Hair Spray.

After a few false starts I started having the problem of the first layer not sticking to the heated bed. A friend of mine suggested that I use hair spray to get the first layer to stick. I did a little googling and sure enough AquaNet came up as the magic trick. I took a little ride sown to the grocery store and picked up a can and sure enough I have the best first layer that I have ever printed. Thanks Jake…

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Back up and running

About a month ago I was cleaning some melted plastic from my hot end while it was printing and poof. I saw a spark and the temperature plummeted to zero. At first I thought that I smoked the RAMPS board but I could have burned up the thermistor. Since I was down for the count I went and ordered both 10 new thermistors and a new RAMPS board on ebay.

I finally had a chance this weekend to sit down and check things out. I used my multimeter to do some testing and it turns out that the thermistor was reading as wide open. I spent a few hours taking the hot end apart and replaced the thermistor and we are back up and running. I guess that I have a few spare parts in the event that this happens again.

Gantry redesign

I had alot of failed prints so late last year I did some redesigning of the printer. The weight of the stepper motor on the gantry was causing acceleration problems and was causing the hot end to bounce around . This was causing the prints to have blobs and eventually would fail the print.

I decided to move the extruder off of the gantry and use the Bowden design. This made a big difference in the prints and now I have been able hit print and walk away without the concern that I will come back to a big blob of plastic on the hot end.

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Moved Y Axis motor mounts to outside

Today I bit the bullet and moved the Y axis stepper motors to the outside of the carriage. This has been annoying me for a while given that the brackets always get in the way and I have to work around them.

Rather than mounting the belt on the top I chose to mount them on the bottom. This enabled me to get the mechanics out of the work area. It also allowed a more compact implementation.

By moving the motors to the outside I gained a few extra centimeters of print area and the X gantry will not bump up against the motor gears.

I have looked at many mods but went with printing motor mounts from thingiverse http://www.thingiverse.com/thing:27860.

I could have used standoffs but chose the printed solution.

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I then cut a small notch in the side of the frame to string the gear pulley through.

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Here are some before and after photos

Before:

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After:

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quick connect attachment

First pass at quick connect attachments.

I am working on different attachments that can be quickly swapped out for different tools.
This requires a software toolset so that I can use RAMPS/pronterface to do printing, milling, drawing, laser cutting.
I have a beta version of the software that I am using to do all of the operations that are not printing. I will post more on this as I test further.

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Z endstops

I had to build a new hot end tip last weekend and in the process it threw my z endstops out of alignment. I think that I spend more time calibrating the printer than making prints.

I added mechanical endstops to my printer early on. The X and Y endstops work as expected but the Z endstop is really inaccurate. Since the Z endstop is mounted to the carriage it really does not measure how far the hot end tip is from the print surface. It is an arbitrary end of travel that always needs calibration anytime the table, glass, heated bed or hotend changes in dimension. So it occurred to me that rather than using a piece of paper or my metal feeler gauges to try to calibrate the endstop, what would it take for the hotend tip to calibrate itself?
What I really wanted is to make the hotend tip the end switch when homing the Z axis. By doing this I can make the system self calibrating for every print. This will save countless hours of tweaking the system everytime a parameter changes.

I implemented a dual switch system one where the hot end is the primary switch and the mechanical switch is a backup to prevent the head from crashing into the glass. The two switches are in parallel so that the first contact wins.
I connected a wire to the hotend assembly to make one end of the switch. The other end I used metal tape mounted to my heated bed to make an electrical trace that is connected with wire an electrical crimp style ring connector.
I also used metal tape on the glass as the surface that the hotend will touch as the switch.

The tape is almost the thickness of a piece of paper and any other offset I can add to the Slic3r settings to get everything in tolerance.