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johnckovacs
07-23-2012, 07:24 PM
Hi,
I've spent a lot of time on CNCzone and other websites learning and researching CNC machines.
I've also spent a very long time drawing and designing my CNC machine on Inventor.

Right now, I have a fixed gantry, 12"x12"x3" cutting area, and a budget of $400 (student's budget).

This week I will be buying all of my parts. Tomorrow, I'm going to the local metal shop to buy angled aluminium, 3/8" Al. rod for motor spacers, 1 1/2" Al. rod for homemade couplers, and 1/4"x1'x2' Al. for reinforcing plates.
Check out my design, it took 2 months of drawing a few dozens pages and designing it in Inventor. Hopefully everything works out!

Quite excited to start,
John


http://i.imgur.com/HUUrzl.jpg


http://i.imgur.com/mCfXSl.png

Dolphin USA
07-23-2012, 07:43 PM
John, looks great! Keep up the good work... And having fun!

JerryBurks
07-23-2012, 08:00 PM
Agree, looks great! I guess you will need to be very creative in sourcing so that you don't blow your budget.

Good luck with the build!

Mr.ChronoM
07-24-2012, 02:35 PM
Good luck man, I almost went trough the same process and started my machine 2 weeks ago. I think the budget will be the hardest part, for me the rails and screws are the most expensive thing.

johnckovacs
07-27-2012, 08:24 PM
Here's what I've been up to:
-Not going to the metal shop to pick up metal, visiting a friend's father's machine shop, who has all the scrap metal I need (saving me $60 :) ).
-Got a old Dell PC from my school's tech room for free! (I hope it doesn't break, there is only 40 more of them in a closet haha)
-Set up XP on the Dell.
http://i.imgur.com/PGilVl.jpg


-Got a power supply off Freecycle (like craigslist, but all free).
This power supply is incredible, its 1300W, about 20lbs., and does 42V at 27.5A!
http://i.imgur.com/Otp3kl.jpg

http://i.imgur.com/NV8fdl.jpg






I am going to Fastenal and Home Depot, then ordering everything else from Enco in the next few days. Hope to be building by the end of next week, very exhilarating!


By the way, can I get by with some Nema 23s from MPJA? They are so cheap, I don't know about the quality of them.
4.5V, 2.5A, 1.8 Deg. NEMA 23 Step Motor-MPJA, Inc. (http://www.mpja.com/45V-25A-18-Deg-NEMA-23-Step-Motor/productinfo/18687+MS/)
or
5.7V, 2.3A, 1.8Deg. Dual Shaft NEMA 23 Stepmotor-MPJA, Inc. (http://www.mpja.com/57V-23A-18Deg-Dual-Shaft-NEMA-23-Stepmotor/productinfo/18729+MS/)

Arnell
07-28-2012, 10:00 AM
John,
I have a Zen Toolworks 12x12 that is very similar to the one you are going to build. Checkout the Zen Toolworks (http://WWW.Zentoolworks.com) website especially the Wiki. You may get some information that will help you.

I would also recommend LinuxCNC for your controller software. It is free and works well.

Hope this helps, good luck.

johnckovacs
07-29-2012, 09:24 PM
Arnell, thanks for the resources, between the Zenworks and microcarve's builds, I decided to do some last minute redesigning of my machine. I cut down about 20 MDF parts, about 75 less bolts, and made a much simpler design.
I also took microcarve's PVC idea and placed more aluminum around bolts, I hope he doesn't mind! ;)

Hopefully this cheaper, simpler idea will work better.

http://i.imgur.com/ZDoQ9l.png

http://i.imgur.com/I8iV3l.jpg

johnckovacs
08-02-2012, 06:50 PM
Yesterday I recieved the metal I needed from a nearby machine shop(for free, thanks!), got a tour and learned tons. I really liked their Haas machines.
Today I got 42 lbs. of hardware from Enco, totaling 1,405 parts for $170.
http://i.imgur.com/gP6SEl.jpg
http://i.imgur.com/z46srl.jpg
http://i.imgur.com/EJ0pNl.jpg



Also received some end mills from ebay, six 2 sided, slightly used bits for $11!
http://i.imgur.com/4bE7ol.jpg


I was most interested in how the bearings would work, for the needle cage is quite small, but it turns easily with minimal preload and there is no noticeable axial movement.
http://i.imgur.com/0Ja4Hl.jpg
You may notice that I'm not using ACME rods, between the cost of the rods and nuts, I'm saved $30-40...probably will change out for ACMEs in the future(maybe if this machine makes me some money :) ).
http://i.imgur.com/ynLcTl.jpg



Won't get my MDF cut until next week, so research on stepper motors is the next step!

johnckovacs
08-08-2012, 12:23 PM
I have been quite busy! In the last two days, I have worked for 22 hours and got 11 hours of sleep. I have gotten my parts cut at my high school's shop on their AXYZ 4008 machine.
http://i.imgur.com/uRY30l.jpg

