[wwendorf]

Hi Everyone,

I'm starting out on building my first cnc machine from scratch, so I figured that I would create a build log about it here. It will be a 2' x 4' router table, gantry style. The goal for this machine is to cut primarily wood. The main use will be 1/16th in hobby ply for use in RC Airplane kits. However, I ultimately still want it to be able to cut aluminum, so I'm trying to build with that goal in mind as well.

I'm planning on using a porter cable trim router for the woodworking spindle, but for metal, I have a Sherline head that I may try using. I may also build my own spindle assembly with an R8 taper in it, but that will be worked on after the wood router is built. One of my future wishes is to have a spot on the machine with a solid state pumping laser diode at 380mw so that I can do engraving on both metal and wood. I'm aiming for accuracy of +/- .001, but will be happy with +/- .003.

As I have a fair amount of aluminum in stock that is 3 1/2" wide x 1/2" thick, I am planning to use that, as well as some 1.25" wide x 1/2" thick material for a bit of structural bracing. I'm also planning on bolting the entire machine together.

I got rather lucky and picked up a fully functional Z axis with what I believe is a ball bearing precision ground lead screw on twin rails which cost me $35. It even came with a stepper motor with encoder (see pics), tho I may not wind up using that particular stepper motor.

I also found 2 - 25 3/8" thk linear slide rails for $15 each. I'm going to use those for my Y axis which the Z axis will ride upon.

I have also purchased some Glacern supported linear rails and ball bearing blocks for the X axis which are 30mm x 1250mm (a little over 49") long. I also purchased 4 bearing blocks which will support the gantry.

I have attached drawings done in alibre which show the layout for the gantry.

I have a Syil SX3 (converted to X4 electronics) which I will be machining the various parts and pieces of the router on. As I'm making some rather long pieces that will need drilling and tapping, I will be pushing the capabilities of my mill to the limit, but I think it will turn out well. I may use 80/20 extrusion for the table assembly, but I haven't decided on that one way or another yet.

I guess that's good for an introduction, so i'll close for now. If anyone has any suggestions on what i've drawn so far, I'm eager to hear from you.

Also, I'm looking for good suggestions for an electronics package and a good source for leadscrews and ball nuts. I've been considering the 405in/oz 3 axis kit from xylotec, but i'm just not sure yet. As far as lead screws, i'd really like to go with ball screws and precision ground or rolled leadscrews, but if I can find a good option with good accuracy, i'd also consider acme screws. I still think i'm going to be stuck with ball nuts tho in order to get the accuracy I want.

Thanks,
Wade

[DIYaholic]

wwendorf,
Looks like it will be a formidable machine!
I'm sure everyone is going to be anxious to see your machine come together (pic's, video & more pic's PLEASE)!
Good luck with your build!

Randy,

[wwendorf]

Thanks! I'm looking forward to this. It should be a real experience.

I've just finished adding in the rails and blocks. Here's a pic of the drawing thus far. Time for a break.

Wade

[Jesse B]

Looking pretty good so far. Good luck with your build

[wwendorf]

I guess i'm on a bit of a roll. So much for taking a break. LOL

Here's the next pic with the lower box assembly all put together.

Wade

[Jesse B]

Just a quick suggestion. I'd have 4 blocks on the Y-Axis rather than the 2 you have. Would add to stability, imo. Looks good otherwise.

[wwendorf]

Just a quick suggestion. I'd have 4 blocks on the Y-Axis rather than the 2 you have. Would add to stability, imo. Looks good otherwise.

Ideally I'd like to do that, but the rails I got only had 1 block per rail. I have an idea for adding stability if I do wind up needing it. I may also look around and see if I can find 2 more blocks to match the rails I have.

Wade

[Jesse B]

Ideally I'd like to do that, but the rails I got only had 1 block per rail. I have an idea for adding stability if I do wind up needing it. I may also look around and see if I can find 2 more blocks to match the rails I have.

Wade

Shouldn't be too hard to find them. Staggering them may help as well, just so it's got a wider footprint.

[wwendorf]

You were right, I was able to find some additional bearing blocks. I got really lucky finding the blocks and rails for $15 each, because the blocks alone are $90 each! I think I may just stay with the 2 blocks for now. I can always add them later if I want to.

