First build - 8020 with servos or steppers

[sandiegocadcam]

I have been a troll for a while now and greatly enjoy reading all the information and experience in the area of router building from all the individuals in the forums. Thank you all for sharing.

So....here goes my attempt. First off, I want my router for making signs of great 3D detail and the making of electric guitars. I think, from the information that I have read here and borrowed parts of others designs, that I have developed a sound machine for myself that hopefully will be rigid enough to push cutting feeds of 200 ipm+. This is where I need the experience of the "elders".

Below is a list of components that I want to use:

- 892 Porter Cable
- Mach 3 software
- THK HSR15A rails / flange blocks w/tapped holes
- 8020 framming - 2020 & 2040

Overall table size - 40 x 25
Actual cutting size - 32 x 21 x 5(base Z travel)
(6.5 clearance from bottom of Z carriage to top of table)

Now....here is my biggest question......what should I use to drive the cutter, stepper motor or servo? Will a high-end stepper get me those feeds I posted earlier? I know that steppers are cheaper, but if I cant get high feed rates, then I will have to move up to servos. I have done a lot of reading on the motors and I very much know and understand the difference. From my machining back ground, I have only worked with servos on mills, multitasking machine, 5 ax routers, 5 ax mills, etc.... So, if I can get away with an accurate, but cheaper stepper solution, then so be it. My wife is already cussing me over the guestimated cost of everything now.

I have no experience when it comes to anything electrical. With what I have asked for, is there a "one stop shopping" place for all of the above mentioned electronics? I have been on the Geckos site and a few others that offer complete kits. My problem is, I have no idea what a complete kit is and is not needed for my specs.

Below are some pics of my design. Please tell me if you guys see anything wrong. You will notice that I have NEMA 34 size motors in my design. I "borrowed" the CAD files from the Lionclaw design. You will also notice that the screw actuators are not there. I will add those parts to my file when I actually know what I will be purchasing.

[LeeWay]

Design looks pretty good. I do have a suggestion or two that would help. Especially with a single screw for the gantry. Bring the back of the gantry down straight rather than angled to offset the router. Leave the front part like it is. This will spread the load on the linear rails for the X. It will both reduce racking and give you a sturdier Y and Z. This will mean either a shorter X or you will need a little longer X rails and screw as well as frame member. Use ball screws. Double nut preffered, but you can get by with a single nut with only little cost on accuracy and longevity.

Also consider a brace between the two endcaps by the screw on bottom. You don't want the screw to flex on the ends trying to move the substantial gantry.

It's difficult to determine what kind of speeds you will actually be able to pull off. A lot depends on machine design, attention to building accuracy as well as motor size and drives.
The speed you are reaching for is attainable with steppers. Especially if all you ever take is minimal cuts. Perhaps some of the other guys will suggest some motors or kits. Good luck with this. I look forward to your progress.

[Mr.Chips]

Nice machine, 80/20 makes construction so much easier.
Just a thought, if you mount the X axis bearings on the top and bottom of the X axis piece it would compress the distance between the X axis and the Z axis, thus giving you a little more cutting direction in the Y axis. This would also widen the attchpoints for a little bit more support.

[sandiegocadcam]

very good replies with great suggestions. i see that i definitely came to the right place. looks like i have some redesigning to do.

thanks....

[pudytat]

I have built an 8020 CNC machine here(Baghdad Iraq) and it works GREAT. I had to scavange for most of the parts since the mailing time to get parts here would take up to 3 months at times. I just have one piece of info you might want to think about. 8020 has linar slides for parts that are really smooth. I made a Z axis with them, that was so simple, that it amazed me. Also, you will only need size 10 parts since they are really strong and sturdy for their size.

I am adding some gearing to the servos right now, but I could post pics of my machine (everyone over here calls it my robot) soon.

[sandiegocadcam]

pudytat....i would love to see some the pics. i looked at 8020's linear slides, but decided to make my machine more like standard cnc's. you never know though. what kind of accuracy, feeds, rapids are you getting?

[southernexplore]

I built a machine similar to K2's design using steppers at first then went with servo afterwards and the servo are much smoother and a lot faster. The servo motors can get up to top speed much quicker than the steppers. I used 8020 on some of the design but also a lot of flat aluminum for gantry
and other parts. Acme screw and nuts work great but ball screws are also a little faster. I had stepper and acme first, then balls screws, then servos
and every step made it faster. My design is not perfect in any way but it runs very good and has been running for about a year and a half with no repairs.

southernexplorer

[High Seas]

Hobby or commercial use? How much is your patience worth?
That may sound like "one hand clapping', -- I applaud your using 8020!
Its great - and has multi-re-configure possibilities.

For my System1 and System2, I had some rail-mounts drilled and taped. These match the holes in the THK rail and then to slip the whole piece in the "wells" on the 80/20 for my THK rails sit on top. Worked great and gave me a chance to "square" the setup -- then finish bolting them in place. (Without "resquaring the whole 8020 frames!)

I'm just now completing a Hot Wire foam cutter using 8020 slides - and they seem like a very useful option too. I really would use that approach - on a router mill setup -- if I didn't need/want .001 precision. You can get them pretty tight and seems like no "slop" but you may pay for extra friction and wear on the HDPE bearings. [NOTE THE guys at 8020 SAY IT WEARS LIKE A PIG'S NOSE - is that good?!!!]

I did note in pre-setup on the foam cutter; if you use only the side bearing plates it can be quite "tight" ie no slop - but not as much friction.

I'd say start steppers the move up - sort of bootstrap your way there.
:Welcome aboard - Jim

Pics or notes as you go are cool! Or at leat a final summary when done ( I am putting one together on the 8020 foamie - should be soon may show the slide I mentioned)

[sandiegocadcam]

i think i have found the motors and drives i will use. can someone tell me the ball screw that would suit the style of my machine to be and the motors? and a few other parts i have listed below.

- NEMA 34 HIGH TORQUE STEPPER MOTOR 640 oz-in single shaft from Keling
- drives from Gecko
- BOB -???
- e-stop -???
- size and kind of ballscrew to use??? i am guessing at least a 5/8 with 5 tpi
- power supply - ???
- home and limit swtiches - ???
- buy enclosure or make one - ???

Sorry for all the questions, but from all the sites I have found thru the forum and a couple of quotes I have for only "some" things I need, it is a bit overwhelming when you start thinking about all the money you may be spending only to find out that the product may not work.

thanks again for all the help.

[sandiegocadcam]

what do you guys think about 16 mm ballscrews with a 2.5 pitch to go with the motors i recently posted?

[LeeWay]

Bigger is better on your X to push the gantry. You would also have less wear and whip on a bigger screw.
My first machine has an extremely heavy steel bridge type gantry. I used the single screw drive for the X as well. My X screw is about 48" long IIRC. I just bought my screws and nuts from Mcmaster Carr. The 5/8" size. They are the cheapest as well. You will need to be able to turn the ends for attachment and bearings. I just used a mini lathe and carbide cutters. Not the way to do hardened steel BTW. Screwed up a couple cutters, but once I got through the hard part, it turned pretty easily. Grinding is the best way to get through the hard candy outside.
I then just used a pillow block bearing on each end. The type that have locking collars. It works fine.
My speeds for the X can be around 75 IPM using Quantum and around 60 IPM with Mach 3. Perfect speed for cutting lexan.

I don't have those big motors, but was considering getting them for the mill I am working on. It is also 80/20 based stuff. They should work very well especially with Gecko's. Go the max you can use on a power supply and you should see close to your 200 IPM.

[sandiegocadcam]

Thanks LeeWay...very information.