Also, I tried cutting my AL parts, which was much more difficult. I started at 15IPM and cutting 1/16" off at a time. The AL was getting stuck on the end mill, so we turned down the RPM of the spindle. After cutting halfway through the 1/4" AL the machine's origin point was erased and I did not start it in a repeatable place. Looks like I will hacksawing alot!
http://i.imgur.com/19PdZl.jpg

I also started to work on my couplers, I turned 1 1/2" AL on a metal lathe and got holes drilled. Already, they look really cool.
http://i.imgur.com/XNfk5l.jpg
http://i.imgur.com/ZBXUDl.jpg



Next up is painting and drilling more holes!
http://i.imgur.com/aMMAMl.jpg
http://i.imgur.com/hqUWVl.jpg
http://i.imgur.com/ZfAHVl.jpg

awerby
08-08-2012, 03:25 PM
Good work so far, John, But those solid couplers aren't such a great idea. If there's any misalignment in the relationship between the screws and the motors (and with a build like yours there can't help but be), then coupling them together solidly will eventually snap the shafts off your motors. That's why people use Oldham, Lovejoy, and helical couplers. Those are a bit difficult to make, but you could make Taig-style couplers pretty easily by producing coupler halves, one for each side, putting 4 matching holes in the facing surfaces in a square pattern, and using pieces of nylon tube fitted in the holes to connect them and transfer motion.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software (http://www.computersculpture.com)

johnckovacs
08-08-2012, 09:38 PM
you could make Taig-style couplers pretty easily by producing coupler halves, one for each side, putting 4 matching holes in the facing surfaces in a square pattern, and using pieces of nylon tube fitted in the holes to connect them and transfer motion.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software (http://www.computersculpture.com)

I was wondering about alignment issues but with low rpms, I wasn't too worried. I believe you are describing a method similar to this one? http://www.cnczone.com/forums/diy-cnc_router_table_machines/41327-home_made_shaft_couplers.html
I will probably take your advice, thanks!




Also, update. Painted my MDF with shellac-based primer/sealant. Should prevent warping and is a very tough shell. I can't scratch or dent the painted MDF easily. I paid $14 for a quart but it was worth the $.
Once assembled, I will coat exterior surfaces with regular interior paint (maybe yellow?).
http://i.imgur.com/1LmxKl.jpg
http://i.imgur.com/ScMG4l.jpg

If anyone is curious, I used Zinsser BIN shellac-based primer from good old Home Depoo.

rocketflier
08-09-2012, 05:37 AM
John's comments http://www.cnczone.com/forums/1151280-post1558.html

CarveOne
08-09-2012, 07:39 AM
Note also that John uses nylon spacers to mount the motors. If there is any very minor misalignment at the motor shaft, the nylon tends to absorb it a little.

I have had one shaft break due to misalignment. I was surprised to find that they are two piece shafts with an electric weld joint that is apparently intended to break as a safety feature. The coupler was a DumpsterCNC delrin part. Obviously, it was a very bad misalignment situation that was self induced from lack of experience with these things.

johnckovacs
08-09-2012, 06:59 PM
Thank you for your inputs, will have to think more about building proper couplers now.

Anyways, I received my 220oz.-in. dual shaft motors from MPJA and a HobbyCNC Pro board. Needless to say, it was a day of electronics.
During my building of the PRO board, I found out I got shipped the wrong 3-lead chip. I ended up with a L7824 instead of a LM317. I had an extra LM317 I took from my bin of LM317s(desoldering old electronics saves time and $). Dave, from HobbyCNC, contacted me already. He was very prompt and friendly.
I added 3 matching heat sinks I took out of an old something. Its thin AL and somewhat small, but there is so much surface area(big factor in heat dissipation) that I think it will run cool. A fan will accompany heat sinks soon.

http://i.imgur.com/LsOdHl.jpg
http://i.imgur.com/kxahSl.jpg
http://i.imgur.com/1h0w6l.jpg

I also got my motors spinning with mach 3 today, glad to not be dealing with any electronic problems for now.
Haha, the messy wiring is driving me crazy!
http://i.imgur.com/G36YYl.jpg

johnckovacs
08-10-2012, 08:59 PM
Today I built the torsion box base. It went quite smoothly, I squared and wood glued the edge pieces one at a time and used little 1" nails(brad nails?) to keep everything in place. Then I filled in the inside and secured with glue and nails. I cut the last row of inner spacers down because they did not fit entirely.
My torsion box is flat, heavy, and does not flex a bit! I would have to jump on it before it would flex.
If anyone else is interested about torsion boxes, this video is pretty useful:
Torsion Box Assembly Table | The Wood Whisperer (http://www.thewoodwhisperer.com/videos/episode-18-assembly-table-torsion-box/)

http://i.imgur.com/5YJg4l.jpg
http://i.imgur.com/qdP1zl.jpg

Weighing down torsion box with heavy things to get glue to stick, haha.
http://i.imgur.com/8KiuTl.jpg

dbsharp
08-12-2012, 02:46 PM
you can get some love joy style flexible shaft couplings on ebay for under $10 a piece. Check out love joy or the rotex catalogs to learn more about couplings and sizing.

