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Project by Ger21 posted 1675 days ago 9702 views 44 times favorited 19 comments Add to Favorites Watch

I’ve had several request asking about my CNC router, so here’s a few pics and some info.

I’d wanted to build a CNC since first seeing pics of homebuilt machines on websites about 10 years ago. About 7 years ago, the hobby cnc movement started bringing lower cost software and electronics that was affordable to hobbiests, so I started designing a machine. It took me over 6 years to finish, due to other commitments (rebuilding my house from bare studs and joists) Most homebuilt machines back then were built from MDF, and left a bit to be desired. I wanted something bigger, and stronger than the ones I’d seen. So i based my design on torsion box construction. Easy to build from wood, and yet extremely strong.

First thing to figure out, was how to make everything move without spending a lot of money. An old FWW had an article about building a sliding cutoff table for a tablesaw, using pipe and inexpensive bearings. (Issue 101) I had used this basic design to built a vertical panel saw, using 2” EMT and rollerblade bearings. It worked very well, so I decided to adapt it to the CNC. In order to keep the EMT from bending, I designed the torsion box ribs so they would cradle the conduit. If the torsion box was straight, the conduit would be too. I used our CNC router at work to cut the interlocking ribs from 3/4” baltic birch, and assembled the main table with 1/2” MDF skins. It’s roughly 31” x 60”. The actual usable cutting area is about 29” x 45”. I wanted to be able to cut and line bore a full cabinet side. This gives me some room to spare. The torsion box for the gantry is built similarly. It’s 40” long. The gantry sides are made from 2 layers of 1/2” MDF, with a 5/8” thick birch torsion box like core, along with some aluminum tubes epoxied in to enhance rigidity.

The bearings for the X and Y axis are rollerblade bearings, mounted to 1/4” thick 1-1/4”x1-1/4” aluminum angle. THe 1/4” thick is much stiffer than the 1/8” stuff available at HD. The brass spacers are cut on the table saw with a cutoff sled, from 1/8” pipe nipples from HD.

For the Z axis, the EMT and rollerblade bearings would take up to much space. I found some 3/4” Stainless linear shafts and linear bearings on Ebay for about $80, so designed around those. My original design used threaded rods to hold the bearings tight and hold everything together, but the design was flawed. Once I started assembly, I realized the rods allowed the top and bottom to roll independantly, so I needed to add side and back panels to stiffen it up. Not perfect, but it does the job.

For motion, I’m using acme screws. 1/2-8 2 start screws, which are 4 turns/inch. Multiple start screws are much more efficient than single start screws, so more power is transferred to motion. To mount the screws, I made a jig (simple box with bearings) to hold the screws. I chucked them in a 1/2” drill, and while spinning in the jig, used an angle grinder to grind down the ends to 8mm to mount them in rollerblade bearings. Grind to slightly oversize, then carefully file to finish diameter. Then use a die to thread the ends for a mounting nut to hold the screws in position. The original plan was to make my own drive nuts from Delrin, a hard and slippery plastic. I made a tap from some scrap acme screw and a grinder, and drilled and tapped the Delrin. I then chucked it in my Nova chuck and turned a mounting flange on it. This was very difficult to do. I only made one, for the Z axis. A few years ago, a guy started offering Delrin anti backlash nuts to the hobby cnc community. Anti Backlash nutsget rid of the “play” in a typical screw and nut when you change direction. It’s very important to not have any backlash in a CNC application, as it reults in inaccuracy and poor cut quality. So, I purchased these nuts from www.dumpstercnc.com They work really well, and save me several hours of work, at a cost of about $75.

6 years ago, there were only a handful of inexpensive motor controllers (known as drives) for the hobbiest, without building your own. I opted for the Xylotex, which was about $175. Stepper motors, at the time, were typically about $100+ each, unless you purchased used surplus from Ebay. It took me 3 auctions, but I found the need 4 identical motors for about $60 each. Today, numerous sources sell chinese made steppers in numerous sizes and configurations for between $30-$60 each. Similar sized motors to mine are only $30 now. I picked up a 24V power supply on Ebay for $10. The PC that runs it is an old Dell GX150, available on Ebay for about $20. I paid $10 for a spare motherboard and processor that I keep for a backup.

Software to control it is Mach3. When I started building the machine, it was $100 with free upgrades for life. Unfortunately, I didn’t buy it back then. I’ve been using the demo version, which still allows you to do quite a lot of things, but will be buying a license this week, at the new price of $175. I created a custom screen with only the options I need to run my machine. www.machsupport.com My screen is available for download there as well. It’s called Mach Aqua, in the download >Screens section.

I finished (99.5%) the machine a few months ago. It works great, but there are some issues with rigidity. Mostly the rollerblade bearings on the long X axis rails. They carry a lot of weight, and have a small amount of flex in them. But, overall, I’ve been very pleased with it. Total cost was around $1000. I’ve already recouped most of that money with a few projects I’ve done with it.

Today, there are a lot more options available to the CNC hobbiest. Most components are available for much less money, and much higher performance is now attainable.

Here’s a few You Tube videos of it in action.
http://www.youtube.com/watch?v=NBc7cpdAiGo
http://www.youtube.com/watch?v=kz9CdBH81Ds

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html





19 comments so far

View SteveMI's profile

SteveMI

845 posts in 1890 days


#1 posted 1675 days ago

Gerry,

Great story that highlights time and effort in building one from scratch. Watched your u-tube videos and have a couple questions;

What did you use to make the dust collection shoe and for what Z height is it practical? I’ve thought about this and concerned about the brush bending inward to get caught on the cutting tool. I cut in Z to just at 1” and wonder how much you can with the brush. My current process is bad, I have a fixed vacuum hole around the cutting tool, which causes me to cut at a depth (6 mm) and then reset the tool in collet for the next iteration (6 mm). This is better than constant cleaning of the acme screws from loose dust.

