Thread: Giant 20' x 3' x 2' router build
started to draw things up the hole y and z bit is proper complex and proving a bit of a head spinner but slowly making progress. just ordered a few bits from kjn to replace the main beam on the z with 80 x 80 and a hole load more t nuts. (You can never under estimate just how many you will need!) The aluminium while expensive is really good if you are not 100% sure on what you are doing as its so easy to go back a step or two if you forget something.
I have all so ordered a number of triangular corner plates to go on the table to give it belt and braces as there is the tinniest bit of movement if you hang from the arm.
While this is a huge machine and a bit of a different design im not sure it that much different to anything else except the x axis is very long!
im allso working on idea for the x axis rack and pinion set up/gear box. I have done a very very crude mock up, i have been told that it is probably safer to go for a fixed pinion setup rather than spring loaded as it is a lot less likely to go wrong and it is very hard to get enough pressure with out a very big spring. I am going to try and work some way of making a manual tensioner to help press the pinion up into the rack before bolting it up tight.
I Started to read the what motor threads and got to admit im wondering if i will ever figure it out myself! im not a great one for maths.
Last edited by charlieuk; 28-11-2014 at 12:19 AM.
Last edited by charlieuk; 27-11-2014 at 11:38 PM.
cheers lee i will have to see if i can come up with something then as a few people have said it can be more effort than its worth as you need to have it under very high tension otherwise it can slip out the rack and then you get even bigger problems. I have been wondering if it is almost posable to get a pice of sprung steel that could work like a leaf spring that you could tension right up.
i also spoke with cnc4 you and zapp regarding motors and drivers cnc4you recommended for the y and z axis ball screws there nema 23 3.1 with there cw6060 driver and zapp recommended there SY60STH86-3008B motor and DM856 driver.
from my very basic knowledge it looks like the motors are the same ? can any one give me any advice on the two drivers that have been suggested on which is better?
DM856 Digital microstepping driver
Stepper Motor Driver 6.0A 20~60VAC or 24~80V CNC Microstepping CW6060AC
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.
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
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.!!
Last edited by JAZZCNC; 11-05-2014 at 07:49 AM.
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.
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.
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