johnckovacs
08-12-2012, 08:53 PM
Working on the x-axis, progress is good.
I finished my torsion box base and added the mounts for my x-axis. I put in PVC with 1/4" threaded rod inside for extra rigidity. Each mount is attached with 6 bolts, in groups of 2 with AL blocks to keep them from smashing down the MDF. I was too cheap to buy cross dowels, so I chiseled square holes in my torsion box and inserted regular nuts. Same principle as a cross dowel, just less pretty.
So far, everything is very rigid, I couldn't be more satisfied with the lack of movement, granted I have not built much, but it is still incredibly strong.
http://i.imgur.com/Dbkd2l.jpg


Also, I finished the 4 clamps to hold my 2 x-axis drill rods in place. They are very similar to the JGRO design. However, I have seen other similar clamps, but made with expensive plastic, tap bolts, or nice hardwood. Among many reasons, I believe some humans build these clamps with other materials to keep the threads from stripping in MDF, not necessary! I took t-nuts, bent the tangs down and off(they split 3/4" MDF), and smashed the t-nuts into slightly smaller holes in my clamp.
http://i.imgur.com/sAa16l.jpg
http://i.imgur.com/jEBuXl.jpg
They stayed firmly in place, glue would definitely keep them from moving at all. When you use them, the force against the drill rod smashes them down even farther, awesome.
Too cheap to buy t-nuts? Buy t-nuts, they're useful in many situations. Or use regular nuts! They won't work as well, but pressing them into the clamp with pliers and gluing would be adequate. Note that a regular nut takes up more space, so a bigger inner circle is needed. It was cheaper for me to use the extra wood, bolts, and nuts than to buy expensive plastic or other part.
http://i.imgur.com/bbzYAl.jpg
These clamps hold the drill rod in place with a tremendous amount of force, its not going anywhere.
Note the clamps are at a 45 degree angle so that gravity doesn't rest the rod on one bolt, but between two.
http://i.imgur.com/KDUYIl.jpg
I actually cut out 5 of these clamps, giving me one to experiment with. Glad I did, split it up and built the rest better.
If I were to build new clamps, they wouldn't be squares, they'd be triangles! Seriously, a triangular clamp is easier to adjust and still would hold the drill rod in place firmly. You could make an argument that a square would let you adjust the rod in the x or y direction without effecting the other direction(i.e. adjust drill rod left without moving it up or down).
But I already have to turn all 4 bolts to move in any direction, a triangle would be a more beneficial arrangement IMO. I vote triangles.

Mr.ChronoM
08-15-2012, 06:04 AM
Very nice build, I have been looking into torsion boxes after checking your link also. Now I have a good reason to start rebuilding my machine héhé.

johnckovacs
08-19-2012, 08:16 PM
Update, lots work, some progress. I have been working on my work table and x-axis, might have a moving axis in a few days.
I drilled holes in my sacrifice work surface for t-nuts, and sunk them in with a bolt.
http://i.imgur.com/9cfcel.jpg
http://i.imgur.com/s10oPl.jpg


For the lower part of my work table, that has moving elements attached to it, I planned to glue 3 pieces of PVC to it. The outside PVC have bushings for the drill rod to slide on, and the inner one has delrin to act as a backlash nut.
To attach the PVC, I drew 3 lines, and used a hand saw to make a shallow V groove.
http://i.imgur.com/h6ek7l.jpg

I took a scrap piece of PVC, taped sandpaper to it, and put a handle on it to make a homemade rounded sanding block. It worked great, but there was ALOT of sanding to do, maybe 1 1/2 hours of sanding.
http://i.imgur.com/rzqd3l.jpg

I could have initially cut a bigger chunk of wood out, or if I had a router bit that was rounded, it would have saved lots of time. Anyways, the PVC fit very well, I proceeded to glue the 3 PVC pipes in with epoxy. I don't have good pictures on keeping everything parallel, I'll get some in the next post.
http://i.imgur.com/TETlMl.jpg


The bushings fit almost perfectly into the 1" PVC. With some epoxy, they remained very secure. I recommend while the glue is drying the bushings to the PVC, slide the drill rod through the PVC and the bushings, so that the bushings are parallel to each other.
I also got a good price on a 7/8" rod of delrin from Enco, $9 for 4' of 7/8" rod. It was about 1/8" to big to fit in the PVC, I filed down the diameter, and filed the inside of the PVC some also. It was about .1" to big, and with the help of a good old hammer, I smashed it in, its not going to turn or slide a bit, very very secure without glue. I put another 2" piece of delrin on the other side.
I made a homemade tap(it's awesome), drilled a 7/16" hole, and tapped the delrin on one end of the PVC. On the other end, there is no threads, just a 1/2" hole the slides over the threaded rod.
http://i.imgur.com/YcF0Ll.jpg

