencys outside the drives compensation field of view or dipping in and out so causing irratic or rough running motors.
If this does happen on fixed range drives then your stuffed and stuck with it but with EM806 drives you have full and fine control of the resonance handling.
If your thinking does this happen.? Then yes it does, esp on large steel framed machines or machines running resonant drive systems like R&P. It's just that often people don't know they have resonance problems as the drive is doing some compensation whick masks it and they just accept that the speeds or way machine runs is just how it is.!! This is Because unless resonance is really bad it doesn't stop motors running it just makes them run rough or lowers the speed you can get from them before stalling.!
Does it happen Often then again some times yes, esp on cheap drives but people don't know it. In most cases then folks won't have a problem but if you do have a resonance issue then you'll be highly pleased you bought the EM806.!!

This takes us nicely into the Stalling motors.? The EM806 as a nice feature in that it detects motor stalls and provides a Fault signal which can be used to E-stop the machine. This for machines running slaved motors is Vital to me and after using these drives I wouldn't run any slaved axis machine without this feature.

There are other nice features the EM806 offers like full Current tuning control and fully adjustable Micro stepping and fine adjustment amp setting 0.1A but they are secondery to the other 2 features which IME are worth that little extra.!!
Between these features if you have any issues you can deal with them and tune them out rather than just having to Live with them.!! . . . Priceless.!!

[charlieuk]

Many thanks for that jazz although i am only just strating to learn about this side of it it does make sense what you are saying.

cnc4you have been super helpful and even dropped in to see them and they spent ages going through everything and offered full support on getting it all wired up correctly and running and even offered to switch parts over if for some reason i needed to so seeing as this is my first build that was quite reassuring. Im not saying zapp dont offer the same but i just have only spoke very briefly to them but they we very quick at giving me advice on the motors.

this was the digital driver i think cnc4u have added recently, i have no idea if it is suitable or similar to the EM806 you recommend
Digital DSP Stepper Driver 7.2A, 80VDC or 60VAC CWD872

when you mention slaved motors are you talking about two motors on one axis or one motor driving the two screw like i am having?

im happy to get the product from were ever but feel it would be nice to support kevin and brian if they have a suitable product as i could do with as much help as posable when it come to getting the motors and electronics up and running.

[JAZZCNC]

this was the digital driver i think cnc4u have added recently, i have no idea if it is suitable or similar to the EM806 you recommend
Digital DSP Stepper Driver 7.2A, 80VDC or 60VAC CWD872

They are similair to the EM806 in that they use PID technology and can tune them selfs to the motors but they still lack the abilty to go in and tweak thru software in the avent of resonance problems. Now in practice it's likely won't have any troubles but if you do then you still can't do anything about it other than alter the Micro stepping which is less than ideal.
To be honest IMO Leadshine lead the way when it comes to this technology and the others are either cheap copy's or better quality copies playing catch up. My gut feeling is these drives are ok Copies of leadshine technology but can't use the Software option for legal reasons.

Don't get me wrong I'm not saying these drives are no good because I've not used them before but they don't give the same flexabilty or features as leadshine drives. That said, it could be said, they don't cost the same either so your not paying for the features either and if you don't need them why pay for them.? . . . Which is fine if you can be sure your not going to run into resonace problems but like I pointed out before if you do you'll wish you'd payed £15-20 more to be able to tune it out.!

Being in business I applaued your attitude regards supporting helpful business or people and Having help and advise on hand is also valuable but hey you have a Forum full of help and I've offered my number so you have experienced phone support if you need it so I wouldn't compromise my machine just to carry favor.! . . You can still support them by buying other items from them, like there motors which are Ok.

when you mention slaved motors are you talking about two motors on one axis or one motor driving the two screw like i am having?

I mean 2 motors working same Axis that need to run in sync. Imagine the carnage that happens when one motor stalls but other keeps going when 2 motors slaved to the same axis.!! . . . You need some way to tell the other motor to stop as well. The stall detect and it's fault signal provide this abilty.
While the stall detect is mostly of benefit to slaved motors it is also useful to stop the machine when using single motors on each axis in case one axis stalls. This can often save the job if a stall does happen and your not around or quick enough to E-stop the machine before too much damage is done.
(Often Stalls happen at higher feeds, like rapid speeds, when torque is at it's lowest. So you can recover from stall before damage is done because rapid move stalls tend to just mean positional loss and are not engaged in the cut or material.!)

[GEOFFREY]

I will do a little more searching to see what I can find for the rack and pinnion and come up with some sort of design unless zany one knows of something avalable for mod 1 rack? Many thanks[/QUOTE]

Hi, first of all let me say that I am a machine user(converter) and have never built a machine. I think that your giant will be awesome for the uses you plan. With regards to tensioning the R&P, I think the most simple way would be to pivot the drive and have an extended arm with an adjustable slide weight to let gravity do the tensioning. Perhaps this is just too easy, I'm sure I will soon hear why its a stupid idea, but I do love simplicity!!! G.

[charlieuk]

i was wondering about that but i from what i have been told it need to be under pretty high tension which would require a lot of weight or a very long arm to hang it from i guess.