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Project by struuus posted 01-19-2010 02:26 AM 3215 views 13 times favorited 24 comments Add to Favorites Watch

I was asked to put a couple pictures of my CNC machine up. It’s a custom machine that I have not really used much, I have a tendency to enjoy the build more than actually using stuff (to my wives dismay). I plan to use it more once I resolve some of the issues..

This is my CNC machine I build a year ago. Built from scratch, used skate board bearings against aluminum angle track, very little slop. Threaded rod gives very high fidelity in linear action. The trade off is that the max jog speed is very low, almost unbearably slow. Motors are 24 volt steppers with (as I recall) 3600 step, I bought some stepper drivers. Pretty simple wiring, an I/O board takes strobes from the pc parallel port and converts them to direction and step signals to stepper motor drivers. I set it up to use a normal porter cable router. The software I bought is Mach3, which is a very cool software package for very little money.

Couple problems, that I still haven’t worked out. The first big problem is that that I have seen the steppers either over step or under step. I think its due to noise on the stepper driver/interface board. I rewired the box to help reduce cross talk. I also want to get a smaller router that generates less EMI, I think these 2 fixes should resolve my major problem. The next minor problem is that the limit switches false trigger, to the point that I disabled them. I tried filtering, shielding, and debouncing but that didn’t help. I think the reduced EMI router will help this.

-- Chris “The most overlooked advantage of owning a computer is that if they foul up there's no law against whacking them around a bit.” Eric Porterfield





24 comments so far

View Rj's profile

Rj

1047 posts in 2318 days


#1 posted 01-19-2010 02:58 AM

Wow Very cool !! way above my head in the technical area .

-- Rj's Woodworks,San Jose & Weed Ca,

View Jimi_C's profile

Jimi_C

507 posts in 1922 days


#2 posted 01-19-2010 03:49 AM

I don’t know if you’ll be able to get a router that emits less EMI, they have pretty powerful motors. If I were you, I’d look to shield the cabling/circuitry better.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View TraumaJacques's profile

TraumaJacques

433 posts in 2187 days


#3 posted 01-19-2010 04:13 AM

I only understood the first 3 lines LOL. like RJ said way too thechnical for me,but it looks like a potentially cool machine. (Once you resolve the issues)

-- All bleeding will eventually stop.

View carpentrymonster's profile

carpentrymonster

57 posts in 1861 days


#4 posted 01-19-2010 04:17 AM

Great project, did you create your own plans or purchase some? If you bought them can you recommend a good source?

View paplou's profile

paplou

324 posts in 2031 days


#5 posted 01-19-2010 05:37 AM

i hope you figure it out. Hell i haven’t figure out why i have to hit start to turn off my pc.

-- PAPLOU

View ARTTdylan's profile

ARTTdylan

72 posts in 1749 days


#6 posted 01-19-2010 05:54 AM

Yeah, but can it email?

-- Dylan - www.arttwood.com -

View Vince's profile

Vince

973 posts in 2116 days


#7 posted 01-19-2010 08:29 AM

Looks good.
Did you do your research on the CnC Zone website?

-- Vince

View woodworm's profile

woodworm

14129 posts in 2277 days


#8 posted 01-19-2010 10:27 AM

Great work.

-- masrol, kuala lumpur, MY.

View hunter71's profile

hunter71

2053 posts in 1873 days


#9 posted 01-19-2010 01:51 PM

Sounds like you are on the right track. Isolating some transient noise can be frustrating.

-- A childs smile is payment enough.

View motthunter's profile

motthunter

2141 posts in 2486 days


#10 posted 01-19-2010 03:26 PM

interesting machine. i have thought about it also.

-- making sawdust....

View jm82435's profile

jm82435

1280 posts in 2429 days


#11 posted 01-19-2010 03:59 PM

Looks like that should be a very handy machine when you get it working. I am no expert so for what it is worth limit switches are nice but not necessary with steppers this size, they stall without harm when they hit something anyway. I tried running mine with a laptop and was losing steps, apparently the cpu doesn’t surrender control of clock cycles with some cpus and it causes you to loose steps, otherwise my experience with losing steps is trying to go too fast.

-- A thing of beauty is a joy forever...

View 8iowa's profile

8iowa

1489 posts in 2448 days


#12 posted 01-19-2010 04:09 PM

I’m just beginning to learn how to use my overarm pin router, the “low tech” method for this type of routing.

-- "Heaven is North of the Bridge"

View struuus's profile

struuus

8 posts in 1739 days


#13 posted 01-19-2010 07:17 PM

Thanks for the comments. I was planning on getting a smaller router, one of those trim routers. Smaller motor should creates less EMI. Also the points on mine are probably wearing so that doesn’t help. I didn’t build it from any plans, I just kind of winged it. If anyone is thinking of building one I can give some of the pointers I learned and tell you the things I would have done different. Also the computer has a wificard built in so, Yes, it can check email.

Regarding not using limit switches, if you dont use them and you command it to jog greater than the axis range of movement (ie go 5 inches up, when there is only 3 inches left of travel). It will (and has) self destructed, You can not hold the stepper when it tries to step, then you add 20TPI threads and gain another 20 power factor. The first time I did it it ripped the dry wall screws out then stripped out the coupler holding the motor to the threaded rod faster than I could hit the E-stop.

Apart from trying to make some inlays, I have actually used it to cut precision templates. You know how Norm breaks out his template and then says, just use your template to cut this crazy curve with a router and a straight bit. He never shows you how the heck to make the template, this thing makes awesome templates, draw it in autocad and it can make it. It’s also good for cutting holes precisely, for shelf hanging pins, although the setup takes longer than just using a template and hand router.

-- Chris “The most overlooked advantage of owning a computer is that if they foul up there's no law against whacking them around a bit.” Eric Porterfield

View Nicholas Dillon's profile

Nicholas Dillon

33 posts in 1918 days


#14 posted 01-19-2010 07:19 PM

For those of you wondering about the design. This is very similar to the design at buildyourcnc.com. The developer of the site has step-by-step videos and even a book. I purchased the book a couple of weeks ago and plan to build this my self. The book is a great step by step writeup, but there are some ommititions which are easy picked up. The creator also has a forum setup for any questions you may have.

If you already have a spare comp, router, and tools you can build this for about $500 – $600. The electronics are are the most expensive part. The rest is made out of MDF, nuts, bolts, aluminum angles, and some skate bearings.

If you are interested in building this I would suggest checking out www.buildyourcnc.com

-- My workshop is a 8 x 8 shed! No Joke!

View jm82435's profile

jm82435

1280 posts in 2429 days


#15 posted 01-19-2010 07:29 PM

wow, mine powers out, so I don’t think about it. (I still try to avoid it since you have to requalify it afterwords) but it has very steep threads, I think 4 start. this helps with more distance with fewer steps but less power.

-- A thing of beauty is a joy forever...

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