I've also made progress on my couplers, they are really cool. I drilled two 1/8" holes through the couplers, and chopped it in half. I took my 7/8" delrin rod, and filed down two 1/8" delrin pins to fit through the holes I drilled.
http://i.imgur.com/NBd7Xl.jpg?1
With ~1/8" gap between the two halves, the coupler can flex quite significantly. Its more than enough flex, the plastic does not twist while the motor turns(did not introduce backlash). I am not worried about the plastic breaking and I am not worried about stressing the motor shaft, thanks for the advice everyone.
http://i.imgur.com/zt90cl.jpg

Next up, spacers. I got a 3/8" aluminium rod that I chopped into 2 1/2" segments. I cut, drilled, and smoothed them out on the metal lathe at my school's shop, the drilled holes were still up to 1/16" off from being centered, but that's OK. Making the all the same distance was somewhat tedious, it would be hard to cutting spacers at the same length and drilling straight holes while keeping the ends flat without the help of a metal lathe. I would hate to see how these would look if I hadn't used a lathe.
I had a old #10x32 tap to tap the holes on the spacers, but after 2 holes, the lower 5 threads on the tap were almost gone and it had bent axially from too much force(oops, never tapped before). Cheap taps start at ~$6 online, and I would probably break those also. Additionally I have a small budget. I took the screws I would be using for the spacers, dremeled flutes, and tapered the end; its a homemade tap that works, awesome.
http://i.imgur.com/UPxdLl.jpg

Even if these taps only last for about 4 inches of tapping (is that how tap life is measured?), its about 5 cents per screw, and I'm going to end up with tons of extra screws anyways. I don't know how fast professionals tap, or how much force they apply, but it took awhile for me(maybe 3 inches an hour?). I had small flutes and did not using tapping fluid. Note, if tapping fluid says, "Do not use on aluminium", do not use on aluminium! I thought it would be only less effective, but it turns red and bubbles!

After ending up with 4 tapped spacers, I mounted them to my motor, no wiggle, flex, or twisting.
http://i.imgur.com/rKZ1Vl.jpg

I debated between mounting the stepper and spacer to the MDF base or an AL block mounted to the MDF base. It was less work to drill the MDF, and if there are alignment issues in the I holes drilled, the softer MDF will give me more flexibility than a hard block of AL. If the MDF later on gives me trouble, with wiggling and it starts to compress, I can always mount it to AL easily enough, I am happy with it.
I know there are a number of ways to mount a stepper, if you have the ability to make good AL rod spacers, I recommend it. 3/8" is a good diameter, #10 screws work perfect, and mounted to MDF, it doesn't twist, wiggle or shake. It's more stable than I would have expected.
http://i.imgur.com/vs572l.jpg


I will have an x-axis moving within a week hopefully. Right now I am trying not to think about the time it will take to finish 2 more couplers and 8 more spacer rods. Unless you are on a tight budget, and $10-20 per coupler is too much, buy premade couplers! It's alot of work to build them!
I did write a lot, but when I was researching other builds, I wished there was more written about details of rigidity, ease of building, and time constraints about different features. Hopefully I have gone into sufficient detail to help others in their research. If anyone ever has questions, let me know.

Also, HUGE thanks to microcarve, his ideas and techniques that he has shared is invaluable.

jasoneule
08-24-2012, 12:08 AM
good build man and excellent documentation.

some advice, you mentioned hacksawing your aluminum parts free. Why not use a table saw to do that job, much faster and accurate. A jig saw and straight edge at the least.

as far as tapping goes, it can be done from beginnings to end in a matter of seconds. There is a very good set of high quality taps from greenlee for a little over $25. Its a tool you will use alot in your life. Save up and Get some when you can.

Amazon.com: Greenlee DTAPKIT 6-32 to 1/4-20 6-Piece Combination Drill and Tap Set: Home Improvement

johnckovacs
09-09-2012, 12:12 AM
good build man and excellent documentation.

some advice, you mentioned hacksawing your aluminum parts free. Why not use a table saw to do that job, much faster and accurate. A jig saw and straight edge at the least.

as far as tapping goes, it can be done from beginnings to end in a matter of seconds. There is a very good set of high quality taps from greenlee for a little over $25. Its a tool you will use alot in your life. Save up and Get some when you can.

Amazon.com: Greenlee DTAPKIT 6-32 to 1/4-20 6-Piece Combination Drill and Tap Set: Home Improvement (http://www.amazon.com/Greenlee-DTAPKIT-6-Piece-Combination-Drill/dp/B0041FIR1E/ref=sr_1_1?ie=UTF8&qid=1345780903&sr=8-1&keywords=greenlee+tap)
jasoneule,
Thanks for your advice, I switched to using a jigsaw, saved lots of time and effort!
Hearing that tapping with good taps takes under a minute is surprising. On my long list of American tools to buy, taps are definitely near the top of that list.




Anyways, update. I have been very very busy with school(learning calc 1 in a week) and haven't had much time for my machine. But I did get the x-axis moving!

