Site Logo

 
It is currently Thu Nov 27, 2014 4:43 am

All times are UTC - 6 hours




Post new topic Reply to topic  [ 8 posts ] 
Author Message
 Post subject: State of the flutterwumper project
PostPosted: Thu Aug 20, 2009 3:30 pm 
Offline

Joined: Tue Jan 13, 2009 8:26 am
Posts: 378
Last night, we had a brainstorming meeting on what we wanted to do for the TCMaker group flutterwumper. Here's how it turned out:

1. We're doing a 2.5 axis Cartesian system. This is your basic, run-of-the-mill gantry with a fairly large X and Y translation along with a more modest Z translation.
2. The targeted method is, at this time, cutting. We decided that there are just too many inherent difficulties with an additive system to make it our first effort, and that most of the projects we want to do are more easily realized by cutting.
3. The largest workpiece will be slightly larger than 2'x4'. This allows us to use 2'x4' pieces of plywood or foam or acrylic or whatever, which is a common stock size.
4. Our base began with an Ikea Sniglar children's bed frame, which gives us a maximum rail length of 1575mm and a width of 750mm. Why? Because I had it in my garage, that's why.
5. We're going to start from the Arduino-based motion code developed for the RepRap, as well as the PC code for the RepRap. It will likely be heavily modified.

At some point in the near future, I'll get some images up, and possibly a "to-do" and "to-find" list of parts and tasks.

EDIT: I had 75mm wide when I meant 75cm. Changed to 750mm.

_________________
Mike H.
My maker blog


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Fri Aug 21, 2009 11:15 am 
Offline

Joined: Tue Jan 13, 2009 8:26 am
Posts: 378
I spent some time toying with this last night, just to see what I could do, and I found a few difficulties.

First, as I was afraid of, getting things parallel and square is a problem. Not a huge one, just...a problem. But that may well be at least partly due to my subpar woodworking skills and equipment- we'll see.

Second, there's a few parts we're going to need to make this go forward, if anyone would care to check their scrap heaps and junk boxes:
- threaded rod, ~2x 5' long, 1x 24"-29" long (can cut down)(I think I have this). Prefer no more than 20TPI, no larger than 3/8" diameter
- slide bearings, ~29.5" wide or less
- motor shaft coupler- this is a somewhat rare piece that may well need to be ordered

When should we schedule another work date?

_________________
Mike H.
My maker blog


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Fri Aug 21, 2009 12:15 pm 
Offline

Joined: Tue Jan 13, 2009 1:23 pm
Posts: 249
uptownmaker wrote:
I spent some time toying with this last night, just to see what I could do, and I found a few difficulties.

First, as I was afraid of, getting things parallel and square is a problem. Not a huge one, just...a problem. But that may well be at least partly due to my subpar woodworking skills and equipment- we'll see.

Second, there's a few parts we're going to need to make this go forward, if anyone would care to check their scrap heaps and junk boxes:
- threaded rod, ~2x 5' long, 1x 24"-29" long (can cut down)(I think I have this). Prefer no more than 20TPI, no larger than 3/8" diameter
- slide bearings, ~29.5" wide or less
- motor shaft coupler- this is a somewhat rare piece that may well need to be ordered

When should we schedule another work date?


Ok a new 6' by 1/4" 20 is $4.

What needs to be super parallel. Perpendicular sure. I see from your request that you intend to drive from both sides. Why not one side and the other floating? That way only one side needs to be truly straight.


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Fri Aug 21, 2009 3:02 pm 
Offline

Joined: Tue Jan 13, 2009 8:26 am
Posts: 378
If you try to drive from one side, that side will need to be improbably rigid to avoid torquing the gantry and introducing twist.

Drive needs to be symmetrical- either drive both sides (with two motors or with one motor and a mechanic linkage between the two) or use one drive which is centrally located.

A center drive screw is also a very possible solution to the problem- the gantry has a "box" around the frame, and the box rides on wheels above and below the side rail, with the cross bar underneath having the drive screw attached to it.

I will try to model it in SketchUp- it's a good excuse to work on my skills.

_________________
Mike H.
My maker blog


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Fri Aug 21, 2009 5:30 pm 
Offline

Joined: Tue Jan 13, 2009 1:23 pm
Posts: 249
uptownmaker wrote:
If you try to drive from one side, that side will need to be improbably rigid to avoid torquing the gantry and introducing twist.

Drive needs to be symmetrical- either drive both sides (with two motors or with one motor and a mechanic linkage between the two) or use one drive which is centrally located.

A center drive screw is also a very possible solution to the problem- the gantry has a "box" around the frame, and the box rides on wheels above and below the side rail, with the cross bar underneath having the drive screw attached to it.

I will try to model it in SketchUp- it's a good excuse to work on my skills.


Does a Drill press have a balanced drive? Is a radial arm saw fixed on both sides? Do High end saw fences have drives on both sides? Some yes. Some no.

You are putting two tasks together. 1 driving the gantry 2. overcoming the torque. Now it may be that combining both may give the simplest cheapest solution. It may be that it wont.


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Sun Mar 07, 2010 9:06 pm 
Offline
Site Admin
User avatar

Joined: Sat Mar 14, 2009 4:14 pm
Posts: 1444
Location: Minneapolis, Minnesota
Hey, while browsing Instructables I found a project for a Parallel Port 3 Axis CNC Driver, Opto-Isolated.

Mike, do you know anything about the motors on your CNC? Would this driver circuit possibly work?

Image

_________________
612-293-MAKE World Community Grid Team Page | Blog | Promo Flyers | Dues Info
Active Topics | Twitter Page | TCM Photos | View Your Posts | YIM waynoid | AIM wammie777


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Mon Mar 08, 2010 8:24 pm 
Offline

Joined: Tue Jan 13, 2009 8:26 am
Posts: 378
Along with the machine I salvaged three or four drivers for it, and half a dozen power supplies so we're set.

The only problem is, the drivers have a pretty complex set of safety lockouts in place. They can be gamed fairly easily (they are, after all, mainly based on NO switches that get closed by the covers and such), but that will take time.

I will likely end up moving the machine to HacFac and leave it there with the documentation for people to work on as they can (thus providing myself with a nice "standing project" for Wednesday nights, too).

_________________
Mike H.
My maker blog


Top
 Profile  
 
 Post subject: Re: State of the flutterwumper project
PostPosted: Mon Mar 08, 2010 9:16 pm 
Offline
Site Admin
User avatar

Joined: Sat Mar 14, 2009 4:14 pm
Posts: 1444
Location: Minneapolis, Minnesota
Thanks Mike. FYI, if you look at our wiki page on this project, I've volunteered as lead documenter (since so far I've really done most of the documenting anyway). So if you could at least show us on the schematics the work that you've done so far with the circuitry and point out other areas that need to be worked on, that would be appreciated. Also, since this is primarily your baby, so to speak, let us know how you'd like further work to be handled - if we need to contract you first, etc. I'll help out though at least by documenting what's being done and providing some sort of log sheet for people to record work they've done on it.

_________________
612-293-MAKE World Community Grid Team Page | Blog | Promo Flyers | Dues Info
Active Topics | Twitter Page | TCM Photos | View Your Posts | YIM waynoid | AIM wammie777


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 6 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Template made by DEVPPL Flash Games