Replies to This Discussion

DistributorPermalink Reply by Dany Thivierge on July 10, 2012 at 11:08am

good to see you back Kev! 

I think that without you or Monroe we will not make the progress we need!  I can find boards or parts but we need the design to really make progress.  I really appreciate your work! 

Dany

Permalink Reply by Kevin Bouchard on July 15, 2012 at 7:05pm

Well one thing you guys could do is keep shopping for electronics and make an attempt at listing a full set of what we need. That'd allow us to put an estimated price on the control system and see what we're gonna work with, then we could start swapping out parts for better/cheaper ones. After all this is just a cartesian bot; the control system can mostly be agnostic to the mechanical setup. It should also let us think about what we're gonna have to build/code ourselves.

Monroe, what kind of leadscrew do you think would work best? Any brand/model in particular? That could help me come up with a mounting solution.

And thanks for your appreciation Dany :) I can draw shapes easily enough, but now that we're diving deeper in design details, my (lack of) experience is starting to show. I'll still try my best though! This is an interesting challenge and a machine that I'd love to build.

Permalink Reply by Ellison Chan on July 15, 2012 at 7:13pm

We started building a spec list in the Brainstorming Specifications.

I would suggest we continue the discussion about the electronics there.  There's a list of all the potential components, and links to detailed pricing.

Permalink Reply by Kevin Bouchard on July 15, 2012 at 9:34pm

Here's the standoff plate. Too low?I can bring it back up the Z-way. It won't interfere with the gib blocks anyhow.

I could add actual standoffs too...

Permalink Reply by Kevin Bouchard on July 18, 2012 at 9:07pm

Worked on this some more tonight.

I wrote some more specific notes in the images' comments; please click on each one.

Permalink Reply by Kevin Bouchard on July 26, 2012 at 3:50pm

Monroe? You still with us? Any advice on what to do next? What parts do you need for the prototype? When do you think you'll have some free time to start it?

I realized my calculations were a bit off for the dimensions, but now I got them down. The machine has a footprint of 35''x24'' for the work cube we agreed on.

Permalink Reply by Kevin Bouchard on July 26, 2012 at 6:43pm

Good! Anything I should design next?

Here's a more up-to-date picture with the right dimensions. That bedway is getting preeettty long to my taste, but I don't see any other way to make the work cube as big as we want. I also added screws to the gantry mounting blocks since bGatti warned us about gantry twist.

Permalink Reply by Kevin Bouchard on July 30, 2012 at 7:58pm

18 inches on the Z? Isn't that a bit much? The machine would get pretty tall, top-heavy and the Z-way would have to sustain a lot more stress. If people insist on taller, maybe I could do 10 inches?

As for the motor, I don't know...

Permalink Reply by John Thomson on July 31, 2012 at 6:16am

Kevin, this site may be of interest, www.syk.tw/catalog/in.html there are line drawings, cad, and pictorials of ball screw assemblies showing screws, nuts, and bearing blocks with all dimensions. The screws are really the heart of the machine from which other components are sized due to attachment points and working clearance.

No idea what these would cost but the dimensions would allow you to incorporate enough room for later use of similar (cheaper) units. You need to know what diameter of ball screw to start with, not thin due to whip and not thick, heavy and expensive. (16mm or 20mm ?)

Permalink Reply by Kevin Bouchard on August 31, 2012 at 7:21pm

Ok, so I continued working on the concept a bit, but I started realizing I was designing a lot of custom parts. So, in an attempt to lighten the load on the machinist's side, I decided to try making most the frame out of T-slots. At this point I wonder if the side plates are even necessary anymore. Maybe just for added weight and protection?

I'm probably gonna mount the t-slot cage up on small spacers so that cooling fluid can flow back and forth and bits of scrap metal can be blown away. Some things need a bit of work to fit as they were before, so tell me what you think before I go any further!

Permalink Reply by R. D. Starwalt on November 17, 2012 at 8:03am

Nice work Kevin! A+

Without doing a complete cost analysis of an 'erector set' system - which there is nothing wrong with BTW - and comparing that to a custom-build-parts-machine, we won't know. We would have to build both or at least get quotes from fabricators.

That being said, I think the 'erector set' system would be more generally accepted and available globally. I have a stash of that the 80/20 material. It is available everywhere and makes great sense to use it.

Having a few custom fabricated parts would reduce the cost of the machine and using the 80/20 would allow folk to adjust the layout as they desired.

 I would toss the side plate sizes and go with two runs of 80/20 to support the cross gantry. It will be sufficient to maintain rigidity. A full surface would be useful to contain chips and flying pieces. These could be made of lexan, acrylic, plexiglass, etc.

While this project moves along, I have started fabricating parts for another machine. Bob of MomusDesign has a very nice set of plans. The machine is capable of aluminum. HERE is a video of it at work.

Even with a 'perfect' set of lines, each builder will do something a little different unless we supply a kit of parts to maintain continuity.

I have not yet decided if I want to use the UHU Servos (previously discussed and in the process of being built) or go with stepper motors on the Momus machine. If you watch the video linked above, know that those are stepper motors. The quality of the VW pan model is very good. I submit good enough for 99% of DIYD folk.

-=Doug

Permalink Reply by Kevin Bouchard on November 19, 2012 at 2:21pm

Wow. That MomusDesign CNC looks pretty good in operation and simple in construction. I'll have to dig deeper into that. Probably order the plans to have a look.

• ‹ Previous
• 1
• 2
• 3
• 4
• 5
• Next ›
• Page