My biggest problem was friction, which was caused by a number of things. When attaching the bushing and backlash nut, I used microcarve's jig to keep the slides parallel to each other when gluing. I took 2 equal sized pieces of wood, cutting notches in them simultaneously, the resting my slides and shafts in them so that they were parallel to each other. Epoxy holds them securely.
If you are still curious in this, check out this thread in which I struggle to understand keep the slides parallel: http://www.cnczone.com/forums/diy-cnc_router_table_machines/157915-one_two_backlash_nuts.html
http://i.imgur.com/UsPqvl.jpg
http://i.imgur.com/DzvfXl.jpg


So, after 2 attempts, I got my rails within 1/16" of parallelness. That's as good as I am gonna get, good enough for my machine. The problem is my oilite bushings are too precise, there isn't any play in them and they give me no tolerance. It was difficult to adjust and keep the rails aligned with each other on my machine. Static friction was exisive. I had thermoplastic bushings with .1" of play, but returned them because I thought they were to imprecise. WHY GOD WHY DID I RETURN THOSE? That .1" of play is the kind of tolerance I need on my sloppy little machine.
Here is what I did, leave 2 oilite bushings on one slide, remove the 2 from the other slide. Replace those oilites with a centered, single, 1" delrin bushing. I made this bushing and gave it ~.1" of horizontal play. If I still had those thermoplastic bushings, I would have used them on one side. Smack it back together, and it moves like it's on ice!
I add the threaded rod and introduce waaayyy too much friction (as the voices of CNCzone members tell me I should have bought ACME thread). Well, I cut my backlash nut from 2 1/2" of thread to 1". Also, I filed down the threadless delrin bushing that was contacting the threads too much. Once again, smack it back together and I'm golden!

My motor lined up well, but one of my spacers was too short. Notice in the picture, I didn't screw it in because it pulled the motor out of axial-alignment with the threaded rod. I might add a washer and then add the screw, but for the time being the motor is secure enough. Note the spacers are not curved, my camera distorts close up pictures.
Also, the little thrust bearings work well for $3 each, but bigger thrust bearings would be nicer, I could put more pressure on them.
For my coupler, it fits very well, i left a 1/4" inside the coupler for the flexing shafts, giving lots of flexibility to the system. I am satisfied with the flexibilty and layout. I don't think it will break on me and it doesn't add backlash(that I can measure).
http://i.imgur.com/9oyakl.jpg
http://i.imgur.com/PFUk8l.jpg
http://i.imgur.com/bd6Kkl.jpg


What I learned/What I wish someone on CNCzone would have mentioned:
-Keep your rails parallel if you follow this microcarve-like setup.
-Buy bigger thrust bearings if you can afford them and want to put more pressure on them, I can't tighten against them too much. (Awesome idea from spalm: http://www.cnczone.com/forums/open_source_cnc_machine_designs/12681-hardware_store_design_cnc_router-25.html#post102831)
-Buy ACME rods! Good grief, buy ACME rods if it is the last thing you can afford! You can go from 20-20% thread-to-nut efficiency to 60-70% efficiency by switching from threaded to ACME. (I have a source for that somewhere)
-I like my flexible coupler, I wouldn't recommend a similar setup with a soild coupler. Unless of course, you are a master craftsman, then you could probably get away with a solid coupler.
-For my slides, the ideal setup would have been 2 oilite bushings on one slide, and 2 thermoplastic busing on the other, my homemade delrin slide works, but isn't as ideal.


I easily span at 30rpm with mach3, will do some tuning and see how fast I can move it.
I have finished the base, x-axis, and work table. Next up is the y-axis, z-axis, and router mount. Probably won't finish this machine in a month, probably not in two months. Even when I do have free time, its usually spent applying for scholarships.

Wish me luck!
-John

CarveOne
09-09-2012, 01:51 AM
If you have places along the all-thread lead screw where the nut feels tight then loose, use the proper size thread cutting die and run the lead screw through it. It should clean up any burrs from the rolled thread operation during manufacturing.

woo
09-10-2012, 12:53 AM
this is bad way to fixing rails. i have this way fixed rails, it works, but its not the best solution, why?

main thing in cnc is to avoid vibrations, adn your rail iz fixed with 8 tiny spots.

what i suggest?

cut square mdf parts so, they tight fit rails, make hols for fixing on base little bigger for adjusting.

when u press rails into those mdf squares, and bolt/setup together u have alot bigger connecting surface, less vibrations.

if u will make your adjustment job more easier, find way to cut parts for each side from one piece. so one part has 2 holes for booth linear rails-so u dont worry abolut distance between rails,it will be same on both sides. then its a kids play, and ofcourse base is still same.

johnckovacs
09-27-2012, 11:46 PM
CarveOne, I don't have die cutting threads! But if I did, I would use them.
woo, I like your idea, my 'loose' bushing with a short area of contact is less effective than a super long 'loose' bushing.
Also, I didn't really capture my excitement in the last post. I HAVE A MOVING X-AXIS! Thank the heavens. Once a machine starts moving, its truly awesome milestone.


