The inevitable build... 2x3ft MPCNC

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Dear All, yes we did build a Giga-MPCNC using 1.25" EMT. The bot was about 1.1 meters in a cube. We scaled up many of the original MPCNC parts and then custom designed some new ones to accommodate large motors, bearings, belts, etc.

To give you some scale reference, please note the package of paper role toweling and the room fan (for part cooling).

Sadly, this bot was retired. However, we will attempt to bring the Giga-MPCNC back to life! Enjoy …Mark

Neat!

Hi Devon.

> a syringe-extruder

Is the syringe-extruder that you used with the MPCNC’s available on thingiverse (as well as the mount for it)?

 

Wow… been a while since I’ve posted an update…

I’m a bit reluctant to admit that the MPCNC has been sitting in my garage pretty much unused for the last few months. Just got busy with other projects… but I’m finally putting it to good use on some wood-working projects! Although, I keep forgetting to snap pics while the machine is running…

Only updates to the machine are drag-chain wire-management and I got the emergency stop button wired into the system (and mounted).

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What?! that’s awesome! I was there for a month last year and I was up in Bouaké for a few days visiting family. We toured the University Alassane Ouattara and I mentioned the idea of a maker-space; they were very interested in making something like that happen. There hasn’t been much progress made in regards to starting something, other than a few emails back and forth with some folks at the University, but when I am back in country in the next year or so, I’ll hopefully have the time to get the ball rolling…

One of my Ivorian cousin’s is visiting here in the US for the next three months. He and I have been working with the MPCNC… might put together some parts for him to take back with him when he leaves, so he can build one over there.

I believe so, if you search mini-MPCNC on thingiverse it should pop-up. Nvm, here it is: https://www.thingiverse.com/thing:2446497

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Nice to hear. Glad it is getting dirty and not just dusty.

First week of milling work completed, why did I wait so long to put this thing to work…!!!

First project was milling a new sailboat rudder for a friends boat. It is a two piece assembly using mahogany and white-oak. I was able to get the mahogany piece cut without any issues other than accidentally kicking the power-cord and turning the machine off mid-job, sending the router straight down into the stock… Luckily, this happened in a OK spot, so no harm done, I was able to re-home the machine and finish the job. I guess I’ll prioritize re-routing the power-cord to a less “kickable” location…

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Second project was a quick carving job. My brother and his gf wanted a Kotatsu (Japanese heated coffee table), so we built one out of re-claimed oak and carved Kotatsu (in japanese) into each leg of the table.

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Third project is a few custom PVC parts for a fan testing apparatus I am building for work. Pretty simple 2D milling job, but the z-axis stepper decided it wanted to leave the party halfway through… Note to self: when the machine sits for a few months make sure to check bolt tension. I was able to salvage two of the parts without issue and the last part will have to be done as a separate job to make due with the stock I have leftover.

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That is awesome! What is this fan apparatus going to be for?

 

I’m working on a product development project focused on the development of a forced-draft biomass cookstove for Sub-Saharan Africa. The prototype stoves use a DC fan to drive airflow into the combustion chamber of the stove to clean-up emissions and increase combustion-efficiency. We are working on modifying the designs for manufacturing and need to know the minimum fan requirements (flow-rate and static-pressure) for the air-injection ducting systems we are using. The fan apparatus is a typical fan testing chamber that allows you to determine fan performance curves, which is just a curve plotting the relationship between fan static-pressure and flow-rate.

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That is a wide range of jobs, I love it. Plastic and wood, carving and cutting…perfect!

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So your DC power source will be solar then?

Yup, exactly. We are working with a few different Pay-As-You-Go (PAYG) solar companies to incorporate our improved-stoves with their systems, so we can provide people with an affordable household energy solution including solar panels, LED lighting, battery storage for charging needs, and a modern-cookstove for household cooking and heating.

