Giant 20' x 3' x 2' router build

**charlieuk** · 06-05-2014

found this on google turns out i was searching the wrong name

is this the sort of thing i need to do? I only have 265mm between the centres of the ball screws ether side so the belt wont need to be that long

**JAZZCNC** · 06-05-2014

Ah ah think I drew that for someone on here long time ago when I used Rhino.!! . . . If not I've done something very similair for someone.

But yes that type of thing thou in your case I'd just offset the motor to one side for ease of build and neatness. Doesn't matter if it's offset with such a short belt.

**charlieuk** · 06-05-2014

cool that should be fairly simple then as i can get a pulley straight on the shaft and motors, i may have to put a extra pice of extrusion across anyway to take the motor mount so not sure go off centre is going to make it to much neater, i think i have a little ocd on things being symmetrical as well.

What i will also do is try and get the bk and bf blocks in line with the top of the alli so the stepper does not drop to far bellow the gantry. I would have loved the belt and motor to be all inside but that doesn't look possible with this design.

**charlieuk** · 08-05-2014

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.

**charlieuk** · 10-05-2014

............

**Lee Roberts** · 10-05-2014

Originally Posted by charlieuk

and figure what i am going to do with the x axis ie a fixed mount or spring loaded for the rack and pinion.

Hi Charlie,

From the diy machine builds i've seen/read, i think they all used the spring loaded method when it came to the R&P. The build is coming along nicely, good luck with the rest.

.Me

**charlieuk** · 10-05-2014

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.

many thanks

**charlieuk** · 10-05-2014

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

many thanks

**JAZZCNC** · 11-05-2014

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.

**charlieuk** · 11-05-2014

Originally Posted by JAZZCNC

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