Author Topic: Getting into CNC - wondering about Sketchup  (Read 7606 times)

presyesc

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Getting into CNC - wondering about Sketchup
« on: September 23, 2009, 01:26:12 AM »
Hello, My name is Preston.

I am looking to build my first CNC machine soon, and was wondering if Google Sketchup (free version) would work with making the 3D models for my machine. I was wondering if you can save the file with the appropriate extension. Also, does anyone have some alternative CAD programs they could suggest? Thank you,

-Preston


BackyardWorkshop

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Re: Getting into CNC - wondering about Sketchup
« Reply #1 on: September 23, 2009, 04:05:32 AM »
Hey Preston!

Gabriel has a tutorial for getting Sketchup files to STL files which can then be opened in a CAM program for generating the toolpaths (I used Artcam and was successful)

http://www.cerebralmeltdown.com/cncstuff/sketchupcnc/

Good luck with the machine and keep us posted! :)

Jamie
http://www.backyard-workshop.com
Check out my CNC projects (and more) at http://www.backyardworkshop.com


travis77

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Re: Getting into CNC - wondering about Sketchup
« Reply #2 on: September 23, 2009, 09:35:15 AM »
Ya, read through the website about sketchup to STL and CamBam. I use the CamBam export plugin for Sketchup that Gabriel has on his site.

On my machine, I use:   Google SketchUp > CamBam > EMC2

SketchUp is my CAD, CamBam I use for CAM, and EMC2 is my CNC software. It works well. And all of those are free software. There are some other CAD programs out there, but its hard to find a free version that works well. Check out    www.cnc4free.org   and look at the essentials page. They have a lot of info on what programs to use that are free if thats what you're looking for. If you have any questions, please ask. You'll probably save yourself a lot of time and headaches.

presyesc

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Re: Getting into CNC - wondering about Sketchup
« Reply #3 on: September 23, 2009, 04:11:00 PM »
Thanks guys for clearing that up for me. From what I can tell Google Sketchup looks like a good intuitive program. I've used Solid Edge before when I was taking a class, but unfortunately I don't have my own copy. I have a general idea of what kind of CNC machine I'd like to start out with, but there's a couple things I am unsure of. I picked up some good sturdy desk drawer slides. They are solid pieces with very little give. If I choose to do a moving gantry, it looks like I could have a 16.5 x 16.5 inch square of cutting area. Do you think these would work? I'm just not sure:

Also Jamie, I notice that on your CNC #2 you have a bar running along the y axis gantry underneath the main frame. Is this for reinforcement? Do you think that I would need this on my smaller design?

I found some motors that look pretty good on Ebay - http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180407778340&ssPageName=ADME:X:RTQ:MOTORS:1123 They seem like they would do well with my smaller design. What do you guys think about wood vs. aluminum frames? I know there are a lot of ideas out there, and I appreciate any advice you may have. Thanks

-Preston
« Last Edit: September 23, 2009, 04:56:33 PM by presyesc »

travis77

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Re: Getting into CNC - wondering about Sketchup
« Reply #4 on: September 23, 2009, 07:12:44 PM »
For steppers, I would really try to use the Nema 23 size instead of the smaller 17 size. I know it costs a little more, but it will be a lot cheaper to spend a little more in the beginning rather than realize afterwards that the motors you have are too small for your machine, then have to go and buy more steppers. Just to give you a perspective, Im using Nema 23 - 180 oz-in motors. I paid $50 on ebay, then bought the Hobby CNC board which was $70 shipped. So $120 total for my electronics.

Have you been lurking around the CNC Zone website? If not, you should definitely check out their DIY wood working CNC section. Look at everyone's builds and see what they are using and what designs are working for them. When you see pictures of designs you like and are similar to what you want to do, save the pictures to a folder on your computer so you can reference them.

A moving gantry design would be better for the rail system you are going to use. That cross bar you see under Jamie's gantry is usually necessary so that your gantry doesn't flex and adds rigidity. I dont think Ive seen anyone try to not have a cross brace underneath. I definitely have seen people use drawer slides before and it worked for them. your's look a lot stronger than the ones I've seen people use.

Are you going to use two slides for the X axis, one for the Y and one for the Z? Do you have an idea of what cutting tool you want to attach to your machine?