On another note, I received the rails and slides I'm going to use for the Y axis today. Dang! Those things are HEAVY!!! The rails alone are 20 lbs each. I've attached a few pics of the rails and slides. They are 30mm rails. That comes out to 1.18" or so. Somehow, I think the gantry will be nice and stable running on those rails.

For the lead screw, I'm vacillating between ball screws and acme screws. I really like the price of the acme screws and nuts better. I'll probably go for ball screws unless I can't afford them. I did find a place that actually reconditions old ballscrews and ball nuts, so I'm going to see if I can get some refurbed ones thru them for a reasonable cost. I've also got a few other surplus stores in the area that I may get lucky at.

On the X axis, I'm going to probably wind up putting the lead screw on the opposite side of the top rail from the linear rails. I've already got a nice little are cordoned off with the 1.25" x .5" aluminum bar on the back side of the gantry, and I won't have to worry about not having enough room between the rails for the lead screw and ball nut.

Wade

[wwendorf]

I haven't done much on this for the past couple days since I've been building and installing a power drawbar on my Syil X3. I'm looking for easier faster toolchanges. I was getting tired of the stupid wrench. It works, now just to hook up a switch. Eventually i'm going to have a tool table as well, but that's going to be a little while down the road too yet. Hopefully i'll get back to the router designing in a day or two.

I'm trying to figure out on the router how I want to support the lead screws, and what KIND of leadscrews I want to buy. I'm tempted to do ACME screws, just because they are cheap and i'm going to 405oz steppers geared at 3:1 to run them, but, my "overengineering" says go ball screws. I'm trying to the best pricing I can.

Wade

[Jesse B]

I haven't done much on this for the past couple days since I've been building and installing a power drawbar on my Syil X3. I'm looking for easier faster toolchanges. I was getting tired of the stupid wrench. It works, now just to hook up a switch. Eventually i'm going to have a tool table as well, but that's going to be a little while down the road too yet. Hopefully i'll get back to the router designing in a day or two.

I'm trying to figure out on the router how I want to support the lead screws, and what KIND of leadscrews I want to buy. I'm tempted to do ACME screws, just because they are cheap and i'm going to 405oz steppers geared at 3:1 to run them, but, my "overengineering" says go ball screws. I'm trying to the best pricing I can.

Wade

If you end up going with Acme screws, I'd recommend getting either a low TPI, or a multi-start screw. Looking great thus far though

[Riceburner98]

Are you going for 'about' 2ft x 4ft? Just thinking that with a 49" long rail and 2 sets of bearing blocks, it's not quite going to reach 48" travel unless 1 set of bearing blocks falls off the ends of the rails.. Same goes with the 25" rails reaching 24"...

As for electronics, I'd personally recommend *not* using the Xylotex drivers... Their motors are fine, but I at *least* doubled my performance by ditching the Xylotex driver board and using separate drivers. (I use 3 IMS483's from eBay, used to be found for $30 each on eBay) Lots of people use the Gecko G540 controller (the all-in-one thing with multiple drivers in one box) with good results. I popped several of the chips on the Xylotex board while doing stupid things on the mill. They're just not as robust as separate drivers, and the more voltage you can pump into the drivers the happier your motors will be. (50v for Gecko, 35v at the very most for Xylotex) Only down-sides I see to the Gecko G540 is the extra $100, and it only has 10-microstep mode..

Wish I had the room for a 2' x 4' router!!! Good luck!

[wwendorf]

Yes, i'm going for 'about' 2' x 4'. I figure I'll loose a few inches on one end, but i'm considering offsetting the table to gain some of that back.

I will look the drivers you mention up on ebay. Now i'm curious about them.

On another note, I was at a meeting for my woodturning association tonight, and it was held at a local woodworking shop. They had a 5' x 10' router. This thing was AWESOME!!! Hmm, I just realized I forgot to take a pic of it, dangit! Anyway, they had a bed on it that was made up of 1" squares of aluminum with 1/4" slots between each square. About every 3 inches was a "port" they could uncover which allowed them to route vacuum up into additonal fixtures. These fixtures stood off from the table by another 2" allowing them to cut pieces and parts that are suspended up in the air. I'm seriously considering trying to make a table like this for my router.

