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What products do you want to see in the store?

2013-05-10 Dan

I’ve been looking for a part that will improve some of my kits for more than a year now. Some samples are finally in the mail and while I wait I’m going slightly crazy. It makes me wonder how many of you might be in the same boat. Heck, it’s not even a boat. It’s a piece of driftwood and on the side it says “if only i had this one thing I could move forward on this project”. I hear that line a lot and it makes so sad. To me nothing sucks more than having to wait for someone else. That’s why I do everything I can to ship kits as fast as possible and with zero mistakes.

But back to my point! So far I’ve only been stocking parts that are (or have been) used in my robots. I think it would be cool to add that conductive paint I’ve been reading about, or shapelock, or sugru… but I don’t want to invest good money if nobody’s interested. So, please, share with me: What parts, materials, or tools are you looking for? I’d be happy to make a bulk purchase to make it less expensive for everyone. Help me help you and we both win.

In the same way, what kind of robot would you like to see? Lawn mowing robots? Chore doing robots? Machine that throws balls for your dog? You tell me.

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Challenges for this week: Can you help?

2013-05-13 Dan

This week I’ve got a lot of challenges coming up and I could sure use a hand.

Maker Faire & VHS

My local Vancouver hack space is moving to a new location this month. I’m helping with the egress crew – that is to say, getting all the stuff out of the old place. It’s about 10h/week out of my time that would otherwise be spent on improving the store. A plan is already firmly in place and ever so slightly ahead of schedule. All I can do is ask people to show up and help move stuff.  If you’ve got a truck, van, or car, it would be very welcome.

Get a Working Laser Cutter

The VHS laser cutter is offline until they finish moving it. I tried a few other laser cutters around town and was disappointed with the accessibility, speed, and quality of the work. I’m looking for a machine with these specs:
– need: cuts at least 12″x24″
– need: doesn’t use a dongle
– need: comes with chiller & venting
– need: >60W power
– want: shows up as a printer on my network
– want: warranty

The budget is $5k including shipping and install. Got any leads?

Makelangelo Code Changes

The request came several weeks ago to change the calibration point to make very very large drawings easier. My demo machine isn’t running as well as I’d like and it’s made testing very challenging. A part of me is tempted to release it and wait for the error messages to come in.

Two fantastic users have submitted pull requests to add more stuff to the project. One fixes a rare race condition.  The other stores pen up/down settings in the arduino EEPROM, which means a firmware upgrade.  Both change a bunch of project settings and need to be merged into the current version.

I don’t know a way to make this code more open so other people can apply the patches themselves. Ideas?

Kit upgrades

I’m waiting on parts to arrive from Hong Kong that should greatly improve the range of motion in the delta robots and the stewart platform.  It’s take a year of negotiating with 3rd party “finders” because the factory won’t deal direct.  If they work as promised then I’ll be over the moon with joy.  In any case for the moment I am actively telling people to wait so that they get the upgrade coming soon (I hope).  Is this the right way to do business?  No.  Is it the right thing to do for my customers?  Yes.  Does it make it harder to do business?  Yes, in the short term.  I believe treating people right is how to make loyal fans, and my business runs on word of mouth.

…and all the rest

RFPs, artist’s projects, existing long-term customers… it’s at a tipping point: I need more help but I can’t afford it and if I had it already then I could probably afford it.  I guess I need to get into subcontracting?  Your thoughts are appreciated.

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Improving the Makelangelo output quality

2013-05-14 Dan

I just ordered 100 v-groove bearings. I’d seen Antonio’s huge drawbot that used the bearings and I realize now he had to put in the bearings to get decent image quality. I’ve made a special request that they arrive before May 31st. I hope they do so I can build my own enormous drawing robot in time for the Vancouver Mini Maker Faire 2013.

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Trying to improve the Makelangelo accuracy with v-groove bearings

2013-05-18 Dan

Makelangelo with bearings
Since I started the Makelangelo project I’ve had varying levels of precision, or repeatable accuracy. It is the end result of every other factor coming together just right – the software, the hardware, even the environment around the machine all play a part.

The original bobbins were friction-fit onto the shafts. Often the motor would turn and the bobbin would slip a little bit. Pictures had noticable “cracks” in them and the pen never finished a drawing where it started.

Then I 3D printed bobbins. They were better but they were still a bit off. The surfaces were uneven and the hole through the center was slightly larger than the motor shaft, which left room for mistakes.

Since Makelangelo v2 I’ve been using milled bobbins that are as close to perfection as modern machining can make. They are a gorgeous fit and exactly the right size. That’s a problem I consider solved.

Now that the bobbins are working correctly I’ve tried changing a few other things. Since the v2 I’ve been putting all the electronics in a nice box to keep things tidy and better looking. to the uninitiated, loose wires = scary. I hoped that less intimidating would mean more sales. Unfortunately, this has created two new problems.

Firstly, making parts: the box is made of laser cut parts in two materials. I could go on for a long time about manufacturing problems. Let’s just say they’re very real and they suck.

Secondly, the strings to the pen holder are much longer and they go around corners. When the bobbins turn the pen holder does not immediately react. For lack of a better word, I’m going to call this string give or just give for short.

The give appears to be the same in either direction when a bobbin turns – the left motor bobbin has almost 1/4 turn of give and the right has about 1/6th. I’ve only eyeballed it so far. I’m going to measure it step by step and confirm my observation, then modify the firmware to compensate.

The amount of give is not the same in each bobbin. I suspect the difference has to do with how much string is on each bobbin, as well as the length of the string. This means any time the strings are replaced – either from wear or breakage – the best practice will be to immediately recalibrate and check that the give has not changed. I wonder what kind of string has the least give?

Anyways, back to the picture at the top of the post: I wanted to eliminate friction as a source of give. I thought maybe a small amount of rubbing of the string on the bobbins was causing the give.
VHS member James saw my post for v-groove bearings on the mailing list and lent me a set to try instead of the eye bolts. In the picture above you can see I replaced them all. So far it looks like the bearings make no difference on friction. Worse, to use them would mean getting new screws, new washers, and increasing the total number of parts in every kit.

So now I ask you, Makelangelo users: Are you seeing similar results? Have you found a solution? Let me know in the forums where we can all join in the conversation. If we can find a solution that works I can move on to more interesting parts of the project – like finally making a pen holder for spray paint.