Anyways, I put some time into my y-axis, progress is good. If you notice in this picture, I have a AL block on each side of my y-risers(is that what the sides that support my y-axis rails are called?).
Even with a jigsaw and drill press, cutting, drilling, and filing these large pieces of AL is tiring. Its definetly helpful, I wouldn't want to tighten bolts down on to MDF alone. The AL also reduces wiggle and gives me a solid mounting spot for my thrust bearings. Speaking of stability, the PVC for the y-axis makes a huge difference. It structurally combines both sides, I really reduce the wiggle of the risers with the PVC. If I were to rebuild and had more $, I would use 2" or 3" dia PVC, the 1" dia is not as stable as I imagined. (Don't get me wrong, I have to push reaalllyyy hard to get small flex) I am very glad I don't have a moving gantry, I dig the sturdiness here.
http://i.imgur.com/oE77Ql.jpg
http://i.imgur.com/coBEXl.jpg
http://i.imgur.com/Mi0LKl.jpg

An unexpected problem that I encountered was the interference between my bolts to adjust my drill rod and where the threaded rod sits. I just cut some of the extra 1/4" threaded rod I had and made super short bolts.
http://i.imgur.com/Z5aP4l.jpg
http://i.imgur.com/s0gXel.jpg


Another thing I noticed is my adjustable blocks for the drill rods is how little adjustment I have. On my x-axis, with bigger adjustable blocks, I have ~1/2" in all directions for adjustment. Here I have ~1/4", which is scary...I must be very precise on my creation of the y-gantry. Masters of CNC machines, I bet my imprecision of alignment makes you cringe, sorry!



I really dig the spacers to mount my motor. Mounting the motor to spacers to my AL block is super sturdy. Its rock solid and I would not want to have to mount it to wood instead. I improved significantly in my thread tapping abilities. I tapped eight #10x32 holes in 20 minutes, instead of 2 hours. Still much more work than if I had true taps, but my homemade ones got the job done this time.
http://i.imgur.com/KeGCXl.jpg
http://i.imgur.com/jLQlOl.jpg
^that picture is my favorite


My y-axis coupler was built much quicker and cleaner than the first one, I'm getting a technique. Check it out.(on left, center one is incomplete for z-axis)
http://i.imgur.com/248D3l.jpg


When I assemble the Y-axis parts, the drill rods, threaded rod, spacers, motor, coupler, and thrust bearings, I have a very tight fit. It is difficult, and in some parts impossible, to get wrenches and screwdrivers in to tight and adjust. Nevertheless, I got this axis together well, fired up mach3, and GOT THIS BAD PUPPY SPINNING!




Next up, my y-gantry. My plan is to build the y-gantry, put it on, test it, take it off, build z-axis, mount motor, reassemble, and be done! I assembled the main body of my y-gantry. Its actually pretty heavy, maybe 5 pounds for what appears to be a little assembly of wood and bolts.
http://i.imgur.com/erF5Dl.jpg
http://i.imgur.com/jq65Il.jpg


For the driving nut, I'm going to once again, smash delrin into some PVC and hand tap it. I took a 3" cut of 1" PVC, and smashed some filed down, 7/8" Delrin into it. The length of the delrin is about 3/4", sitting in the center of the PVC.
These pictures are of rear of y-gantry.
http://i.imgur.com/xrm3Jl.jpg


I used my awesome homemade clamps to keep it in place and from spinning. Without much force on the clamps, the PVC does not spin. I could have added epoxy to keep it even more in place, but I'm not worried at all. (Also 2 clamps are needed, 1 will not suffice). You may notice my bolts are too long, and instead of a dozen washers, I used extra 3/8" nuts on the 1/4" bolt. I'm going to have eighty 3/8" nuts left over and no extra 3/8" bolts, so its a perfect use.
http://i.imgur.com/jhvVxl.jpg
http://i.imgur.com/MuO8yl.jpg




Next time I shall have tapped the delrin, added bushings, and have a working y-axis! Performance and stability has exceeded my expectations, I'm truly overjoyed.


Total side note - I was thinking I could consider this as my "senior project" (for high school, although that seems to be uncommon), but how am I going to top this for my college senior project? - food for thought

tjb1
09-28-2012, 12:44 AM
An unexpected problem that I encountered was the interference between my bolts to adjust my drill rod and where the threaded rod sits. I just cut some of the extra 1/4" threaded rod I had and made super short bolts.
http://i.imgur.com/Z5aP4l.jpg
http://i.imgur.com/s0gXel.jpg


Looks good...but I have to ask, why not cut the bolts down instead of making new ones? Also, I am making a plasma table as my senior project for college (See it here - http://www.cnczone.com/forums/diy-cnc_router_table_machines/154609-4x8_-_plasma_router.html) but I am working with about 7 times your budget and a full machine shop at college :)

kevincnc
09-28-2012, 01:21 PM
Total side note - I was thinking I could consider this as my "senior project" (for high school, although that seems to be uncommon), but how am I going to top this for my college senior project? - food for thought

Make a 5 Axis for your College project :D

One thing I noticed on your first page- it looks like you are using bronze washers on each size of the thrust bearings for your leadscrews. Normally there would be hardened steel washers, or just the bronze washers by themselves. I'm not sure how well the bronze will hold up like that. Maybe it will be fine with light loads.

