Started my build this week on a 4'x8' router made of 8020 and some quality linear drive components. Here are some of the parts I am using

25mm Hiwin Linear rails on all axis
.75" x .5" lead, Roton Ball screws x and y
.625 x .2"lead on z
welded steel 2" square tubing frame
8020 table frame and gantry assembly

thinking im going to use keling servo motors on all axis most likely the largest servos they have for the x and y and drop down a few sizes for the z.

Pictures are of the overall design. Keeping in mind the z axis isnt worked out yet still in the design stage. I initially was going to mount the y rails on the gantry, on the plane perpendicular to the table. But decided that by mounting them on the top and bottom of cross members the z axis assembly will move back a few inches giving me less moment on the x axis bearings. Also im thinking becuase of this the cross members can be shortened so that they do not extend pass the gantry uprights cleaning up the design a bit.

I will post pictures of the build so far tomorrow.

let me express my interest in your project
i am almost ready to build
cabnet
www.mcgrewwoodwork.com

Here are some pictures of the first day of building. Sorry for the poor quality of the later ones, the battery in my digital cam ran out had to use my phone.

The one picture shows (althought very dark) the method i used for insuring the rails were straight relative to the 8020 frame rails.

I recieved the ball screws the other day now i have to try and turn down the ends of the y axis. The x axis is going to have a rotating nut. Due to its length of 9 feet rotating the screw was not an option. The pictures in the first post have some details on how i hope to achieve this.

i am studying all of this please keep details rolling and get some sleep
the biggest mistakes i make are when i work until i screw up the do it all over
cabnet

i'm very interested (i'm also in canada) in your parts and material sourcing
your build looks like it's off to a good start

At first glance im not entirely that satisfied with the roton ball screws. Althought they appear very effiecient there is an awful lot of play. Without mounting them and driving them with a dial attached i cant tell how much is actually axial play (lash). I got them to put the larger balls in the nuts which from what i hear, that will give me around .003", we shall see. Im a design engineer in the nuclear industry where money is no object in the design process. The high quality of components i usually encouter may have me expecting more.

Just bought a router today, Craftsman (Sears Brand), 12000-25000 variable speed, 11 amp, 2hp, soft start. Has built in led work light in the main casing which is an interesting feature for this application. Also 2 year warranty. for $129 CAD i couldnt pass. It looks alot like the porter cable because it has the metal cylindrical casing, this was something that seems critical to me for assuring a rigid mount.

we're watchin

are you usibg anyones plane or are these your's

cabnet

Those models shown there are mine I spent some time before starting the design process looking at a few other 8020 type machines and took some ideas from them. The one thing i wanted to try and achieve that i havent been able to get any feedback from was the rotating nut. I havent found anyone that has tried this in a diy type machine. I have some of the parts made for that assembly, this week im hoping to get that finished.

Im starting to convince myself that i may need to get a second set of ball nuts and preload these axis.

Take a look at this thread. Dan Kemp (Hoss26) built a rotating nut for his z-axis.
http://www.cnczone.com/forums/showthread.php?p=370663

Alan

Just signing on and admiring your CAD skills

Coop,I have been following the rotating nut posts for a while.Are you incorporating A/C bearings in the nut drive?Here is rotons suggested ballscrew uses.
* hospital beds
* medical examination equipment
* servo drives
* log splitters
* dish antenna drives
* door actuators
* scanners and test equipment
* plotters
* robotics
* web tensioners
* automatic pilots
* trim tab drives
* back gage positioners
* fork lift remote
I assume they are not designed for critical applications.
Larry

At first glance im not entirely that satisfied with the roton ball screws. Althought they appear very effiecient there is an awful lot of play. Without mounting them and driving them with a dial attached i cant tell how much is actually axial play (lash). I got them to put the larger balls in the nuts which from what i hear, that will give me around .003", we shall see. Im a design engineer in the nuclear industry where money is no object in the design process. The high quality of components i usually encouter may have me expecting more.

Hey, I worked up a rotating nut for you. This may be what you are looking for. It is very basic, but may give you an idea on how to do it.

Al :)

Thanks for the drawings, that looks very similar to what I have madeled and what i have started building. If you look at the first post you can see picture/models of what i was going for, its kinda hard to see the deatils without looking at the crosssectional view alon with the full model. Feel better knowing we are on the same page.

I am just using normal abec 5 roller bearings, 1.125 ID 2.0625 OD, however, i will be able to preload them with the method i have designed, im thinking this will be sufficient to remove any play.

Ok I put some thought into preloading these nuts. Attached is a picture of what I was thinking.. I built some of these components today after work they seem to fit up nicely so far. This new design is just an expansion of the old one. Im thinking I can use some cap screws to apply a preload to each of, or one of the nuts. The green flange will have threaded holes in it and will be fixed to the rotating shaft. Any thoughts on this idea i cant immediately see to many issues with this other than the massive amount of space this assembly takes up. I have plenty to spare so this isnt a problem.

Thanks for the drawings, that looks very similar to what I have madeled and what i have started building. If you look at the first post you can see picture/models of what i was going for, its kinda hard to see the deatils without looking at the crosssectional view alon with the full model. Feel better knowing we are on the same page.

