Hey everybody! Here's an article about my second homemade CNC machine!
Machine #1 is working! BUT! There is too much flex! So I decided to start on machine #2 already! :)
Aluminum Extrusion T-Slot!
I got this off of eBay and I was a little worried that it might not be "beefy" enough... but it's very strong and sturdy.
The base is put together and here's a look at it. I'm using standard L-Brackets to join them together - 2 on each join so it should be sturdy enough. The thing I like most about this design is I'm not locked into this once I'm done - things are easily adjusted and tightened up - something I don't have with machine #1. (UPDATE - I am no longer using the L-brackets for holding the base frame together - I made my own brackets from angle aluminum, the one piece design is more solid...)
You can see in the bottom left corner of the first picture - Yup :) Machine #1 :) looks very small in comparison to the new machine - which, by the way, measures 57" X 36" so far.
Finally an update :) It's not so much as I've been procrastinating a little because my other project is underway (the Aluminum Foundry) and I'm hoping some of my first parts will be for this machine (probably re-do the Y Axis Rails as they flex just a little) - after you're done checking this update out - check out that project :)
Here are the linear rails and trucks I won off eBay - these are very nice and should be perfect for the Z Axis - I need to make a linear stage for the router to be mounted to next!
Back with a small update...
I've cast two bearing holders to hold the bearings for my new Acme threaded rod I got for my lead screw
I've spent the weekend casting some parts for the Z Axis. I cast the lead screw bearing holders and installed them. Check out a few different angles of how the z axis is shaping up.
Ok - after checking out a few posts on CNCzone.com I came up with this latest idea... I found these V bearings on eBay and have been dying to try them out - they are for a "Butcher Boy" (which I really don't know what that is) and they were pretty cheap! Turns out they have a bit of play in them - and if that ends up being a problem I figure I can swap them out with more precision V Bearings if this idea holds up...
For the "track" I installed 5/16 round steel in the slot of the t-slot aluminum - in this mock up I just wire tied the ends, but if this idea works I'll probably put a few welds along the rod to hold it there permanently.
Well, for this idea the pictures really tell the story - and there's one video to see the movement...
I thought for sure the last idea would completely solve my racking problem - those new linear trucks are really tight and smooth - BUT sure enough, once I put everything together - I could still rack the gantry about an inch... So I jumped on CNC Zone and posted my dilemma - and thankfully BigMike reminded me of THIS thread concerning the racking problem. So I ran down to Home Depot and bought some wire rope and some turnbuckles and implemented the idea... Luckily I had room on the bolts that are holding the trucks together for the cable bearings (which if you notice I've switched to the patio door bearings for the rail rather than the Butcher Boy bearings from last post) the patio door bearings have a lot less slop and fit perfectly onto 1/4" round steel - but the Butcher Boy bearings are perfect for the wire rope idea :) I drilled and tapped the legs to hold the eye bolts, ran my wire rope and anchored it on two legs and then ran the rope though the eye bolts at the other end and attached each to a turnbuckle in the middle so I could tension up the cable... Now I cannot rack the machine at all! Finally I think I can move on! :)
Edit: I have since swapped out the patio door bearings with some home made V bearings because even the patio door bearings just had too much play to be good
Here's the pictures - they really tell the story as usual and there's a video below them that shows the movement... I also included a few shots of the Shopsmith in drill press mode - just because I think it's cool :)
Here's a few pictures of the Lead Screw Nut that I made... I also made my own ACME tap to tap the Delrin and I will post that in it's own article :)
You can see in the pictures how the cables (to prevent the racking) are JUST missing the screw and nut! Whew - hopefully that doesn't end up causing any trouble!
Here's the pictures!
I also tested the Gantry and lead screw with my cordless drill - just to watch it :) so here's the video - sorry the quality is so poor - I promise I'll break out the nice camera soon and get some decent footage!
I spent the weekend casting and finishing the Y-Axis motor mount and here's the picture - it's just the picture of the finished part but I made a whole video of the entire process! Check that out HERE
Here are some pictures of what I'm calling a "Z-Axis Adapter" - basically the way that I designed the Y-Axis, I wanted a way to have the Z-Axis rails on the other side of the linear bearing assembly and I also wanted the rails to be a little wider than the assembly would allow. So I came up with this adapter. This allows me to attach the rails on the side that I want and have just enough clearance from the t-slot extrusion, but not too much. My goal is to conserve as much of the X-Axis travel as I can, and I think I'm squeezing a good 2 inches by making these adapters and having the Z-Axis opposite the linear bearing assembly... Here are some pictures. The first is how the part looked in Mastercam, then there are the pictures of the two foamies with sprues attached, then one of the parts on my bench after a little cleaning up, and finally a few pictures of them installed...