Anyway, keep up the good work!

harryn
09-28-2012, 03:20 PM
Total side note - I was thinking I could consider this as my "senior project" (for high school, although that seems to be uncommon), but how am I going to top this for my college senior project? - food for thought

I would not worry about this at all. Consider how much you have learned doing this project. Now consider that in college you will learn how to actually "engineer and design" rather than just estimating.

It seems to me that you will have no problem making something even more awesome.

IBBruin
09-29-2012, 07:38 PM
I read your thread from beginning to end just now. I have a working Joe's hybrid and have really enjoyed reading your build log. Very well documented. I don't have any doubt you will blow them away when you build something for your college project. Good job.

johnckovacs
11-12-2012, 08:39 PM
Looks good...but I have to ask, why not cut the bolts down instead of making new ones? Also, I am making a plasma table as my senior project for college (See it here - http://www.cnczone.com/forums/diy-cnc_router_table_machines/154609-4x8_-_plasma_router.html) but I am working with about 7 times your budget and a full machine shop at college :)
Good question, no great reason. The threaded rod is softer than the hard, coated bolts so it was quicker to file down the threaded rod. I've seen your build and it's spectacular!


Make a 5 Axis for your College project :D

I love your thinking!


One thing I noticed on your first page- it looks like you are using bronze washers on each size of the thrust bearings for your leadscrews. Normally there would be hardened steel washers, or just the bronze washers by themselves. I'm not sure how well the bronze will hold up like that. Maybe it will be fine with light loads.

Yes, I didn't consider this until I ordered the bronze thrust washers, I returned them for hardened steel washers actually. Great minds think alike.

IBBruin, thanks for the positive feedback! I'll definitely be up to no good for a senior project! ;)


_______________________________________________________________________________________


So, last time I left off I was working on the y-gantry. Let's see, almost a month and a half since my last post?!?! Oh gracious! Where does the time go? I certainly haven't been working much on my machine in that time. Rather, lots of ACT prep, some fat scholarships, and classic old schoolwork.


http://i.imgur.com/9CHK2l.jpg
http://i.imgur.com/4HWfCl.jpg
What have I got done on my machine? Well I made progress on my y-gantry, z-axis, and mount for my router. And, if I hadn't mentioned it, my y-axis is a'spinnin'! I mounted my half complete y-gantry, jogged it a few times, and took down the gantry to continue working on it.


http://i.imgur.com/Gnp1Ul.jpg
So, I mounted my stepper to 1/4" AL and mounted that to the top of my y-gantry. The AL block doesn't sit squarely on the y-gantry but I file the front to make it appear as if it does. This was so the stepper would be concentrically aligned with the hole for the threaded rod.


http://i.imgur.com/DwTXIl.jpg
I finished my last coupler and made this one very polished. I mistakenly drilled to big of a hole to tap for my #10x32 screws. NOOOO! NO! What a bummer. Instead I filed a slot for a nut to fit and used a longer screw. It doesn't look as clean, but I can put much more pressure and clamp against the threaded rod and stepper motor much easier! I like using a nut better than tapping in the coupler.


http://i.imgur.com/Ed11Jl.jpg
http://i.imgur.com/iKk4Ql.jpg
I then started working on my router mount(the moving part of the z-axis). It looks very crude and beaten up, I will touch it up soon.


http://i.imgur.com/ZY6hbl.jpg
For my anti backlash nut, I took a section of 3/4" delrin rod and shoved it into a drilled hole in the center of my router mount. With a little glue, its pretty firm in place. Also, the movement of the threaded rod won't put much force on it, its securely stuck in place(but we shall see). Next step is to attach my drill rod, router, and test the z-axis!

Maybe I will be done before the end of the year, I sure hope so because this machine has taken so long! Lately I've been looking at 3D printers, I saw this sweet delta printer and I really like it. Perhaps my next big project...
Rostock delta robot 3D printer prototype - YouTube (http://youtu.be/AYs6jASd_Ww)

johnckovacs
12-04-2012, 06:22 PM
Hello, I've finished my last axis!

http://i.imgur.com/jqALTl.jpg
It is surprisingly sturdy, not perfect but it doesn't shake while the router spins.



http://i.imgur.com/z1Junl.jpg
If you can see these hose clamps, they work really well. At the top of the gantry, I drilled holes in the wood but not the AL top. I shoved the drill rod into those holes and kept them from sliding down with the hose clamp. Alignment wasn't critical on this axis for me, and it goes up and down so I can't complain.



http://i.imgur.com/JVazEl.jpg
My router mount is mediocre. I didn't know what the radius of my router would be when I designed the mount, so it doesn't fit the router perfectly. Tightened down, it still provides enough pressure to keep the router from moving.


http://i.imgur.com/TeBIfl.jpg
Whoa, that's embarrassing! I guess I should have made that a little bigger. Let's hope it holds up long enough to let me cut that piece again.