I was invited back to the shop, so I may ask if I can dismantle one of the fixtures to see how they are constructed inside.

Wade

[wwendorf]

Same goes with the 25" rails reaching 24"

My X rail is 26.5", so i'll get a close to my 2' of movement.

As for electronics, I'd personally recommend *not* using the Xylotex drivers... Their motors are fine, but I at *least* doubled my performance by ditching the Xylotex driver board and using separate drivers. (I use 3 IMS483's from eBay, used to be found for $30 each on eBay)

I wasn't able to find the IMS483's, but I did find these which look pretty interesting. http://cgi.ebay.com/5-AXIS-TB6560-CN...item1c11694647
Any thoughts?

Lots of people use the Gecko G540 controller

I'm considering them as well, but so pricey.

Wade

[Riceburner98]

Sorry, that should have been "IM483" drivers.. The company that makes them is IMS, guess I threw the extra S in there. Looks like there's some on eBay at the moment, but for more $$ than it would cost to just buy Gecko's.. I (and others) got them from a guy selling them as used take-outs from some machine, they were in sets of 3 attached to a larger circuit board for $90. They used to go for $300+ new. Good deal at $30 each, but I wouldn't pay more than say $60 for them..

The eBay driver board you posted uses all-in-one driver chips that seem awfully similar to the Xylotex ones.. From this thread -> http://www.mycncuk.com/forums/showth...r-Boards/page4 it looks like the chips can handle an absolute max of 40v (so 41v = pop), and can only do 270 RPM.. (I think that's with full steps too, so microstepping might be even slower) Check out the chip carnage on page 3 of the thread! That's what the chip on my Xylotex board did. The eBay board is also pre-set at 2.5A max, so you'll need to solder on new resistors if you need to change that to match your motors. (though you can pick a few lower currents with a switch)

All that said, if the price stays at $99 + shipping it might not be bad to at least start with.

Looks like you can get the Gecko G251's on eBay for close to Xylotex prices too.. (but you'd need a breakout board as well) $180 for 3, $234 for 4 of them.. Those are what's in the G540 driver box. Search "Gecko CNC" and it comes back with all kinds of fun stuff.

[roborouter]

Here are a few suggestions for you...

Look here for a good selection of affordable NEW screws and nuts:

http://www.roton.com/

One downside of purchasing the ballscrews and nuts from Roton is that they don't offer any low volume/one-off ball screw machining. So, you'll have to turn the ends of the ball screws for the support bearings, or find a local machine shop to do it. This might require some annealing, depending on which screw you get (see their Engineering Data/Faqs on machining them).

Also, I see that you're using 405 oz-in motors going through a 3:1 drive reduction. Although this will give you more torque at the screw, it will cut WAAYYYY down on your overall bed speed, especially if you go with an acme screw with a high lead pitch. I made this mistake on my Enco R40 cnc conversion by going through a 3:1 reduction from 450oz-in steppers. Like Jesse B pointed out below, go with a low TPI screw, so that your motor can spin slower (and the slower a stepper spins, the more torque you have), and you can maintain a useful feed/speed. I have to spin my steppers at high speeds to get a somewhat liveable feed rate, and that cuts down on my overall torque. It's ANNOYING!!! I'm actually planning on ripping out the 10 TPI acme screws, and replacing them with 5 TPI ball screws.

Also, I would definitely double up on your Y-axis bearing blocks! You'll thank all of us in the end!

Lastly, I used a Porter-Cable router on my first cnc machine, and while it was the best low cost spindle available (and a really great product), they are not designed for z-plunging...Specifically, the spindle shaft is support by two ball bearings, which is fine for radial forces, but when you apply repeated axial force to them (drilling holes, and plunging into material for pocketing), they tend to wear out fast, which means replacements every 9months to a year.

If you do go with a high-end router, stick with Porter-Cable. Don't go buy Bosch no matter what...Their quality has declined. I went through 3 of them within 1 month before I finally took my refund, and went up to the Porter-Cable.

You might look into some of the water cooled chinese spindles (1.5hp to 4hp) on this forum. For a few hundred more $$$, you can get a hefty spindle + VFD that's designed with 3-4 angular contact bearings for axial loads.

Hope this helps!

Good luck on your build! It's looking great so far!