What would the downside be to mounting the angle iron that holds bearing directly above the conduit? Seems that would use gravity and not need as much rigidity in the gantry to keep bearings in contact. I’m thinking of making a second machine a bit bigger than my latest at 16” by 24”.

Steve.

View Ger21's profile

Ger21

611 posts in 1726 days


#2 posted 1675 days ago

The brushes are 3”. Actually, the bristles are about 2-5/8”. Since the router is 3.5” diameter, the brush is at least 2” away from the bit. I like to have the brush just below the bottom of the bit, so that means I’d have to cut over 2” deep for the brush to get to the bit. As the video shows, there’s no dust in the air, and only a minimal amount that I vacuum up when done. In about 2 hours of cutting, with a 1/4” bit, my dust collector had over 6” of dust in it.

For the next machine, I’ll be using Dual V wheels instead of bearings. Imo, at least for my needs, rollerblade bearings just can’t give the needed rigidity.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

View Stewy's profile

Stewy

33 posts in 1686 days


#3 posted 1675 days ago

Impressive shop made machine, I have been studying them for 3 years and have not made one yet.
I have looked at most designs and of course the best mechanical drive system which is way out of site for a home shop. The software and the electronics are considerably cheap now compared to a few years ago. I am still looking for the bearings and ball screws or something in between what most have used. I am not sure how
good it has to be to get accuracy and repeatability? Any info would be appreciated if you have time!
I have tried several times to get an Mechanical Engineer friend to design a home built machine plans as well as
in a kit form but no luck so far. I have experience in the software and electronics but not the mechanical side
of it. Thanks for the great post

-- Dennis in Iowa "You can have 30 years experiance or 1 year 30 times!!!!"

View SPalm's profile

SPalm

4739 posts in 2477 days


#4 posted 1674 days ago

Gerry, nice to see it.
Lady’s and Gentelmen, this machine and this man, caused a revolution in the quality of home built CNC.

We should be so lucky to have him at LJs.

Steve

-- -- I'm no rocket surgeon

View zlatanv's profile

zlatanv

689 posts in 1830 days


#5 posted 1674 days ago

Incredible machine! Six years? Extreme dedication and patience. Very professional looking. You win!

-- Z, Rockwall, TX

View Ger21's profile

Ger21

611 posts in 1726 days


#6 posted 1674 days ago

Steve, thank you for the kind words. Hopefully the next one I’m working on will be as well received.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

View WistysWoodWorkingWonders's profile

WistysWoodWorkingWonders

11908 posts in 1752 days


#7 posted 1674 days ago

very nice… would love to have one in my shop, but don’t have the time right now to build it…

-- New Project = New Tool... it's just the way it is, don't fight it... :)

View Splinterman's profile

Splinterman

23058 posts in 1957 days


#8 posted 1674 days ago

Hey Gerry,
Excellent job.

View hunter71's profile

hunter71

1953 posts in 1782 days


#9 posted 1674 days ago

I did some research on a shop built CNC router when I was perplexed about making my tractor tires. I finally applied the KISS theory and built my “tire machine” using a Roto-zip ….............
That’s another story, this one is about your accomplishment. Very nicely done Gary!

-- A childs smile is payment enough.

View Jordan's profile

Jordan

1358 posts in 1720 days


#10 posted 1673 days ago

I’d say you’re pretty well a genius! You saved yourself a lot of money! Is it capable of 3 or 2 dimensions?

-- http://www.jordanstraker.com

View Ger21's profile

Ger21

611 posts in 1726 days


#11 posted 1673 days ago

Thanks. It’s capable of full 3D work.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

View Wayne's profile

Wayne

10 posts in 1700 days


#12 posted 1672 days ago

Amazing work! Did you make detail drawings of your design? I’d love to get a set of them if they’re available.

-- Wayne, Utah,www.waynewerk.com

View Ger21's profile

Ger21

611 posts in 1726 days


#13 posted 1672 days ago

Sorry, but I never finished them. I’m currently designing a new machine and will have a full set of detailed drawings when finished. But it’ll be at least a year away.

-- Gerry, http://home.comcast.net/~cncwoodworker/CNC_Woodworker.html

View Jim Jakosh's profile

Jim Jakosh

11038 posts in 1701 days


#14 posted 1658 days ago

That is really neat that you can build you own CNC machine. You must be totally computer savvy.

Great project. Thanks for sharing!

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View Dan Lyke's profile

Dan Lyke

1467 posts in 2720 days


#15 posted 1658 days ago

So looking at the X axis rails, it looks like you’ve got four bearings on each side and are pulling the bearings towards each other with an under/over mechanism on the carriage. I was planning on doing 8 bearings on each side, so that the linear bearing functionality of each side was identical. Any design suggestions one way or the other?

And I’ve got an essentially unlimited quantity of smaller-than-I’d-like steppers, so I was going to take care of racking/skew issues by just putting a motor and worm drive on each side. I can’t tell, are you using a belt drive for the X? and does your Y have any skew issues by having the single worm drive at the top?

-- Dan Lyke, Petaluma California, http://www.flutterby.net/User:DanLyke

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