I am just using normal abec 5 roller bearings, 1.125 ID 2.0625 OD, however, i will be able to preload them with the method i have designed, im thinking this will be sufficient to remove any play.


Sorry about being so blind. All I can say is: (chair)(chair)(chair) LOL. I looked after your reply. Glad you didn't chew me out. LOL :withstupi :)

BTW very nice work.

Al

Bonjour Coop2005,

I have built such a machine, have a look at http://www.cnczone.com/forums/showthread.php?t=33585 It weighs about 350kg.

I used rack and pinion on the long axis as rotating nut gets too complicated too quickly! The arrangement is backlash free and self compensating for wear.

Regards,
Greg

www.cncdirect.co.za

Hope this helps.

sorry for the lack of progress last week, i was in vegas... its amazing the components i could have bought had i not gone there. Hope to finish up the some parts this week and get it put together next weekend.

hang in there look forward to more photos

cabnet

The rotating nut assembly is pretty much finished, i attached some photos of the assembly so far. I built an extra flange to potentially attach another nut if i need to preload these axis, i will have to wait and see. Going to use some 3"x3" angle on each open end to attach it to the gantry. It seems to be pretty solid and runs nice and smooth. Looking forward to the next step. Work is slow due to the cold canadian winters and being on the road. Need spring to come.

Hey you guys have the same nuts! ,Now I get to watch what happens next ;) Just putting the thread into "my replies" :beer:

Well the warm weather is back so im continuing work, I finished the zaxis design and ordered some parts for it going to start machining some plates sometime in the next week or so. Here are some pictures of the design. Ive gone with a lower cost but i feel sufficient linear bearing system. Also i have tried to keep all the machining to simple plate through holes or threaded holes. This should keep the machining time to a minimum.

I have made some progress on the z axis, this thing is a beast. Everything always seems so small in the model. I knew the 8" wide zaxis was much larger than nessesary but i plan on integrating some gas shacks to counterbalance the weight of the carriage as well as a vaacume attachment. It weights 19 lbs as shown in the picture and is very rigid, slight binding issue with the rails i think its just a matter of tightening the bearings in the right sequence.

The linear bearing bushings, rails and roller bearings and retainers all came from http://www.misumiusa.com/ i highly reccomend this site, they have great prices and the ability to configure all the components to your application is great and cheap. Also there catalogue has all the prices in it which is a huge advantage for these types of projects.

Motors, drives, powersupply should be here this week look forward to puting some power to this thing.

Anyone know where to get some way covers for a good price, thinking about making some on my own but if the price is right i may buy some.

Anyone know where to get some way covers for a good price, thinking about making some on my own but if the price is right i may buy somehttp://www.ixen-cnc.com/2007/10/miscellaneous-videos.html.... check this out

thanks for the link that is helpful seeing the folding patterns. Gotta figure a way to make this work for a 8 foot span without any sag. Im thinking i can use the adjacent t slots some how to hold some of the folds as they traverse the length on the rails.

Years ago I used 20 ga. aluminum sheet and cut it to fit underneath and stiffen the width every foot or so. I would just make it conform to the shape of the bellows and clearance underneath much like this guy did on the ends, then just glued it in place on the folds.

got all the motors, power supply, breakout board and motor drives. Ended up going with the keling NEMA 34 package steppers. The coarse lead on my screw made the steppers seem like the better solution, due to the low speed high torque characteristic with this type of motor. Went with 1200 oz*in for the x-y and a 640 oz*in for the z. This will be more than sufficient to achieve accel and velocitys that i will require. What those are i havent really decided yet :)

I purchaced some timing belts and pulleys as well for the x-y axis, going with a 2:1 to get some more torque and counter that coarse lead.

i will post some pictures tomorrow of the progress.

I wired up my control box almost completely had some frustrating issues getting the motors turning. THe problem lies somewhere from the motherboard to the motor drives themselves.
I was able to get them spinning with a signal generator just pulsing the step pins with a TTL square wave. However the Parallel port will not do the same for me. I hooked the port pins up to the osscilloscope and saw a square wave on the pulse pin however from what i was seing it was only around 750mV pk-pk. not sure if i was taking ground from the right spot tho.
This leads me to think that the problem is in the breakout board. Now maybe its just me but it seems ridiculus that this cnc4pc breakout board has a female DB25 on it when the PP on a PC also has a female. I have 20 printer cables and printer extension cables lying around but understandably they are male to female. what is the logic behind puting this connecter on here.
Im going to play with this a little more tomorrow see what i can come up with,
anyone have any input or maybe had the same problem id love to hear. I am fairly confident that this thing is wired exactly as instructed maybe an output issue?

here are some updated photos on the progress that was made this weekend. The the rotating nut assembly mounted and the z carriage mounted. The control box is wired up and the motors are spinning. Looking forward to getting the ball screws fixed in place and tuning in these motors.

I had an issue with the motors loosing steps in testing even under no load and not very high speed, im not sure if i have the phases connected properly there is no documentation on the keiling website that specifically relates color to each phase and polarity of this motor. It is the 1200 oz in motors if anyone has this information and can confirm what i have is right that would be great.

ok heres the pictures