Just a few updates and things are coming together - it's starting to look like something now :)
I've installed the motor onto the X-Axis... I still need to get some couplings, and it's ready for that now.
I also attached the Y-Axis and the Z-Axis rails and linear bearings - I've got clamps holding them up for now otherwise they'd fall right off the end ;)There's also nothing really securing the Z-Axis screw yet so it's just loose in the bearing holder. Here's the pictures and one little video just showing the Y-Axis movement
Just a quick and small update... I've been having trouble casting the Router Mount part (see "Metal Casting Failings") - but I wanted to at least make a little progress this weekend so I made and mounted my Y Axis Lead Screw Nut - nothing too exciting but this allows me now to measure and make the Motor Mount and Bearing Mounts for the Y Axis.
I picked up some new motors because the others just wern't powerful enough. I also picked up some Lovejoy couplers too!
I made a lot of progress on the CNC this weekend! I added a second bar for the X axis and another set of wheels for stability - it really helped with the little bit of play I was getting from the cheap patio door bearings and the second bar helped a lot with some shaking / vibrating I was getting as well... I also added a bar across the middle of the table because the aluminum bed was flexing ever so slightly near the middle - now it's rock solid!
I also bolted down a piece of MDF that will cover the bed and I ran the router across it to true it up - it was actually only off about .003" from one side to the other but I decided to true it up anyway... if you can see the lines going lengthwise - those must be because my router isn't exactly vertical :( it's off about .0005" maybe but it's going to be difficult to adust and I'll probably just live with that one ;)
After pocketing out at the extents of the machine - I'm going to get about 31" X 48" of routable area - which is about what I was shooting for, so I'm happy!
There's only a few things left to do - limit switches, wire manangement, and I have to make some kind of dust / vacuum attachement. I'm also going to drill and put threaded inserts in the table for clamping... and then lastly I'll probably put a layer of hardboard that will be my sacrificial material that I will replace as it gets used...
Check out the pictures! and I've got a "job" to cut out a small yard silhouette already so I'll take pictures and video of that! Stay Tuned! ;)
Here's a picture of the completed machine! I've added a mount for the shopvac hose and some fringe to catch the dust so it won't go all over the shop before it gets sucked up into the hose! I also build a base for it so it's up in the air and I can reclaim some shop space by putting a shelf underneath
Here's some links for some of the changes I've made to the CNC machine
New Z Axis router mounting assembly
New Anti-Backlash Nuts from Dumpster CNC
Stay tuned! As I update the machine I will post the links here!
Many people email me and ask me about the cost for the machine - so I will list as much as I can here to give people an idea of the costs associated with building your own CNC machine (at least one like mine).
For some of the things I won off of ebay there's no link - you just have to check often and get lucky. A small tip for eBay - you can save your searches and have them email you daily the new stuff that's listed...
Also for the V Bearings - mine are home made so I'm listing the price it cost me to make them - and making them saved me about $100, but I've included a link to where you could buy some too.
I've also included links as much as I could to show you where I bought some stuff. Most of the misc hardware was bought at Home Depot or Lowes.
These are in no particular order....
- Hobby CNC Pro Controller Board (with 4th Axis Upgrade) - $ 99.00
- 4 X 425oz Stepper motors ($49 each) - $196.00
- 40' of Stepper Motor Wire ($5.00 per 10 feet) - $20.00
- 3 X Lovejoy Couplers (approx $9 a set) - $ 27.00
- 3 X Lead Screw Nuts - Mine are homemade but you can buy similar for $16.50 each - $49.50
- 2 X 6' Long 1/2"-10 Acme Lead Screws (approx $9.50 each) - $19.00
- 1 X 3' Long 1/2-10 Acme Lead Screw - $6.00
- 9 X Acme Nuts for holding Lead screws in place (approx $2 each) - $18.00
- Hitachi M12VC Router (eBay) - $120.00
- Aluminum T-Slot Extrusion (eBay) - $80.00
- THK Linear bearings for Z Axis (ebay) - $35.00
- 16 X V Bearings ($6 a piece) - $96.00
- 3 X Motor Mounts - Hard to price homemade, you can buy mounts for $12.00 each - $36.00
- Tons of misc nuts bolts and other misc hardware - $200 (This is a wild guess really)
That puts the grand total at about $1000.00 or so, and I probably saved about $200 making my own parts :) (plus it was fun making them!)
I hope this helps some people when they are figuring out about how much it will cost them to build a machine like mine