Forewarning, if you do start, be prepared to spend a lot of time working on your machine. It takes a while, and will more than likely take more money than you first expect. Take your time and plan everything out to the best of your ability. Get some paper out and sketch different parts of your machine and how you plan to build it. You might find that you change or notice something you didnt think about. I spent a lot of time looking at other people's machines to get an idea of what I wanted. Learn from their failures!


presyesc

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Re: Getting into CNC - wondering about Sketchup
« Reply #5 on: September 23, 2009, 10:41:20 PM »
Man there's a massive amount of info. So, how do you know which CNC board is compatible with your motors? Anyways, I'm going to look over CNCzone and spend a lot of time there. I hope to stamp out a Sketchup model of the design I have in my head. I'll post it here if you want to take a look at it. Thanks again for sharing your knowledge with me.

Oh, and I have a pretty powerful Dremel 2-speed I hope will work as the router.

-Preston

travis77

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Re: Getting into CNC - wondering about Sketchup
« Reply #6 on: September 24, 2009, 11:29:48 AM »
Here's a good site to check out. They explain bipolar and unipolar pretty well. Basically when you have to match your motors with your driver board. Driver boards do one or the other. 6 or 8 wire stepper motors can be used for either, it just depends on the way you wire them to the driver board. 4 wire steppers are bipolar only I believe, and 5 wire are unipolar and not sure if you can use 5 wire on a bipolar board. http://www.probotix.com/stepper_motors/unipolar_bipolar/

I'd love to check out your SketchUp model when you finish it. Spend time reading CNC Zone; it will help a lot. If you have questions, just ask or send me a PM.

Edit: Wow look at what I just found. http://www.hobbycnc.com/ez-driver-board-single-shaft-stepper-combo/   I use this driver board and so do some others on here. This is a pretty good deal for $140. The board is $70 so they're charging $70 for 3, 130 oz-in motors with a parallel and motor cable. If you have basic soldering skills, this is an awesome board. Pretty simple to put together.
« Last Edit: September 24, 2009, 11:41:40 AM by travis77 »

presyesc

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Re: Getting into CNC - wondering about Sketchup
« Reply #7 on: September 25, 2009, 03:55:41 PM »
Hello Travis,

It was a challenge to get Sketchup to do what I wanted but I have a prototype ready if you want to look at. I know there are details missing but I wanted to get a concept version finished and get some advice on it. I can't figure out how to get the z-axis rails shorter, so try to ignore it. Thanks

http://site.gamevidia.com/slide_piece.skp

-Preston

travis77

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Re: Getting into CNC - wondering about Sketchup
« Reply #8 on: September 27, 2009, 09:16:02 PM »
I checked out your design. X and Y axes seem pretty standard and look fine. Are you going to go with V groove bearings or something similar to what Geeks Gone Bad has used for your Y axes?

Your Z axes definitely looks interesting. I like how you offset the two mounting plates to make the width narrower. I think this will be the hardest part to make for you since there are many pieces that have to go together precisely.

How you are mounting your X axes motor, you could bring it up a little and mount it directly to the front board instead of having a bracket hanging down like I have mine. Also instead of your threaded rod going through the cross brace, mounting the motor up a little higher would allow you to have your nut mounted to the top of the cross brace, just an idea. If my explanation doesn't make any sense, oh well lol

presyesc

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Re: Getting into CNC - wondering about Sketchup
« Reply #9 on: September 28, 2009, 03:16:34 AM »
Thank you Travis for looking it over, I will definitely implement the things you suggested. And I am going to do something similar on the y-axis rail with the roller bearings, or maybe the screen door rollers like backyard-workshop did. What do you think about this? Do you think this setup would have too much "give"?

Oh, and do you know the name of that hard white plastic material I see a lot of builders use for the structure on their machines?

-Preston

travis77

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Re: Getting into CNC - wondering about Sketchup
« Reply #10 on: September 28, 2009, 02:36:15 PM »
As long as you have a way to preload or tighten the bearings down to the track, you shouldn't have any "give" or free play. On Backyard Workshop's he is able to tighten the two bolts which pull the grooved bearings down to the rail. After you build your first one, you will realized weak points of your design and you'll end up re-building those parts.

The white plastic is HDPE i believe. I've seen it in black too. I dont think home improvement stores sell it, at least I haven't seen it there.

There is a store near me called Tap Plastics http://www.tapplastics.com/ that's where I've seen it. You could search other places, they have it too.

Gabriel

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Re: Getting into CNC - wondering about Sketchup
« Reply #11 on: September 30, 2009, 05:01:28 AM »
It's seems that I accidentally locked this thread yesterday. They make it entirely too easy to click the lock button.  ::)

Sorry about that. It should be fixed now.

pie_row

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Re: Getting into CNC - wondering about Sketchup
« Reply #12 on: September 30, 2009, 08:02:30 PM »
And I was trying to brake in  :'(

J K