You are currently working for a company or through a university for these stoves? Either way very cool and would be interested to see how it goes. But you are giving power and heat, but what about clean water…

I work for the University of Washington in the Environmental Combustion and Energy Lab (I’m finishing my master’s in ME) Our current project is funded by Global-Good/Intellectual-Ventures, who in turn are funded by Bill Gates and Nathan Myhrvold. This project is partially funded to validate the impact of improved cookstoves for Bill to see if he wants to invest the B&H foundations time and effort into improved biomass cookstoves. Our industry partner is BURN Manufacturing (Nairobi, Kenya); they are who we are designing stoves for.

I’m not sure if the PAYG Solar companies offer any clean-water services or if they partner with anyone that does, but most of the population we design stoves for boil-water to sterilize it for drinking, so we focus mainly on reducing the energy (fuel) required to do this while making sure the stoves do this fast and without emitting harmful emissions.

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Couple quick upgrades:

When milling wood and plastic last week my shop floor quickly became covered with chips/dust. I noticed most of the debris shoots straight-horizontal off the table when milling, so I added a “blast-shield” around the entire perimeter of the x and y axes. They are centered below the rails and are quite rigid, so they shouldn’t interfere with anything. My hope is that they contain the mess to the build area, making it easier for me to manage dust during/after a milling job. I’m not quite ready to add a proper dust hood to the router (and I may never, I like watching the milling process too much!), so hopefully these do the trick.

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I had these old switched power-strips laying around from an old saltwater fish tank system a tore apart and figured they would be a nice addition to this project. Being that they were used near saltwater, they were a bit rusty, so I tore one apart, gave’er a good sanding, painted it, and re-assembled all the electronic bits. I also wired the emergency stop button so that it controls power to the last two switches (one for the control-board and one for the router). Now, when I hit the e-stop it will cut power to those two switches killing power to the board and router. No more hitting the e-stop and then scrambling for the switch on the router during an “oh Sh!t” moment.

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Fire-extinguisher…

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Looking real good. Much cleaner than any of my builds…yet!

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Finally got around to milling the other half of this sailboat tiller I am making for a friends boat and we kept running into issues when trying to mill deep contours.

In certain lengths of the outer contour of our machining operation the bit seemed to bind and resonate quite violently causing the surface finish to go to sh!t and causing me to pucker-up a bit due to the combination of tool chatter and machine vibration.

You can see that in this stretch surface finish is satisfactory and there wasn’t any problems with machine vibration or binding…

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And here is an image of where we had problems.

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There were some specific locations where the bit would start to vibrate and would cause the whole machine to resonate for an instant, creating a gouge in our contour walls, and then everything would go back to normal after passing over this location.

Is this mainly due to the relation of feed direction and grain direction in the work piece (we are using red-oak)? Improper spindle speed? Improper feed rate? Insufficient chip clearing? Or are deep contours (this was 35mm, w/3mm stepdown) just not reasonable to do with a 1/4’’ up-cut end-mill without more clearance for chip clear-out?

We were able to mitigate the problem by increasing spindle speed and reducing the feed rate, but the problem still persisted, only with less frequency and magnitude.

What seemed to further solve the problem was using a compressed air nozzle to constantly clear chips out of the contour as the machine did its thing.

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I think the problem is a combination of everything I mentioned, but I’d be interested to hear if anyone has recommended feeds/speeds for deep contour work in hardwoods, such as oak, that doesn’t require me to widen the outer contour or use a finish pass…

Nice looking project!

I am not really sure about a fix. Cutting that deep is always sketchy. Varying the RPM was the right idea, another would be to raise the material if at all possible. Single flute vs dual flute, different cut rate or direction. I have made a ton of cuts and sometimes I just can’t get it right.

I decided to drop in on the forums and actually post since my builds finally complete and I thought, hey I have a few crappy phone pics I could use, I wonder what other posts look like (its been a while). This is now my new favorite thread. Man there is so much motivation in here! (Not to say theres not elsewhere!). Not to mention a ton of ideas on how I want to actually setup my bench!

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Your build looks awesome!

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