http://i.imgur.com/mde6Bl.jpg
Looks good huh? I think it does, it needs a few minor changes, but I'm about done with this machine. One change however...



http://i.imgur.com/p8LjOl.jpg
Just wHat is this? Another embarrassing design flaw. I thought I gave myself 3" of z-axis cutting height, but I only have ~1" between the gantry and the work table. Poo. How did this happen? I've been looking over my autoCAD drawings and can't find it. I think it might have happened when I redrew my sides to DWG to get them routed. Solution? I will replace my sacrifice work table with a 1/2" or 1/4" surface instead of a 3/4" piece. I can also take away 3/4" of an inch from my gantry. That will give me about 2 1/2" of z-height which is good enough for me.



http://i.imgur.com/jdzH6l.jpg
Next up? Wiring! My favorite part in fact. I am working on a enclosure for my hobbyPRO board so it doesn't get dusty.

kgtiger
12-11-2012, 12:27 PM
You've done well mate!

Looking forward to seeing some photos of it in action.

voltsandbolts
12-11-2012, 04:35 PM
Nice Job!

Your first build is always a great learning experience. Learning what works... and what doesn't.

And were all the better for it.

PaulRowntree
12-12-2012, 12:21 AM
Congrats John!

I would take the time to fix those mounts now. Set the size more accurately for the router body, and it looks like both the top and bottom clamps are cracked. You really don't want to turn on a router that is held on by defective supports ... it could easily ruin much more than your day. Safety over speed.

johnckovacs
12-16-2012, 09:53 AM
I thought I would take a moment of silence to recognize the tools who made great sacrifices for this conception of this CNC machine.




http://i.imgur.com/ero7Kl.jpg
http://i.imgur.com/PeMvUl.jpg
http://i.imgur.com/Obt2Ol.jpg
First of, my drill press. It's not even mine! I am borrowing it and it decided to break. The cheap torsional spring that retracts after you drill a hole decided to break on me. Fortunately I employed some great engineering put a regular spring in its place.



http://i.imgur.com/PD0Bnl.jpg
http://i.imgur.com/1ntA5l.jpg
Next, my awful jigsaw. I got it for a dollar at a garage sale, it was already beat up beyond normal wear. After lots of my work, the metal plate on the bottom broke from vibrations. I flipped around the blade for convenience, and the plastic that touch the parts i cut melted a bunch. Smoke radiates from the entire unit after a few minutes of use. Until I get shocked or it catches on fire, I will remain to use it. yeehaw

doorknob
12-16-2012, 10:15 AM
Note to self:

Do not, I repeat, do not loan any of my good tools to johnckovacs under any circumstances.

:D

johnckovacs
12-16-2012, 10:36 AM
kgtiger and voltsandbolts, thanks for the feedback! I've definitely enjoyed the experience of building a CNC.
PaulRowntree, I think you are right about the mounts being a safety concern. I plan to cut out new mounts on my schools router before I run this one.


Soooo wiring! yay


http://i.imgur.com/LxMIMl.jpg
http://i.imgur.com/nAtf6l.jpg
I've been working a enclosure for my HobbyPRO board, its just a computer power supply box and I am adding connectors to make connections and disconnections quick and reliable.


http://i.imgur.com/eTH4fl.jpg
http://i.imgur.com/QVkccl.jpg
For HobbyPRO boards, if a wire from stepper is disconnected while it is being used, it can easily ruin the driver on the board. The terminal lugs are known for loosening over time and causing failures. So, I went nutso with hotglue, the wires don't wiggle and are unlikely to escape. These wires go to a different type of connector, which doesn't loosen like a terminal lug. I would rather have ugly amounts of hot glue than weak plugs and poor connections.



http://i.imgur.com/41kOgl.jpg
http://i.imgur.com/V0V2Xl.jpg
These pictures show my connectors. On the back I have a fan with a filter. For $90, I think this board, case, connectors, and wires is great! Next up is the limit and home switches.

johnckovacs
01-02-2016, 07:56 PM
Thought I'd post an update here.

My last post was in Dec 2012. I finished this machine during the Summer of 2013, right after I graduated high school.

As of Jan 2016, I'm a junior in college now. I have this machine at the college radio station, where I'm the chief engineer.

While it isn't accurate enough for precise PCB routing, I still use this machine, often for simple engravings.

I have trouble with backlash. Every component has a bit of flex, wiggle, or slop (which is expected for MDF, delrin, and PVC). I haven't tried reducing backlash in Mach 3, because I happy enough with the results.

CNC design has evolved a lot in the last 3 years and new techniques are better documented and discovered than ever before. I'd probably keep the same 12"x12"x3" work area, use no wood, and switch to a standard material for the frame (like 8020 extrusion).

Nonetheless, between the experience and the end product, I have no regrets. See a consice summary at Summary – 12″x12″x3″ $400 CNC Build – PCB Isolation (http://pcbisolation.com/blog/cnc-summary/)

-John

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